SOME TESTS OF THE MIGRATION-HYPOTHESIS FOR ANADROMOUS DOLLY-VARDEN (SOUTHERN FORM)

Some aspects of a previously described migratory paradigm for the sout hern form of anadromous Dolly Varden Salvelinus malma were investigate d with seven 3-year mark-recapture experiments on fish that used lakes in eight watersheds as their winter residence. Weirs on Kodiak Island , around Prince William Sound, and near Juneau, Alaska, were used to c apture Dolly Varden as they emigrated td the sea each spring. Dolly Va rden (greater than or equal to 200 mm fork length) were individually m arked during the first year of each experiment (1989 or 1990), and log -linear models of their capture histories were used to estimate probab ilities of capture during the second year (1990 or 1991). Our observat ions on timing of spring emigration and dispersal of Dolly Varden at s ea confirm observations from earlier studies. Our results support the paradigm that Dolly Varden home to the same lacustrine watershed when overwintering in fresh water, as more than 98% of the recaptured fish did so. Our results contradicted the paradigm that Dolly Varden return to lakes each fall, for across study populations, 14-58% failed to re turn. The most probable explanation for this anomalous behavior is tha t some Dolly Varden spend the winter at sea. Differences in maturity, size, and growth of Dolly Varden and timing of their entrance into sal t water during spring emigration were excluded as causes of this anoma lous behavior.