FISHERY BULLETIN: VOL. 74, NO. 4 

 Table 3.-Mercury concentration in heads-off eviscerated Pacific halibut from southeast Alaska. 



(36% of the sample) were over the guidehne (Table 

 5). None of these fish weighed more than 80 

 pounds, and only six weighed more than 60 pounds; 

 31% of the 5- to 60-pound fish and all of the 61- to 

 80-pound fish were over the guideline. In fish from 

 this area, as in those from British Columbia, the 

 concentrations of mercury increased with the 

 incidence of fish over the guideline. 



It is apparent that the mean level of mercury in 

 the edible tissue and the incidence of fish over the 

 guideline increases from the northern to the 

 southern part of the range of the Pacific halibut 

 (Figure 1, Table 6). There is also a relationship 



786 



between the size of fish and the level of mercury in 

 the muscle. Because of the sex-size relationship of 

 halibut, i.e., males rarely exceed 80 pounds 

 regardless of age, the correlation of mercury to 

 age should be closer than that of mercury to size. 

 However, age data were collected on only 76% of 

 the total sampling, whereas weight was obtained 

 on all samples. For this reason, and as a guide to 

 industry, we have worked mostly with the mer- 

 cury-size relationship. Evaluation of the data by 

 regression analyses showed that the data are well 

 described by the exponential function {y = ax*). 

 Comparisons of the weights of halibut against 



