Growth and stamina of sea-water acclimated juvenile fall chinook salmon

Graduation date: 1970Juvenile fall chinook salmon were acclimated to full strength sea water at 66, 73, and 80 days after hatching. Survival in sea water for 14 days was used as the criterion for successful acclimation. The growth of salmon acclimated to sea water was slower over the period of observation (134 days) than the growth of fish from the same parental stock held in fresh water and 50 percent sea water at similar temperatures. The additional energy required for osmoregulation in full-strength sea water was thought to reduce growth. The larger size of fish held in fresh water and 50 percent sea water was reflected in their higher stamina as determined by their ability to swim against a current of known velocity. Where fish acclimated to sea water were similar in size, though older in age, to fish held in fresh and low salinity water, there were no obvious differences in stamina. From the results of this work, it seems feasible to acclimate juvenile fall chinook salmon to full-strength sea water within 90 days after hatching. Low mortality can be anticipated from exposure to high salinity, but growth will be slowed at least temporarily. Successful acclimation can be achieved by placing fish in 50 percent sea\ud water 40 days after hatching and feeding them for 50 days before transferring them to full-strength sea water