Cooper et al.: Fecundity of Sebastolobus alascanus and Sebastolobus altivelis 



19 



Table 2 



Paired fecundity estimates (number of oocytes) by method and by section of the ovary (middle, posterior, anterior) where oocyte 

 samples were taken. 



Specimen 



Shortspine 1 

 Shortspine 2 

 Shortspine 3 

 Shortspine 4 

 Shortspine 5 



Shortspine 6 



Position in the ovary Gravimetric Stereological Ratio of gravimetric to stereological 



Middle 



Middle 



Middle 



Middle 



Middle 



Posterior 



Anterior 



Middle 



Posterior 



Anterior 



150,448 

 195,356 

 427,717 

 414,594 

 131,934 

 110,456 

 111,425 

 269,453 

 230,992 

 257,427 



184,853 

 187,037 

 307,771 

 561,258 

 122,180 

 87,504 

 111,758 

 313,131 

 257,378 

 304,348 



O.K14 

 1.044 

 1.390 

 0.739 

 1.080 

 1.262 

 0.997 

 0.861 

 0.897 

 0.846 



Mean ratio 0.993 



2500 



2000  



£ 1500- 



1000  



O West Coast 



x Alaska gravimetric 



• Alaska stereological 



Combined data regression 



- - • Miller (1985) regression (r>=60) *J 



500 



20 40 60 



Fork length (cm) 



Figure 3 



Shortspine thornyhead {Sebastolobus alascanus) 

 fecundity-at-length estimates by location and method, 

 and regression of combined data (our study) and by 

 regression of data from Miller's study (1985). 



decrease in fecundity at length when compared to fish 

 collected before spawning had begun (n = ll) (F test, 

 P=0.71) (Fig. 5). 



Longspine thornyhead 



Longspine thornyhead fecundity data conformed more 

 closely to a linear regression on somatic weight (Fig. 6): 



Fee = 183.8l(Wt 8omatic (g))- 4617 (/- 2 = 0.536, n=29) 



than to a nonlinear regression on length (Fig. 7): 



Fee = 0.889Q(Fork Length(cm)) 



(r 2 =0.442, n=29). 



A majority of the predicted fecundity values at somatic 

 weight were higher than those derived from Wakefield's 

 (1990) regression line on somatic weight (Fig. 6), but 

 Wakefield's (1990) raw data were not published. 



Wakefield (1990) estimated spawning to begin in Feb- 

 ruary and created separate fecundity-at-weight relation- 

 ships for fish collected in October-November and in 

 February-March). He noted a decline in fecundity as 

 the spawning season progressed but did not test this 

 fecundity difference for statistical significance. Similar 

 groupings (October-December, n = \l; and February- 

 March, n=ll) in our study did show a statistically sig- 

 nificant difference in fecundity as the spawning sea- 

 son progressed (F test, P=0.004) (Fig. 7); however, the 



