Depredating sperm whales in the Gulf of Alaska: local habitat use and long distance movements across putative population boundaries

• Published in: Endangered species research Vol. 24; no. 2; pp. 125 - 135
• Main Authors: Straley, JM, Schorr, GS, Thode, AM, Calambokidis, J, Lunsford, CR, Chenoweth, EM, O’Connell, VM, Andrews, RD
• Format: Journal Article
• Language: English
• Published: Inter-Research 01.01.2014
• Subjects: Marine; Physeter catodon; INE, USA, Alaska, Alaska Gulf; INE, Pacific, California Current; INE, USA, Alaska
• ISSN: 1863-5407; 1613-4796
• DOI: 10.3354/esr00595

Satellite tags were attached to 10 sperm whales Physeter macrocephalus (1 whale was tagged in 2 different years) to determine the movements of sperm whales involved in removal of sablefish from longline fishing gear in the Gulf of Alaska (GOA). Tags transmitted from 3 to 34 d (median = 22) in 2007 and 7 to 158 d (median = 45) in 2009. Seven whales stayed in the GOA; all were associating with fishing vessels along the slope. Two whales headed south in June shortly after being tagged; one reached the inner third of the Sea of Cortez; the other's last location was offshore Mexico at 14 degree N. A third whale stayed in the GOA until October and then headed south, reaching central Baja, Mexico, 158 d after tagging. The whales that travelled to lower latitudes followed no pattern in timing of departure, and at least 2 had different destinations. All whales passed through the California Current without stopping and did not travel to Hawaii; both are areas with known concentrations of sperm whales. Whales travelled faster when south of 56 degree N than when foraging in the GOA (median rate of median horizontal movement = 5.4 [range:4.1 to 5.5] and 1.3 [range:0.6 to 2.5] km h super(-1), respectively). Tagged sperm whales primarily travelled over the slope, but one spent considerable time over the ocean basin. Information on the timing and movement patterns of sperm whales may provide a means for fishermen to avoid fishing at whale hot spots, potentially reducing interactions between whales and fishermen.