Comparing Habitat Suitability Forecasts for the Gulf of Maine and Southern New England American Lobster Stocks

Abstract

ABSTRACT The future of American lobster (Homarus americanus; H. Milne Edwards, 1837) habitat has been extensively studied in the Gulf of Maine and Georges Bank regions, but studies quantifying spatiotemporal changes to suitable habitat in Southern New England (SNE) regions remain sparse. The American lobster stock assessment for SNE is conducted separately from the northern stock because of negligible migration and recruitment sharing between them. This fact, coupled with the assumption of spatial nonstationarity between the two stocks when it comes to environmental preferences, suggests that analyses of suitable habitat must be conducted for each stock region independently. This study employs the use of a previously developed habitat suitability index model for American lobster to map historical and forecasted habitat in both the Gulf of Maine and SNE stock regions so that comparisons between long-term forecasts can be accurately made. The suitability indices generated in this study support the hypothesis of environmental nonstationarity between the stocks, with lobster in SNE preferring significantly different environments than their northern counterparts. In the coming decades, the Gulf of Maine lobster fishery may see changes in lobster migration timing as spring suitability decreases and fall suitability rises, whereas the SNE fishery will most likely see the continued use of northern waters by lobsters as more southern waters become less suitable. The rate of change in SNE remains smaller than in the Gulf of Maine owing to the lesser rate of warming observed.