Validation and Application of Lipofuscin-Based Age Determination for Chesapeake Bay Blue Crabs Callinectes sapidus

Abstract

Quantifying lipofuscin (LF), a metabolic byproduct that accumulates in postmitotic cells. serves as one of the principal approaches for aging crustaceans, but the accuracy of this method remains an important issue. Here, we quantified LF accumulation as a function of chronological age and temperature (degree-days) in all economically important crustacean, the blue crab Callinectes sapidus, to test the accuracy of LF-based age estimates and determine the age-specific partial recruitment of juveniles to summer and fall commercial fisheries. Three known-age juvenile cohorts (63-83 d) were reared in ponds up to L8 years of age. Field collections were conducted in two subestuaries of Chesapeake Bay from June to October during 2003 and 2004. Lipofuscin accumulation oscillated seasonally in known-age cohorts. Significant (log(e) transformed) LF accumulation occurred at average intervals of 2.5 months. with the exception of winter months (mean temperature = 8 degrees C). Seasonalized von Betalanffy functions accurately depicted age-specific LF accumulation but were cohort specific. The relationship between LF and temperature degree-day (TD day) was similar among cohorts and genders, and a single LF-TD day model was applied to field-collected crabs. The mean age prediction error of this model was 2.0 months. Lipofuscin-based age composition of field collections indicated that the peeler-soft crab and hard crab fisheries were predominately composed of recruits less than age 1.5 from August to October. The consequences of this short (approximately annual) generation time is that recruitment and landings will be responsive to environmental factors affecting growth and the annual variations in egg production, settlement. and postsettlement survival.