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The following are publications by scientists at the Provincetown Center for Coastal Studies. PCCS authors are noted by an asterisk
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Abstract: Estimating the abundance of long-lived, migratory animals is challenging but essential for managing populations. We provide the first abundance estimates of endangered humpback whales Megaptera novaeangliae from their breeding grounds in Oceania, South Pacific. Using fluke photo-identification (1999â2004, n = 660 individuals) and microsatellite genotypes (1999â2005, n = 840 individuals), we estimated abundance with open capture-recapture statistical models. Total Oceania abundance and trends were estimated from 4 primary and 5 secondary sampling sites across the region. Sex-specific genotype data enabled us to account for the difference in capturability of males and females, by doubling male-specific estimates of abundance derived from genotypes. Abundance estimates were congruent between primary- and secondary-region data sets, suggesting that the primary regions are representative of all Oceania. The best estimate of total abundance was 4329 whales (3345â5313) in 2005, from a sex-specific POPAN super-population model, which includes resident whales and those migrating through the surveyed areas. A doubled-male POPAN abundance estimate from 2003 (n = 2941, 95% CI = 1648â4234) was considered the most plausible for the 4 primary survey areas and was similar to the 2003 doubled-male estimate derived from Pradel capture probabilities (n = 2952, 95% CI = 2043â4325). Our results confirm that Oceania is the least abundant humpback whale breeding population in the southern hemisphere. Pradel models showed no significant trend in abundance, which contradicts the recovery seen in most other populations throughout the world. Thus we suggest that the whales in this area warrant continued study and management attention.
Abstract: North Atlantic right whales are critically endangered and, despite international protection from whaling, significant numbers die from collisions with ships. Large groups of right whales migrate to the coastal waters of New England during the late winter and early spring to feed in an area with large numbers of vessels. North Atlantic right whales have the largest per capita record of vessel strikes of any large whale population in the world. Right whale feeding behaviour in Cape Cod Bay (CCB) probably contributes to risk of collisions with ships. In this study, feeding right whales tagged with archival suction cup tags spent the majority of their time just below the water's surface where they cannot be seen but are shallow enough to be vulnerable to ship strike. Habitat surveys show that large patches of right whale prey are common in the upper 5 m of the water column in CCB during spring. These results indicate that the typical spring-time foraging ecology of right whales may contribute to their high level of mortality from vessel collisions. The results of this study suggest that remote acoustic detection of prey aggregations may be a useful supplement to the management and conservation of right whales.
Abstract: We document patterns of distribution and relative abundance of marine megavertebrate fauna around Cornwall and the Isles of Scilly from a combination of aerial and boat-based surveying. Between January 2006 and November 2007, 20 aerial surveys were undertaken, comprising over 40 hours of on-effort flying time. In April to October of these years, 27 effort-corrected ferry surveys were also conducted from a passenger ferry travelling between Cornwall and the Isles of Scilly. Opportunistic sightings were also logged by the crew members of the ferry and another vessel travelling regularly along the same route on 155 days. Ten megavertebrate species were sighted: basking sharks Cetorhinus maximus, sunfish Mola mola, common dolphins Delphinus delphis, harbour porpoise Phocoena phocoena, grey seals Halichoerus grypus, Risso's dolphins Grampus griseus, bottlenose dolphins Tursiops truncatus, minke whales Balaenoptera acutorostrata, long-finned pilot whales Globicephala melas and killer whale Orcinus orca. During aerial surveys, 206 sighting events of seven species were made, compared with 145 sighting events of eight species during ferry surveys and 293 sighting events of 10 species from opportunistic ship-board data collection efforts. Seasonal and spatial patterns in species occurrence were evident. Basking sharks were the most commonly-sighted species in the region and were relatively abundant throughout the estimated 5 km-wide strip of coastal waters covered by the aerial surveys, during spring and summer. Ferry surveys and opportunistic vessel-based sightings data confirmed that the distribution of surface-feeding aggregations of this species was largely around the coasts. Despite the limited scope of this study, it has provided valuable baseline data, and possible insights into the marine biodiversity of the region.
Abstract: Evaluating impacts of human activities on marine ecosystems is difficult when effects occur out of plain sight. Oil spill severity is often measured by the number of marine birds and mammals killed, but only a small fraction of carcasses are recovered. The Deepwater Horizon/BP oil spill in the Gulf of Mexico was the largest in the U.S. history, but some reports implied modest environmental impacts, in part because of a relatively low number (101) of observed marine mammal mortalities. We estimate historical carcass-detection rates for 14 cetacean species in the northern Gulf of Mexico that have estimates of abundance, survival rates, and stranding records. This preliminary analysis suggests that carcasses are recovered, on an average, from only 2% (range: 0â6.2%) of cetacean deaths. Thus, the true death toll could be 50 times the number of carcasses recovered, given no additional information. We discuss caveats to this estimate, but present it as a counterpoint to illustrate the magnitude of misrepresentation implicit in presenting observed carcass counts without similar qualification. We urge methodological development to develop appropriate multipliers. Analytical methods are required to account explicitly for low probability of carcass recovery from cryptic mortality events (e.g., oil spills, ship strikes, bycatch in unmonitored fisheries and acoustic trauma).
Abstract:
Genetic identification of individuals is now commonplace, enabling the application of tagging methods to elusive species or species that cannot be tagged by traditional methods. A key aspect is determining the number of loci required to ensure that different individuals have non-matching multi-locus genotypes. Closely related individuals are of particular concern because of elevated matching probabilities caused by their recent co-ancestry. This issue may be addressed by increasing the number of loci to a level where full siblings (the relatedness category with the highest matching probability) are expected to have non-matching multi-locus genotypes. However, increasing the number of loci to meet this âfull-sib criterionâ greatly increases the laboratory effort, which in turn may increase the genotyping error rate resulting in an upward-biased markârecapture estimate of abundance as recaptures are missed due to genotyping errors. We assessed the contribution of false matches from close relatives among 425 maternally related humpback whales, each genotyped at 20 microsatellite loci. We observed a very low (0.5â4%) contribution to falsely matching samples from pairs of first-order relatives (i.e., parent and offspring or full siblings). The main contribution to falsely matching individuals from close relatives originated from second-order relatives (e.g., half siblings), which was estimated at 9%. In our study, the total number of observed matches agreed well with expectations based upon the matching probability estimated for unrelated individuals, suggesting that the full-sib criterion is overly conservative, and would have required a 280% relative increase in effort. We suggest that, under most circumstances, the overall contribution to falsely matching samples from close relatives is likely to be low, and hence applying the full-sib criterion is unnecessary. In those cases where close relatives may present a significant issue, such as unrepresentative sampling, we propose three different genotyping strategies requiring only a modest increase in effort, which will greatly reduce the number of false matches due to the presence of related individuals.
Abstract: Sea lampreys Petromyzon marinus were observed on 109 occasions on 47 individual minke whales Balaenoptera acutorostrata. Bloody lesions could be identified as previous attachment sites, indicating P. marinus feeding on B. acutorostrata blood.
Abstract: Static acoustic monitoring is a cost-effective, low-effort means of gathering large datasets on echolocation click characteristics and habitat use by odontocetes. Heavisideâs dolphins (Cephalorhynchus heavisidii) were monitored using an acoustic monitoring unit, the T-POD, in July 2008 at a site of known high abundance for this species in Walvis Bay, Namibia. The T-POD successfully detected clicks from Heavisideâs dolphins, and these clicks were detected in the 120 to 140 kHz frequency range. A distinct diel pattern to the hourly mean inter-click interval was observed, with higher values during daylight hours than at night, suggesting that click trains are produced at faster rates at night time. There was no apparent diel pattern in the proportion of buzz trains produced, however. A diel pattern in click activity was observed, with many more detection-positive minutes per hour recorded between dusk and dawn, and vocalization activity dropping to low levels in the middle of the day. This corresponded with visual observations made on abundance of dolphins in the study area. These results suggest that Heavisideâs dolphins use this site primarily during the night. Static acoustic monitoring proved to be an effective technique for monitoring patterns of habitat use by Heavisideâs dolphins.
Abstract: Aquaculture has developed into a global industry, providing an increasing portion of the worldâs food supply. However, aquaculture can cause environmentally and socially adverse impacts if ecosystem carrying capacity is exceeded or resource-use conflicts occur between multiple stakeholders. The definition of sustainable aquaculture has evolved into an ecosystem approach that addresses spatial and temporal dimensions of environmental, economic, and social parameters. The development of sustainable marine shellfish aquaculture in the U.S.A. is largely limited by the regulatory, siting and public policy issues that surround the use of coastal waters. This project provided technical support to two Northeast U.S.A. towns (Provincetown and Truro, Massachusetts) in order to identify areas suitable for community aquaculture development areas (ADAs) large enough to contain grow-out sites for use by multiple individual farmers. Mapping efforts incorporated publicly available habitat type data and management boundaries, as well as local traditional knowledge of human use and shellfish habitat, in an iterative Geographic Information System (GIS)-based approach. Combined with sustainable aquaculture site selection criteria, the above data were used to identify a suitable site for a 0.2 km2 (50-acre) subtidal ADA in town waters. Acoustic backscatter data collected with an interferometric sonar system were used to classify habitat within the proposed ADA site, and underwater surveys were conducted at 25 stations to qualitatively assess habitat type and document presence of shellfish and benthic fauna. Qualitative characterization of bottom habitat type using sonar data and dive surveys indicated no submerged aquatic vegetation and a smooth, sandy bottom. The only shellfish encountered during underwater surveys was the surf clam (Spisula solidissima); abundance at all stations was < 1 organism/m2. The unique combination of traditional knowledge, publicly available data, and advanced technology proved to be highly useful for practical, cost-effective site selection for sustainable shellfish aquaculture development areas.
Abstract: The interchange of individual humpback whales between the wintering grounds of Oceania (South Pacific) and the east coast of Australia were documented by individual identification photographs collected from 1999 to 2004. Interchange was assessed using regional catalogues of fluke photographs, totalling 672 individuals from Oceania (represented by New Zealand, New Caledonia, Vanuatu, Fiji, Samoa, Tonga, Niue, Cook Island, French Polynesia and American Samoa) and 1,242 individuals from Hervey Bay and Byron Bay representing the southbound and the northbound migration along the east coast of Australia (EA). Overall, there were seven documented movements between EA and Oceania. Four instances of movement of four individuals were documented between EA and the closest breeding grounds of New Caledonia. A further three movements were recorded between EA and a small catalogue (n = 13) from the New Zealand migratory corridor. In contrast, during this same period, 20 cases of interchange were documented among nine breeding grounds: French Polynesia, Cook Islands, Niue, American Samoa, Samoa, Tonga, Fiji, Vanuatu and New Caledonia. The low level of interchange between Oceania and the east coast of Australia has important implications for understanding the stock structure and abundance of humpback whales in the South Pacific.
