Does Lobster Trap Bait Influence the Maine Inshore Trap Fishery?

Abstract

The potential role of lobster trap bait as a significant food subsidy contributing to unprecedented recent increases in abundance and landings of the American lobster Homarus americanus is seldom considered seriously outside the fishing community. Although bait input is a very small source of organic carbon compared with primary production, the yearly input of bait per unit area to the inshore waters of the Gulf of Maine is about 85 kg/ha, an amount equal to a very productive fishery yield from a marine area. Because much of the bait is imported from outside the inshore area of the Gulf of Maine, it represents a direct subsidy to secondary production within this portion of the system. An empirical relationship between fish yield and primary production in phytoplankton-based marine systems suggests that inshore primary production would have to be increased by about 80% to provide an increment in fish yield equal to the bait input. Moreover, a simple trophic calculation based on an estimated amount of bait consumed in traps and the growth efficiency of juvenile American lobsters also shows that the bait could potentially support one-quarter to one-third of the recent American lobster landings from the inshore area of the Gulf. This preliminary assessment suggests that lobster bait may make a substantial contribution to American lobster production—a contribution that, if confirmed, should be further examined and carefully considered in future American lobster management.