Long-term effects of EPA and DHA enriched diets on digestive enzyme activity, aerobic scope, growth and survival in age-0 Lake Sturgeon (Acipenser fulvescens)

Abstract

Nutritional condition during early life could have long lasting effects on metabolism, growth trajectory and ultimately ecological fitness. We examined effects of Artemia nauplii enriched with eicosapentaenoic acid (EPA; C20:5n3) and docosahexaenoic acid (DHA; C22:6n3) on fatty acid profile, digestive enzyme activity, energy density, aerobic scope, growth and survival in age-0 Lake Sturgeon (Acipenser fulvescens). Four diets were used in the study: 1) control (absence of EPA and DHA): freshly hatched Artemia nauplii, 2) low DHA: Artemia enriched with Chlorella vulgaris, 3) high DHA: Artemia enriched with Red AlgaMac and 4) time-control: Artemia left for the time to match growth that would occur during the enrichment. At 20 days post hatch (dph), fish were fed one of four diets three times a day ad libitum for 29 days after which all fish were fed the same diet of bloodworm twice a day ad libitum until the end of the experiment, which included a simulated overwintering event for 45 days at 3 °C. Fish were sampled after 24 days of feeding the aforementioned diets, as well as before and after the simulated overwintering event at 145 and 190 dph, respectively. Fish fed the high DHA diet did not change the measured parameters compared to fish fed the control diet after 24 days of feeding; however, before overwintering fish fed high DHA showed higher lipase activity (p = 0.01) compared to the control group and significantly increased body mass when temperature decreased (p < 0.05). Further, fish fed the high DHA diet showed a substantially lower mortality than fish fed the control diet following the diet transition from Artemia to bloodworm (44%; p < 0.05). Our results suggest the importance of EPA and DHA during early life on growth and survival, which could be used to improve post-release survival rates in conservation aquaculture of Lake Sturgeon, a species at risk or endangered across its natural range.