Jaenicke and Celewycz: Marine distribution and size of juvenile Pacific salmon 



for later species identification and size measure- 

 ments (fork length [FL] to nearest mm). If more 

 than 100 juvenile salmon were captured in a set, the 

 excess fish were released alive. 



Graphs (Chambers et al., 1983) and exploratory 

 data analysis (Tukey, 1977) were used to present 

 catch data because the data had a nonnormal dis- 

 tribution with values clumped at zero (many seine 

 sets did not capture juvenile salmon). Transforma- 

 tions of catch data were ineffective in making the 

 distribution more symmetrical. Quantile plots 

 (Chambers et al., 1983), which show individual 

 catches from smallest to largest, were used to de- 

 scribe the statistical distribution of catches of each 

 species. Chinook salmon (O. tshawytscha) were ex- 

 cluded from the remaining analyses because few 

 were caught. Morisita's Index of Aggregation 

 (Morisita, 1959; Poole, 1974) was used to test 

 whether each salmon species was randomly dis- 

 persed or aggregated in marine waters of Southeast 

 Alaska. 



Morisita's index is defined as 



N 



£«,(«,-!> 



i l 



rc(n-l) 



N, 



where N is the number of samples, n { is the num- 

 ber of individuals in the z'th sample, and n is the 

 total number of individuals in all samples. The sig- 

 nificance of I & is tested with the Ftest described by 

 Poole (1974). Spearman's rho (p) correlation test 

 (Daniel, 1978) was used to measure association be- 

 tween each possible pairing of the four main species 

 caught (pink, chum, sockeye, and coho salmon). 



For comparisons, catch data were split into cells 

 by 1) species, 2) habitat (outside waters, outer coast 

 inlets, and inside waters), 3) region (northern South- 

 east Alaska, southern Southeast Alaska, and Brit- 

 ish Columbia), and 4) time period (August 1983, 

 July 1984, and August 1984). CPUE was used as an 

 index of abundance; frequency of occurrence (FO) 



