My main interests are acoustic monitoring of small cetaceans, development of sustainable marine wildlife-watching tourism industries, generating baseline data on cetacean populations in West Africa and socio-economic studies of the links between local communities and marine environments.
Abstract: Humpback whales Megaptera novaeangliae found off west South Africa (WSA) are known to display an
atypical migration that may include temporary residency and feeding during spring and summer. At a regional
scale there is uncertainty about how these whales relate to the greater West African Breeding Stock B as a
whole, with evidence both for and against its division into two substocks. A database containing sighting
information of humpback whales intercepted by boat in the WSA region from 1983 to 2008 was compiled.
It included a total of 1 820 identification images of ventral tail flukes and lateral views of dorsal fins. After
systematic within- and between-year matching of images of usable quality, it yielded 154 different individuals
identified by tail flukes (TF), 230 by left dorsal fins (LDF), and 237 by right dorsal fins (RDF). Microsatellite
(MS) matching of 216 skin biopsies yielded 156 individuals. By linking all possible sightings of the same
individuals using all available identification features, the periodicity and seasonality of 281 individual
whales were examined. In all, 60 whales were resighted on different days of which 44 were between different
calendar years. The most resightings for one individual was 11 times, seen in six different years, and the
longest interval between first and last sightings was about 18 years. A resighting rate of 15.6% of whales at
intervals of a year or more indicates long-term fidelity to the region. Shorter intervals of 1â6 months between
sequential sightings in the same year may suggest temporary residency. The TF image collection from WSA
was compared to TF collections from four other regions, namely Gabon, Cabinda (Angola), Namibia and the
Antarctic Humpback Whale Catalogue (AHWC). Three matches were detected between WSA (in late spring or
summer) and Gabon (in winter), confirming direct movement between these regions. The captureârecapture
data of four different identification features (TF, RDF, LDF and MS) from six successive subsets of data from
periods with the highest collection effort (2001â2007) were used to calculate the number of whales that utilise
the region, using both closed- and open-population models. Dorsal fins have never been used to estimate
abundance for humpback whales, so the different identification features were evaluated for potential biases.
This revealed 9â14% incidence of missed matches (false negatives) when using dorsal fins that would result
in an overestimate, whereas variation in individual fluke-up behaviour may lower estimates by as much as
57â66% due to heterogeneity of individual capture probability. Taking into consideration the small dataset and
low number of recaptures, the most consistent and precise results were obtained from a fully time-dependent
version of the Jolly-Seber open-population model, with annual survival fixed at 0.96, using the MS dataset.
This suggests that the WSA feeding assemblage during the months of spring and summer (Septemberâ
March) of the study period numbered about 500 animals. The relationship of these whales to those (perhaps
strictly migratory) that may occur in other seasons of the year, and their links to possible migratory routes
and other feeding or breeding areas, remain uncertain.
Abstract: Marine vertebrate strandings data can provide insights into the long-term dynamics of cetacean populations, and the threats they face. We investigate whether the spatio-temporal patterns of cetacean strandings around Cornwall, SW Britain, have changed in the past century. Analysis of strandings from 1911 to 2006 (n = 2,257) show that, since the mid-1970s, the relative frequency of strandings of common dolphins (Delphinus delphis), harbour porpoises (Phocoena phocoena) and pilot whales (Globicephala melas) has increased significantly. Seasonal peaks in strandings frequencies are apparent, between December and March for harbour porpoises and common dolphins, and between November and January for pilot whales. There were significant positive trends in the number of common dolphin and harbour porpoise strandings, as a proportion of total strandings, over time. Strandings of common dolphins, porpoises and all other species occur more frequently on the south coast of Cornwall. A total of 415 cetaceans were subject to full veterinary necropsy to determine cause of death, between 1990 and 2006, and 253 (61%) of these individuals were determined to have died due to bycatch in fishing gear. Analyses of industrialised fishing pressure in UK waters show the seas around Cornwall to be one of the most heavily fished areas of the UK. We suggest a number of factors that could be responsible for the recent increases in cetacean strandings in southwest UK waters in recent years, including survey effort, as well as abundance and range shifts that are potentially linked with climate change. Although detectable levels of bycatch rate have not increased over time, fisheries interactions are in significant part responsible for mortality patterns and are worthy of more detailed investigation.
Abstract: Not all delphinids are similarly affected by acoustic deterrent devices (pingers). At-sea trials were carried out to assess a range of acoustic signals and deterrents on the behaviour of common dolphins. In initial tests two acoustic deterrent devices, which previously produced an evasive response by bottlenose dolphins, failed to elicit any similar behaviour in common dolphins. A new signal output device, which permitted a range of signals to be tested at various source levels and characteristics was subsequently developed but again no significant effects on the behaviour of common dolphins were observed. Two commercially available acoustic deterrents, which had deterred common dolphins in previous studies, produced an occasional mild evasive response. Significant modification of the signal type or source level may be more effective, but our results suggest that pingers, at their current state of development, may not provide a consistently effective deterrent signal for common dolphins.
