SWIM BLADDER INFLATION PHYSOCLISTOUS FISH

EVALUATION, THE FINAL ONE FOR THE PROJECT, IS BASED ON EXAMINATION OF RESEARCH DATA TO BE PUBLISHED SHORTLY IN FINAL FORM. IN GENERAL, RESEARCH WAS CONDUCTED AS PLANNED. HOWEVER, WHEN IT BECAME OBVIOUS IN THE EARLY STAGES OF RESEARCH THAT DISSOLVED OXYGEN RATHER THAN TEMPERATURE WAS OF CRITICAL IMPORTANCE, RESEARCH FOCUS WAS SHIFTED TO OXYGEN AND TEMPERATURE COMPARISONS WERE DELETED. AS A RESULT, ONLY ONE TEMPERATURE WAS USED DURING EXPERIMENTATION. RESEARCH DEMONSTRATED THAT LOW DISSOLVED OXYGEN LEVELS (LEVELS PREVIOUSLY BELIEVED TO BE SUITABLE FOR LARVAL FISH CULTURE) CAN CAUSE ABNORMAL DEVELOPMENT OF THE SWIM BLADDER IN PHYSOCLISTOUS FISH. THIS PROBLEM HAS BEEN A SEVERE ONE, CAUSING HEAVY HATCHERY MORTALITIES OF MULLET AND STRIPED BASS, AND WAS PREVIOUSLY BELIEVED TO BE CAUSED BY IMPROPER DIET. WORK TO CORRECT THE PROBLEM HAS BEEN DIRECTED TOWARD DIET MODIFICATION, WHILE REARING WAS CONTINUED IN PONDS AND TANKS AT IMMEDIATE DISSOLVED OXYGEN LEVELS KNOWN TO BE SUITABLE FOR LARGER FISH. SINCE DISSOLVED OXYGEN LEVELS CAN BE CONTROLLED EASILY IN FISH HATCHERIES, APPLICATION OF RESEARCH RESULTS AND CORRECTION OF THE PROBLEM CAN BE EXPECTED TO FOLLOW PUBLICATION OF RESEARCH FINDINGS. RESEARCH HAS BROAD IMPLICATIONS FOR HATCHERIES THAT ARE BEING USED AND DEVELOPED WORLDWIDE TO REAR BRACKISH WATER AND MARINE FISH OF ECONOMIC IMPORTANCE IN AQUACULTURE. THE PRESENT PROJECT IS A GOOD EXAMPLE OF THE CONSTRUCTIVE USE OF SMALL PROJECT RESEARCH FUNDS. THE WORK, WHICH HAS RESULTED IN AN IMPORTANT BREAKTHROUGH IN HATCHERY TECHNOLOGY, WOULD PROBABLY NOT HAVE BEEN FUNDED BY OTHER US AGENCIES, BECAUSE THE SPECIES INVOLVED ARE MOSTLY LOW-PRICED FISH OF LITTLE ECONOMIC IMPORTANCE IN THE US. APPENDED ARE COPIES OF TWO GRANT-FUNDED RESEARCH PAPERS AND THE ABSTRACT OF A THIRD (PD-AAH-298-C1) AND A BIBLIOGRAPHY ON RESEARCH-RELATED ISSUES (XD-AAH-298-1).