K. D. Reppond

Change in Biochemical Composition During Development of Snow Crab, Chionoecetes opilio, Embryos

Abstract Adult oveigerous female snow crab, Chionoecetes opilio, were obtained approximately bimonthly from the eastern Bering Sea for embryonic sampling and biometric information. Biochemical analysis of embryo samples included determination of moisture, ash, total lipid, protein content, fatty acid profile, and lipid profile. Moisture increased as the embryos matured. Protein content remained unchanged, ash content increased, and lipid content decreased on a dry weight basis coincident with embryonic development indicating that lipids were the main energy source of developing embryos. The utilization of saturated, monounsaturated, and polyunsaturated fatty acid categories during development was similar but individual fatty acids within each category varied considerably. Over 75% of the C14:0, C18:4(n-3), and C20:1(n-11) fatty acids were consumed during the embryonic development from nauplius to pre-hatch while C22:5(n-3), C20:5(n-3), and C18:1(n-9)cis fatty acids were utilized at 49%, 57%, and 48% respectively. Docosahexaenoic acid, DHA, C22:6(n-3), was among the least utilized fatty acid at 36%. Forward stepwise general discriminant analysis of fatty acid profiles indicated that determination of fatty acid profiles could be used to distinguish between embryos at the nauplius stage and the prehatching stage of development but not among embryos at intermediate stages. Triacylglycerides provided the energy source during development. This research highlights the potential nutrient requirements critical to early life-history development of Bering Sea snow crabs.

Enzymatic Digestion of Eye and Brain Tissues of Sockeye and Coho Salmon and Dusky Rockfish Commercially Harvested in Alaska

Potential feed ingredients with high lipid content were made by enzymatic digestion followed by centrifugation of eye tissue from dusky rockfish (Sebastes ciliatus), coho salmon (Oncorhynchus kisutch), and sockeye salmon (Oncorhynchus nerka), and brain tissue from sockeye salmon. Supernatant fractions contained significant levels of docosahexaenoic acid and eicosapentaenoic acid and were essentially pure triacyglycerides. For the digest of sockeye salmon brain tissue, the lipids were mainly composed of phospholipids (74%) and sterols (22%). Assays for amino acid profiles and mineral content of the precipitant layers were also performed.