Abstract: Cultural transmission, the social learning of information or behaviors from conspecifics [1,2,3,4,5], is believed to occur in a number of groups of animals, including primates [1,6,7,8,9], cetaceans [4,10,11], and birds [3,12,13]. Cultural traits can be passed vertically (from parents to offspring), obliquely (from the previous generation via a nonparent model to younger individuals), or horizontally (between unrelated individuals from similar age classes or within generations) [4]. Male humpback whales (Megaptera novaeangliae) have a highly stereotyped, repetitive, and progressively evolving vocal sexual display or song [14,15,16,17] that functions in sexual selection (through mate attraction and/or male social sorting) [18,19,20]. All males within a population conform to the current version of the display (song type), and similarities may exist among the songs of populations within an ocean basin [16,17,21]. Here we present a striking pattern of horizontal transmission: multiple song types spread rapidly and repeatedly in a unidirectional manner, like cultural ripples, eastward through the populations in the western and central South Pacific over an 11-year period. This is the first documentation of a repeated, dynamic cultural change occurring across multiple populations at such a large geographic scale.
Abstract: The movement of individual humpback whales between regional breeding grounds of Oceania (South Pacific) was documented by individual identification photographs collected from 1999 to 2004. Photographs were collected with comparable effort across the six years in four primary island breeding grounds: New Caledonia, Tonga (Vavaâu) the Cook Islands and French Polynesia (Moâorea and Rurutu); with smaller effort in adjacent regions: Vanuatu, Fiji, Samoa, Niue and American Samoa. Interchange among wintering grounds was assessed first with all usable photographs included in each regional catalogue, representing 1,080 regional sightings (including within-region and between-region resightings) of 949 individual whales from Oceania. From this, 28 cases of movement between (mostly adjacent) regions were documented. Previously undocumented interchange was found between regions of central Oceania and the western South Pacific. No individual was sighted in more than two regions during this six-year period. The documented movement between regions was one-directional, except for one individual sighted first in French Polynesia, then in American Samoa and then back in French Polynesia (each in different years). Only one whale was resighted in more than one region during the same winter season. No directional trend was apparent and movement between regions did not seem to be sex specific. A systematic quality control review of all catalogues was then implemented to calculate standardised indices of within-region return and betweenregion interchange, resulting in a quality controlled catalogue of 776 regional sightings of 659 individuals. The standardised indices confirmed that
the probability of between-region interchange was low, relative to within-region return, supporting the assumption of multiple management units or stocks in Oceania. The relative isolation of breeding regions and the movement of individuals across the longitudinal borders of Antarctic management Areas V and VI has important implications for the allocation of historical catches from the Antarctic and therefore, for assessing current levels of recovery for breeding stocks.
Abstract: Humpback whales Megaptera novaeangliae are seasonal migrants that mate and calve at low latitudes and feed at mid- to high latitudes. Connections between most Southern Hemisphere breeding and feeding areas are not well understood, but are critical for assessing stock structure and human impacts. Photo-identification was performed to identify the feeding grounds of an Endangered sub-population that breeds in the central South Pacific Ocean (CSP). Identification photographs were obtained from 159 ind. at American Samoa and compared to 3508 Southern Hemisphere humpback whales in the Antarctic Humpback Whale Catalogue (AHWC), including 1352 from Antarctic feeding grounds. Two individuals from American Samoa were seen on 3 occasions at the Antarctic Peninsula. This is the first known feeding site for American Samoa and one of few reliably identified for the CSP. AHWC #2950 was confirmed to have undertaken a round-trip movement of no less than 18840 km, spanning 108 longitudinal degrees. This represents the largest mammalian migration known to date and a departure from historical assumptions about CSP migratory patterns. The frequency, causes, and fitness implications of such movements have yet to be determined. However, distance is the only known extrinsic barrier to humpback whale movement within oceans, and so maximum individual range is 1 factor potentially affecting population exchange and colonization of new habitats. The movement documented here may place this Endangered sub-population at risk if conservation efforts are relaxed in unidentified parts of its range. Yet, the ability of humpback whales to undertake such extensive movements may have also contributed to the apparent recovery of some populations versus other historically exploited whale species.
Abstract: Seasonal feeding behavior and high fidelity to feeding areas allow humpback whales (Megaptera novaeangliae) to be used as biological indicators of regional contamination. Biopsy blubber samples from male individuals (n = 67) were collected through SPLASH, a multi-national research project, in eight North Pacific feeding grounds. Additional male samples (n = 20) were collected from one North Atlantic feeding ground. Persistent organic pollutants were measured in the samples and used to assess contaminant distribution in the study areas. North Atlantic (Gulf of Maine) whales were more contaminated than North Pacific whales, showing the highest levels of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and chlordanes. The highest dichloro diphenyl trichloroethane (DDT) levels were detected in whales feeding off southern California, USA. High latitude regions were characterized by elevated levels of hexachlorocyclohexanes (HCHs), but generally non-detectable concentrations of PBDEs. Age was shown to have a positive relationship with PCBs, DDTs, chlordanes, and total percent lipid. Contaminant levels in humpback whales were comparable to other mysticetes, and lower than those found in odontocete cetaceans and pinnipeds. Whereas these concentrations likely do not represent a significant conservation threat, levels in the Gulf of Maine and southern California may warrant further study.
Abstract: Background
The objective of this study was to enhance removal of fishing gear from right whales (Eubalaena glacialis) at sea that evade disentanglement boat approaches. Titrated intra muscular injections to achieve sedation were undertaken on two free swimming right whales.
Methodology/Principal Findings
Following initial trials with beached whales, a sedation protocol was developed for right whales. Mass was estimated from sighting and necropsy data from comparable right whales. Midazolam (0.01 to 0.025 mg/kg) was first given alone or with meperidine (0.17 to 0.25 mg/kg) either once or four times over two hours to whale #1102 by cantilevered pole syringe. In the last attempt on whale #1102 there appeared to be a mild effect in 20â30 minutes, with duration of less than 2 hours that included exhalation before the blowhole fully cleared the water. Boat avoidance, used as a measure of sedation depth, was not reduced. A second severely entangled animal in 2009, whale #3311, received midazolam (0.03 mg/kg) followed by butorphanol (0.03 mg/kg) an hour later, delivered ballistically. Two months later it was then given midazolam (0.07 mg/kg) and butorphanol (0.07 mg/kg) simultaneously. The next day both drugs at 0.1 mg/kg were given as a mixture in two darts 10 minutes apart. The first attempt on whale #3311 showed increased swimming speed and boat avoidance was observed after a further 20 minutes. The second attempt on whale #3311 showed respiration increasing mildly in frequency and decreasing in strength. The third attempt on whale #3311 gave a statistically significant increase in respiratory frequency an hour after injection, with increased swimming speed and marked reduction of boat evasion that enabled decisive cuts to entangling gear.
Conclusions/Significance
We conclude that butorphanol and midazolam delivered ballistically in appropriate dosages and combinations may have merit in future refractory free swimming entangled right whale cases until other entanglement solutions are developed.
Abstract: Fidelity of individual animals to breeding sites is a primary determinant of population structure. The degree and scale of philopatry in a population reflect the fitness effects of social facilitation, ecological adaptation and optimal inbreeding. Patterns of breeding-site movement and fidelity are functions of social structure and are frequently sex biased. We report on a female humpback whale (Megaptera novaeangliae) first identified by natural markings off Brazil that subsequently was photographed off Madagascar. The minimum travel distance between these locations is greater than 9800 km, approximately 4000 km longer than any previously reported movement between breeding grounds, more than twice the species' typical seasonal migratory distance and the longest documented movement by a mammal. It is unexpected to find this exceptional long-distance movement between breeding groups by a female, as models of philopatry suggest that male mammals move more frequently or over longer distances in search of mating opportunities. While such movement may be advantageous, especially in changeable or unpredictable circumstances, it is not possible to unambiguously ascribe causality to this rare observation. This finding illustrates the behavioural flexibility in movement patterns that may be demonstrated within a typically philopatric species.
Abstract: North Atlantic right whales, Eubalaena glacialis, remain endangered, primarily due to excessive anthropogenic mortality. Current management protocols in US waters are triggered by identifying the presence of at least one right whale in a management area. We assessed whether acoustic detection of right whale contact calls can work as an alternative to visual aerial surveys for establishing their presence. Aerial survey and acoustic monitoring were conducted in Cape Cod Bay, Massachusetts, in 2001â2005 and used to evaluate and compare right whale detections. Over the 58 d with simultaneous aerial and acoustic coverage, aerial surveys saw whales on approximately two-thirds of the days during which acoustic monitoring heard whales. There was no strong relationship between numbers of whales seen during aerial surveys and numbers of contact calls detected on survey days. Results indicate acoustic monitoring is a more reliable mechanism than aerial survey for detecting right whales. Because simple detection is sufficient to trigger current management protocols, continuous, autonomous acoustic monitoring provides information of immediate management utility more reliably than aerial surveillance. Aerial surveys are still required to provide data for estimating population parameters and for visually assessing the frequency and severity of injuries from shipping and fishing and detecting injured and entangled right whales.
Abstract: Balancing human uses of the marine environment with the recovery of protected species requires accurate information on when and where species of interest are likely to be present. Here, we describe a system that can produce useful estimates of right whale Eubalaena glacialis presence and abundance on their feeding grounds in the Gulf of Maine. The foundation of our system is a coupled physicalâbiological model of the copepod Calanus finmarchicus, the preferred prey of right whales. From the modeled prey densities, we can estimate when whales will appear in the Great South Channel feeding ground. Based on our experience with the system, we consider how the relationship between right whales and copepods changes across spatial scales. The scale-dependent relationship between whales and copepods provides insight into how to improve future estimates of the distribution of right whales and other pelagic predators.
Abstract: The ability to determine the age of individual humpback whales Megaptera novaeangliae and estimate population age distributions is fundamental to assessments of status and long-term viability. Existing methods of ageing large whales rely either on limited longitudinal sighting studies of individual whales from their year of birth, or on post-mortem procedures to extract tissues suitable for determining age. Here we describe a potential method for ageing live free-ranging humpback whales using low-impact biopsy sampling techniques. Shallow outer-blubber samples were obtained from known-age whales from 2 distinct populations (North Atlantic, Gulf of Maine, n = 39; North Pacific, Southeast Alaska, n = 31), and analyzed for their fatty acid (FA) compositions. Multilinear FA-age models were derived for these known-age whales, and serve as the basis from which the age of unknown-age whales can be estimated. Four FA-age models were developed; one for each humpback population analyzed separately, and an additional 2 by combining both populations into a single dataset and deriving models based on âexactâ and âexactâ plus âminimumâ known-age whales independently. Each of these empirical models was based on a linear combination of 2 FA ratios rather than individual FA compositions, and shown to be largely independent of sex, diet and nutritional status. Although the precision (Ï) of these models was somewhat variable (ranging between 3.1 and 5.3 yr for the specific populations modeled), the results suggest that it may be possible to estimate the age of individual humpback whales from any population with better than decadal resolution using this approach.
Abstract: Intra-specific variation in social organization provides valuable insights into the selective forces driving social evolution. Sperm whales are distributed globally and live far from shore, thus obtaining large sample sizes on social organization in multiple areas is logistically challenging and few comparative studies exist. In order to address how ecological factors influence sociality, we investigated the social organization of sperm whales in the Gulf of California (GoC) using a long-term study (1998 â2004) and compare our results to other published studies. Standard photo-identification and behavioural observation techniques were used. Group size was calculated from photographic mark ârecaptures using a Petersen estimator. Social organization was investigated using SocProg 2.3. Mean typical group sizes in the GoC were similar to those in the Galapagos Islands, Chile and Seychelles (24.7, 24.8, 30.4 and 18 individuals respectively), but substantially larger than in the Sargasso Sea, Caribbean and northern Gulf of Mexico (12.0, 6.4 and 6.9 individuals respectively). Sperm whale social organization in the GoC best fitted a constant companion/casual acquaintance model, where permanent units sizes were 12.5 individuals and two units usually associated together to form a group. This structure is similar to the situation in the Galapagos Islands and Chile areas. However, groups were more stable in the GoC than in the South Pacific, as groups stayed together for periods of about 80 days versus about ten days in the Gala ´pagos Islands and Chile. It is likely that differences in the social organization between the study areas in the Pacific and Atlantic Oceans were due to differences in predation pressure and/or food resources. We suggest that, site-specific ecological factors are likely to influence fundamental aspects of sperm whale social organization.
