EVALUATION OF THE EFFECTS OF AN ALTERNATIVE FEEDING REGIME APPLIED IN THE HATCHERY ON GROWTH AND BODY COMPOSITION OF JUVENILE CHINOOK SALMON Oncorhynchus tshawytscha

The environment of hatchery raised fish is significantly different from the conditions in the wild with regard to food/ feeding rates and water temperature.  Some hatcheries have very little temperature fluctuation during the fishes' rearing period.  Even if the hatchery used the available creek water, the feeding regimes and the food used is quite different from the wild fish diet.  The conditions under which the fish are raised could have a great effect on their growth/morphology.

A feeding trial was conducted at a National Fish Hatchery to determine the effects on the fish of alterations in the level of feed provided at a key developmental period.  Test fish were fed one half of normal rations from July through November while control fish were fed normal rations. The reduced ration treatment did significantly reduce the whole body lipid level, fork length and percent weight gain in the fish. When the full ration was resumed and fed until April, the fish gained whole body lipid to equal the full fed treatment fish.  However, the fork length and percent weight gain remained significantly less.