Lipid class dynamics during development in early life stages of shortbellyrockfish and their application to condition assessment

Lipid class dynamics and the relationship between weight and length were an alysed during early life stage (ELS) development in wild populations of sho rtbelly rockfish Sebastes jordani to investigate their utility in a conditi on or nutritional status assessment. Analyses from more than 3000 field-cap tured shortbelly rockfish indicated little variation in weight for a given length and provided limited application in the assessment of condition. The fractionation of total lipids into individual classes revealed trends in l ipid metabolism throughout development. These trends were described best us ing a stage-specific regression model, since Sebastes show defined early li fe history transitions. Among developmental stages, triacylglycerols (TAG) and polar lipids (PL) were the dominant lipid classes and cholesterol (CHOL ). sterol/wax esters. and nonesterified fatty acids were found in lower con centrations. In the preflexion stage, low concentrations and constant level s of TAG alone with the combined influence of endogenous and exogenous sour ces of energy compromised the use of TAG as an index of nutritional status. However. during flexion through juvenile stages, TAG levels increased indi cating an accumulation of energy reserves with development, thus providing a valid indicator of nutritional status in later stages. Large fluctuations in PL concentrations during development suggested complex metabolism which may be due to changes in cell volume and cell membrane proliferation with development as well as catabolism. CHOL declined in larval stages, then rem ained constant with increasing size through the juvenile stage. negating it s use as a normalizer for variations of mass in a TAG/CHOL ratio prior to j uvenile transformation. This study provides the first documentation of lipi d dynamics during early life stages following parturition in a marine vivip arous teleost.