100 



90 



- 80 



IxJ 

 N 



«« 70 



z 

 o 



►- 60 



0- 50 

 o 



AREA 3 





AREA 4 



1st tagging - 



APR 



MAY 



JUNE JULY 



TIME (MONTHS) 



AUG 



SEPT 



Figure 4. Trend in modified Schnabel population estimates (N) 

 with time for study areas 3 and 4 



The observed rate of change in N for Areas 3 and 4 are not considered to be 

 natural seasonal fluctuations since the lobster populations of Areas 1 and 2 

 remained relatively constant throughout the study period. Mortality through 

 predation by nurse sharks, Ginglymostoma cirratimi , and jewfish, Epinephalus 

 itajara , is considered likely in Areas 3 and 4. Nurse sharks and jewfish were 

 sighted in Areas 3 and 4 during July and September. Similar sightings were 

 non-existent or infrequent in Areas 1 and 2. 



Petersen estimates of N for area 3 are N - 53 (April) and N = 46 (September). 

 The computation of these estimates is as follows: 



(April) N = M (c-Fl) = 

 R+1 



(31) (48) 

 28 



= 53 



(September) 



N = M (c-Fl) 

 R-fl 



= (17) (27) = 46 



The estimate for April is similar to the Schnabel estimates for the same period 

 (Table 3) . The Petersen estimate of 46 for September is accepted as a rela- 

 tively unbiased estimate (Ricker, 1958) compared to the highly biased 



VI -43 



