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Fishery Bulletin 103(1) 



where Fee = estimated fecundity; 



I = fork length; and 

 parameters a and b were estimated by nonlinear regres- 

 sion with SPSS software (version 11.0, SPSS Inc., Chi- 

 cago, ID. 



Weight-fecundity relationships were estimated by using 

 the following equation 



Fee = mW somatic ) + bl, 



where Fee = estimated fecundity; 

 Wt somallc = somatic weight; and 

 m and 61 were estimated by using linear regression in 

 EXCEL (Microsoft, Redmond, WA). 



Reduction in variance F tests (Quinn and Deriso, 

 1999) were used to compare fecundity relationships 

 between areas, studies, and before and during spawn- 

 ing season. 



the gravimetric versus stereological estimates showed 

 that they follow a 1:1 trend line (Fig. 2). The gravimet- 

 ric method gave a somewhat lower coefficient of varia- 

 tion than the stereological method, based on multiple 

 samples of the same ovaries (Table 1). An F test (Quinn 

 and Deriso, 1999) did not show a significant difference 

 (P=0.84) between the gravimetric (n=16) and stereologi- 

 cal (??=10) methods in the length-fecundity relationships 

 obtained for Alaskan shortspine thornyhead, and the 

 data were therefore combined (Fig. 3). 



Shortspine thornyhead 



Shortspine thornyheads from Alaska (/!=26) and the 

 West Coast (n = 30) had similar fecundity at length 

 (Fig. 3). An F test did not indicate fecundity at length 

 for the two areas was significantly different (P=0.53); 

 therefore the data were combined to obtain the relation- 

 ships (Figs. 3 and 4): 



Fee = 0.0544(Fork Lengthicm )) 



(r 2 = 0.792, 7i=56) 



Results 



Ovary location differences 



We tested for difference in oocyte density between 

 middle, posterior, and anterior sections of six ovary 

 pairs with the stereological method (ovaries from the 

 migratory nucleus to late hydration phase) and did not 

 find a significant difference in ovary location (two-way 

 ANOVA, P=0.148) (Table 1). 



Stereological method versus gravimetric method 



The gravimetric method and the stereological method 

 provided similar results. For shortspine thornyhead, the 

 average ratio of gravimetric to stereological estimates 

 for ten pairs of data was 0.993 (Table 2), and a plot of 



Fee = 0.223(Wt somatic (g))- 63.079 (r 2 = 0.781, n=53). 



A majority of the shortspine thornyhead fecundity at 

 length data points obtained in this study fell below the 

 regression line reported by Miller (1985) (Fig. 3). The 

 raw data from Miller (1985) were not published; there- 

 fore no statistical test was possible. 



The data were also separated into months preced- 

 ing the start of spawning and those after the start 

 of spawning (Pearson and Gunderson, 2003) to look 

 for evidence of batch spawning. Shortspine collected 

 between October and November were grouped as speci- 

 mens before the start of spawning. Shortspine collected 

 from April through June in Alaska and from March 

 through May off the West Coast were grouped as speci- 

 mens after the start of spawning. Fish collected after 

 spawning had begun (/;=41) did not show a significant 



