Climate Changes and Lobster in the Gulf of Maine: Investigating the Temporal Impact on Moulting

The American lobster (Homarus americanus) is a major part of Maine’s economy. The Maine lobster fishery is mainly a recruitment fishery with most landings consisting of individuals newly moulting into the fishery. Thus, the timing of the annual moult is critical to the fishery, resulting in adverse effects if moulting occurs too early, creating an oversupply of lobster and price depression, as it did in 2012. We hypothesize that the spatial and temporal variability of the lobster moult is linked to variability in cumulative bottom temperature effects, both acute and long term, in the Gulf of Maine (GOM). The hypothesis was tested by quantifying the distribution of moult timing and evaluating the annual variability in the moult timing distribution. This annual variability was compared to the distribution of cumulative average temperature and degree-day events in nearshore bottom temperatures in the GOM that precede the annual peak moulting date. Lobster sea sampling data from the Maine Department of Marine Resources and bottom temperature data modelled by Finite Volume Community Ocean Model (FVCOM) were used during this investigation. This study will better inform both lobstermen and regulators as to how climate changes may influence lobster moulting and, in turn, the lobster fishery.