Migratory Movements of Ovigerous Lobsters, Homarus americanus, Tagged off Grand Manan, Eastern Canada

Abstract

A total of 2139 ovigerous lobsters, Homarus americanus, were tagged and egg development recorded off Grand Manan, eastern Canada, during 1982–83. Recaptures during August 1982 to January 1984 totaled 1877, representing 1046 individuals including 457 that were captured 2–10 times. The single recapture data indicate that the majority (75%) of the lobsters moved < 15 km. Use of distance moved information from single recaptures of lobsters at liberty for long periods can be misleading, since exact distance moved between tag release–recapture points usually is unknown. Multiple recapture and depth at recapture data gave more information on the movements of the lobsters. Many lobsters showed seasonal shallow-deep migrations of > 20 km with recaptures in shallow (< 20 m) water during summer–fall and in deep (> 200 m) water during winter–spring. Many ovigerous females returned to the Grand Manan area the following summer. A few (7%) moved north > 30 km into the Bay of Fundy and south as much as 322 km along the coastline of Maine. Examination of the multiple recapture data between months indicated positive correlations between change in depth, distance moved, and water temperature. The seasonal depth migrations of ovigerous lobsters appear to be associated with maximizing temperatures which provide sufficient degree-days for completion of egg development. Also, hatching eggs in relatively warm shallow waters may confer a survival advantage for pelagic lobster larvae by decreasing development time to the benthic stage.