EFFECT OF RATION AND SEAWATER TRANSFER ON FOOD-CONSUMPTION AND GROWTHOF ATLANTIC SALMON (SALMO-SALAR) SMOLTS

In Atlantic salmon smelts, fed at ration levels of 0.5, 1.0, and 3.0% body weight . day(-1), growth performance in fresh water was not a sig nificant determinant of subsequent seawater growth (P > 0.05). X-radio graphy was used to measure food consumption rates of individual fish. Consumption rates of fish fed low and intermediate rations were simila r in fresh water and seawater (P > 0.05). However, consumption rates f or fish fed a high ration level were two times greater in seawater tha n in fresh water (P < 0.05), possibly owing to higher temperatures. Sp ecific growth rates were generally negative in the period immediately following transfer to seawater and food consumption rates were lower t han in fresh water for fish on high ration levels. Specific growth rat es increased with increasing ration level in both fresh water and seaw ater. A linear regression model gave the best description for the rela tionship between individual specific growth rates and food consumption for all ration groups in both fresh water and seawater. Slopes and in tercepts for the low ration groups in fresh water were similar to valu es for the same fish in seawater (P > 0.05). The intermediate and high ration groups had steeper slopes in seawater than in fresh water (P < 0.001).