Demographic Assessment of the Blue Crab (Callinectes Sapidus) in Chesapeake Bay Using Extractable Lipofuscins as Age Markers

The blue crab (Callinectes sapidus) plays an important economic and ecological role in estuaries and coastal habitats from the Gulf of Mexico to the east coast of North America, but demographic assessments are limited by length-based methods. We applied an alternative aging method using bio­ chemical measures of metabolic byprod­ ucts (lipofuscins) sequestered in the neural tissue of eyestalks to examine population age structure. From Chesa­ peake Bay, subsamples of animals col­ lected from the 1998–99 (n=769) and 1999–2000 (n=367) winter dredge sur­ veys were collected and lipofuscin was measured. Modal analysis of the lipo­ fuscin index provided separation into three modes, whereas carapace-width data collected among the same indi­ viduals showed two broad modes. Lipo­ fuscin modal analysis indicated that most adults (carapace width >120 mm) were <2 years old. The results indicate that use of extractable lipofuscin can provide a more accurate and better resolved estimation of demographic structure of blue crab populations in the field than size alone. Manuscript accepted 21 October 2002. Manuscript received 31 December 2002 at NMFS Scientific Publications Office. Fish. Bull 101:312–320 (2003). Demographic assessment of the blue crab (Callinectes sapidus) in Chesapeake Bay using extractable lipofuscins as age markers*