A comparison of first feeding characteristics in two populations of Chinook salmon

Timing, growth, and survival during the transition from yolk absorption to active feeding were examined in two hatchery populations of chinook salmon Oncorhynchus tshawytscha from southeastern Alaska (Andrew Creek and the Tah ini River). Alevins were divided into fed and nonfed groups and cultured un der experimental conditions from hatching to yolk absorption. Andrew Creek alevins benefited from feeding earlier in their development than Tahini Riv er alevins and were significantly larger in size than nonfed alevins at yol k absorption (P < 0.001). Fed Tahini River alevins were also larger in size than nonfed fish at yolk absorption (P = 0.03), but the relative increase in size was considerably less than for Andrew Creek alevins. Survival excee ded 93% for all groups; it did not differ within (P > 0.32) or between (P > 0.09) populations, but the survival of Andrew Creek alevins was significan tly higher than that of Tahini River fish (P = 0.03). Intraspecific variati on in feeding ontogeny should be considered in determining the optimum time to initiate feeding in chinook salmon.