THE BIOENERGETICS OF THE SABLEFISH ANOPLOPOMA FIMBRIA OCCURRING OFF SOUTHERN CALIFORNIA AND ENERGY ALLOCATION DURING LOW-FREQUENCY FEEDING IN DEEP-LIVING BENTHOPELAGIC FISHE

Large benthopelagic marine fishes are noted to congregate at bait falls on the ocean floor. Deep-living benthopelagic fish, such as Macrourids, have been found with both benthic and midwater organisms in their stomachs. For these large deep-sea fishes living in close association with the sea floor, it is speculated that food supplies are low, or episodic in occurrence. The physiological and biochemical energetics of feeding on large, infrequent meals is investigated utilizing the sablefish, Anoplopoma fimbria, a benthopelagic fish that occurs as deep as 1500 meters at the southern end of its range. Sablefish were used as a model of endemic deep-sea fishes because they can be brought into the laboratory alive for physiological studies.;Field studies showed that sablefish were attracted to bait falls, and were commonly caught with Macrourid species in the Southern California Bight area. In the laboratory, growth, excretion, ingestion and respiration rates were measured. Sablefish fed on large rations (15% of the wet body weight of fish) every seven to ten days showed growth rates two to three times higher than known growth rates for field fish. Starved sablefish in the laboratory had sufficient energy to survive up to 200 days at 8(DEGREES)C. Energy allocation showed slow growth rates, low conversion efficiencies, and low metabolic rates as adjustments made to large, infrequent meals.;The influences of body size, ration size, season and latitude on several biochemical properties of the skeletal muscle and liver were examined in sablefish to understand how biochemical parameters reflect physiological condition of an organism. Activities of muscle glycolytic enzymes (lactate dehydrogenase, (LDH) and pyruvate kinase (PK)) increased significantly with increased body size. Starvation led to a large decrease in the muscle glycolytic enzyme activity. The LDH activity in the muscle was directly proportional to the amount of food ingested.;Monitoring the respiration and excretion rates of sablefish during long term food deprivation experiments showed that the fish were able to suppress respiration rates, and switch between protein and lipid energy stores throughout the course of starvation. It appears possible, with further investigation, to estimate ration levels of deep-sea benthopelagic fishes from biochemical parameters alone.