NOTE Loza no-Alvarez et al.: Occurrence and seasonal variations of Panulirus argus 



during the winter than during the summer (?=4.21, 

 df=9, P< 0.01) (Table 1). No significant differences in 

 sex ratio were found between the two seasons 

 ( X 2 = 1.332, df=l). The mean CL of the whole catch 

 (Z=8.25, df=460, P<0.001), and of both males (Z=5.99, 

 df=237, P< 0.001) and females (Z=4.15, df=222, 

 P<0.001), was significantly greater in summer than 

 in winter (Table 2). 



Newly molted lobsters (carapace state 1) were more 

 abundant in winter (74.4%) than in summer (35.8%), 

 whereas lobsters with old, heavily fouled exoskeletons 

 were more evident in summer (8.95%) than in winter 

 (0.5%) (Table 3). During the summer, 11 (38%) of the 

 29 females were reproductive, while only 28 (14%) of 

 the 194 females caught in winter were in this condi- 

 tion (Table 4). In both seasons, reproductive females 

 measured over 80 mm CL, and most^were in stage EC 

 (Table 4). Only 2 females in summer and 1 in winter 

 were actually carrying eggs (EE). 



Size structure and catch composition of 

 lobsters from casitas within the bay 



The 1,402 lobsters caught beneath the casitas during 

 May-June 1986 comprised 713 (51%) males and 688 

 (49%) females. No significant difference from unity was 

 found in sex ratio. Mean CL of males (65.9 mm) was 

 significantly larger (r=2.50, df= 1000, P<0.01) than that 

 of females (64.4mm) (Table 2, data from Lozano- 

 Alvarez et al., 1991a). Most of the lobsters within the 

 bay were in carapace states 1 and 2, i.e., recently 

 molted (Table 3). Only five of the 688 females from 



within the bay were reproductive (stage EC ), but these 

 were among the largest in size (87.0-100.3 mm CL), 

 and were found in sites close to the reef (Lozano- 

 Alvarez et al. 1991a). 



Comparison of size distribution between the 

 shelf and bay segments of the population 



Figure 2 shows the size distribution of a) the sample 

 taken from casitas within the bay (modified from 

 Lozano-Alvarez et al. 1991. a and b) the total sample 

 taken on the shelf outside the bay. Both males and 

 females were significantly larger on the shelf than in 

 the bay <r=25.88. df=948, P<0.001 for males, and 

 £=18.47, df=917, P<0.001 for females), but females com- 

 posed a small proportion of shelf lobsters >90.0mm 

 CL(Fig. 2B). 



Size structure of lobsters in the commercial 

 catch from the bay and adjacent shallow 

 reefs 



Table 5 shows the monthly size distribution of the 

 catch taken by the fishermen. Peak catches occurred 

 in the 69.3-76.3 mm CL size class (which includes the 

 minimum legal size) throughout the fishing season, 

 except in July, where the peak was located in the 76.3- 

 82.4 mm CL class. Lobsters >102.2mm CL probably 

 represented the catch from the adjacent shallow reefs, 

 and represented a small proportion of the catch dur- 

 ing most of the fishing season. 



