American lobster dynamics in a brave new ocean

Dynamic food webs and climate are changing lobster ecology and management. American lobsters (Homarus americanus) evolved in the North Atlantic under conditions of intense predation from large finfish such as Atlantic cod (Gadus morhua). Lobster's relatively extended brood period and large larval size result in high per capita pelagic phase survival, which, coupled with settlement habitat selection for predator refugia, contributes to the species' high lifetime reproductive success. However, the western North Atlantic is an extremely low diversity ecosystem prone to booms and busts. Extirpation of coastal predators released past constraints on lobster population growth such that lobster landings increased three-to five-fold since 1980 in Canada and the US. Climate change may stress lobsters in some regions and enhance stocks elsewhere, but it also facilitates warm-water species distribution shift northward. As lobster population densities and water temperatures increase, so do risks and consequences of disease. In the future we must expect the unexpected. Equilibrium conditions on which traditional fisheries management depends simply do not exist. This creates new challenges for managing this species regionally and into the future.