504 



Fishery Bulletin 102(3) 



Table 1 



Distinctive external morphological features for defining the degree of digestion (condition category) as good(G), fair (F), and poor 

 (Pi for selected cranial structures of walleye pollock and Atka mackerel. Features are given in order of importance. See Table 2 

 for definition of structure codes and Figure 1 and 2 for illustrations. WP = walleye pollock. 



Species and 



structure code Category Distinctive external morphological features 



Walleye pollock 

 INTE 



HYPO 



PHAR 



ANGU 



QUAD 



DENT 



OTO 



G 1) Retains characteristic shape, notably the ridge and swan neck. 2) Both ends show no damage 

 (except for the loss of the point and minor nicks) and do not affect length measurement. 



F li Ridge and swan neck clearly defined. 2) One end can show limited damage with <159c reduction. 

 Minor nicks on opposite end acceptable, if there is no further loss in length measurement. 



P 1) Loss of characteristic shape, with ridge or swan neck (or both) ill defined. Body of structure 

 contains holes. 2) Both ends show clear damage. 



G 1) Retains characteristic shape, with cone ~2x the length of the tube. 2) Tube end and area 1 show no 

 damage (except for minor nicks) and do no affect the total length measurement. 3) Cone end angled 

 when viewed from the front elevation (back elevation shown in Fig. 1). 



F 1) Tube end or area 1 shows limited damage (cone end no longer angled) clearly preventing an 

 accurate length measurement. 



P 1) Both tube end and area 1 show damage, and a general loss of characteristic shape evident. 



G 1) Retains characteristic shape, notably a raised spout, honeycomb, and crown. 2) Crown clearly 

 projects above honeycomb (front elevation) and is intact at area 2. 3) Clear projection of honeycomb 

 (back elevation — see area 3). 4) No affect on measurement. 



F 1) No clear projection of honeycomb at area 3 or crown shows damage at area 2 (preventing an 

 accurate width measurement). 2) Crown or spout (or both) can show minor damage. 



P li Characteristic shape lost, often only honeycomb present. 2) Honeycomb smooth, crown heavily 

 eroded with areas 2 and 3 eroded or damaged. 3) Both ends show clear damage. 



G 1) Point sharp and well defined with no impact to measurement. 2) Area 4 in good condition and 

 angled curve complete. 3) Neck present, but with minor damage. 4) Material of cap continues to point 

 tip. 



F 1 ) Point no longer extensive or sharp or area 4 damaged and poorly defined. 2 ) Neck usually present, 

 but with wear. 



P 1 ) Characteristic shape lost with neck often absent. 2 ) Point heavily eroded. 3 ) Area 4 shows damage 

 or no definition. 



G 1) Groove defined from all angles and observable with the naked eye. 2) Horns rounded. 3) Angle of 

 area 5 is clearly curvilinear. 4) Evidence of ridge and spike often observable. 



F 1) Groove unclear, forming only an indisctinct notch. 2) Horns have lost rounded definition and may- 

 be pointed or worn on one side. 3) Ridge and spike often only residual. 



P 1) Horns pointed, notch absent. 2) Ridge and spike often absent. 3) Angle of area 5 flattened. 

 4 1 Unable to determine side with assurance. 



G 1) Hammerhead retains rounded end elevation features (note: both sides are not exactly symmetrical), 

 allowing full width measurement. 2) Material in addition to the stock may be present. 3) Stock 

 clearly curved from side elevation. 4) Width and breadth of "rounded" stock similar. 



F 1) Hammerhead shows erosion on one side, affecting full width measurement. 2) Breadth of stock 

 reduced, but not flattened. 



P li Hammerhead eroded and flattened with both sides showing erosion. 2) Breadth of stock flattened, 

 stock less rounded and less robust. 3) Unable to determine side with assurance. 



P 1) Sulcus and scalloping (on most margins) well defined, and no obvious reduction in size due to 

 digestion. 2) Able to determine side. 3) Inside strongly convex, retains characteristic shape. 



F 1) Sulcus worn but shows definition. 2) Able to determine side. 3) Scalloping worn but shows no 

 reverse scalloping. 



P 1) Unable to determine side. 2) Scalloping worn completely smooth and reverse scalloping present. 

 3) Clearly broken, worn, flattened, and unable to obtain an accurate measurement. 



continued 



