Migration and population structure of northeastern Pacific whales off coastal British Columbia: An analysis of commercial whaling records from 1908-1967.

Data recorded from 24,862 whales killed by British Columbia coastal whaling stations between 1908 and 1967 revealed trends in the abundance, sex ratio s, age structure, and distribution of sperm (Physeter macrocephalus), fin ( Balaenoptera physalus), sei (Balaenoptera borealis), humpback (Megaptera no vaeangliae), and blue (Balaenoptera musculus) whales. The catch data were a nalyzed using annual and monthly mean values. Monthly and annual variation in whaling effort was deduced from accounts of the history of British Colum bia coastal whaling, and biases arising from changes in effort were conside red in the interpretation of the results. During the later years of whaling (1948-1967), the mean lengths of captured whales declined significantly an d pregnancy rates dropped to near zero in fin, sei, and blue whales. Monthl y patterns in numbers killed revealed a summer migration of sei and blue wh ales past Vancouver island, and confirms anecdotal suggestions that local p opulations of fin and humpback whales once spent extended periods in the co astal waters of British Columbia. Furthermore, the data strongly suggest th at sperm whales mated (April-May) and calved (July-August) in British Colum bia's offshore waters. The historic whaling records reveal much about the m igratory behavior and distribution of the large whales species as they once were, and may continue to be, in the northeastern Pacific. Verifying the p ersistence of these trends in the remnant populations is a necessary and lo gical next step.