Abstract: Management plans to reduce human-caused deaths of North Atlantic right whales Eubalaena glacialis depend, in part, on knowing when and where right whales are likely to be found. Local environmental conditions that influence movements of feeding right whales, such as ultra-dense copepod patches, are unpredictable and ephemeral. We examined the utility of using the regional-scale mean copepod concentration as an indicator of the abundance of right whales in 2 critical habitats off the northeastern coast of the United States: Cape Cod Bay and Great South Channel. Right whales are usually found in Cape Cod Bay during the late winter and early spring, and in the Great South Channel during the late spring and early summer. We found a significant positive relationship between mean concentration of the copepod Calanus finmarchicus in the western Gulf of Maine and the frequency of right whale sightings in the Great South Channel. In Cape Cod Bay we found a significant positive relationship between the mean concentration of other copepods (largely Pseudocalanus spp. and Centropages spp.) and the frequency of right whale sightings. This information could be used to further our understanding of the environmental factors that drive seasonal movement and aggregation of right whales in the Gulf of Maine, and it offers a tool to resource managers and modelers who seek to predict the movements of right whales based upon the concentration of copepods.
Abstract: Little is known about the species composition, distribution, abundance or stock structure of odontocetes in the central and western tropical Pacific Ocean, including those inhabiting the US Exclusive Economic Zone (EEZ) waters of American Samoa.While some information on species presence in this region has been gleaned from anecdotal sightings and whaling and stranding records, odontocete diversity in the waters of American Samoa has never been formally investigated. This lack of information precludes efforts to determine the sustainability of cetacean populations within US EEZ waters. This paper reports on the first dedicated surveys to document the presence and distribution of odontocete cetaceans in the waters of American Samoa. A series of small-boat photo-identification and biopsy surveys for cetaceans were conducted in the nearshore waters of Tutuila during 2003-06. In addition, ship-based visual surveys were conducted in the waters surrounding the Manuâa Islands, Rose Atoll and Swains Island in summer 2006. A total of 58 groups of odontocete cetaceans were encountered during both small-boat and ship-based surveys: spinner dolphins (Stenella longirostris, n=34), rough-toothed dolphins (Steno bredanensis, n=10), sperm whales (Physeter macrocephalus, n=3), false killer whales (Pseudorca crassidens, n=5), bottlenose dolphins (Tursiops truncatus., n=1), dwarf sperm whales (Kogia sima, n=1), short-finned pilot whales (Globicephala macrorhynchus, n=1), and three groups of unidentified odontocetes. Photographs were analysed for quality and individuals with distinctive markings were selected for entry into a photo-identification catalogue. The resultant catalogue included 46 spinner dolphins, 41 rough-toothed dolphins, 2 bottlenose dolphins, 5 false killer whales, 4 pilot whales, 1 dwarf sperm whale and 4 sperm whales. Thirteen spinner dolphins and 14 rough-toothed dolphins were sighted in multiple years. To investigate stock structure, spinner dolphin genetic data were used to compare mitochondrial control region genetic diversity and allele frequencies between American Samoa and the Hawaiian Islands. American Samoa had a higher genetic diversity, and populations at the two locations were genetically distinct (FST = 0.21). The high diversity at American Samoa indicates that spinner dolphins at this location are not reproductively isolated, but the data do not rule out the possibility that these dolphins may be demographically isolated on ecological timescales.
Abstract: Cape Cod Bay (Massachusetts) is the only known winter and early spring feeding area for concentrations of the endangered North Atlantic right whale (Eubalaena glacialis) population. During January-May, 1998-2002, 167 aerial surveys were conducted (66,466 km of total survey effort), providing a complete representation of the spatiotemporal distribution of right whales in the bay during winter and spring. A total of 1553 right whales were sighted; some of these sightings were multiple sightings of the same individuals. Right whale distribution and relative abundance patterns were quantified as sightings per unit of effort (SPUE) and partitioned into 103 23-km(2) cells and 12 2-week periods. Significant interannual variations in mean SPUE and timing of SPUE maxima were likely due to physically forced changes in available food resources. The area of greatest SPUE expanded and contracted during the season but its center remained in the eastern bay. Most cells with SPUE > 0 were inside the federal critical habitat (CH) and this finding gave evidence of the need for management measures within CH boundaries to reduce anthropogenic mortality from vessel strikes and entanglement. There was significant within-season SPUE variability: low in December-January, increasing to a maximum in late February-early April, and declining to zero in May; and these results provide support for management measures from 1 January-15 May.
Abstract: The movements of female and immature sperm whales Physeter macrocephalus in the tropical Pacific Ocean and adjacent waters are described using photoidentifications over time scales of 3 d to 15 yr and the tracks of followed groups over scales of 1 to 48 h. The female/immature whales frequently made movements of less than 2000 km and occasionally made movements of about 4000 km. There were no recorded movements of greater than 5000 km (for instance, between the eastern and western Pacific). On average, displacements for female/immature whales were about 4 km after 1 h of movement, 50 km after 1 d, 200 km after 3 d, and 1000 km after periods of 1 yr or more. Members of the 2 principal cultural clans of female and immature sperm whales that use waters near the Galapagos had distinctive movement patterns over all time scales greater than 3 h, with 1 clan's displacements about 50 % greater than the displacements of the other. Displacements were greater than predicted by the correlated random walk over scales of 12 to 48 h because of auto-correlation in displacement, approximately as predicted by the correlated random walk over periods of days to weeks, but less than predicted by the correlated random walk over scales of years because of boundaries of home ranges. The adaptive movement of sperm whales over large spatial and temporal scales likely contributes to their substantial trophic impact, and reduces geographic population structure. These movements, together with cultural heterogeneity, complicate the management of the species, including the designation of management stocks.
Abstract: Sperm whales occur worldwide and feed largely on meso- and bathypelagic squid, but little is known about the behavioral ecology of this predator and its prey. In the Gulf of California, sperm whales are thought to feed on the abundant jumbo (Humboldt) squid, an ecologically and commercially important species. In this study, we attached satellite-linked dive recorders to 5 sperm whales and pop-up archival transmitting tags to 3 jumbo squid in the same area and time period in order to record their diving behavior and movements. Most (91 %) deep dives by whales ranged from 100 to 500 m (average 418 +/- 216.0 m) and lasted 15 to 35 min (average 27 +/- 9.1 min). During daytime hours, jumbo squid spent about 75 % of the time in the 200 to 400 m depth range, and sperm whales showed a similar dive-depth preference. The vertical distribution pattern of squid changed during the night, with squid spending about half the time at depths of < 200 m and the remainder at 200 to 400 m. Although the whales shifted their nighttime diving to somewhat shallower depths, about 75 % of dives remained in the 200 to 400 m depth range. Analysis of squid nighttime diving behavior, based on archival time-series data, showed that excursions into warm surface waters were often terminated by deep dives to typical daytime depths, after which the squid appeared to be relatively quiescent. Diving behavior by whales is thus consistent with the idea that they feed on jumbo squid at depth during the day, and we suggest that deep nighttime foraging may target squid that are recovering from stress after recent surface activity and are therefore more susceptible to predation.
Abstract: The Massachusetts Bay (MB) and Cape Cod Bay (CCB) system is a unique coastal embayment, with CCB serving as a high-use feeding ground for endangered North Atlantic right whales Eubalaena glacialis during winter and early spring. We used a hydrodynamic model, observed Calanus finmarchicus (the preferred prey of right whales) abundance, and right whale sightings during 1997-2004 to examine the transport and retention of C. finmarchicus in MB-CCB and the implications for right whale activity. A particle-tracking program was embedded into the model to simulate the Lagrangian residual circulation, and the transport and retention of passive particles. The results indicate significant correlations in the inter-annual variability of coastal transport, circulation pattern, C. finmarchicus abundance, and right whale sightings in spring. In normal years (with prevailing northwesterly winds), the monthly mean distributions of particles and Lagrangian residual currents show a coherent pattern with 2 particle retention areas in central CCB and central MB, respectively. The CCB retention area closely matches the area of high probability of right whale occurrence and feeding activity, indicating that this is an area favorable to zooplankton aggregations. In other years (e.g. 2002), the coastal current is significantly reduced due to prevailing southwesterly winds, and the particle retention zone is shifted northward, coincident with low C. finmarchicus abundance and whale sightings in CCB. The study also suggests that the North Atlantic Oscillation may influence C. finmarchicus abundance and distributions, and hence, right whale feeding activity in CCB through surface winds affecting MB-CCB circulation, and hence, zooplankton distributions.
Abstract: Certain populations of killer whales (Orcinus orca) feed primarily or exclusively on marine mammals. However, whether baleen whales represent an important prey source for killer whales is debatable. A hypothesis by Springer et al. (2003) uggested that overexploitation of large whales by industrial whaling forced killer whales to prey-switch from baleen whales to pinnipeds and sea otters, resulting in population declines for these smaller marine mammals in the North Pacific and southern Bering Sea. This prey-switching hypothesis is in part contingent upon the idea that killer whales commonly attack mysticetes while they are in these high-latitude areas. In this study, we used photographic and sighting data from long-term studies of baleen whales in twenty-four regions worldwide to determine the proportion of whales that bear scars (rake marks) from killer whale attacks, and to examine the timing of scar acquisition. The results of this study show that there is considerable geographic variation in the proportion of whales with rake marks, ranging from 0% to over 40% in different regions. In every region the great majority of the scars seen were present on the whales'; bodies when the animals were first sighted. Less than 7% (9 of 132) of scarred humpback whales with multi-year sighting histories acquired new scars after the first sighting. This suggests that most killer whale attacks on baleen whales target young animals, probably calves on their first migration from low-latitude breeding and calving areas to high-latitude feeding grounds. Overall our results imply that adult baleen whales are not an important prey source for killer whales in high latitudes, and therefore that one of the primary assumptions underlying the Springer et al. (2003) prey-switching hypothesis (and its purported link to industrial whaling) is invalid.
Abstract: Population spatial structuring among North Atlantic humpback whales Megaptera novaeangliae on the summer feeding grounds was investigated using movement patterns of identified individuals. We analysed the results from an intensive 2-year ocean-basin-scale investigation resulting in 1658 individuals identified by natural markings and 751 individuals by genetic markers supplemented with data from a long-term collaborative study with 3063 individuals identified by natural markings. Re-sighting distances ranged from <1 km to >2200 km. The frequencies (F) of re-sighting distances (D) observed in consecutive years were best modelled by an inverse allometric function (F=6631D1.24, r2=0.984), reflecting high levels of site fidelity (median re-sighting distance <40 km) with occasional long-distance movement (5% of re-sightings >550 km). The distribution of re-sighting distances differed east and west of 45°W, with more long-distance movement in the east. This difference is consistent with regional patterns of prey distribution and predictability. Four feeding aggregations were identified: the Gulf of Maine, eastern Canada, West Greenland and the eastern North Atlantic. There was an exchange rate of 0.98% between the western feeding aggregations. The prevalence of long-distance movement in the east made delineation of possible additional feeding aggregations less clear. Limited exchange between sites separated by as little as tens of kilometres produced lower-level structuring within all feeding aggregations. Regional and temporal differences in movement patterns reflected similar foraging responses to varying patterns of prey availability and predictability. A negative relationship was shown between relative abundance of herring and sand lance in the Gulf of Maine and humpback whale movement from the Gulf of Maine to eastern Canada.
