Trap-induced mortality of the spiny lobster, Panulirus argus, in Florida, USA

Abstract

In Florida’s lobster fishery, sublegal-sized spiny lobsters, Panulirus argus, are commonly placed in traps to attract legal-sized lobsters. Many died from exposure to air during transport before the use of live wells and still die because of confinement in traps. Much of this mortality is not apparent during normal trap-fishing operations, and the magnitude of the unobserved mortality remains the subject of controversy between fishermen and fishery managers. After fishermen began using live wells in the 1987–88 fishing season, the harvest of legalsized lobsters increased. Initially, the increase was smaller than predicted, apparently because the average number of traps in the fishery increased from 576 000 during the 1977–78 to 1986–87 fishing seasons to 854 000 during the 1987–88 to 1992–93 seasons. High numbers of traps in the fishery have been implicated as contributing to increased mortality of sublegal-sized lobsters. When the average number of traps was reduced to 605 000, after the 1993–94 season, the harvest predictions attributed to live-well use were largely achieved. Observations on commercial fishing vessels were used to reevaluate previous harvest predictions and develop additional coefficients for fishing mortality related to exposure and confinement in traps.