FISHERY BULLETIN; VOL. 85, NO. 4 



Table 2. — Continued. 



NS = P > 0.05; "P s 05; "P s 01; "•P < 0.005. 



agree with visual impressions of negligible pro- 

 portional changes with growth, gained from 

 working with the species in the field. 



To compare measurement variability for sexual 

 and geographic factors in untransformed data, in 

 the section on character discrimination, I ob- 

 tained symmetrical estimates of variation about 

 mean values by taking limits formed by one 

 standard deviation (about each regression by sex 

 within region) on each side of the transformed 

 means. I then back-transformed the limits and 

 halved the difference between them. This sym- 

 metrical substitute for the asymetrical standard 

 deviation about regression is called the "alternate 

 standard deviation". 



Westrheim (1975) studied sexual maturity in 

 Pacific ocean perch from the Gulf of Alaska and 

 concluded that onset occurred between 195 and 

 260 mm SL (fork length (FL) converted to SL by 

 relationships established from the present mor- 

 phometric data: SL= -3.272 + 0.879 FL, where 

 N- 1,528 and R^=0.997]. In the present study, 



the boundary between juveniles and adults is 

 taken as 230 mm SL. 



Body Form Varied 

 Geographically and by Sex 



Although later, more detailed, analyses dis- 

 closed that the constant slopes required by the 

 ANCOVA program BMDP P2V (Dixon et al. 

 1977) for each character (transformed data) were 

 technically unmet, a preliminary analysis with 

 this program indicated likely significant geo- 

 graphic and sexual variation in all characters 

 (subsequently confirmed in detailed analyses 

 with a more general ANCOVA model. Table 2), 

 and a general lack of interaction between these 

 factors. Also, I determined that only negligible 

 bias has been induced in the regressions by loga- 

 rithmic transformation of data by computing 

 mean response variables, at 260 mm SL, for un- 

 transformed measurements fit by nonlinear least 

 squares (BMDP PAR, Dixon et al. 1977). For six 



668 



