DIGESTIVE ENZYME SUPPLEMENTS TO INERT FEEDS FOR SMALL-EGG FISH LARVAE

INADEQUATE STARTER FEEDS SEVERELY HOLD BACK NEW AQUACULTURE ENTERPRISES SUCH AS PRESENT ATTEMPTS TO RAISE FISHES WHOSE LARVAE DEVELOP FROM SMALL EGGS AND HAVE VERY "DIFFICULT" FOOD REQUIREMENTS. INERT LARVAL FEEDS HAVE NOT SUCCESSFULLYELIMINATED THE STRICT DEPENDENCY ON NATURAL FORAGE DURING THE CRITICAL POST-LARVAL STAGE AFTER YOLK ABSORPTION AND BEFORE THE DEVELOPMENT OF A DIGESTIVE SYSTEM WITH A MORPHOLOGIC/FUNCTIONAL STOMACH AND, PRESUMABLY, TRUE EXOCRINE FUNCTION. WE PROPOSE TO TEST THE HYPOTHESIS THAT EXOGENOUS DIGESTIVE ENZYMES ARE ESSENTIAL WITH INERT FEEDS AND THAT BY SUPPLEMENTING AN OTHERWISE COMPLETE NUTRIENT "PACKAGE" IN MICROPARTICULATE FORM WITH A FULL COMPLEMENT OFPROTEASES, LIPASES, CARBOHYDRASES, AND CO-FACTORS, WE CAN ESTABLISH A FEASIBLE APPROACH TOWARD PERFECTING LARVAL FEEDS. OUR APPROACH WILL BE TO FIX DIGESTIVE ENZYME ACTIVITIES ON MICROPARTICULATE SUBSTRATES TO BE FED TO LARVAE ALONG WITH ASTANDARD LARVAL FEED (AP-100). THE "STANDARD" LARVAL FEED (AP-100) IS A VERY HIGH-QUALITY FORMULATION OF MACRO-AND MICROINGREDIENTS AND AS A SUPPLEMENT TO LIVE FORAGE UP TO 50% GIVES THE BEST GROWTH AND SURVIVAL OF ANY LARVAL FEEDINGSTRATEGY THUS FAR TESTED AND REPORTED, E.G. 25% SURVIVAL IN WALLEYE TRIALS (EHRLICH, 1986). CRITERIA FOR EVALUATING THE ENZYME SUPPLEMENTS' EFFICACY ARE TO BE GROWTH AND SURVIVAL THROUGH LARVAL METAMORPHOSIS AS STATISTICALLY CORRELATED WITH TREATMENT.