Spatiotemporal variation in the reproductive dynamics of female American lobsters, Homarus americanus, on the northeastern continental shelf of the United States

Abstract

The American lobster, Homarus americanus, fishery in the United States occurs along the northeastern continental shelf. It is managed as two biological stock units – the Southern New England stock and the Gulf of Maine / Georges Bank stock. Recruitment has declined over the last decade, but there is a lack of broad-scale and high-resolution information on spatiotemporal variation in female reproductive traits, especially in offshore waters. This study addressed this issue using geolocated biological data sampled over an eleven-year period by the Commercial Fisheries Research Foundation’s Lobster and Jonah Crab Research Fleet. We detected significant heterogeneity in the spatial distribution of female lobsters, and in the spatial distribution and phenological variations in ovigerous lobsters. The prevalence of ovigerous female lobsters decreased in spring and increased in fall. However, the timing of the spring and fall events, and the magnitude of the summer decrease, differed between stocks and between areas within each stock. In general, warmer areas were associated with an earlier spring decrease, a later fall increase, and a greater depletion of ovigerous females during summer. Regional differences were associated with phenological variation in egg development. Our results provide the first shelf-wide, high-resolution overview of female lobster reproductive phenology on the U.S. continental shelf and offer a foundation for future research into links between lobster reproduction and long-term shifts in harvesting, environmental conditions, and conservation policies.