The impact of ocean warming on juvenile American lobster recruitment off southeastern Massachusetts

During the 1990s, coastal habitat off southeastern Massachusetts (SEMA) supported commercially viable fisheries for American lobster (Homarus americanus). Over the past two decades, landings and post-larval settlement of lobsters in this region, which is near the southern edge of the species' range, have declined substantially, concurrent with a period of significant warming of the coastal waters off southern New England. Previous work has suggested that rising ocean temperatures may adversely impact the survival of larval and early benthic phase (EBP) lobsters and may cause adult lobsters to seek cooler offshore waters during the critical time of larval release. To investigate the manner in which the observed decline in lobster abundance may be linked to warming coastal waters, a high-resolution hydrodynamic model was used to quantify the increase in water temperature experienced by EBP lobster off SEMA and to supply input to an individual-based model of lobster larval transport from release areas delineated using fishery-dependent data of late-stage egg-bearing lobsters. The results indicate that rising coastal water temperatures may have adversely impacted EBP lobster recruitment off SEMA by (1) causing an offshore shift in the area of larval release that resulted in a reduction in the delivery of larvae to suitable nearshore EBP habitat and (2) dramatically increasing thermal stress experienced by recently settled EBP lobsters. These findings highlight the implications of warming coastal waters on southern New England lobster population connectivity and provide insight to an understudied mechanism by which climate change affects marine species recruitment.