782 



Fishery Bulletin 91(4), 1993 



0.00 0.01 0.02 



0.03 

 R 



0.04 0.05 0.06 



Figure 2 



Contours of relative population size (current abundance 

 divided by historical abundance) for the eastern spin- 

 ner dolphin iStenella longirostris onentalis), as a func- 

 tion of maximum net recruitment rate (/J„,l and 

 maximum net productivity level (MNPLi. 



0.00 0.01 0.02 



0.03 

 R 



0.04 0.05 0.06 



Figure 3 



Contours of the upper 95% confidence limit for rela- 

 tive population size for the eastern spinner dolphin 

 iStenella longirostris orientalis), as a function of maxi- 

 mum net recruitment rate (R,„) and maximum net pro- 

 ductivity level (MNPLi. The shaded region represents 

 the area where the confidence limit was above MNPL. 



The confidence limits around relative population size 

 were not much greater proportionally than the confi- 

 dence limits around A/,. (Fig. 6). For example, from the 

 simulation the confidence limits for relative popula- 

 tion size with values of 0.04 for R m and 0.60 for MNPL 

 were 0.29-0.62, representing a coefficient of variation 



(CV) of 19%, whereas the CV of N c was 17% (Table 1). 

 Although one might have expected the precision of the 

 estimate of relative population size to be much less 

 than the precision of AT , this was not the case because 

 of the independence of most of the kill estimates. Sam- 

 pling variance in the kill estimates would therefore 



2000 

 ' 1750 



1500- 



1250 



1000 



750 



= 500 



250 



Figure 5 



Population model trajectories for the eastern spinner dolphin (Stenella 

 longirostris orientalis\ for three different parameter combinations of 

 maximum net recruitment rate i/f,„i and maximum net productivity 

 level (MNPL): (Al fl,„=0.00 and MNPL=0.50. iBi R,„=0.04 and 

 MNPL=0.60, and (Ci ft,, =0.06 and MNPL=0.80. A and C represent tin- 

 lowest and highest estimates of relative population size, respectively. 

 B represents the combination of the best estimates for the parameters 

 based on available life history data. 



