Peter T. Stevick

Genetic tagging of humpback whales

The ability to recognize individual animals has substantially increased our knowledge of the biology and behaviour of many taxa. 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, 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.

Segregation of migration by feeding ground origin in North Atlantic humpback whales (Megaptera novaeangliae)

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 (r 2 = 0.97,F1,3 = 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.

Current Knowledge on the Distribution and Relative Abundance of Humpback Whales ( Megaptera novaeangliae ) off the Cape Verde Islands, Eastern North Atlantic

During the winter/spring months from 1990 to 2009, 13 cetacean surveys were conducted around the Cape Verde Islands off West Africa. The main target species was the humpback whale (Megaptera novaeangliae). Study periods varied from 14 to 90 d in duration. Study platforms included a 5-m inflatable boat, a 12-m catamaran, and/or 15-m sailing or motor vessels. Collectively, we obtained 88 individual humpback fluke photographs from this region. These fluke photographs have been compared to over 6,500 individual fluke photographs maintained in the North Atlantic Humpback Whale Catalogue. Based on photoidentification, humpbacks in the Cape Verde Islands have a relatively high interannual resight rate (> 22%) compared to other studied breeding locations in the West Indies. While this is partly due to increased probability of detection in a small population, this result nonetheless suggests strong site fidelity to this breeding ground. Three photo-identified individuals from the Cape Verde Islands had been previously photographed on high-latitude feeding grounds off Bear Island, Norway, and Iceland. One Cape Verdean humpback was resighted in the Azores, possibly en route to the northern feeding grounds. These findings are consistent with the belief that the Cape Verde Islands represent a breeding ground for northeastern Atlantic humpback whales. Tourism activities in the Cape Verde Islands are rapidly increasing. A balance is needed whereby conservation, whale watching guidelines, habitat preservation, and enforcement are fully enacted in order to provide protection to both this species and its habitat. In addition, further research is required to clarify the importance of this small population and its breeding ground.

EXTRALIMITAL RECORDS OF HOODED SEALS (CYSTOPHORA CRISTATA) FROM THE BAY OF FUNDY AND NORTHERN GULF OF MAINE

Since the mid 19th century, only eight records of hooded seals (Cystophora cristata) have been documented from the Bay of Fundy and north- ern Gulf of Maine. Between 1994 and 1998 thirty-one additional records have been reported, suggesting a recent and dramatic increase in this ice-breeding seal in the region. Sergeant (1975) has noted the proclivity for juvenile hooded seals (Cystophora cristata), to wander outside their normal range of arctic and subarctic waters. Extralimital records of hooded seals have been reported occasionally from the east coast of North America as far south as Florida (Miller 1917), and even Puerto Rico (Guzman-Ramirez and Mignucci-Giannoni 1998). However, Squires (1968) commented that this species is infrequent along the Gulf of St. Lawrence coast of New Brunswick, in spite of whelping in small numbers in the Gulf (Sergeant 1974), and Gilpin (1874) was aware of only a single Nova Scotia record, from off the eastern shore. Since the mid-19th century, only three reports of hooded seals have been documented in the Bay of Fundy and perhaps five from the entire coast of Maine. Here we review the status of the hooded seal along the Maine coast and the Bay of Fundy and document 31 additional records from the Bay of Fundy and northern Gulf of Maine. These records show that there has been a dramatic increase in occurrences of this ice-breeding seal in the region since 1994.

Using opportunistic photo-identifications to detect a population decline of killer whales ( Orcinus orca ) in British and Irish waters

An assemblage of killer whales that has been sighted in waters off the west coast of the British Isles and Ireland has previously been shown to be isolated from other North Atlantic killer whale communities based on association patterns. By applying a Bayesian formulation of the Jolly–Seber mark-recapture model to the photo-identification data compiled from opportunistic photographic encounters with this population of killer whales, we show that such sparse and opportunistically-collected data can still be valuable in estimating population dynamics of small, wide-ranging groups. Good quality photo-identification data was collected from 32 encounters over 19 years. Despite a cumulative total of 77 identifications from these encounters, just ten individuals were identified and the remaining 67 identifications were re-sights of these ten animals. There was no detected recruitment through births during the study and, as a result, the population appears to be in a slight decline. The demography of the population was highly skewed towards older individuals and had an unusually high ratio of adult males, and we suggest that demographic stochasticity due to a small population size may be further impacting the population growth rate. We recommend that this population be managed as a separate conservation unit from neighbouring killer whale populations.

