Sublethal and lethal effects of confinement of Caribbean spiny lobsters, Panulirus argus, in ghost traps

Abstract

Ghost fishing occurs when lost or abandoned fishing gear continues to capture animals, resulting in lethal and sublethal effects. Though ghost fishing by lost traps is a known cause of lobster mortality in the Florida lobster trap fishery, the sublethal effects of long-term confinement in these traps remains largely unknown. Here, we examine the nutritional condition and overall health (e.g., incidence of injuries and disease) via three assays: a field survey to compare nutritional condition and overall health of lobsters in existing ghost traps to natural shelters via blood serum protein (BSP) and hepatopancreas dry weight indices (DWI); a field experiment to monitor the effects of confinement on individual lobsters over time; and a laboratory experiment to simulate starvation and recovery of the BSP of lobsters associated with confinement and escape from traps. Overall, lobsters in existing ghost traps were in poorer nutritional condition, had a higher prevalence of injuries and shell disease, and were lethargic. There was a clear deterioration of the health and increased mortality of lobsters as confinement duration increased in our experimental ghost traps. After 2 wks, BSP of lobsters decreased by 23.7%; lobsters in this poor nutritional condition were less likely to escape and more likely to die in traps. Laboratory experiments indicate that if escape does occur, recovery may be slow or unlikely. Our study highlights the drastic sublethal effects of long-term confinement in ghost fishing traps on lobsters and the need for further research on ways to mitigate these effects.