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Fishery Bulletin 102(3) 



Figure 1 



Photographs showing the changes in morphological features in seven cranial structures of walleye pol- 

 lock iTheragra chalcogramma) resulting from digestion. Within each section of the figure three condi- 

 tion categories (good, fair, and poor) are represented from left to right for (A) interhyal (INTEi. iBi 

 hypobranchial 3 (HYPOl, (Ci pharyngobranchial 2 (PHARl, (D) angular (ANGU), lE i quadrate (QUAD), 

 (F) dentary (DENTi and (G) sagittal otolith (OTO). Key features used in classification are labeled (see 

 Table 1 for details), and the measurements taken to calculate fish length (solid line between dashed lines i. 



specific DCF technique described by Tollit et al. (1997). 

 We began by examining the external morphological 

 features and surface topography of selected structures 



from undigested fish (<12 cm to >53 cm) and compared 

 these with the topography of the same structures recov- 

 ered from scats collected from wild and captive animals 



