Exploring the consequences of introducing alternative fishing gear in an effort-limited fishery: Casita utilization in the spiny lobster, Panulirus argus, fishery in Florida

Commercial harvest of spiny lobsters in Florida by divers increased in the early 2000s with the expanded utilization of artificial shelters called “casitas.” Casitas were an illegal fishing gear in Florida, making the proliferation of the amount of gear and landings difficult to assess. This led to an intensifying conflict between commercial lobster divers and commercial lobster trap fishers, who were competing for the same resource and prompted the need for a reassessment of the fishing capacity and harvest potential for the commercial dive fishery. In response to the introduction of casitas to the lobster fishery, we evaluated the effect on landings by gear type, the performance of casitas against traps and explored the potential caveats and consequences of introducing new fishing gear into an existing, already overcapitalized fishery. Overall, casita use increased the de facto allocation of landings to divers. Trap fishers experienced a decline in trap catch during years with increased casita use, but this time period also overlapped with a period of low annual landings for all sectors and likely intensified the perception that divers were the cause of low landings in the trap sector. Field studies indicated an average of 81.4 ± 10.6 kg of lobster per casita were harvested over the course of the fishing season, or 17 times more than the average for a single trap. Eighty percent of catch (kg of lobster) from casitas occurred during the first four weeks of the season, after which catch dropped precipitously. While casitas appear to have greater initial catch and lower discard mortality than traps, it remains unclear if casitas could be used efficiently throughout the duration of the fishing season to maintain the current harvest in the fishery. The major impediments to inclusion of casitas as a regulated gear in the lobster fishery in Florida are disruption of the established social and economic structure of the fishery that is dominated by traps, logistical challenges to enforcement, prohibitions on casita use in the Florida Keys National Marine Sanctuary where the majority of harvest takes place, and hurdles to add to fishing effort in an effort-limited fishery. • Limited entry to one fishing gear sector promoted expansion of alternative gear. • Lobster catch per casita was 17 times greater by weight than the catch per trap. • 80 % of catch (kg) from casitas was during the first month of the season. • Increased use of alternative gear compromised trap fishing effort reduction goals. • It remains unclear if casitas could maintain the current harvest in the fishery.