Evaluation of commercial diets on the growth performance of cultured Lake Whitefish

ABSTRACT Objective Populations of Lake Whitefish Coregonus clupeaformis in Lakes Huron, Ontario, and Michigan and some areas of Lake Superior have been in decline, affecting Indigenous communities and commercial fishing in the Laurentian Great Lakes region. To maintain access to this valuable resource, the Lake Whitefish is being explored as a new aquaculture species in Ontario, Canada. This study aimed to evaluate the growth performance, somatic indices, and whole-body carcass composition of cultured Lake Whitefish that were fed three commercial diets. Methods Commercial diets designed specifically for Lake Whitefish do not exist. Three commercial aquaculture diets with similar gross energy (22 MJ/kg) and differing levels of crude protein and crude fat were examined: Skretting Nutra RC (52% protein; 17% lipid), Bluewater Trout (43% protein; 21% lipid), and Bluewater Tilapia (45% protein; 19% lipid). Results After juvenile Lake Whitefish (125 g) were fed the diets for 140 d at 14°C, no significant differences in performance (weight, fork length, specific growth rate, thermal growth coefficient, and survival) were observed among dietary treatments. Fish that were fed the Bluewater Trout diet exhibited numerically higher body weight (mean ± SE = 294.18 ± 8.65 g) and viscerosomatic index (7.836 ± 0.159) compared to those fed the other diets, but the differences were not statistically significant. No effect on whole-body carcass composition was observed. Conclusions Juvenile Lake Whitefish were successfully reared on existing trout and tilapia diets, with no significant differences in growth or survival among treatments. Fish that received the higher-lipid Bluewater Trout diet showed a numerical growth advantage, suggesting that dietary lipid influences energy utilization and tissue deposition. Further research should determine species-specific protein-to-energy requirements to optimize growth and fillet yield.