EFFECTS OF INJURIES ON SPINY LOBSTER, 



PANULIRUS ARGUS, AND IMPLICATIONS 



FOR FISHERY MANAGEMENT 



The spiny lobster, Panulirus argus, supports im- 

 portant commercial and recreational fisheries 

 throughout its range from Bermuda to Brazil. Its 

 ecology- and physiology are typical of a number of 

 other commercially important palinurid species, 

 which collectively have pantropic distributions 

 (Phillips and Cobb 1977). 



A variety of decapod crustacean responses to 

 injuries, primarily limb loss, have been recorded. 

 Aiken 11977) summarized a number of studies 

 conducted in laboratories, some of which found 

 that limb loss greatly accelerated ecdysis. Other 

 observers noted limb loss resulted in reduced 

 growth rates (Chittleborough 1975; Ford 1977; 

 Savage and Sullivan 1978). This paper reports the 

 effects of injuries on growth rates of wild juvenile 

 spiny lobsters, P. argus, in Florida and discusses 

 the implications of these effects on P. argus biol- 

 ogy and its fishery. 



Spiny lobsters (Palinuridae) have complex life 

 cycles. Larval, early juvenile, and adult stages of 

 the spiny lobster in Florida, P. argus, are 

 ecologically dissimilar and are found separately in 

 relatively discrete habitats. The planktonic phyl- 

 losoma larvae spend 5 to 9 mo in the open ocean 

 before metamorphosing into actively swimming 

 postlarvae, called pueruli (Lewis 1951). Pueruli 

 swim into shallow coastal waters where they set- 

 tle onto the bottom, assuming the benthic exis- 

 tence they will follow the rest of their lives. Post- 

 larval and small juvenile spiny lobsters are found 

 scattered throughout seagrass beds, particularly 

 in shallow inshore areas like Biscayne Bay. Larger 

 juveniles concentrate around rocky outcrops, 

 sponges, and groups of sea urchins for shelter dur- 

 ing the day (Khandker 1964; Davis 1971; Berrill 

 1975). They forage nightly on adjacent grassbeds 

 and open sand areas for small mollusks, echinoids, 

 and crustaceans (Herrnkind et al. 1975). Mature 

 lobsters are generally associated with coral reefs, 

 or other hard bottom, offshore to depths >150 m. 

 The transition from inshore juvenile habitat to 

 habitat offshore is sometimes accomplished by 

 spectacular mass migrations, marked by long 

 queues of lobsters (Herrnkind and Cummings 

 1964; Kanciruk and Herrnkind 1978). 



The fishing season for P. argus in Florida ex- 

 tends slightly more than 8 mo from late July 

 through March, with a special 2-d sport fishing 



season 5 d prior to the beginning of the regular 

 sport and commercial season (Florida Statute 

 370.14). Recreational diving activity directed at 

 spiny lobster harvest is particularly intense in 

 nearshore areas during the first 6 to 8 wk of each 

 season (Austin 1976). There are also over 1,000 

 commercial trappers, fishing up to 2,000 traps 

 each, in the fishery (Beardsley et al. 1975). 



Methods 



At weekly or monthly intervals during 1976 and 

 1977, spiny lobsters were captured in southern 

 Biscayne Bay, Fla., by hand, bully net, or tail 

 snare and marked with spaghetti tags. The details 

 and efficacy of this tagging procedure were re- 

 ported by Davis (1978). Data on size (as carapace 

 length, CL), injuries, molt condition, location, and 

 water temperature were recorded. Injuries were 

 recorded as the number of missing legs or anten- 

 nae, or damage to the abdomen, cephalothorax, or 

 supraorbital horns. 



Grovvi:h of spiny lobsters takes place as the re- 

 sult of a series of molts, during which discontinu- 

 ous size changes occur. The rate of growth is de- 

 pendent on both magnitude of change in size with 

 each molt (molt increment) and the length of the 

 intermolt period. In this study, growth rate was 

 expressed as change in carapace length per week, 

 since nearly all observations of marked lobsters 

 were made at weekly intervals. To reduce the var- 

 iability inherent in measuring discontinuous 

 changes in carapace length that resulted from 

 random observations of growi:h during the molting 

 cycle, all changes in size were summed over each 

 class of observations (i.e., wdnter, summer, injured, 

 or uninjured) and expressed as rates per week. 



Results 



A total of 7,643 P. argus were examined from 

 February 1976 to December 1977. They ranged 

 from 15 to 101 mm CL, with a mean of 60.7 mm CL 

 (Table 1). Mean monthly water temperatures var- 

 ied from 16° to 32° C. 



Observations of growth were made for 844 time 

 intervals, ranging from 1 to 82 wk (mean 20 wk), 

 on 534 individual lobsters in the wild, ranging 

 from 38 to 83 mm CL. Carapace length mea- 

 surements were replicated by independent obser- 

 vers on the same day for 153 lobsters during the 

 22-mo tagging period to evaluate the precision of 

 the carapace length measurements by various 



FISHERY BULLETIN: VOL. 78. NO. 4, 1981. 



979 



