Condition of laboratory-reared and wild-caught larval Atlantic menhaden Brevoortia tyrannus as indicated by metabolic enzyme activities

Abstract

As part of the South Atlantic Bight Recruitment Experiment (SABRE), the condition of larval Atlantic menhaden Brevoortia tyrannus from Onslow Bay, North Carolina, USA, was determined. The activities of the metabolic enzyme lactate dehydrogenase (LDH) were assayed in larval Atlantic menhaden to determine nutritional condition of laboratory-reared and wild-caught larvae on cruises in 1992 to 1994. In laboratory calibrations, larvae whose first feeding was delayed had depressions in protein-specific LDH activities, and LDH activity appeared to scale with length. Wild larvae had LDH activities within the range of activities found in laboratory-reared larvae and were classified into 3 nutritional categories based on length and LDH activities. Fewer than 30% of larvae collected from the majority of stations were classified in superior condition. No differences were detected between larvae collected during the day and those collected at night. Significant decreases in condition were evident with increasing distance from the Gulf Stream Front. LDH activities indicated that a substantial percentage of wild-caught menhaden larvae were poorly nourished during the period examined.