272 



Fishery Bulletin 90(2), 1992 



since 1976 (except for 1985) and the declining length- 

 at-age over the same period guarantees a statistically 

 significant result, the real role of the Canadian fishery 

 in determining length-at-age can be established only 

 in a wider context that considers the magnitude and 

 the geographic pattern of the fishery for Pacific whit- 

 ing in U.S. waters. The region-year interaction coeffi- 

 cients in Figure 7 show that, up until 1984, the sever- 

 ity of the decline in length-at-age was similar in all 

 three geographic regions in U.S. waters, extending 

 from California north to the U.S. -Canada border. This 

 is difficult to reconcile with the contention that the 

 Canadian fishery is primarily responsible for the decline 

 in length-at-age. 



Both Smith et al. (1990) and this study used growth 

 models that do not take into account the dynamics of 

 the population, and as a consequence both have short- 

 comings which limit the growth- related phenomena to 

 which they can be applied. An important direction for 

 further research is the development of models for 

 Pacific whiting that simultaneously model the growth 

 and the population dynamics of the stock, including 

 size-specific migratory behavior. 



Acknowledgments 



I thank Anne Hollowed, Daniel Kimura, Patricia 

 Livingston, and Richard Methot for their comments on 

 a preliminary version of this paper. In addition, sug- 

 gestions by two anonymous reviewers significantly 

 improved this paper. 



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