Graduation Year

2012

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Marine Science

Major Professor

Kendra L. Daly

Keywords

Aging, Blue Crab, Callinectes sapidus, Crustaceans, Growth, Lipofuscin

Abstract

The blue crab, Callinectes sapidus, represents an ecologically and economically important component of marine and estuarine ecosystems. In Florida, blue crab landings accounted for $9.6 million dollars during the 2010 fishing season. Accurate stock assessments for this valuable fishery are essential. Age is a critical biological component of accurate stock assessments; however, blue crabs and other crustaceans are especially difficult to age because of the complex nature of discrete growth. Biochemical extraction of an aging pigment, lipofuscin, was developed using blue crab eyestalks. The current study investigated the effects of freezing preservation on lipofuscin extracts and examined whether the extraction methodology, developed by Chesapeake Bay researchers, was useful for aging Tampa Bay blue crabs populations. Significant differences in lipofuscin index were found between samples frozen (2 weeks at -80°C) prior to analysis and those processed and assayed immediately (p < 0.001). Quarterly assays of the cohort of known-age individuals revealed a negative linear trend (y = -0.12x + 0.49, p < 0.001) in lipofuscin index over a 12-month period. This result suggests that extraction of lipofuscin is not appropriate for age determination of Florida blue crabs. Investigations into possible causes of the negative trend in lipofuscin suggest this method deserves further examination and refinement before it is acceptable as a reliable method for age determination in Florida blue crabs. Growth data of the known-age population collected during this study revealed that blue crabs in Tampa Bay can reach exploitable size in under sixth months and female crabs can reach sexual maturity within seven months of hatching. These growth patterns have the potential to enhance future Florida stock assessments.

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