FISHERY BULLETIN. VOL. 78, NO. 1 



Table 7. — Correlation matrix between the life-history 

 parameters for flatfishes (order Pleuronectiformes). For sources 

 of data see Appendix I. The number in parentheses represents 

 the significance value for that particular coefficient since the 

 number of data cases was different for each correlation. 



'Thie parameter from the von Bertalanffy growth equation was used to 

 represent the actual characteristic. 



Table 8. — Summary of the number of agreements between pre- 

 dicted and observed correlation coefficients among life-history 

 parameters within selected taxonomic groups. 



Level of agreement 



Number in 

 agreement 



Number 

 possible 



Percent in 

 agreement 



Sign 



5% probability level 



1% probability level 



46 

 40 



31 



46 

 46 

 46 



100 

 87 

 67 



domly (i.e., p = probability of agreement = 0.5, 

 and q = probability of disagreement = 0.5), then 

 the number of agreements would follow a binomial 

 distribution. The binomial test (Hollander and 

 Wolfe 1973 ) can be used to test the hypothesis that 

 the number of agreements between the predicted 

 and observed correlations differs from the number 

 that would have occurred randomly. The number 

 of agreements is significantly different than would 

 have occurred randomly iz = 4.86, P<0.001), 

 when only correlations that were significant at the 

 5% level were used. 



maximum age of a fish. From r andK selection, we 

 can predict how these parameters will vary. Con- 

 sider a situation with three hypothetical species: 

 one species will be more r selected, another species 

 will be moreK selected, and another will be inter- 

 mediate between the first two. The biological 

 parameters will vary as shown in Table 9. Bever- 

 ton and Holt yield per recruit curves were calcu- 

 lated for a constant age at first capture {t^ = 4.2 yr) 

 with varying fishing mortality (Figure 1), and for 

 a constant fishing mortality (F = 0.25) with a 

 varying age at first capture (Figure 2). 



The yield per recruit analysis points up that 

 there are specific differences in fisheries based on r 

 or K selected species. In fisheries based on K 

 selected species, the maximum yield per recruit 

 would occur at a lower level of fishing mortality 

 and at a later age at first entry than in fisheries 

 based on r selected species. The curves also indi- 

 cate that K selected species would be much more 

 sensitive to overfishing both in terms of fishing 

 mortality and age at first entry. 



The surplus production model of Schaefer com- 

 bines reproductive and mortality functions into 

 one parameter (Ricker 1975). The biological 

 parameters in this model are 5x, the maximum 

 stock size (or carrying capacity in weight), and /e, 

 the instantaneous rate of increase of the stock at 

 densities approaching zero. Again these parame- 

 ters can be predicted for the three hypothetical 

 species from r and if selection (Table 10). In the 

 surplus production model analysis (Figure 3), ther 

 selected species have the highest productivity. As 

 in the yield per recruit analysis, the maximum 

 yield occurs at a lower fishing mortality for the A" 



RESPONSE OF r AND K SELECTED 

 SPECIES TO HARVESTING 



The interaction of life history characteristics 

 will have a strong affect on the response of a 

 species to fishing pressure. The Beverton and Holt 

 yield per recruit equation estimates the yield that 

 can be harvested from the growi:h of a cohort. The 

 model assumes that fish grovvi:h is described by the 

 von Bertalanffy growth curve and that mortality 

 processes are exponential (Beverton and Holt 

 1957; Ricker 1975). The biological parameters in 

 the model are: 1) M, the instantaneous rate of 

 natural mortality, 2) Wy-, the mean asymptotic 

 weight which corresponds to Ly-_, 3) k, the von 

 Bertalanffy growth coefficient, and 4) t^, the 



Table 9. — Biological parameters for use in yield per recruit 

 analysis for three hypothetical r andK selected species. 



Table lO. — Biological parameters for surplus production model 

 analysis for three hypothetical r and K selected species. 



