Seasonal and fishery impacts on the nutritional condition of the Caribbean spiny lobster Panulirus argus in Florida, USA

Abstract

The sublethal effects of fisheries (e.g. reduced nutritional condition or injuries) on the target species population are poorly understood, yet have the potential to reduce fishery efficiency and sustainability. The Caribbean spiny lobster Panulirus argus trap fishery in Florida (USA) uses live, sublegal-size lobsters as bait to lure other lobsters into the ~462000 traps employed by the fishery. Long-term confinement of lobsters used as live bait causes stress, leading to the degradation of their nutritional condition or mortality; however, cumulative effects of confinement on nutritional condition throughout the fishing season and the effect on the population were unknown. We sampled sublegal- and legal-size lobsters hand-caught from a fished area (potentially affected by traps) and caught in commercial lobster traps in the fished area to determine how lobster health varies throughout the year and whether the intense recreational and commercial fisheries exhibit sublethal effects on lobster health. We compared the health of lobsters monthly for 1 yr using 2 nutritional indices (hepatopancreas dry weight and blood serum protein), and by the presence of external injuries and shell disease. Lobster blood serum protein and dry weight index varied throughout the year, peaking in late summer to early fall, dropping sharply during the winter, and rising again through the spring, likely in response to seasonal changes in environmental factors, such as water temperature. Both legal and sublegal lobsters within actively fished traps showed lower nutritional condition than lobsters from the surrounding population throughout the fishing season, suggesting that few lobsters escape traps.