Killer Whales (Orcinus orca) Chasing Gray Whales (Eschrichtius robustus)

• Main Authors: In The Northern Bering Sea, Donald K. Ljungblad, Sue E. Moore
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Bering Sea; Lawrence Island; Arctic; Killer Whale; Orca; Orcinus orca; St Lawrence Island; Alaska; Killer whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.504.1130; http://pubs.aina.ucalgary.ca/arctic/arctic36-4-361.pdf

ABSTRACT. Sixteen killer whales ( O r c i w o m) were observed for 90 minucs as they approached and then chased gray whales (fichrichtiw robustus) in the Bering Sea north of St. Lawrence Island, Alaska. The killer whales swam in four discrete lines that blew synchronously as they a p proached an area in which gray whales were feeding. Once in the gray whales ' feeding area, the killer whales broke into small groups and dispersed. The gray whales, which had been dispersed while feeding, formed groups of three to six and swam away from the killer whales, except for one in-dividual. That whale was pursued by four killer whales swimming nearly abreast in a loose crescent formation with about 300 m between individuals. Although a sonobuoy was deployed throughout the observation period, no sounds were recorded from either species. The absence of whale sounds raises questions about how the whales detected one another and communicated between nearby conspecifics. Key words: killer whale (Orcinus orca), gray whale (Eschrichtius robustus), Bering Sea, predator/py, acoustics &UMfi. Seize tpaulards ( O r c i w orca) ont t t t observts pendant 90 minutes en train d'approcher et ensuite de chasser des baleines grises de Californie (Eschrichrius robwrus) dans la mer de Bering au nord de I'ile St. Lawrence, en Alaska. A I'approche de I ' d d'alimentation des baleines grises, les tpaulards nageaient en quatre lignes discdtes soufflant leurs colonnes d'eau de facon synchroni&. Une fois arrivts, les 6paulards se divisbrent en petits groupes et s'bparpillbrent. Les baleines grises, disper&s lors de la prise de nourriture, f o d r e n t des groupes de trois h six animaux et s'tloigdrent B la Rage des tpaulards, sauf un seul individu. Celuici fut pwrsuivi par quatre 6paulards nageant presque cBte h c6te dans une formation peu serf & en forme de croissant laissant quelque 3Ml m entre les individus. Bien qu'une radio-balise acoustique eut W dtployb durant la durte entikre de la Nriode &observation, aucun son n'a kt6 ...