Temperature and Lobster, Homarus americanus, Yield Relationships

Abstract

Commercial landings of American lobster (Homarus americanus) have increased dramatically in many areas along the east coast of Canada since the late 1970's. Average annual sea surface temperatures (SST) were analysed to test if lobster landings were related to changes in the marine environment. Time series models were fitted to lobster landings and SST data from Maine (USA), Halifax County (Nova Scotia), and Charlotte County (New Brunswick). Including temperature in the models improved forecasting ability for lobster catches for Maine and Halifax but not Charlotte. In Maine, lobster landings in year t were related to SST in year t. In Halifax, however, landings were related to SST in the previous 4 yr but not by SST of the current year. Lower fishing effort levels for Halifax compared with Maine probably extended the yield from strong year-classes through a number of years. We surmise that an increase in sea temperature near Halifax during the early 1980's increased the survival and growth rates of lobster juveniles. This provided a strong pulse of recruits to the fishery throughout coastal Nova Scotia during the mid- to late 1980's. Similar increases in temperature and landings were not observed for Maine and Charlotte.