The effect of casitas on Panulirus argus mortality, growth, and susceptibility to disease in The Bahamas

The fishery for Panulirus argus (Latreille, 1804) in The Bahamas, which is the largest in the Wider Caribbean Sea, was historically trap-based, but casitas surpassed traps as the primary fishing gear in the 1990s. Casitas are artificial shelters that aggregate lobsters for ease of capture, but they are unregulated in The Bahamas and their effects on fishery sustainability are unknown. Concerns about whether overcrowding of lobsters within casitas detrimentally alters lobster growth, disease, or mortality prompted our study. Tethering and videography were used to compare lobster mortality and predation risk at casitas and in the natural environment, whereas nutritional condition, growth, injury, and prevalence of disease were compared for lobsters within casitas and traps. We found no difference in predation on subadult or adult lobsters in casitas compared to natural areas, although predators were more abundant near casitas. Lobsters in casitas had higher blood protein indices and fewer had shell disease than those in traps; the PaV1 virus was absent from lobsters we sampled. Starvation experiments in which lobsters were held in "ghost" traps during the closed season revealed a significant decline in lobster nutritional condition and an increase in shell disease after 3 wks, with nearly all lobsters afflicted after 6–12 wks. In summary, we found no evidence that casitas negatively affect subadult and adult P. argus in The Bahamas. Juvenile lobsters were rare in our study so potential effects of casitas on them were not investigated. Traps, however, pose a risk to the fishery if not properly managed.