McDermott et al: Annual fecundity, batch fecundity, and oocyte atresia of Pleurogrammus monopterygius 



27 



o 



2 60000 



0, 60000 

 O) 



E 



40 



B 



28X3234363840 42 44464850 52 



28 30 32 34 36 38 40 42 44 46 48 50 52 

 Fisfi lengtfi (cm) 



Figure 5 



Fecundity of Atka mackerel ^Pleurogrammus monopterygius) at the 

 prespawning (clear triangles) and spawning (solid squares) phase 

 for (A) total number of oocytes at stage 4 and above, (B) oocytes at 

 stage 5+, and (C) for oocytes at stage 4 only. Regression lines for 

 prespawning and spawning fish are indicated by solid and dashed 

 lines, respectively. 



developed and spawned late in the spawning season. 

 However, knowledge of batch size, length of spawning 

 season, and the spawning interval between batches 

 (1-2 weeks) (Gorbunova, 1962; Zolotov, 1993; McDer- 

 mott and Lowe, 1997), gives us confidence that our 

 estimate of fecundity is realistic. Given that there are 

 14 days between batches, a 75-day incubation period 

 (Lowe et al., 2003; McDermott, 2003), and that 4.6 

 batches are spawned annually, the spawning season 



would be 120 days, which is similar to that observed 

 in the present study. 



Conclusions 



Prespawning Atka mackerel did not show much atresia 

 during egg development; however high levels of atresia 

 became apparent when ovaries of postspawning fish 