Abstract: Trials were carried out in the Shannon estuary, Ireland, to test the effects of continuous (CPs) and responsive pingers (RPs) on bottlenose dolphin behaviour. In controlled trials, active and control pingers were deployed on fixed moorings, with T-PODsâacoustic monitoring devices to detect cetacean activity. In a separate trial, pingers were deployed from a moving boat which actively located dolphin groups in the estuary, and dolphin behaviour was recorded. In the static trials, overall detection rates of dolphin vocalizations on the T-POD were significantly lower in the presence of active CPs, but this was not the case for RPs. Mean inter-click interval values were longer for click trains produced in the presence of inactive RPs than for active RPs, active or inactive CPs. In boat-based trials, both active CPs and RPs appeared to affect bottlenose dolphin behaviour, whereby dolphins immediately left the area at speed and in a highly directional manner, involving frequent leaps.
Abstract: EXECUTIVE SUMMARY
In 2008, the right whale surveillance program supported by the Commonwealth of Massachusetts Division of Marine Fisheries (DMF) was conducted in Cape Cod Bay (CCB) and adjacent waters from 1 January through 15 May by the right whale research team at the Provincetown Center for Coastal Studies (PCCS). Weather permitting, the program included bi-weekly aerial surveys and weekly habitat sampling. Upon completion of each survey, all sightings were reported to the NOAA Fisheries Sighting Advisory System (SAS) and the US Army Corps of Engineers Cape Cod Canal Field Station.
During the 2008 winter and spring season, PCCS observers performed 28 aerial surveys totaling 158.5 hours of flight time covering CCB and adjacent waters east of the Cape. Although a large proportion of the identification photographs taken during these flights and during habitat sampling cruises have already been matched to the existing right whale catalogue by two independent experienced researchers, most of the matches are still awaiting final confirmation by the New England Aquarium. Therefore, the results outlined in the present report may change slightly once confirmation is obtained.
In 2008, right whales were observed in CCB and adjacent waters during 125 days (from 12 January to 15 May). This period of occupation of the area was considerably longer than in previous years (92 days in 2007; 100 days in 2006; 97 days in 2005). A very large number of individuals were identified in CCB and adjacent waters in 2008, compared to previous years of the project. To date, sightings of 148 unique individual whales have been confirmed, and a number of other individuals have yet to be identified. This is comparable with 2007, when 161 different individuals were identified in the area, a number which is twice the yearly average between 1998 and 2006. 47 right whales that had never been identified before in the area since photographic records of right whales began in the bay in 1958, were observed in CCB and adjacent waters in 2008. This likely implies that resources in CCB were exceptionally favorable in 2008.
There was an average of 11.1 days between the first and last sighting of an individual right whale. This is substantially shorter than in 2007 (average of 18.4 d) and 2005 (13.2 d), but longer than in 2006 (average of 7.4 days), suggesting that whilst more whales than usual visited CCB and adjacent waters in 2007, their residency time was somewhat reduced compared to recent years.
In 2008, as in 2007, right whales abundance increased from a mean of 0.1 and 0.9 individuals per 100 nm in January and February, respectively, to 7.3 in March and a maximum of 28.6 per 100 nm in April, before then dropping dramatically in May to 0.6 individuals per 100 nm. Right whale distribution in CCB varies considerably between years. Sightings were distributed throughout the bay, with some concentrations in southern and western areas. Right whales were also abundant at Race Point during April, in 2008, a pattern which has been observed in previous years. 15 sightings of 22 individuals occurred outside of the critical habitat boundary.
78% of all right whales in CCB and adjacent waters were adult whales. Of those individuals of known sex, 34% were female and 66% were male. In 2008, the length of time between the first and last sighting of individuals in Cape Cod Bay averaged 11.3 days. The maximum possible residency time for an individual in CCB (time from first to last sighting) was 63 days, for an adult female whale. The mean maximum possible residency time was 11.3 days, and unlike 2007, there was no significant difference between female and male maximum possible residency times. Three mother and calf pairs were sighted in CCB and adjacent waters. Mother-calf pairs were, on average, sighted on more days (minimum residency time) than males or females, but the period over which they were sighted (maximum residency time) was shorter, suggesting that mother-calf pairs are more resident in the bay once they arrive, but, at least in 2008, used this habitat over a shorter period than other whales.
The mean cluster size was 1.7 individuals, and clusters ranged in size from one to 13. Clusters of one or two whales were the most numerous. Larger clusters were more frequently observed in March and April. Mean cluster size in 2008 was greater then the mean cluster size for all clusters documented between 1999 and 2007. 31 SAGs were observed in 2008, involving between two and 13 individuals. Mean SAG size was 4.1 individuals. In 2008, SAGs in CCB were only sighted during March and April.
A summary is given of the studies on right whale vocalization behavior, made in 2006 and 2007. 111 hours of recordings were made, resulting in 3,506 right whale vocalizations which were of suitable quality for analysis. Tonal calls were by far the dominant call type. Only 15.4 % of all vocalizations recorded occurred during feeding behavior, and foraging or traveling whales produced a mean of just four vocalizations per hour. No upcalls were recorded from traveling whales. In contrast, 83.4% of the vocalizations recorded came from whales engaged in SAG behavior, and these whales produced a mean of 165 vocalizations per hour.
