LIMITATIONS OF CARRAGEENAN MICROBOUND DIETS FOR FEEDING WHITE STURGEON, ACIPENSER-TRANSMONTANUS, LARVAE

Utilization of carrageenan microbound (CMB) diets by white sturgeon la rvae was evaluated using biochemical, histological and histochemical m ethods. Compared with a control group fed Biodiet, a commercial salmon id diet, larvae fed the CMB diets for 16 days had a significantly (P < 0.05) higher moisture content but lower growth, survival, and whole b ody amino acid and lipid contents. Although growth and survival of CMB -fed larvae were significantly higher than those of starved larvae, hi stological signs such as degenerated cells in liver and intestine are indicative of starvation-like conditions. Feeding CMB diets also induc ed a decrease in activity of alkaline phosphatase, aminopeptidase M, a nd nonspecific esterase in the brush border of intestinal cells. Even though the CMB diets present three desirable characteristics for sturg eon larvae such as appropriate size, soft texture and availability on the bottom of tanks, they an not recommended because they have three m ajor drawbacks. First, CMB diets have to be kept fresh, and distribute d in solution for a bottom feeder like sturgeon. Second, sturgeon larv ae have trouble locating and ingesting the CMB diets. Finally, assimil ation of nutrients from CMB diets is possibly restricted by limited ab ility of sturgeon larvae to break down and digest the carrageenan matr ix.