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Fish Consumption Advice for Alaskans

Although there were only nine samples of salmon shark, the Committee determined that sufficient data existed upon which to base recommendations for reduced consumption of this species because the data lacked substantial variability and were consistent with expected levels for this species. All nine salmon shark samples contained mercury in excess of 0.75 parts per million (ppm) wet weight. Shark species in general contain relatively high mercury levels because they are long-lived and occupy a predatory position in the food chain. In their generic federal advisory, the EPA and FDA advise women of childbearing age and young children not to eat shark (all species) due to its high mercury content.

Weight, Pounds*

Length, Inches

N

Mean

Median

Std Dev

Min

Max

Percent fish > 1 ppm

0 – 19.9

25 to 34.9

52

0.122

0.086

0.129

0.026

0.793

0%

20 – 29.9

35 to 39.9

186

0.218

0.166

0.152

0.052

0.994

0%

30 – 39.9

40 to 43.9

119

0.265

0.188

0.221

0.067

1.512

2%

40 – 49.9

44 to 46.9

124

0.370

0.272

0.266

0.094

1.745

3%

50 – 59.9

47 to 49.9

85

0.466

0.388

0.340

0.053

1.947

9%

60 – 69.9

50 to 51.9

23

0.458

0.345

0.328

0.165

1.578

9%

70 – 79.9

52 to 53.9

22

0.602

0.559

0.367

0.159

1.616

18%

80 – 89.9

54 to 55.9

13

0.636

0.439

0.463

0.168

1.653

15%

90 – 99.9

56 to 57.9

12

0.687

0.600

0.513

0.133

1.571

33%

100 – 200

58 to 71.9

4

0.682

0.602

0.436

0.279

1.245

25%

200+

> 72

3

0.950

1.059

0.342

0.567

1.224

67%

Alaska halibut data from the Fish Monitoring Program were interpreted by weight class as calculated from total fish length (Table 4a). Despite substantial variability in mercury content within each weight class, the mean mercury level increased with weight across all weight classes evaluated. Mean mercury levels in the heaviest halibut (greater than 200 pounds) were approximately 8-fold higher than those for the lightest halibut (less than 20 pounds). Because of this, the Committee found it necessary to give halibut consumption advice specific to each weight class. Similarly, Alaska lingcod data were interpreted by length class (Table 4b) due to the trend of higher mean mercury concentrations among longer fish.

Table 4a. Halibut Mercury Statistics by Weight Class, Statewide (ADEC Fish Monitoring Program)

Total Mercury (ppm)

*Calculated by IPHC; WR =[(6.921x10-6 x L3.24) x 1.33], where WR = round (whole) weight and L = fork length in cm

Length, Inches

N

Mean

Median

Std Dev

Minimum

Maximum

Percent fish > 1 ppm

20 to 29.9

9

0.081

0.041

0.068

0.033

0.199

0%

30 to 34.9

13

0.177

0.133

0.126

0.054

0.531

0%

35 to 39.9

21

0.276

0.241

0.172

0.070

0.653

0%

40 to 44.9

12

0.638

0.533

0.385

0.122

1.350

17%

45 to 49.9

27

0.731

0.724

0.263

0.196

1.428

11%

50 to 54

7

0.774

0.753

0.140

0.614

1.011

14%

Table 4b. Lingcod Mercury Statistics by Size Class, Statewide (ADEC Fish Monitoring Program)

Total Mercury (ppm)

Other researchers in Alaska also generate contaminant data for Alaska fish, including the University of Alaska Fairbanks, the U.S. Fish and Wildlife Service, Alaska Native tribes, and other entities. The Alaska Scientific Advisory Committee for Fish Consumption acknowledges the important contributions these research projects can make towards the development of fish consumption advice, and some of these data may be included in future updates to this DPH guidance. Inclusion of other data sources will require the Committee to establish internal guidelines for evaluation of data quality, representativeness, comparability of data type, and other criteria. These guidelines will allow the Committee to objectively determine which data are appropriate to merge with the ADEC Fish Monitoring data for the purpose of fish consumption guidance development.

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