During 2008, Cornell University ran three cell phone-linked acoustic buoys in CCB. A basic cross-validation analysis of the coarse-scale buoy data with aerial survey data was possible. Visual and acoustic techniques provided the same daily presence-absence results on 64% of days for which both datasets were available. There was also a positive association between the number of up-calls per operational buoy, and number of right whales sighted per 100 nm of survey effort on a given day.
Support of the PCCS Disentanglement Team formed a major part of the work carried out by the Aerial Survey Team in 2008, due to the unusually high number of entangled right whales sighted this season. Entangled or seriously injured right whales were sighted on nine of 28 survey days carried out; these sightings involved four individual whales (EG 1140, 1980, 2645, all entangled, and 3530, severely injured). Hours spent in support of the Disentanglement Team amounted to 20 h 35 min over the course of the survey season; this was 12.9% of all flight hours undertaken by the Aerial Survey Team and represents a significant proportion of the survey time.
Interactions between vessels and right whales were observed and recorded four times during the 2008 season. In addition to right whales, five other species of cetacean and two pinniped species were sighted during aerial surveys in 2008. Baleen whale sightings were more numerous in April and May than earlier in the year. Sightings of both odontocetes and baleen whales were distributed throughout the study area, but were especially abundant around Race Point and near to Provincetown harbor.
During the 2008 field season, 19 habitat study cruises were conducted, during which 521 zooplankton samples were collected and analyzed to describe the zooplanktonic food resources that control the distribution of right whales in Cape Cod Bay. This yearâs sampling focused on characterizing the distribution, composition, and density of the winter-spring Cape Cod Bay zooplanktonic resource, which serves as a continuum of the last 29 years of habitat studies at PCCS. Collections were taken by surface and oblique net tows at eight regular stations throughout the bay, as well as by horizontal transect samples and discrete depth pump samples in locations of particular interest to zooplankton-right whale ecology. Information collected and analyzed during the season was delivered to the Division of Marine Fisheries of the Commonwealth of Massachusetts and to more than 80 colleagues via e-mail in the form of three assessment instruments: the rapidly produced "Preliminary Assessmentâ and âRight Whale Risk Alert" reports, and the detailed "Right Whale Habitat Assessment" documents. The former reports continue to underpin our effort to alert of the Division of Marine Fisheries of areas that present imminent risk of ship strike or entanglement, while the latter provides detailed background data for forecasting aggregation and feeding by right whales. All documents focus on forecasting the locations where right whales and industrial activities may overlap. In 2008 the rapid production of the preliminary assessment instrument resulted in the dissemination of four management advisories, intended to alert mariners to the probable presence of right whales performing risky behaviors, and at the end of the season, the termination of the risk alerts. In 2008, two special reports were also distributed to the same recipients of the habitat assessments. These reports were intended to describe some of our directed habitat research aimed at honing our understanding of right whale-zooplankton dynamics.
The 2008 zooplankton resource followed previously documented patterns of enrichment and impoverishment with the primary food resources being the three dominant calanoid copepod taxa: Centropages spp., Pseudocalanus spp., and Calanus finmarchicus. The pattern of productivity of these three taxa overlapped, as in past years, to produce a fairly steady and increasing total zooplankton resource from January through May. The cycle of increased Centropages resource in the early winter, likely the remains of the late summer and fall stock, was again observed in 2008. The enrichment of Pseudocalanus spp., usually peaking during March, was also observed; this resource was extremely rich in the surface waters compared with previous years, peaking in mid-March. Typical of most other years, the Calanus resource increased from very low densities before late February to relatively high concentrations in April, but unlike past years, the resource steeply declined in both surface waters and the water column.
The 2008 season was extraordinary in that the aerial survey reported an unprecedented high number of right whales in the bay, with peak abundance occurring between the Pseudocalanus spp. and Calanus finmarchicus peaks. While Pseudocalanus spp. abundance also reached a maximum higher than any previous year, an analysis of whale abundance and Pseudocalanus spp. density in the past eight years showed no strong correlation. Additionally, in 2008, as in 2007, right whales left Cape Cod Bay during a period in May when zooplankton, principally Calanus, remained broadly available and occasionally at densities exceeding the feeding threshold throughout large areas of the bay system. This pattern, the departure of right whales from a habitat that appeared acceptable, was also observed and noted in previous years (e.g. 2004) and we believe may be explained by the "competition between habitats" that we have proposed in past years. The temporal and spatial stability of the zooplankton resource may have a profound influence upon the medium-term acceptability of Cape Cod Bay as a foraging habitat for right whales. The instability in the zooplankton resource observed at the end of the 2008 season appeared, at least in part, to be the result of major counter clockwise flushing currents within the Bay. Because of the importance of determining the departure time of whales, future research will likely focus on comparing the temporal and spatial stability with the distributional stability of the whales within Cape Cod Bay.
Another area explored in 2008, which will be a focus of research in 2009, is that of varying levels of risk to right whales, associated with different zooplankton taxa, which are present at different times of the year and at different depths in the water column. A fine-scale study is planned for 2009, to comprehensively investigate this issue.
