ARTIFICIAL SHELTERS FOR SPINY LOBSTER PANULIRUS-ARGUS (LATREILLE) - AN EVALUATION OF OCCUPANCY IN DIFFERENT BENTHIC HABITATS

In spiny lobster, Panulirus argus (Latreile), fisheries in Cuba, Mexic o and the Bahamas, artificial shelters (casitas) are successfully used as fishing gears. However, the mechanisms underlying the operation of these artificial shelters and their long-term effects on the resource and benthic communities are unclear. Lowered predation-induced mortal ity due to casitas has led to the proposal that they be placed in bent hic habitats with adequate food, but where natural shelter is lacking. In this study, firstly the availability of natural habitat types was measured and secondly, habitat features which could influence the occu pancy of artificial shelters by lobsters were evaluated. Casitas were placed in benthic habitats differing in the relative availability of s eagrass and hard bottom. Spiny lobsters and faunal assemblages were mo nitored from December 1993 to July 1994 at six stations, two for each benthic habitat type. The study area was a typical spiny-lobster nurse ry area, with bottom cover dominated by seagrass and macroalgae (79.7% ); while hard bottom, including patch reef, amounted to only 0.2%. Hen ce, a population bottleneck probably occurred, negatively affecting po stalgal juveniles and subadult lobsters. The results suggest that seag rass availability was the key factor determining casitas' occupancy by lobsters. The lowest occupancy was found where seagrass was scarce an d hard bottom was available. Given seagrass availability, casitas harb ored a similar number of lobsters irrespective of the hard bottom avai lability; allowing to infer that artificial shelters provided critical habitats (refuges) for postalgal and subadult lobsters. The mean size of lobsters did not vary among stations, and commercial-sized lobster s were scarce. An index of predator presence showed a significant vari ation among stations and with time, with higher values from April to J une. Sea temperature was positively correlated with lobster abundance and predator index; the latter two variables were not correlated. Thes e study results support the use of casitas for the enhancement of prea dult lobster populations. (C) 1998 Elsevier Science BTV. All rights re served.