Abstract: Knowledge of whale length is important to ecological studies. However, photographic techniques to measure sperm whales traditionally require high vantage points or a complicated stereo system. Furthermore, these traditional techniques require an alongside approach that often prevents individual identification. For simple and fast size measurements at sea, I used a laser range finder alongside a digital camera to obtain distance to the fluke at the same time as photo-identification. The camera/lens and laser range finder were calibrated on objects of known lengths. The coefficient of variation (CV) for test objects was low (CV = 0.21%). Forty-seven individually identified sperm whales were measured repetitively on up to 12 different occasions, and the CV was lower (CV = 1.3%) than for other photogrammetric techniques (CV = 4.4%-5.1%). A regression of log fluke span to log total length from whaling and stranding data yielded an r (2) of 0.87 (CV of residuals = 6.7%). Thirty-eight female/immature sperm whales were measured in the Gulf of Mexico (median = 9.3 m, range = 7.1-12.3 m), 167 in the Gulf of California (median = 10.7 m, range = 8.4-13.1 m) and 13 bachelor males off Kaikoura, New Zealand (median = 14.2, range = 11.7-15.8 m). The results were within known sperm whale size and suggested that the population in the Gulf of Mexico was made up of smaller animals than that of the Gulf of California. This technique is easy to implement and allows the measurement of identified individuals.
Abstract: North Atlantic humpback whales migrate annually between discrete high latitude feeding areas and shared low latitude breeding areas. St. Vincent and the Grenadines is a low density breeding area in the Lesser Antilles and the site of the only ongoing aboriginal humpback whale hunt in the North Atlantic. The Scientific Committee of the International Whaling Commission recently concluded that catches were likely drawn from a large, panmictic breeding population, but encouraged the collection of additional data. On 6 March 1999, two humpback whales were landed at St. Vincent and the Grenadines and we obtained images from an opportunistic source. Photographic matching identified one individual as "Haar" (NAHWC #0694), a cataloged whale from the Gulf of Maine. This is the first stock assignment from this fishery and the most southeasterly sighting of a Gulf of Maine whale. Based on its reported length, the second animal was likely a calf and, if so, a member of the same population. This match provides further support for the hypothesis that catches at St. Vincent and the Grenadines involve a variety of high-latitude populations. Furthermore, it reinforces the scientific and management value of collecting and sharing individual identification data when hunts are performed.
Abstract: Cape Cod Bay is the only known winter-feeding ground of the highly endangered North Atlantic right whale Eubalaena glacialis, and is thus a critical habitat for right whales. As with most coastal ecosystems, Cape Cod Bay is a dynamic system with a high degree of variability in both physical and biological parameters. However, the extent of these fluctuations and their effect on the suitability of the bay as a right-whale feeding ground are not known. This study was conducted to address variability in the biological and physical environment of the bay and the possible impacts of this variability on the right whales' use of the area as a feeding ground. This study synthesized data collected from January to May, in 2000 to 2003. During 2002, the whales made very limited use of the bay compared to the other 3 yr, providing a unique opportunity for comparing conditions in the bay during this change in pattern of usage by the whales. Data on the physical and biological environment of Cape Cod Bay were collected during weekly cruises. These data indicated that there was significant interannual variation in the wind-forcing affecting Cape Cod Bay. Coincident with this variation were changes in the hydrography of the bay, suggesting that circulation patterns changed during the course of the study. Circulation changes affected the zooplankton prey of the whales either directly through changes in advection, or indirectly by affecting the production of the zooplankton.
Abstract: The North Atlantic right whale, a seriously endangered species, is found in Cape Cod Bay (Massachusetts, USA) during the winter and early spring. During their residency in these waters, these whales are frequently observed feeding. This study evaluated spatial and temporal changes in the chemical composition (carbon weight and C/N ratio) of the food resource targeted by the right whales in Cape Cod Bay. The three taxa measured (Centropages typicus, Pseudocalanus spp., and Calanus finmarchicus) had highly variable chemical compositions resulting from the different life strategies and from fluctuations in their surrounding environment. The impact of seasonal variability in the energy densities of the food resource of right whales was calculated and compared to the energetic requirements of these whales. Calculations indicated that differences in the nutritional content of the zooplankton prey in Cape Cod Bay could have a considerable effect on the nutrition available to the right whales. Therefore, it is likely that using more precise estimates of the energetic densities of the prey of right whales would lead to a re-evaluation of the adequacy of the food resource available to these whales in the North Atlantic.
Abstract: Interactions between marine mammals and fishing gear is an issue of global concern. Entanglements in the western North Atlantic are a major source of injury and mortality for endangered large whales. In this study, entanglements of 31 right whales (Eubalaena glacialis) and 30 humpback whales (Megaptera novaeangliae) were analyzed to determine the types and parts of gear involved. When gear was identified, 89% (n=32) of the entanglements were attributed to pot and gillnet gear; however, a wide range of specific gear types were implicated. Despite gear recovery, gear type was not identified in 20% (n=9) of the cases. Although pot gear was recovered from both species equally, gillnet gear was less frequently retrieved from right whales (n=2) than humpback whales (n=11). When gear part was identified, 81% (n=21) involved entanglements in buoy line and/or groundline. For right whales, the most common point of gear attachment was the mouth (77.4%); for humpback whales, the tail (53%) and the mouth (43%) were common attachment sites. Four right and three humpback whales in this sample were known to have died subsequent to entanglement. However, when identified, the gear types and parts involved in lethal cases were not substantially different from entanglements with non-lethal outcomes. In conclusion, large whales can become entangled in a wide variety of fishing gear types and parts. Additional insight will depend on continued efforts to document entanglements and recover associated gear.
Abstract: From May to July, 2005, an extensive bloom of Alexandrium fundyense occurred along the coast of southern New England. The outbreak eventually closed shellfish beds from central Maine to Massachusetts, including Nantucket Island and portions of Martha's Vineyard, and resulted in the closure of 40,000 km 2 of offshore federal waters as well. The coastal Alexandrium bloom was exceptional in several ways: high toxin levels were measured farther south than ever before in New England; levels of toxicity in many locations were higher than previously observed at those stations; for the first time toxicity at some locations was above quarantine levels; cell concentrations far exceeded those observed in the coastal waters of southern New England in the past; and for the first time in the region the governors of Maine and Massachusetts officially declared the red tide to be a disaster, clearing the way for federal assistance. Initial observations suggest that several factors contributed to this bloom. Abundant rainfall and heavy snowmelt substantially increased the amount of fresh water entering the Gulf of Maine. Combined with other freshwater inputs, we hypothesize that this provided macro- and micro-nutrients, a stratified water column, and a transport mechanism that led to high cell abundances and broad, region-wide dispersal of the organism. Warm temperatures in western waters also would have favored A. fundyense growth. In addition, several storms with strong winds out of the northeast occurred at times when cells were abundant and in locations where the winds could advect them into Massachusetts and Cape Cod Bays and keep them there, leading to high cell concentrations and toxicity. Another contributing factor may have been the high abundance of newly deposited cysts in western Gulf of Maine sediments, as documented in a fall 2004 survey. Here, we evaluate this bloom and the patterns of toxicity in light of the conceptual models for A. fundyense dynamics developed during the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB)-Gulf of Maine (GOM) program. Several features of the 2005 bloom conform to the mechanisms proposed in those models, including the alongshore transport of cells in major water masses and episodic intrusions of cells toward shore due to downwelling-favorable wind forcings. The models need to be refined and expanded, however, based on new data and observations. For example, it is now clear that cells and bloom patches can reach the outer side of Cape Cod and even Nantucket and Martha's Vineyard. Transport to the coastal waters of Rhode Island and even Connecticut/Long Island is also possible. A critical modification also may be necessary in terms of mechanisms through which A. fundyense cells occur in Massachusetts Bay. In the past, toxicity only developed when blooms were transported from the north and into the bay via the western segment of the Maine Coastal Current. Now, it is possible that the bay might serve as a source of cells through the germination of cysts deposited in those waters during the 2005 bloom. If proven in subsequent surveys, this potential for in situ bloom development Could have major implications on the timing and extent of toxicity within Massachusetts Bay and southern New England waters in future years. (c) 2005 Elsevier Ltd. All rights reserved.
Abstract: Few data exist on the marine distribution and host organisms of the parasitic sea lamprey, Petromyzon marinus. Some observers have speculated that cetaceans serve as hosts for these fish based on scars, but few lamprey-cetacean interactions have been described in detail in the literature. Here we discuss 35 previously unreported records of sea lampreys that were observed while attached to western North Atlantic right whales, Eubalaena glacialis, during the period 1984-2002. Of these observations, 11 were photographically documented with images of sufficient quality to identify the lamprey as P. marinus based on morphological characteristics. The majority of the attachments were recorded in the Bay of Fundy during the summer months when P. marinus are preparing to spawn. It is unknown how lampreys might benefit from this association or what cost may be incurred by their right whale hosts. Feeding and transport are two possible reasons for the attachments.
Abstract: The Gulf of Maine is one of the principal summer feeding grounds for humpback whales (Megaptera novaeangliae) in the North Atlantic, and was one focus of effort in an ocean-basin-wide study known as the Years of the North Atlantic Humpback (YONAH) project. Data from that project and from subsequent surveys were used to assess stock boundaries, abundance and demographic parameters for Gulf of Maine humpbacks. Surveys on the Scotian Shelf in the summers of 1998 and 1999 produced the first substantial data set of identified individual humpbacks observed in this region, which lies between the well-studied areas of the Gulf of Maine and Newfoundland. The results gave a match rate of approximately 27% (14 of 52 individuals) between the Scotian Shelf and the Gulf of Maine, with evidence that many of the matched whales were transient in the Gulf of Maine; there were no matches to any other location in the North Atlantic. These data suggest that the range of most whales from the Gulf of Maine usually does not extend as far east as the Scotian Shelf or Newfoundland. Only one whale was observed on the Scotian Shelf in both the 1998 and 1999 surveys, and another seen in 1998 had also been sighted there in 1994. This low inter-annual match rate suggests that the abundance of humpback whales on the Scotian Shelf is larger than previously recognized. Three different but overlapping estimates of abundance for the Gulf of Maine population were calculated. Mark-recapture data from 1992/93 gave an estimate of abundance of 652 (CV=0.29); however, this estimate is likely biased because of heterogeneity in sampling and in animal distribution. Photo-id data also provided a minimum population estimate of 497 humpbacks known to be alive in 1997; this estimate is also likely to be negatively biased because of heterogeneity. Finally, line-transect surveys conducted in 1999 yielded estimates of 816 (CV = 0.45) or 902 humpback whales (CV=0.41, including a portion of the eastern Scotian Shelf stratum); these transect-based estimates are more consistent with the number of humpbacks (1,273, including dead animals) in the current photo-id catalogue for the Gulf of Maine. Overall, the size of the Gulf of Maine population is likely to be in the high hundreds, but no more precise estimate can be calculated at this time. The growth rate for the Gulf of Maine population was estimated using an interbirth interval method using data from 1992 to 2000. The estimate was either 1.00 (for a calf survival rate of 0.51) or 1.04 (for a calf survival rate of 0.875). Although confidence limits are not available (because maturation parameters could not be estimated), both estimates of population growth rate are outside the 95% confidence intervals of the previous estimate of 1.065 for the period 1979 to 1991 (Barlow and Clapham, 1997). It is unclear whether this apparent decline is an artifact resulting from a shift in distribution or is a real phenomenon; if the latter, it may be related to known high mortality among young-of-the-year whales in the waters of the U.S. mid-Atlantic states. However, calf survival appears to have increased since 1996, presumably accompanied by an increase in population growth.
