Abstract.- In Bahia de la Ascen- 

 si6n, Mexico, the fishery for Panu- 

 lirus argus is based on artificial shel- 

 ters called "casitas." Highest catch- 

 per-unit-effort (kg tails/boat  day) in 

 the fishery occurs each year immedi- 

 ately after the opening of the fishing 

 season, and declines sharply over the 

 next months. This trend probably 

 reflects combined effects of natural 

 mortality, fishing mortality, and emi- 

 gration of lobsters from the bay. 



In 1985, 3470 tagged lobsters were 

 released during the closed season, 

 and 849 (24.5%) were recaptured by 

 fishermen, mainly during the first 

 three months of the following fishing 

 season. In 1986, an additional 1324 

 tagged lobsters were released, and 

 407 (30.7%) were subsequently re- 

 captured. Growth of recaptured lob- 

 sters was highly variable, and sexes 

 had different growth rates, that of 

 males being higher. Von Bertalanffy 

 parameters for each sex were calcu- 

 lated using two different techniques; 

 most reasonable estimates were ob- 

 tained by a maximum likelihood ap- 

 proach. Ninety-nine percent of the 

 recaptured lobsters were caught 

 within the bay, but movements gen- 

 erally tended to be toward the reef 

 in front of the bay. Longest straight- 

 line distance moved was 45 km. 



The population fished in the bay 

 was composed entirely of juveniles, 

 and we hypothesize that an unfished 

 population of adults exists outside 

 the bay. Testing of this hypothesis 

 would benefit future management 

 plans. In addition, the long-term ef- 

 fects of casitas on the lobster popula- 

 tion and on the ecology of the sea- 

 grasses and their associated benthic 

 communities need to be understood. 



Fishery Characteristics, Growth, 

 and Movements of the Spiny Lobster 

 Panulirus argus in Bahia de la 

 Ascension, Mexico 



Enrique Lozano-Alvarez 

 Patricia Briones-Fourzan 



Universidad Nacional Autonoma de Mexico 



Institute) de Clencias del Mar y Limnoiogia, Estacion "Puerto Morelos" 



P O Box I 152, Cancun. Q R .. 77500 Mexico 



Bruce F. Phillips 



Commonwealth Scientific and Industrial Research Organization (CSIRO) 

 Marine Laboratory. PO Box 20. North Beach, W.A.. 6020 Australia 



Manuscript accepted 12 September 1990. 

 Fishery Bulletin, U.S. 89:79-89 (1991). 



Panulirus argus accounts for approx- 

 imately one-third of Mexico's spiny 

 lobster production of about 2400 t 

 (mean for 1978-87), 80% of which is 

 produced in the state of Quintana 

 Roo (Secretaria de Pesca 1987). The 

 fishery for lobsters in Bahia de la 

 Ascension began in 1965. Initially, 

 traps and skin diving were used, but 

 in 1968 "casitas cubanas" were intro- 

 duced (Miller 1982). These "casitas" 

 consist of a frame of about 1.8 x 

 1.2 m made of the trunks of a local 

 palm, and a "roof" of the same wood, 

 metal, asbestos or, more recently, 

 ferrocement. Casitas are sunk over 

 seagrass-covered bottom. The fisher- 

 men check the casitas by skin diving, 

 and catch the lobsters with a gaff 

 (Lozano et al. 1989). The bottom of 

 the bay suitable for setting casitas 

 has been divided into several parcels 

 of different sizes, alloted to the older 

 fishermen. Miller (1982) suggested 

 that the casitas might increase the 

 fishing pressure on the population 

 and cause overfishing, and Eggleston 

 et al. (1990) propose that casitas pro- 

 vide critical refuge for juvenile lob- 

 sters from their predators. The long- 

 term effects of casitas on the lobster 

 population remain to be determined. 

 Here we report the results of an in- 

 vestigation using tag and recapture 



methods to study the structure, move- 

 ments, and growth rates of the spiny 

 lobster population in Bahia de la As- 

 cension during 1985-87. 



Methods 



Fishing methods in 

 Quintana Roo 



The coast of Quintana Roo can be 

 divided into three areas on the basis 

 of the lobster fisheries (Fig. la): 



In the northern area, from Holbox 

 to Tulum and especially around Isla 

 Mujeres, the fishery is well devel- 

 oped. Lobsters are caught mainly by 

 traps in depths of 15-60 m, and by 

 Scuba and "hookah" diving to depths 

 near 40 m. An annual migration of 

 lobsters occurs along the northeast- 

 ern coast of the Yucatan Peninsula 

 in a southerly direction, at the end of 

 autumn or in winter (Kanciruk and 

 Herrnkind 1978). During this migra- 

 tion, fishermen use lobster bottom- 

 nets in areas 2-10 m deep. Twelve 

 cooperatives, involving 65% of the 

 1084 lobster fishermen of the state, 

 operate in the northern area. 



In the central area, where Bahia de 

 la Ascension is located, skin diving 

 and "casitas cubanas" are used. In 

 this area, where three cooperatives 



79 



