CASTRO AND ERZINI: COMPARISON OF LENGTH-FREQUENCY PACKAGES 



catch size and can be regarded as unbiased. Exam- 

 ples of simulated length frequencies for each of the 

 four situations are presented in Figures la-d and 

 examples of component distributions contributing 

 to the composition of a particular distribution are 

 given in Figures 2a-d. In what follows, the word 

 cohort refers to the fish recruited in a particular 

 period. For one spawning peak a year cohort and 

 age class are equivalent. However, in the situa- 

 tions where multiple recruitment periods were 

 simulated, more than one cohort will contribute to 

 a given age class. In multiple recruitment situations 

 the word cohort does not have its traditional 

 meaning. 



The Choice of Parameters 



The following four situations were simulated and 

 the parameters are given in Table 1: 1) A sardine- 

 like species, characterized by small size, fast growth, 

 high mortality, very intense fishing mortality, and 

 with one recruitment peak per year (situation 1); 

 2) a small sparid/lutjanid type species, with larger 

 size, slower growth with moderate to high fishing 

 mortality, and one recruitment peak per year (situa- 

 tion 2); 3) a species with the same characteristics 

 as the one described previously, but with two re- 

 cruitment peaks per year (situation 3); and 4) a 

 species with the same characteristics as the two 



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3 5 7 9 11 13 15 17 19 21 23 25 27 29 



Length classes (1 cm) 



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3 5 7 9 11 13 15 17 19 21 23 25 27 29 



Length classes (1 cm) 



Figure Ic— Example of simulated length-frequency distributions for situation 3, the sparid/lutjanid-type species with two recruit- 

 ment peaks a year. Only 6 of the 12 months are represented. 



Figure Id.— Example of simulated length-frequency distributions for situation 4, the sparid/lutjanid-type species with random recruit- 

 ment. Only 6 of the 12 months are represented. 



647 



