NATIONAL MARINE MAMMAL LABORATORY (NMML) (cont.)

Cetacean Assessment and Ecology Program

SPLASH Surveys

In the 2004 field season, NMML participated in the SPLASH (Structure of Populations, Levels of Abundance, and Status of Humpbacks) project by surveying summer feeding areas of humpback whales (Megaptera novaeangliae) in the waters of Alaska, including the inland waters of lower Southeast Alaska, the waters around the Aleutian Islands, and the southeast Bering Sea. SPLASH is an international cooperative effort to understand the population structure of humpback whales across the North Pacific and to assess the status, trends, and potential human impacts to this population. SPLASH brings together national research programs and independent whale researchers from the United States, Canada, Mexico, Russia, and Japan. This project is partially funded by NOAA Fisheries, with additional funding provided by other government organizations in the United States, Canada, and Mexico and private research foundations.

Humpback whale populations were depleted due to commercial exploitation and are still listed as endangered today. The most complete recent estimate of North Pacific humpback whale abundance is based on mark-recaptures of individual whales photo-identified between 1990 and 1993. Data from photo-identification and genetics studies have provided some information on North Pacific stock structure, verifying a high degree of site fidelity to feeding areas and some intermixing in the wintering areas. SPLASH will conduct the first-ever comprehensive field study of humpback whales throughout the North Pacific. Photographs of tail flukes and dorsal fins will be used to identify individual whales. By determining where and when individuals are seen, the abundance of breeding populations and feeding aggregations can be estimated using mark-recapture methods, and distribution and movements can be determined. A wealth of information can be obtained from biopsy samples, including sex, genetic structure and flow, pregnancy, toxicology, and feeding information. Portions of each biopsy sample will be archived for future use. Finally, photographs of tail stocks will be used to assess human impacts, including evidence of past entanglement or ship strike.

NMML worked in conjunction with local Alaska-based researchers and the SPLASH steering committee to determine which areas to survey. Four cetacean surveys were conducted by NMML throughout the 2004 field season: 1) in the southeast Bering Sea aboard the NOAA ship Miller Freeman during an acoustic-trawl survey for walleye pollock conducted by the AFSC’s Resource Assessment and Conservation Engineering (RACE) Division, from 5 June to 3 July; 2) in Southeast Alaska aboard the NOAA ship John N. Cobb from 1 to 12 July; 3) in the waters around the eastern and central Aleutian Islands and in the southeast Bering Sea aboard the charter vessel Alaskan Enterprise from 21 July to 27 August; and 4) in Southeast Alaska aboard the John N. Cobb from 11 to 24 September.

Although the cetacean research on the Miller Freeman was secondary to the activities of the walleye pollock survey in the southeast Bering Sea, samples collected from five encounters with humpback whales resulted in photographs of approximately 30 whales and biopsies of 6 whales. Additional information on this cruise is available in the April-June 2004 AFSC Quarterly Report.

During the July survey in Southeast Alaska on the John N. Cobb, 67.15 hours of search effort were conducted and 26.17 hours were spent with humpbacks during 26 encounters over 9 days. Photographs of tail flukes were collected for 58 individual whales and photographs of dorsal fins were collected for 10 whales for which tail fluke photographs were not obtained. In addition, photographs of dorsal fins were collected from 19 whales whose tail flukes may also have been photographed; however, these matches need to be verified by other Southeast Alaska humpback whale researchers. Four whales were positively identified during two different encounters, including a whale whose calf was tentatively identified (by matching photos of the right and left sides of the dorsal fin) in two encounters. Finally, during 18 biopsy attempts, seven biopsy samples were collected over the course of three encounters.

Photographic data are still being analyzed from the Alaskan Enterprise survey of the Aleutian Islands and Bering Sea and the September John N. Cobb survey in Southeast Alaska; however, preliminary results are available. The Alaskan Enterprise survey collected photographs of 118 individual humpback whales and biopsies from 45 whales. The September John N. Cobb survey collected 57 photographs of tail flukes and 5 photographs of dorsal fins during nine encounters with humpback whales.

By Nancy Friday and Christy Sims.

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AFSC Quarterly Research Reports July-Sept 2004