Meeting Abstract

28.4  Friday, Jan. 4  Declining Reproductive Output of the Blue Crab, Callinectes sapidus: A Changing Reaction Norm? WELLS, S.L.*; MCCONAUGHA, J.R.; Old Dominion University; Old Dominion University swells@odu.edu

In recent years there has been a reduction in the spawning stock of the Chesapeake Bay blue crab population, as well as lower than expected female reproductive output. The past five years this population has demonstrated strong inter- and intra-annual differences in eggs/brood, egg size, and reproductive energetics. The number of eggs/brood has significantly decreased since the late 1980�s. The previously determined allometric relationship between carapace width and fecundity is no longer valid suggesting that metabolic factors, including reduced prey availability, may be controlling reproduction. We examined the allocation and availability of energetic resources in the forms of lipids and proteins in the hepatopancreas, ovaries, and eggs. The concentrations in the hepatopancreas were lowest when the ovarian concentrations were highest indicating that stored resources had been mobilized to reproduction. Egg lipid and protein concentrations were highest at the beginning and peak times of the spawning season, but declined as the season progressed. Lipid fractions (triglyceride, phospholipid, and cholesterol) were quantified on inter- and intra-annual time scales. The lipid fraction concentrations of the hepatopancreas and ovaries were generally lowest during spawning, but varied before and after spawning. Concentrations of each fraction in the eggs were highest at the peak of each reproductive season, and then significantly decreased at the end of the season. The concentrations of each fraction for 2006 were much higher than 2005. The declines in lipid and protein concentration, as well as the lipid fraction concentrations, throughout the spawning season suggests that larvae produced later in the season may not be as viable as those produced earlier.