Storage and utilization of lipid classes and fatty acids during the early ontogeny of blue king crab, Paralithodes platypus

Stock enhancement, through the release of cultured juveniles, has been suggested as a possible recovery tool for depleted red (Paralithodes camtschaticus) and blue (Paralithodes platypus) king crab populations in Alaska, USA. Considerable progress has been made in the past decade in red king crab culture technology, but similar technologies are less developed for blue king crabs. We examined changes in organic content, lipid classes, and fatty acids (FAs) during the larval (zoeae), post-larval (glaucothoe), and first juvenile stages to understand energetics, nutritional requirements, and potential dietary deficiencies of this new aquaculture species. Total lipids increased throughout the larval stages and then showed a decrease in both total lipids and neutral storage lipids (triacylglycerols) during the non-feeding glaucothoe phase. The proportions of C18 polyunsaturated FAs (PUFAs) dramatically increased from the first zoeal (Z1) to the second zoeal stage (Z2), reflecting the uptake of enriched Artemia FAs. Both the selective retention of C20 & 22 PUFAs relative to their diet and the proportional increase in these PUFAs during the non-feeding glaucothoe stage suggest that they are essential for early growth and survival. Analytical measures of total lipids were highly correlated with a hatchery-based visual assessment of maximum lipid droplet size, an index of relative nutritional health. Formulated hatchery larval diets containing high levels of C20 & 22 PUFAs may optimize nutrition in early ontogeny for blue king crabs, but future research should refine specific ratios and absolute amounts.