Humpback and blue whale photographic identification: Report of research in 1995

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Calambokidis, J., G.H. Steiger, and K. Rasmussen. 1996. Humpback and blue whale photographic identification: Report of research in 1995Final report to Monterey Bay, Channel Islands, and Olympic Coast National Marine Sanctuaries and Southwest Fisheries Science Center.Cascadia Research, 218? W Fourth Ave., Olympia, WA 98501. 37 pp.

Executive summary

This report summarizes research on humpback and blue whales along the west coast of the United States conducted by Cascadia Research in 1995. This research is part of a long term research effort designed to examine the distribution, population size, movements, migration patterns, and other aspects of the biology of these species. Research in 1995 was conducted with support of three National Marine Sanctuaries (Channel Islands, Monterey Bay, and Olympic Coast), Southwest Fisheries Science Center, and the University of California at Santa Cruz (as a part of the Marine Mammal Research Program) and was also designed to meet specific more regional objectives.

Photographic identification of natural markings was used to recognize and track individual whales. We conducted small boat surveys off the coast of Washington and California. Cascadia personnel conducted 59 days of surveys aboard either Cascadia inflatables or from the NOAA ship McArthur with deployed inflatables (Table 1). These surveys involved about 500 hours of effort and covered about 4,380 nmi. Additional research was conducted from whale watch boats, other opportunistic platforms, and by scientific collaborators. Survey coverage was extensive with heaviest effort off northern Washington, Monterey Bay to Bodega Bay, and the southern California Bight.

From 491 sightings of 1,039 humpback whales we identified 695 whales which revealed 352 different individuals (many whales were identified several times). This is the second highest number of identifications in a year since our research began and brings the total number of different humpback whales identified to 813. Primary areas where humpback whales were identified included the Santa Barbara Channel, Monterey Bay and waters north to off Half Moon Bay, the Gulf of the Farallones and Cordell Bank, and off the northern Washington coast. Frequent movement and interchange was seen among most of these regions with the exception of the northern Washington coast which appears to primarily be used by a separate group that feeds off northern Washington and British Columbia. A close connection including short transit times were documented between animals feeding off California and those wintering off Costa Rica and Panama (the furthest south a North Pacific humpback whale has been documented).

From 321 sightings of 550 blue whales we identified 379 whales which revealed 239 different individuals . As with humpback whales, this is the second highest number of identifications in a year since research began and brings the total to over 900 different individuals identified off California (more than 1,000 including Baja California). The vast majority of sightings and identifications were made in the southern California Bight. Although blue whales were seen and identified in other areas, including Monterey Bay and the Gulf of the Farallones, fewer animals were seen and identified in these regions compared to previous years. Movements of individual blue whales during the season were documented, including transits from southern California to northern California and from southern California to southern Baja California.