Changes in the Numbers of Cetaceans near the Pribilof Islands, Bering Sea, between 1975-78 and 1987-89

We compared the number of cetaceans seen during surveys of seabird distribution in the vicinity of the Pribilof Islands, Bering Sea, during two periods, 1975-78 (3867 km surveyed) and 1987-89 (6101 km surveyed). During the 1980s, we saw increased numbers of fin whales (Balaenoptera physalus) (0 to 6...

Full description

Bibliographic Details
Published in:ARCTIC
Main Authors: Baretta, Lariann, Hunt Jr., George L.
Format: Article in Journal/Newspaper
Language:English
Published: The Arctic Institute of North America 1994
Subjects:
Online Access:https://journalhosting.ucalgary.ca/index.php/arctic/article/view/64359
Description
Summary:We compared the number of cetaceans seen during surveys of seabird distribution in the vicinity of the Pribilof Islands, Bering Sea, during two periods, 1975-78 (3867 km surveyed) and 1987-89 (6101 km surveyed). During the 1980s, we saw increased numbers of fin whales (Balaenoptera physalus) (0 to 66 individuals), minke whales (B. acutorostrata) (3 to 38 individuals), humpback whales (Megaptera novaeangliae) (0 to 24 individuals), killer whales (Orcinus orca) (5 to 58 individuals), and Dall's porpoises (Phocoenoides dalli) (101 to 241 individuals). It could not be determined whether these changes reflected changes in the numbers of these species in the Bering Sea, or simply local changes in their foraging or distribution patterns. Fin, humpback and minke whales were seen foraging in the vicinity of large flocks of birds that were eating euphausiids (Thysanoessa raschii and T. inermis).Key words: Fin whale, minke whale, humpback whale, killer whale, Dall’s porpoise, Balaenoptera physalus, Balaenoptera acutorostrata, Megaptera novaeangliae, Orcinus orca, Phocoenoides dalli, Bering Sea, whale foraging On a comparé le nombre de cétacés aperçus durant des relevés de la répartition d'oiseaux marins dans le voisinage des îles Pribilof, dans la mer de Béring, durant deux périodes de trois ans, de 1975 à 1978 (3867 km de distance de relevés) et de 1987 à 1989 (6101 km de distance de relevés). Au cours des années 1980, on a aperçu un plus grand nombre de rorquals communs (Balaenoptera physalus) [de 0 à 66 individus], de petits rorquals (B. acutorostrata) [de 3 à 38 individus], de rorquals à bosse (Megaptera novaeangliae) [de 0 à 24 individus], d'épaulards (Orcinus orca) [de 5 à 58 individus] et de marsouins de Dall (Phocoenoides dalli) [de 101 à 241 individus]. On n'a pu déterminer si ces changements reflétaient une évolution du nombre de ces espèces dans la mer de Béring, ou simplement des modifications locales dans les schémas d'alimentation ou de répartition. On a aperçu des rorquals communs, des rorquals à bosse et des petits rorquals en train de se nourrir à proximité de grandes volées d'oiseaux qui se nourrissaient d'euphausiacés (Thysanoessa raschii et T. inermis).Mots clés: rorqual commun, petit rorqual, rorqual à bosse, épaulard, marsouin de Dall, Balaenoptera physalus, Balaenoptera acutorostrata, Megaptera novoaeangliae, Orcinus orca, Phocoenoides dalli, mer de Béring, alimentation des baleines