Abstract: Humpback whales Megaptera novaeangliae in the North Atlantic Ocean were severely depleted by exploitation. With legal protection since 1955, substantial recovery is likely to have occurred, but information on abundance and rates of increase has been limited. We present an assessment of humpback whale abundance in the North Atlantic Ocean based upon capture-recapture estimates using naturally marked individuals. These data result from a long-term collaborative effort combining large-scale dedicated projects and incidental data collection, leading to extensive geographical coverage. The application of robust statistical techniques produces estimates of greater accuracy and precision than has previously been possible. Abundance estimates ranging from 5930 to 12 580 individuals, with coefficients of variation (CVs) from 0.07 to 0.39, were calculated for the West Indies breeding population using data from 1979 to 1993. The most precise estimate for the West Indies breeding population is 10 752 (CV = 0.068) for 1992 and 1993. Due to application of new analytical methods, these estimates are larger and more precise than those previously published from similar time periods. The average rate of increase for the West Indies breeding population over a 14 yr period was estimated to be 0.031 (SE = 0.005). The best available estimate for the entire North Atlantic population of humpback whales is 11570 (95% CI 10 290 to 13 390) based upon samples from 1992 and 1993. However, this estimate may be biased downwards to an unknown extent due to heterogeneity in capture probabilities that do not influence the West Indies estimates.
Abstract: Results from a large-scale, capture-recapture study of humpback whales Megaptera novaeangliae in the North Atlantic show that migration timing is influenced by feeding ground origin. No significant differences were observed in the number of individuals from any feeding area that were re-sighted in the common breeding area in the West Indies. However, there was a relationship between the proportion (logit transformed) of West Indies sightings and longitude (r2 = 0.97, F-1.3 = 98.27, P = 0.0022) suggesting that individuals feeding farther to the east are less likely to winter in the West Indies. A relationship was also detected between sighting date in the West Indies and feeding area. Mean sighting dates in the West Indies for individuals identified in the Gulf of Maine and eastern Canada were significantly earlier than those for animals identified in Greenland, Iceland and Norway (9.97 days, t179 = 3.53, P = 0.00054). There was also evidence for sexual segregation in migration; males were seen earlier on the breeding ground than were females (6.63 days, t105 = 1.98, P = 0.050). This pattern was consistently observed for animals from all feeding areas; a combined model showed a significant effect for both sex (F1 = 5.942, P = 0.017) and feeding area (F3 = 4.756, P = 0.0038). The temporal difference in occupancy of the West Indies between individuals from different feeding areas, coupled with sexual differences in migratory patterns, presents the possibility that there are reduced mating opportunities between individuals from different high latitude areas.
Abstract: Commercial exploitation reduced the North Atlantic right whale (Eubalaena glacialis) population from c. 12 000 in the 11th century to around 300 by the 21st century. We examine the effect of this population decline on levels of genetic variation at 16 microsatellite loci and contrast levels of variability to that in a closely related species (E. australis). Of the 13 loci developed from the E. glacialis genome, 100% were polymorphic in E. australis. In contrast, nine loci were polymorphic in E. glacialis and four were fixed. Both allelic diversity (A) and heterozygosity (H) were significantly lower in E. glacialis than E. australis (A = 3.2 +/- 2.6 vs. A = 6.9 +/- 3.3, P < 0.001; H = 0.31 +/- 0.25 vs. H = 0.72 +/- 0.23, P < 0.001, respectively). Bottleneck anlayses indicate that the population is in mutation-drift equilibrium and that a genetic bottleneck did not occur during the most recent decline (18th-20th centuries). Nevertheless, low frequency alleles are relatively uncommon in E. glacialis, suggesting that genetic variability has been reduced in this population. Possible origins of low genetic variability are discussed, including the slow but continual erosion of alleles during the 800-year period of decline.
Abstract: Whale bones recovered from the excavation of a 16th century Basque whaling station in Red Bay, Labrador are providing valuable data for archaeological interpretation as well as for biological studies of extant whale populations. Zooarchaeological studies on several hundred bones found during exploration of the harbour, and of specific activity areas such as wharves and ovens, give insight to Basque whale hunting, flensing, oil production and carcass disposal techniques. The principal prey species, the North Atlantic Right Whale (Eubalaena glacialis) and the Bowhead (Balaena mysticetus), are endangered species not native to the area today. Work now underway will compare DNA extracted from bone dust or shavings from the archaeological specimens with DNA isolated from skin samples obtained from the extant populations of these prey species. This molecular work could help determine the historic levels of genetic variation within the whale populations, the mitochondrial sequence profiles of the populations of whales hunted by the Basques, and confirm the species identification of whale bones.
Abstract: In recent years, humpback whales (Megaptera novaeangliae) have been observed in the waters of the US mid-Atlantic states (USMA; New Jersey to North Carolina), notably in winter. The level of the mortality in this area (52 recorded deaths from 1990-2000), makes it important to understand the nature and population identity of this aggregation. Of the approximately 100 humpback whales documented in this study, photographs of 41 (live or dead) were of sufficient quality to be compared to catalogues from the Gulf of Maine (GOM, the closest feeding ground) and elsewhere in the North Atlantic. Of 22 live whales, 10 (45.5%) matched to the GOM, 5 (22.7%) to Newfoundland and 1 (4.5%) to the Gulf of St Lawrence (GSL). Of 19 dead whales, 6 (31.6%) were known GOM whales. Although the population composition of the USMA is dominated by GOM whales, lack of recent photographic effort in Newfoundland makes it likely that the observed match rates under represent the true presence of Canadian whales in the region. Length data from 48 stranded whales (18 females, 22 males and 8 of unknown sex) suggest that 39 (81.2%) were first-year animals, 7 (14.6%) were immature and 2 (4.2%) were adults. However, sighting histories of five of the dead whales indicate that some were small for their age and histories of live whales further indicate that the population contains a greater percentage of mature animals than is suggested by the stranded sample. The authors suggest that the study area primarily represents a supplemental winter feeding ground that is used by humpbacks for more than one purpose. From a management perspective, although the only successful matches of mortalities to date have been to the GOM, the observed mixing of live whales from different summer stocks might suggest that the high numbers of mortalities occurring there may not be impacting this single stock alone. Although further data are required before conclusions can be drawn, the mortality rate may be significant for the GOM population and this warrants further investigation.
Abstract: The history of whaling in the Gulf of Maine was reviewed primarily to estimate removals of humpback whales (Megaptera novaeangliae), especially during the 19th century. In the decades from 1800 to 1860, effort consisted of a few localized, small-scale, shore-based whaling enterprises on the coast of Maine and Cape Cod (Massachusetts). Provincetown and Nantucket whaling schooners occasionally conducted short cruises for humpback whales within New England waters. With the development of bomb-lance technology at mid-century, the ease of killing humpback whales and fin whales (Balaenoptera physalus) increased. As a result, by the 1870s there was considerable local interest in hunting rorquals (baleen whales in the family Balaenopteridae, which include the humpback and fin whales) in the Gulf of Maine. A few schooners were outfitted explicitly to take rorquals in the late 1870s and 1880s although their combined annual take was probably no more than a few tens of whales. Also in about 1880, fishing steamers began to be used to hunt whales in the Gulf of Maine. This steamer fishery grew to include about five vessels regularly engaged in whaling by the mid-1880s but dwindled to only one vessel by the end of the decade. Fin whales constituted at least half of the catch, which exceeded 100 animals in some years. In the late 1880s and thereafter, few whales were taken by whaling vessels in the Gulf of Maine.
Abstract: We present a Bayesian method for paternity analysis in natural populations based on genotypic data. The method allows paternity assignment to be performed in a decision theoretic framework. Simulations were performed to evaluate the utility of the method and to assess how many loci are necessary for reliable paternity inference. In addition we present a method for testing hypotheses regarding relative reproductive success of different ecologically defined groups as well as a new method for estimating the current population size of males from genotypic data. Throughout, the methods were applied to genotypic data collected from North Atlantic humpback whales (Megaptera novaeangliae). We test if two behavioral groups differ in their reproductive success and find no significant trend. Estimates of male abundance were in accordance with previous estimates obtained using mark-recapture methods.
Abstract: Few studies have examined systematic relationships of right whales (Eubalaena spp.) since the original species descriptions, even though they are one of the most endangered large whales. Little morphological evidence exists to support the current species designations for Eubalaena glacialis in the northern hemisphere and E. australis in the southern hemisphere. Differences in migratory behaviour or antitropical distribution between right whales in each hemisphere are considered a barrier to gene flow and maintain the current species distinctions and geographical populations. However, these distinctions between populations have remained controversial and no study has included an analysis of all right whales from the three major ocean basins. To address issues of genetic differentiation and relationships among right whales, we have compiled a database of mitochondrial DNA control region sequences from right whales representing populations in all three ocean basins that consist of: western North Atlantic E. glacialis, multiple geographically distributed populations of E. australis and the first molecular analysis of historical and recent samples of E. glacialis from the western and eastern North Pacific Ocean. Diagnostic characters, as well as phylogenetic and phylogeographic analyses, support the possibility that three distinct maternal lineages exist in right whales, with North Pacific E. glacialis being more closely related to E. australis than to North Atlantic E. glacialis. Our genetic results provide unequivocal character support for the two usually recognized species and a third distinct genetic lineage in the North Pacific under the Phylogenetic Species Concept, as well as levels of genetic diversity among right whales world-wide.
Abstract: DNA sequences of the mitochondrial control region of 180 North Atlantic right whales (Euhalaena glacialis) and 16 South Atlantic right whales (E. australis) have been determined using a combination of direct DNA sequencing and single stranded conformation polymorphism (SSCP) analysis. Five haplotypes were found in E. glacialis, and 10 in E. australis, but none were shared, supporting the reproductive isolation and separate species status of the North and South Atlantic right whales. One haplotype in E, glacialis was found in only three males born before 1982 and this matriline will likely be lost soon. The nucleotide diversity estimates for the five North Atlantic right whale haplotypes was 0.6% and 2.0% for the 10 haplotypes found in the South Atlantic right whales. The average haplotypic diversity was 0.87 in E. glacialis and 0.96 in E. australis, which is consistent with other studies showing a lower level of genetic variation in the North Atlantic right whale. Phylogenetic analysis identified two major assemblages of haplotypes in E. australis from the samples collected from Peninsula Valdes, suggesting a mixing of two historically divergent populations. Using genetic distance measurements with a divergence rate of 0.5%-1.0%/myr, we estimate E. glacialis diverged from E. australis 3-12.5 mya.