The reaction of humpback whales to underwater explosions: Orientation, movements, and behavior

In 1992, local fishermen reported unusually high net collision rates by humpback whales in Bull Arm, Trinity Bay, Newfoundland (47° 45’N, 53° 50’W), an area of underwater industrial activity. As part of a study to investigate this phenomenon [see also Ketten et al., this meeting], levels and types of noise—including underwater explosions—were sampled. The location and movement of a small group of humpbacks (71 individuals identified over a 19‐day period) resident in Bull Arm were monitored; when possible, behavior of individuals was recorded directly. CTD profiles and bait abundance were also noted. Explosions were of high amplitude and low frequency. Measured at 1 mile from source, levels typically reached 150 dB (re: 1 μPa at 1 m, at 350 Hz). Following explosions, residency time and location of individual humpbacks did not change. When individuals could be observed directly, no behavioral reaction to explosions (sudden dives, abrupt movements) were seen. Although not statistically significant, more anim...

A longitudinal study of humpback whales in Irish waters

conor ryan, pa’draig whooley, simon d. berrow, colin barnes, nick massett, wouter j. strietman, fredrik broms, peter t. stevick, thomas w. fernald jr and christian schmidt Irish Whale and Dolphin Group, Merchant’s Quay, Kilrush, Co. Clare, Ireland, Hebridean Whale and Dolphin Trust, 28 Main Street, Tobermory, Isle of Mull, PA75 6NU, UK, Marine and Freshwater Research Centre, Galway-Mayo Institute of Technology, Dublin Road, Galway, Ireland, Cork Whale Watch, Reen Pier, Union Hall, Co. Cork, Ireland, Stichting Rugvin, Jeruzalem 31A, 6881 JL Velp, the Netherlands, Akvaplan-Niva AS, Fram Centre, 9296 Tromso, Norway, Allied Whale, College of the Atlantic, 105 Eden Street, Bar Harbor, Maine 04609, USA, Husavik Whale Museum, Hafnarstett, PO Box 172, 640 Husavik, Iceland

There and back again : Multiple and return exchange of humpback whales between breeding habitats separated by an ocean basin

In species that aggregate for reproduction, the social and fitness costs of movement between groups frequently lead to restricted exchange between breeding areas. We report on four individual humpback whales identified in both the Cape Verde Islands and Guadeloupe; locations separated by an ocean basin and >4000 km. This rate of exchange is rarely encountered between such geographically discrete breeding areas. Two individuals returned to the area where they were originally identified. In contrast, no individuals from the Cape Verde Islands were resighted to the much larger sample from the Dominican Republic, though the migratory distances from the feeding areas are comparable between these areas. The social factors driving the stark difference between groups that is observed here are not clear. Effective conservation requires an understanding of the extent and pattern of movement between population units. The findings presented here suggest that there may well be more than one behaviourally distinct group within the West Indies. More broadly, they argue that considerable caution is warranted in assumptions made regarding the number, boundaries and status of population units based solely on spatial separation or proximity.

A note on the unprecedented strandings of 56 deep-diving whales along the UK and Irish coast

In the first seven months of 2008, eighteen Cuviers beaked whales ( Ziphius cavirostris ), four Sowerbys beaked whales ( Mesoplodon bidens ), five unidentified beaked whales and twenty-nine long-finned pilot whales ( Globicephala melas ) were reported stranded in the UK and Ireland. Decomposition of those animals investigated puts the predicted time of death at mid-January. Concerns that an unusual mortality event had taken place prompted further investigations. Most carcasses were too decomposed for necropsy. A summary of findings is presented here. Although the initial stranding of five Cuviers beaked whales in Scotland shared some similarities with atypical mass stranding events linked in time and space to mid-frequency naval sonars, there were two important differences with the remaining strandings during this period. First, the geographical range of the event was very wide and second, the strandings occurred over a prolonged period of several months. Both of these factors could be related to the fact that the mortalities occurred offshore and the carcasses drifted ashore. The cause(s) of this high number of strandings of mixed offshore cetacean species during this period remain undetermined.