Egg Loss from the American Lobster, Homarus americanus, in Relation to Nemertean, Pseudocarcinonemertes homari, Infestation

Abstract

The relationship between nemertean (Pseudocarcinonemertes homari) infestaton and egg loss from ovigerous American lobsters, Homarus americanus, trapped near Grand Manan, New Brunswick, was investigated during 1980–83. The proportion of lobster eggs lost each month was variable, but generally increased to a maximum of 0.38–0.43 at the end of each of the three egg incubation periods. Up to 6.3% of the newly ovigerous lobsters tagged (N = 1413) during July–October 1982 has lost all their eggs by April–July 1983. Most ovigerous lobsters (74%) were infested with P. homari, but many lobsters had low mean densities of nemerteans (< 2/1000 lobster eggs). There was a significant but low correlation between P. homari densities and the proportion of eggs lost; however, egg losses could not be attributed solely to P. homari. Egg loss did not differ significantly between uninfested and nemertean-infested lobsters during each of the three egg incubation periods. The few lobsters that acquired high densities (> 4) of P. homari during the early stages of egg incubation appeared to suffer extensive or complete egg mass destruction. However, most lobsters maintained low densities (< 2) of nemerteans and hatched most (> 60%) of their eggs.