Abstract: We examined six historical specimens of the endangered North Atlantic right whale (Eubalaena glacialis) using DNA isolated from documented baleen plates from the late nineteenth and early twentieth centuries. Sequences from the mitochondrial DNA (mtDNA) control region from these samples were compared with those from a near-exhaustive survey (269 of approximately 320 individuals) of the remaining right whales in the western North Atlantic Ocean. Our results suggest that there has been only relatively modest change in maternal lineage diversity over the past century in the North Atlantic right whale population. Any significant reduction in genetic variation in the species most likely occurred prior to the late nineteenth century. One historical specimen was from the last documented female capable of propagating one of the maternal lineages in the population today; no females in the existing population have been found to carry this mtDNA haplotype. Analysis of the only specimens from the eastern North Atlantic right whale population ever to be examined revealed that eastern and western North Atlantic right whales may not have been genetically differentiated populations. Loss of gene diversity experienced by North Atlantic right whales over the last century has been modest and the six decades of protection have been successful in maintaining much of the maternal lineage diversity that was present in the late nineteenth century.
Abstract: Although much is known about the humpback whale, Megaptera novaeangliae, regional studies have been unable to answer several questions that are central to the conservation and management of this endangered species. To resolve uncertainties about population size, as well as the spatial and genetic structure of the humpback whale population in the North Atlantic, we conducted a two-year ocean-base-wide photographic and biopsy study in 1992-1993. Photographic and skin-biopsy sampling was conducted of animals in feeding and breeding areas throughout most fo the range of this species in the North Atlantic, from the West Indies breeding grounds through all known feeding areas as far north as arctic Norway. A standardized sampling protocol was designed to maximize sample sizes while attempting to ensure equal probability of sampling, so that estimates of abundance would be as accurate and as precise as possible. Druing 666 d at sea aboard 28 vessels, 4,207 tail fluke photographs and 2,326 skin biopsies were collected. Molecular analyses of all biopsies included determination of sex, genotype using six microsatellite loci, and mitochondrial control region sequence. The photographs and microsatellite loci were used to identifiy 2,998 and 2,015 individual whales, respectively. Previously published results from this study have addressed distribution, migration, and genetic relationships. Here, we present new estimates of total abundance in this ocean using photographic data, as well as overall and sex-specific estimates using biopsy data. We identify several potential sampling biases using only breeding-area samples and report a consistent mark-recapture estimate of oceanwide abundance derived from photographic identification, using both breeding and feeding-area data, of 10,600 (95% confidence interval 9,300-12,100). We also report a comparable, but less precise, biopsy-based estimate of 10,400 (95% confidence interval of 8,000-13,600). These estimates are significantly larger and more precise than estimates made for the 1980s, potentially reflecting population grwoth. In contrast, significantly lower and less consistent estimates were obtained using between-feeding-area or between-breeding-area sampling. Reasons for the lower estimates using the results of sampling in the same areas in subsequent years are discussed. Overall, the results of this ocean-basin-wide study demonstrate that an oceanwide approach to population assessment of baleen whales is practicable and results in a more comprehensive understanding of population abundance and biology than can be gained from smaller-scale efforts.
Abstract: The North Atlantic right whale (Eubalaena glacialis) inhabits five areas along the east coast of North America at different times of the year. During 17 years of field observations, it has been found that only 59% of the newborn calves are brought to the Bay of Fundy nursery area. To examine whether this is because of population structuring, the mitochondrial DNA (mtDNA) control region haplotypes were determined for 269 individuals. Seven polymorphic sites were found to define five haplotypes. Calves were divided into two groups based on whether or not they were brought to the Bay of Fundy nursery. Significant genetic structuring of mitochondrial haplotypes was found between these groups (p = 0.002). Mothers that have had more than three calves demonstrated significant fidelity (p = 0.005) to the Bay of Fundy, suggesting that philopatry is the basis for the genetic structuring. Although this study clearly identifies the existence of two subpopulations and an alternative nursery area(s), the location(s) of the alternative area(s) is unclear and remains an important issue for the conservation of the species.
Abstract: We conducted several studies of Roseate Terns Sterna dougallii around Cape Cod, Massachusetts, USA, during the post-breeding period (July-September) in 1990-1998. We also reviewed reports and estimates of numbers in regional publications. We identified 20 discrete sites where Roseate Terns and Common Terns S. hirundo staged (rested in flocks during daylight hours) between 24 July and 22 September. All sites were on open beaches or sand flats, usually near the end of barrier islands or barrier beaches. Only one site was found where Roseate Terns were present in thousands, but three other such sites have been documented during the last 20 years. All of these major staging sites are on outer beaches of Cape Cod adjacent to cold Atlantic Ocean waters. Roseate Terns appear to disperse throughout the breeding area in July and August, re-aggregating on outer Cape Cod in late August and September prior to southward migration in mid-September. Roseate Terns ringed at eight colony-sites throughout the breeding area in northeastern North America were identified at staging sites around Cape Cod. We found only two sites on Cape Cod where Roseate Terns roosted at night in 1998; one of these has been a major roost site for many years. The concentration of a large fraction of this endangered regional population into a small area during September makes it vulnerable to human disturbance (especially at night) and to North Atlantic hurricanes.
Abstract: A demographic model is developed based on interbirth intervals and is applied to estimate the population growth rate of humpback whales (Megaptera novaeangliae) in the Gulf of Maine. Fecundity rates in this model are based on the probabilities of giving birth at time t after a previous birth and on the probabilities of giving birth first at age x. Maximum likelihood methods are used to estimate these probabilities using sighting data collected for individually identified whales. Female survival rates are estimated from these same sighting data using a modified Jolly-Seber method. The youngest age at first parturition is 5 yr, the estimated mean birth interval is 2.38 yr (se = 0.10 yr), the estimated noncalf survival rate is 0.960 (se = 0.008), and the estimated calf survival rate is 0.875 (se = 0.047). The population growth rate (lambda) is estimated to be 1.065; its standard error is estimated as 0.012 using a Monte Carlo approach, which simulated sampling from a hypothetical population of whales. The simulation is also used to investigate the bias in estimating birth intervals by previous methods. The approach developed here is applicable to studies of other populations for which individual interbirth intervals can be measured.
Abstract: It is widely assumed that the mating system of the humpback whale, Megaptera novaeangliae, is similar to that of most mammals in that it represents some form of polygyny or promiscuity, but this cannot be tested without observations of copulation or data on paternity of offspring. Microsatellite DNA markers were used to examine the paternity of calves born to individuallyidentified mature female humpback whales from the Gulf of Maine. Skin biopsies were obtained from three females, and several (range: three to five) oftheir known offspring. Multiple paternity of offspring, indicated by the presence of at least three different paternal alleles, was evident in all three females at either three or four of the six microsatellite loci surveyed. Such promiscuous mating is expected given current knowledge of the socialecol species. It is also consistent with resightings of individually identified female humpbacks with different male associates during two or more breeding seasons.
Abstract: Mitochondrial DNA haplotypes of humpback whales show strong segregation between oceanic populations and between feeding grounds within oceans, but this highly structured pattern does not exclude the possibility of extensive nuclear gene flow. Here we present allele frequency data for four microsatellite loci typed across samples from four major oceanic regions: the North Atlantic (two mitochondrially distinct populations), the North Pacific, and two widely separated Antarctic regions, East Australia and the Antarctic Peninsula. Allelic diversity is a little greater in the two Antarctic samples, probably indicating historically greater population sizes. Population subdivision was examined using a wide range of measures, including F-st, various alternative forms of Slatkin's R(st), Goldstein and colleagues' Delta mu, and a Monte Carlo approximation to Fisher's exact test. The exact test revealed significant heterogeneity in all but one of the pairwise comparisons between geographically adjacent populations, including the comparison between the two North Atlantic populations, suggesting that, gene flow between oceans is minimal and that dispersal patterns may sometimes be restricted even in the absence of obvious barriers, such as land masses, warm water belts, and antitropical migration behavior. The only comparison where heterogeneity was not detected was the one between the two Antarctic population samples. It is unclear whether failure to find a difference here reflects gene flow between the regions or merely lack of statistical power arising from the small size of the Antarctic Peninsula sample. Our comparison between measures of population subdivision revealed major discrepancies between methods, with little agreement about which populations were most and least separated. We suggest that unbiased R(st) (UR(st), see Goodman 1995) is currently the most reliable statistic, probably because, unlike the other methods, it allows for unequal sample sizes. However, in view of the fact that these alternative measures often contradict one another, we urge caution in the use of microsatellite data to quantify genetic distance.
Abstract: The ability to recognize individual animals has substantially increased our knowledge of the biology and behaviour of many taxa(1). However, not all species lend themselves to this approach, either because of insufficient phenotypic variation or because tag attachment is not feasible. The use of genetic markers ('tags') represents a viable alternative to traditional methods of individual recognition, as they are permanent and exist in all individuals. We tested the use of genetic markers as the primary means of identifying individuals in a study of humpback whales in the North Atlantic Ocean. Analysis of six microsatellite loci(2,3) among 3,060 skin samples collected throughout this ocean allowed the unequivocal identification of individuals. Analysis of 692 'recaptures', identified by their genotype, revealed individual local and migratory movements of up to 10,000 km, limited exchange among summer feeding grounds, and mixing in winter breeding areas, and also allowed the first estimates of animal abundance based solely on genotypic data. Our study demonstrates that genetic tagging is not only feasible, but generates data (for example, on sex) that can be valuable when interpreting-the results of tagging experiments.
Abstract: Samples from 136 humpback whales Megaptera novaeangliae, representing 5 feeding aggregations in the North Atlantic and 1 in the Antarctic, were analyzed with respect to the sequence variation in the mitochondrial (mt) control region. A total of 288 base pairs was sequenced by direct sequencing of asymmetrically amplified DNA. Thirty-one different haplotypes were identified. The nucleotide diversity for the total sample was estimated to be 2.6 %, which is high relative to other North Atlantic cetaceans. The degree of genetic differentiation in various subsets of the samples was estimated and tested for statistical significance by Monte Carlo simulations. Significant degrees of heterogeneity were found between the Antarctic and all North Atlantic areas, as well as between Iceland and the western North Atlantic samples. A genealogical tree was estimated for the 31 haplotypes and rooted with the homologous sequence from a fin whale Balaenoptera physalus. The branching pattern in the genealogical tree suggests that the North Atlantic Ocean has been populated by 2 independent influxes of humpback whales. The combined results from the homogeneity tests and the genealogical tree indicate that behaviour (in this case maternally directed site fidelity to a foraging area) can influence the population structure of marine cetaceans on an evolutionary time scale.
