NOTE Gregg et a\ Otolith preparation methods adapted lor fragile sagitlae 



647 



E 60 



surface 

 cross-section 



- V b surface 



- V b cross-section 



5 10 15 20 25 30 35 



Age (yr) 



Figure 4 



A comparison of plots of length at age for surface ages and cross-section ages of 

 Greenland halibut iReinharcltius hippoglosso/des). Von Bertalanffy (vbl growth 

 curve fits for surface aging (solid line) and cross-section aging (dashed line) 

 are shown. 



age estimate increased by 4.7 years for 226 fish with 

 mean length of 75 cm. The oldest surface age estimate 

 was 28 years and the oldest cross-section estimate was 

 36 years (Fig. 3A). Maximum ages of Greenland halibut 

 reported in the literature rarely exceed 20 years (Alton 

 et al.. 1988). These older ages result in smaller size-at- 

 age and have the effect of decreasing estimates of von 

 Bertalanffy "s L^ (Fig. 4). 



The older cross-section age estimates for Greenland 

 halibut are consistent with natural mortality estimated 

 by the gonadosomatic index method (M=0.112; Cooper et 

 al., in press). Our maximum cross-sectioned age of 36 

 years indicates M = 0.115, as opposed to an M = 0.149 

 as indicated by the maximum surface age of 28 years 

 (Hoenig, 1983). Current natural mortality parameters 

 used in management are 0.18 in the Bering Sea and 



