Biology and Marine Biology
University of North Carolina Wilmington
601 S. College Road
Wilmington, NC 28401
This project continued exploratory work funded by Sea Grant in 2007 (DV-07-009) to evaluate various factors influencing the quality of eggs produced by American lobsters. Larger lobster eggs have been shown to have higher lipid contents, faster growth, and result in larger larvae; and that the lipids and fatty acids comprising the fat content of an egg will have a significant influence on growth rates and size of larvae at hatching, which increases the probability of survival to adulthood. In this preliminary survey, University of North Carolina researcher Heather Koopman found that large lobsters in fact did not have the greatest amount of lipid in their eggs and had consistently lower levels of omega-3 fatty acids than small or medium lobsters. The second round of funding supported further sample collection and analysis of lobster egg size, lipid content, energy content, and seasonal variation.
"There is little support for the generalization that the largest females are producing the best eggs," said Koopman. "Rather, our data suggest that some of the very large females may be producing fewer eggs, with less lipid content, and lower Omega-3 levels, than would be expected. In addition, egg size appears to be maximized at an intermediate female size." Koopman thinks it possible that some very large (and by assumption, very old) female American lobsters may be exhibiting reproductive senescence (defined as a decline in reproductive performance prior to mortality). Reproductive senescence is unusual in invertebrates, and is normally known to be a characteristic of mammals. However, the American lobster is extremely long-lived (believed to live up to 100 years and perhaps longer) with indeterminate growth, making it an excellent test subject to study this phenomenon. Koopman will continue investigating this question, which has implications for the lobster fishery.