Abstract: Lateralized behaviour has been documented in non-human species, although many observers believe that it occurs at the individual rather than the population level. Its occurrence in humpback whales, Megaptera novaeangliae, in Massachusetts Bay was investigated by examining active behaviour types in which preference could be given to one direction or side. These included head breaching (direction of spin), flippering (right or left) and tail breaching (direction of movement). In addition, persistent abrasions on the right or left jaw resulting from turns to one side during bottom feeding were noted. Of 75 individuals with jaw abrasions, 60 (80%) showed abrasions on only the right jaw, while 15 (20%) had abrasions on only the left. No whales had abrasions on both jaws. Location of abrasions was consistent in all resighted individuals for up to 12 years. Two of the three active behaviour types were not strongly lateralized: directional bias was seen in only five of 21 bouts (23.8%) of breaching, and in three of 11 bouts (27.3%) of tail breaching. However, 22 of 34 bouts (64.7%) of flippering showed a bias towards one direction (generally the right). Furthermore, direction of bias in all behaviour types was individually consistent between bouts and was strongly correlated with abrasions on the corresponding jaw (P=0.0032). The sex ratio of individuals with jaw abrasions, and of those showing directional bias in active behaviour, did not differ significantly from that of the overall population. Overall, these data suggest that humpback whales exhibit some behavioural asymmetries, at least one of which is at the population level. This result suggests assymmetry of function in motor or somatosensory representations, although too little is known about the brain of this species to permit definitive conclusions.
Abstract: Humpback whales, Megaptera novaeangliae, on Stellwagen Bank of eastern Massachusetts, U.S.A., apparently bottom feed on northern sand lance, Ammodytes dubius. The feeding behavior is characterized by the whales brushing the bottom in depths of less than 40 m, causing sand lance burrowed in the bottom to be flushed up into the water column. The greatest densities of sand lance were in beds of shells and shell debris, termed ''shell hash.'' The brushing against or along the bottom, particularly in these shell hash areas,caused the humpbacks to acquire abrasions and wounding, sometimes rather extensive, of the lateral lower jaw, and lateral and dorso-lateral upper jaw, here termed ''jaw scuffing.'' Scuffing of the dorsal fin and fluke edges was also common and may be at least partially related to this feeding behavior. Both mature and immature, and male and female, humpbacks exhibited jawscuffing. The bottom-feeding behavior was not exclusive, as jaw-scuffed individuals were also observed to use other feeding behaviors. In recent years (1991-1933), however, bottom feeding appears to have became relatively more common, particularly among young animals. Overall, in the Stellwagen Bank area between 1979 and 1993, a majority of the population engaged in, or had engaged in, bottom feeding and the associated prey flushing.
Abstract: Ventral fluke patterns of humpback whales Megaptera novaeangliae were assessed to determine if pigmentation shows geographical variation across different breeding areas. Fluke photographs (n = 3854) were collected from 7 major breeding grounds worldwide and were ranked into categories 1 (white) through 5 (black) based on the proportion of white and black pigment on the ventral surface. Average coloration varied primarily between oceanic populations, with the Southern Ocean stocks (Area IV, western Australia, and Area V, eastern Australia) characterized by significantly more light-colored flukes, while the North Pacific subpopulations consisted of individuals with significantly more dark-colored flukes. Results of statistical analyses revealed that all populations differed significantly from one another in the distribution of pigmentation classes, with the exceptions of Hawaii vs Japan, Mexico vs Japan, Mexico vs Hawaii, eastern Australia vs western Australia, and West Indies vs Colombia. Results of pigmentation analyses reveal historic and current interactions among oceanic subpopulations of humpback whales and reflect population sub-division in this species.
Abstract: The patterns of association of juvenile male and female humpback whales, Megaptera novaeangliae, in the southern Gulf of Maine were studied for evidence of maturational changes. Both males and females became less solitary with age. In males, time spent alone changed from a mean of 55.8% of observations at age one to 26.8% at age six. Females were alone in a mean of 49.9% of observations at age one, but in only 20.5% by age six. However, females that produced calves at five, six or seven were associated with no whales but the calf in 73.8% of observations. Males exhibited a clear age-related trend of increasing associations with adults, notably with adult females which constituted approximately 80% of the associates of males aged six years or more. Females showed a similar trend of increasing associations with adults of both sexes. Tests of association data for whales of known age with similar data for adults of the same sex showed that the association patterns of young males and females became statistically indistinguishable from those of adults by the ages of five and four, respectively. The data suggest that the observed changes in social behaviour are closely linked to the attainment of sexual maturity and preparation for adult roles. The different patterns of males and females after maturity may reflect differing reproductive and life-history strategies.
Abstract: A study of humpback whales (Megaptera novaeangliae) was conducted between 1988 and 1991 in Samana Bay, Dominican Republic. Humpbacks were observed asearly as the earliest survey (3 January) and as late as the latest (16 March). Local abundance varied from 0 whales per hour to a maximum of 3.2 whales per hour (mean = 1.70, SD = 0.79), and densities calculated from track surveys ranged from 0.09 to 0.82 whales per square nautical mile (mean = 0.31). Abundance generally peaked in February, but variation was observed bothwithin a season and between years. Almost all. whales were observed in theeastern part of the bay, towards or at its mouth. In all, 397 individuals were photographically identified during the study period. Of these, 18 wereobserved in more than 1 year (17 in 2 years, 1 in 3 years). A total of 15.8% of identified individuals were observed on more than 1 day in a year (maximum 5 days), with mothers representing 33.3% of all resightings Observed occupancies of resighted animals ranged from 1 to 33 days (mean = 6.3 days,SD = 7.14). The mean group size was 1.95 (range = 1-15, SD = 1.30, n = 652groups). Ninety-nine groups contained a calf, and all groups larger than three (n = 45) were competitive in nature. Comparisons of fluke photographs with the North Atlantic Humpback Whale Catalogue revealed 141 matches of 118 individuals to other areas. Of these, 76 were to high-latitude feeding grounds (including the Gulf of Maine, Newfoundland, Labrador, the Gulf of St.Lawrence, and west Greenland), while the remaining 65 were to other areas of the West Indies (Silver Bank, Navidad Bank, Puerto Rico, Virgin Bank, orAnguilla Bank) or to Bermuda. We suggest that Samana Bay is one of the most important winter habitats in the West Indies for humpback whales from allover the western North Atlantic, although whaling records suggest that theabundance of whales in this area may be a relatively recent phenomenon. Sightings of other marine mammal species in Samana Bay are summarized.
Abstract: The relative amount of pigmentation on the flukes of 3812 humpback whales from five feeding and three breeding regions in the western North Atlantic Ocean was ranked subjectively into categories 1 (white) through 5 (black). The distribution of rankings was examined to determine whether differences existed between regions or sexes. Fluke pigmentation differed significantly among whales photographed in the five northern feeding regions (Iceland, southwestern Greenland, Newfoundland (including the Labrador coast), the Gulf of St. Lawrence, and the Gulf of Maine). Whales photographed in the Gulf of Maine were characterized by a significantly higher proportion of dark-colored flukes than whales in all feeding regions except Iceland. Whales photographed near Greenland were characterized by significantly more light-colored flukes than other feeding regions. Fluke pigmentation also varied significantly among whales photographed in the three southern breeding regions (Virgin Bank, Puerto Rico, and the Dominican Republic). The flukes of whales photographed near Virgin Bank differed from those of whales near the Dominican Republic and included a higher proportion of light flukes. Fluke pigmentation of males and females differed significantly in the Gulf of Maine and in the Dominican Republic. Both areas showed higher proportions of dark-fluked females and light-fluked males. Sex bias differences in other regions were not examined because sample sizes were small. Fluke pigmentation of whales photographed only on the summer range did not differ significantly from the pigmentation of those photographed only on the winter range, supporting the belief that all northern feeding aggregations mix on the southern breeding grounds. Regional differences in fluke pigmentation suggest that the western North Atlantic humpback whale population includes a number of relatively isolated subunits, as suggested previously by photoidentification and DNA studies.
Abstract: Hunting during the last 200 years reduced many populations of mysticete whales to near extinction. To evaluate potential genetic bottlenecks in these exploited populations, we examined mitochondrial DNA control region sequences from 90 individual humpback whales (Megaptera novaeangliae) representing six subpopulations in three ocean basins. Comparisons of relative nucleotide and nucleotype diversity reveal an abundance of genetic variation in all but one of the oceanic subpopulations. Phylogenetic reconstruction of nucleotypes and analysis of maternal gene flow show that current genetic variation is not due to postexploitation migration between oceans but is a relic of past population variability. Calibration of the rate of control region evolution across three families of whales suggests that existing humpback whale lineages are of ancient origin. Preservation of preexploitation variation in humpback whales may be attributed to their long life-span and overlapping generations and to an effective, though perhaps not timely, international prohibition against hunting.
Abstract: Competitive groups of humpback whales, Megaptera novaeangliae, were observed in Samana Bay, Dominican Republic, West Indies. Photographs of ventral fluke patterns were used to identify individuals, and skin biopsies were taken for molecular determination of sex. Nine groups contained two or more whales previously identified from different high-latitude areas. In seven groups, males from different feeding grounds were observed to compete with each other, and in six cases the group's female was from a different area thanat least one of her male escorts. These results provide further support for the hypothesis that the western North Atlantic population of this speciescan be considered a single panmictic unit.
Abstract: Data from a long-term study of individually identified humpback whales, Megaptera novaeangliae, were used to describe patterns of association and grouping of this species on one of its principal North Atlantic feeding grounds in the southern Gulf of Maine. Most groups were small and unstable, and individual whales of both sexes and all age classes were associated with many conspecifics. Only six instances of stable associations were recorded. Analysis of the class composition of singles and pairs showed that: (1) among singles, juveniles of both sexes were significantly over-represented and mature females significantly under-represented; (2) male-female adult pairs were over-represented; (3) adult-juvenile pairs of any gender combination were under-represented; and (4) pairings between adult males were under-represented except during feeding. Only 12 of 2690 pairs consisted of animals that were known to be related. It is suggested that the fission-fusion sociality that characterized the study population represents a response to two ecological factors. Firstly, absence of predation nullifies the need for large groups for predator detection or communal defense. Secondly, the spatial characteristics of piscene prey favour a foraging strategy involving frequent changes in group size. In this system, kinship and dominance probably play reduced roles, while the apparent lack of territoriality is typical of taxa confronted by heterogeneously distributed and mobile resources. The apparent preference by mature males for associations with mature females may represent an attempt to establish bonds with potential future mates.
Abstract: We photographically identified 534 individual fin whales (Balaenoptera physalus) in the Gulf of Maine from 1980 to 1988, including 64 females and 40 young. Arrival patterns of mother-young pairs were similar to other whales within years. Individual females showed strong site fidelity to either the northern or southern Gulf of Maine, suggesting substock separation on the feeding range. Gross annual rates of reproduction (proportion of individuals that were young-of-the-year) for the Gulf of Maine ranged from 0.03 to 0.12 (XBAR = 0.08) among years. Greater proportions of young were observed in samples from the southern Gulf of Maine (XBAR = 0.12) than in the northern Gulf of Maine (XBAR = 0.05). Greater proportions of females also were observed in the southern Gulf of Maine (XBAR = 0.22) than in the northern Gulf of Maine (XBAR = 0.10). The average time between consecutive births was 2.71 years, which represented a crude birth rate of 0.37 young per mature female per year. We estimated a potential mean interval of birthing of 2.24 years by making some assumptions for three females with incomplete sighting histories. The overall gross annual rates of reproduction that we observed were similar to rates predicted by harvest data, but rates from the northern Gulf of Maine were less than predicted. Spatial segregation of sexes or age classes may be occurring within the Gulf of Maine.
Abstract: A study of 518 individually identified humpback whales (Megaptera novaeangliae) in the southern Gulf of Maine between 1979 and 1988 showed high ratesof both within-season occurrence and annual return. On average, 77.3% of whales were resighted on more than 1 day during the year (maximum 83 days), with occupancies ranging from 1 to 324 days (mean 88.1 days). The mean rateof return of individuals in consecutive years was 73.2 % (range 59.1 - 87.4 %), and the majority of whales were still being resighted up to 10 years later. Only 13 humpbacks were recorded during 50 midwinter surveys. Variation in the occurrence of individuals appears to be related to variability inthe abundance of prey and perhaps to regional preferences.
