HALL ET AL.: MERCURY IN PACIFIC HALIBUT 



cussed here. Therefore, these data cannot be 

 interpreted to indicate the approximate percent- 

 age of the commercial catch that is likely to 

 contain mercury in concentrations over the 

 guideline. 



In 152 halibut taken from the Bering Sea, the 

 mercury level in the muscle of 7 fish (5% of the 

 sample) was over the guideline (Table 1). The 

 incidence (percentage over the guideline of the 

 total number of fish within a weight range) was 

 highest among fish weighing more than 80 pounds. 



Most of our samples, 761 fish, were taken from 

 the Gulf of Alaska. We found that mercury in the 

 muscle of 38 fish (5% of the sample) exceeded the 

 guideline (Table 2). The highest incidence occurred 

 in fish weighing more than 80 pounds. The weight 

 ranges contributing most to the incidence were 

 those of 126 to 150 pounds and those of more than 

 150 pounds. These two weight ranges contribute 

 21% and 32%, respectively, in contrast with only 3% 

 in each of the weight ranges 81 to 100 pounds and 

 101 to 125 pounds. 



The analytical data on 70 fish taken from south- 



east Alaska area showed that mercury in the 

 muscle of 9 fish (13% of the sample) was 0.50 ppm 

 or higher (Table 3). The small number of fish in the 

 larger weight ranges makes it impossible to be 

 definitive, but it is reasonably clear that in this 

 group, too, the incidence of mercury levels over the 

 guideline was greatest among the largest fish. 



Analyses on 163 fish from the British Columbia 

 area showed that 44 of these (27% of the sample) 

 were over the guideline (Table 4). In addition to 

 this relatively high incidence, we saw for the first 

 time the presence of significant numbers of high- 

 mercury-level fish in all weight groups, i.e., 10% of 

 the fish were over the guideline in the 5- to 

 60-pound range, 75% in the 61- to 80-pound range, 

 73% in the 81- to 100-pound range, 100% in the 101- 

 to 125-pound range, and 67% in the 126- to 150- 

 pound range. We also saw that the concentration 

 of mercury tended to increase with an increase in 

 the incidence of fish that were over the guideline. 



The analytical results on 81 fish taken from the 

 Washington-Oregon area, the most southerly area 

 of the range of the Pacific halibut, showed 29 fish 



Table 1. -Mercury concentration in heads-off eviscerated Pacific halibut from the Bering Sea. 



785 



