ECOLOGICAL STUDIES OF THE PUERULUS LARVAL STAGE OF THE 

 CALIFORNIA SPINY LOBSTER, PANULIRUS INTERRUPTUS' 



Steven A. Serfung and Richard F. Ford' 



ABSTRACT 



Ecological and related behavioral studies of the puerulus larval stage of the California spiny lobster, 

 Panulirus interruptua, involved the development and use of artificial and natural seaweed habitat 

 traps, special paired neuston nets, and underwater night-lights for collecting and observing pueruli in 

 nature. The results obtained indicate that pueruli first enter the coastal waters off San Diego, Calif., 

 during May, and continue to appear regularly through September, but with no apparent relationship to 

 lunar or temperature cycles. 



Pueruli exhibit a strong attraction to floating habitat traps containing the surfgrass Phyllogpadix 

 torreyi and to bright lights at night. The results also suggest that the puerulus is a surface-swimming, 

 pelagic form which may actively seek out specific nearshore areas for settlement, and thereby serve the 

 important function of returning larval stages to areas suitable for demersal life of the young juveniles. 



Previous studies of the California spiny lobster, 

 Panulirus interruptus (Randall), and other spiny 

 lobster species have concentrated primarily on 

 either the adult or phyllosoma larval stages, leav- 

 ing the biology of the intermediate, yet very im- 

 portant, puerulus and juvenile stages relatively 

 unknown. This is particularly true for P. in- 

 terruptus. Prior to the present study, essentially 

 nothing was known about the ecological 

 requirements or behavior of the puerulus or early 

 juvenile stages, which together represent a period 

 of 2-3 yr in the life history of this species. This is an 

 unfortunate situation for an animal as heavily 

 exploited by a commercial fishery as the California 

 spiny lobster because, as Thorson (1950) has in- 

 dicated, the abundance of any adult population is 

 primarily dependent on the recruitment, survival, 

 and growth of its larval and juvenile stages. Con- 

 sequently, attempts to improve fishery yields 

 through a better understanding of adult behavior 

 and population ecology alone provide only a partial 

 and temporary solution to the problem. 



Increasing fishing pressure on the steadily 

 declining stocks of P. interruptus and other spiny 

 lobster species urges more than an academic 

 interest in the ecological requirements of their 

 puerulus and juvenile stages. On the basis of this 



'Contribution No. 3 from the San Diego State University 

 Center for Marine Studies. 



'Center for Marine Studies, San Diego State University, San 

 Diego, CA 92182. 



information, for example, it may be possible to 

 protect their natural habitats or to develop 

 supplementary artificial habitats for them in na- 

 ture. Techniques for culturing these stages under 

 artificial conditions, as a means of supplementing 

 natural stocks, must also be given serious con- 

 sideration for the following reasons. 



Evidence concerning P. interruptus (Johnson 

 1956, 1960, 1971) and other palinurid species (see, 

 for example, Chittleborough and Thomas 1969) 

 suggests that a majority of the phyllosoma and 

 puerulus larvae may be lost from the population 

 due to their long larval life (5-10 mo), during which 

 they may be swept hundreds of kilometers 

 offshore. Because of their small size, the surviving 

 postpuerulus and early juvenile stages probably 

 experience much higher predation mortality rates 

 than do the adults (Winget 1968). In addition, 

 evidence from limited studies of other spiny lob- 

 ster species, including P. argus, P. longipes cygnus, 

 and Jasus edwardsii, suggests that the nursery 

 grounds of their postpuerulus and early juvenile 

 stages are located in protected bays or estuaries 

 (Sheard 1949; Lewis et al. 1952; Witham et al. 1964, 

 1968; Sweat 1968; C. B. Kensler, pers. commun.). If 

 such estuarine nursery grounds are required by 

 the early benthic stages of P. interruptus, reduc- 

 tion of this type of natural habitat as the result of 

 commercial developments and water pollution 

 may create a "weak link" in the life history of this 

 species, at least within part of its geographical 

 range. 



Manu.script accepted .June 1974. 



FISHERY BULLETIN; VOL. 73, NO. 2, 1975. 



360 