Abstract: Reactions of humpback whales, Megaptera novaeangliae, to the taking of skin biopsies and to associated activities were studied on one of their principal West Indies breeding grounds on Silver Bank (Dominican Republic). Results were in some cases different from those reported from a similar study ofthis species in a high-latitude feeding area. Almost half (44.1%) of 565 biopsied whales showed no immediate reaction to a hit, while a further 22.5%showed only low-level reactions. A total of 375 (87.8%) of 427 misses involved no reaction. Only one strong reaction was recorded. Behavior changes were recorded following 31 (5.5%) of 569 hits, and 18 (4.5%) of 404 misses. Evasive behavior related to vessel approach was exhibited prior to 72 (12.0%) of 598 hits and 100 (24.1%) of 415 misses. Mothers showed significantly fewer reactions to hits than other whales, and a similar frequency and typeof behavior changes, although they tended to be more evasive before a shot was made. Presumed males in competitive groups also showed significantly fewer reactions to shots, and very few behavior changes. Overall, this study supports the belief that the biopsy itself has little effect on a whale and that, if the associated vessel approach is conducted with care, samples can usually be taken with minimal disturbance to die target animal. However,approaches may affect the probability of obtaining fluke photographs for individual identification.
Abstract: The hypothesis that maternal condition can affect the sex ratio of offspring was investigated by examining the sex of calves born to mature female humpback whales, Megaptera novoeangliae, in the southern Gulf of Maine. Maternal condition was inferred from calving interval: females calving at intervals of 3 or more years were judged to be in 'superior' condition, while those calving at the modal 2-year interval were considered to be in 'average' condition, and those at an interval of 1 year in 'poor' condition. The sex ratio of calves horn to females in superior condition deviated significantly from the expected 1:1 (X2 = 8·05, N = 21, df = 1, P< 0·01), and was biased towards sons. Females in average and poor condition produced calves with a sex ratio that did not differ from parity (X2 = 0·09, N = 42, df = 1, P>0·7). Interpretation of these results according to the Trivers & Willard (1973, Science, 179, 90-92) hypothesis would suggest that mature female humpbacks in superior body condition bias their reproduction towards the sex (males) with the greater variance in reproductive success, although rejection of the central assumption of this study (that a longer calving interval results in superior maternal condition) would render such an interpretation invalid.
Abstract: Twelve female humpback whales (Megaptera novaeangliae) in the southern Gulf of Maine produced first-observed calves at ages ranging from 5 to 7 years. These data confirm that most females of this species attain sexual maturity at an average age of approximately 5 years. Observations in the West Indies of two males, aged 6 and 7 years, engaged in breeding-related behavior that is characteristic of mature animals suggests that males attain sexual maturity within a similar range of ages to females, although they may not be able to successfully engage in intrasexual competition until later in life. These data imply that the examination of ear plugs to determine the age of dead humpback whales should be based upon an assumed annual growth rate of two growth layer groups, not one.
Abstract: Sei whales (Balaenoptera borealis) are noted for major fluctuations in distribution, often in response to local availability of prey. An influx of sei whales occurred in the southern Gulf of Maine during summer 1986. Forty-seven individuals (including four mothers with calves) were photographically identified using natural markings, including dorsal-fin notches, placement of small circular scars on the animal's flank, and natural variation in dorsal-fin shape and pigment swaths along the dorsal surface behind the blowholes. Seventeen of these whales (36.1%) were photographed on more than one day, and the period between first and last sighting of individuals ranged from one to 66 days. Only six animals were sighted in more than one region in the southern Gulf of Maine. Observed behavior included traveling, nearsurface skim feeding, lunge feeding, and (rarely) "milling" or breaching. Group sizes were small and variable. Two individuals were matched to photographs taken in other regions in or near offshore Gulf of Maine waters. We hypothesize that the southern Gulf of Maine represents a short term feeding sight. The occurrence of individuals without sufficient marks for individual recognition suggests that photoidentification is of limited value in the study of this species.
Abstract: It has been hypothesized that humpback whale, Megaptera novaeangliae, competitive groups represent intrasexual competition by males for access to a mature female. The composition and dynamics of these groups was studied between 1989 and 1991 in Samana Bay, West Indies. The sex of group participantswas determined by molecular analysis of skin biopsies. Groups showed similar characteristics of size and movement as those described from other breeding areas, except that only one group contained a calf. The sex was determined of 141 participants in 44 competitive groups. In 21 of these groups, wewere able to biopsy all participants. No group contained more than one female, but seven of the wholly sampled groups (all of them small) consisted entirely of males. Of 22 animals who were "positively" assigned the role of Nuclear Animal, 17 were female, and five were male. Similarly, of 24 biopsied Principal Escorts, 23 were male and one female. All 24 biopsied Challengers were male. Of 55 animals who were either classified as Secondary Escort, or whose role could not be categorized, 51 were male and four female. In 8 cases, associated pairs of males exhibiting no aggression towards each other were observed to either enter or leave a competitive group together. Of16 individuals resighted on more than one day, all but one were males. These data suggest that: 1. While most groups (as predicted) represent male-male competition for a single female, observers should be cautious in their assumptions; 2. All-male groups may represent dominance sorting by unfamiliar conspecifics; 3. Females may occasionally aggressively repel advances by unwanted males; 4. While unlikely in light of present knowledge, the possibility that males form coalitions cannot be dismissed. We suggest that competitive groups may be asymmetrical contests in which a female Nuclear Animalis of more value to the Principal Escort than to a Challenger, particularly if the former's defence of her represents mate-guarding.
Abstract: Right whales in Cape Cod Bay, Massachusetts, were studied to determine the relationship between their surface feeding behaviour and the density and composition of their planktonic prey. The swimming path characteristics of whales feeding, socializing, and travelling were compared. Zooplankton samples collected in the feeding path were contrasted with those from areas where whales were not present. Surface prey patches where right whales fed were dominated by Calanus finmarchicus (21 samples), Pseudocalanus minutus (n = 13), Centropages sp. (n = 3), and larval barnacles (n = 2). The zooplankton density in the feeding path of the whales tested significantly higher (MannâWhitney U-test, P < 0.001) than at stations where whales were not present (mean total densities were 6.54 à 103 (SE = 1.03 à 103) and 0.87 à 103 (SE = 0.19 à 103) organisms/m3, respectively). Feeding was rarely observed in locations where the total zooplankton density was less than 1000 organisms/m3. The rate of change of direction in the feeding path (mean 19.3°/10 m of path) was significantly higher (P < 0.001) than for paths of whales travelling (mean 5.3°/10 m of path), reflecting area-restricted foraging behaviour.
Abstract: Vessel surveys were conducted during the winters of 1985 and 1986 to investigate the abundance and distribution of humpback whales on Virgin Bank and in the northern Leeward Islands. Nonrandom track surveys conducted on Virgin Bank in 1986 produced observed densities ranging from 0 in late January and mid-March to 0.082 whales/naut. mi. sq. (1 naut. mi. = 1.852 km) in mid and late February. The number of whales sighted per hour on Virgin Bank was similar for both 1985 and 1986, with a peak value of more than 1.3 whales/h in mid to late February. On Anguilla Bank, the number of whales sighted per hour ranged from 0 in late March to 0.66 in mid-February. Comparisons with data from Mona Passage, Puerto Rico, suggest a possible shift in abundance from east to west, with the peak abundance occurring in the second half of February on Virgin Bank and at the beginning of March in Puerto Rico. A total of 105 whales were individually identified during the study. Photographic matches demonstrate that Virgin Bank is used by whales from all of the major known western North Atlantic feeding grounds, and suggest that this may also be true of Anguilla Bank. Overall, the data suggest that Virgin Bank may be more important as a mating and calving ground than Mona Passage, Puerto Rico, but considerably less important than Silver Bank. Sightings of other cetacean species in the study area are summarized, and include observations of a minke whale (Bafaenopteru acutorostrata) mother-calf pair on Anguilla Bank.
Abstract: Between 14 February and 19 March 1984, 19 d were spent observing humpback whales, Megaptera novaeangliae, on Silver Bank. In total, 317 whales were individually identified from photographs of ventral fluke patterns. Comparison of these photographs with the North Atlantic humpback whale catalogue revealed that 97 of the whales had previously been observed in other areas. Matches were made with all of the major known high-latitude feeding grounds: Greenland (6), Newfoundland â Labrador (43), the Gulf of St. Lawrence (7), and the Gulf of Maine (12). Matches were also made with habitats in the winter range of this population: Bermuda (1), Silver Bank in other years (26), Puerto Rico (18), Virgin Bank (1), and Anguilla Bank (1). Analysis of matches suggests that whales from the various high-latitude feeding stocks mix randomly on Silver Bank. Seven surface-active groups contained whales from different high-latitude feeding stocks, providing the strongest evidence to date for genetic mixing among these stocks. The behavior and composition of surface-active groups are discussed. Overall, the number of whales, calves, and surface-active groups observed during this study confirms the apparently singular importance of Silver Bank to the breeding ecology of western North Atlantic humpback whales.
Abstract: During a 5âwk period beginning in late November, 1987, 14 humpback whales, Megaptera novaeangliae, died in Cape Cod Bay after eating Atlantic mackerel, Scomber scombrus, containing saxitoxin (STX), a dinoflagellate neurotoxin responsible for paralytic shellfish poisoning in humans. We propose a line of evidence to explain how whales, by virtue of their diving adaptations, may be particularly vulnerable to this systemic neurotoxin. Absence of STX in New England waters and shellfish during the episode suggests that the mackerel, representing the northern stock which spawns in the Gulf of St. Lawrence, accumulated the toxin there and delivered it to the Gulf of Maine and Cape Cod Bay in the fall of 1987. These findings challenge common perceptions of the manner in which planktonic toxins move through the food chain, and offer new insights into natural mortality and standings of marine mammals. It seems appropriate to search for STX and other phytotoxins when investigating marine mammal mortalities.
Abstract: Humpback whale mother-calf pairs from a currently unexploited population were observed in Massachusetts Bay between 1979 and 1985. During this period, 44 individually identified mature females were observed, with a total of 72 calves. Of the 20 mothers observed with more than one calf during the study period, 12 had two calves and 8 had three calves. The observed calving intervals were 1 year (n=1), 2 years (n=16), 3 years (n=10) and 4 years (n=1). The crude birth rate varied from a low of 0.045 in 1981 to a high of 0.103 in 1983 (mean=0.075). An alternative calculation of reproductive rate yielded a range of 0.30-0.43 calves per mature female per year. Mature females were observed significantly more frequently in years when they had a calf than in years when they did not. Females with calves associate with other whales less frequently than females without calves. Observations of calves feeding suggest that weaning may begin when calves are 5-6 months of age. Forty-five of the 49 calves born before 1985 separated from their mothers during the calf's second winter, while 37 of 49 were observed to return to the study area in 1 or more years after separation from their mothers. One calf is known to have died. Two females born during the study period returned with calves of their own in later years. This high rate of return of calves in years after separation strongly suggests that the composition of a humpback whale feeding stock is determined matrilineally.
