Table 3, Percent frequency of occurrence of organochlorine residues in eggs of Alaskan seabirds, 1973-76, by species within regions.“ 



Residues 
No. of Heptachlor Frequency 
Region and species samples DDD DDT Dieldrin epoxide = Mirex Oxychlordane Cis-chlordaneb Cis-nonachlor HCB  Toxaphene index® 
Gulf of Alaska 
Common loon l 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 0.923 
Northern fulmar 16 75.0 100.0 50.0 6.2 56.2 100.0 0.0 0.0 68.8 0.0 0.505 
Fork-tailed storm-petrel 4 100.0 100.0 100.0 50.0 75.0 100.0 100.0 75.0 100.0 0.0 0.769 
Double-crested cormorant 4 0.0 0.0 0.0 50.0 0.0 50.0 0.0 0.0 100.0 0.0 0.308 
Pelagic cormorant 1] 36.4 81.8 100.0 100.0 0.0 100.0 100.0 63.6 9.1 90.9 0.678 
Red-faced cormorant l 0.0 0.0 0.0 0.0 0.0 0.0 100.0 100.0 0.0 100.0 0.385 
Glaucous-winged gull 113 46.0 23.9 79.6 68.1 16.8 78.8 53.1 20.4 81.4 18.6 0.525 
Mew gull D 80.0 60.0 100.0 100.0 0.0 100.0 40.0 40.0 0.0 0.0 0.554 
Black-legged kittiwake 31 99.6 6.4 35.5 29.0 12.9 87.1 41.9 12.9 67.7 22.6 0.417 
Arctic tern 8 0.0 0.0 0.0 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.231 
Common murre 7 58.8 41.2 29.4 47.1 0.0 82.4 35.3 58.8 41.2 Bod 0.484 
Thick-billed murre 6 0.0 0.0 33.3 50.0 0.0 83.3 16.7 0.0 83.3 0.0 0.359 
Pigeon guillemot 4 0.0 0.0 25.0 0.0 0.0 50.0 25.0 75.0 100.0 100.0 0.442 
Horned puffin 4 50.0 50.0 75.0 75.0 25.0 100.0 100.0 75.0 100.0 50.0 0.692 
Tufted puffin 63 84.1 41.3 69.8 74.6 44.4 92.1 88.9 55.6 95.2 41.3 0.682 
Total 983 52:6, .34.3 65.4 59.7 23.0 85.2 56.5 3275 75.6 27.6 0.547 
Aleutian Islands 
Fork-tailed storm-petrel 7 71.4 85.7 57.1 28.6 100.0 100.0 100.0 57.1 100.0 100.0 0.769 
Leach’s storm-petrel 1] 63.6 63.6 27.3 9.1 0.0 63.6 63.6 90.9 100.0 100.0 0.601 
Pelagic cormorant 2 0.0 50.0 0.0 50.0 0.0 0.0 100.0 0.0 100.0 100.0 0.462 
Aleutian Canada goose ] 0.0 0.0 100.0 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.308 
Glaucous-winged gull 7 42.9 57.1 57.1 49,9 100.0 100.0 57.1 14.3 100.0 0.0 0.593. 
Black-legged kittiwake 3 100.0 100.0 0.0 100.0 100.0 100.0 100.0 oad 100.0 0.0 0.718 
Aleutian tern 6 66.7 0.0 100.0 66.7 0.0 100.0 50.0 0.0 100.0 83.3 0.590 
Common murre 8 12.5 0.0 75.0 62.5 0.0 75.0 1235 50.0 rot Be 0.0 0.442 
Thick-billed murre 8 0.0 0.0 0.0 0.0 0.0 12.5 0.0 0.0 100.0 0.0 0.240 
Ancient murrelet ha 60.0 0.0 0.0 60.0 0.0 20.0 60.0 100.0 60.0 100.0 0.508 
Horned puffin 1 100.0 0.0 100.0 0.0 0.0 100.0 100.0 0.0 0.0 100.0 0.538 
Tufted puffin 2 0.0 0.0 100.0 100.0 0.0 100.0 0.0 0.0 100.0 100.0 0.538 
Total 61 44.3 34.4 44,3 41.0 67.2 67.2 50.8 41.0 91.8 54.1 0.536 
Bristol Bay 
Double-crested cormorant A 33.3 0.0 100.0 66.7 0.0 66.7 0.0 100.0 100.0 0.0 0.513 
Glaucous-winged gull 3 0.0 33.3 100.0 100.0 100.0 100.0 66.7 100.0 66.7 0.0 0.667 
Black-legged kittiwake 9 0.0 0.0 100.0 29.9. 99.9. 77.8 0.0 55.6 88.9 0.0 0.436 
Common murre 9 0.0 0.0 88.9 55.6 0.0 66.7 0.0 66.7 100.0 0.0 0.444 
Tufted puffin 6 66.7 33.3 83.3 66.7 83.8 83.3 83.3 66.7 100.0 0.0 0.667 
Total 30 16.7 10.0 93.3 53.3 33.3 76.7 23.3 70.0 93.3 0.0 0.515 
Pribilof Islands 
Northern fulmar 6 83.3 100.0 83.3 50.0 33.3 100.0 83:3 33.3 100.0 100.0 0.705 
Black-legged kittiwake 10 0.0 0.0 10.0 50.0 0.0 100.0 0.0 0.0 100.0 100.0 0.431 
Common murre 21 52.4 47.6 61.9 95.2 0.0 100.0 4.8 95 100.0 81.0 0.579 
Total 37 43.2 43.2 51.4 Tot 5.4 100.0 8.1 10.8 100.0 89.2 0.559 
Seward Peninsula 
Black-legged kittiwake 9g 99.9 0.0 92.2 44.4 22.2 100.0 44.4 33.3 100.0 0.0 0.453 
Common murre 10 90.0 0.0 10.0 40.0 0.0 100.0 40.0 20.0 100.0 0.0 0.462 
Thick-billed murre 10 70.0 0.0 40.0 70.0 10.0 100.0 40.0 20.0 100.0 20.0 0.515 
Total 29 62.1 0.0 24.1 51.7 10.3 100.0 41.4 24.1 100.0 6.9 0.477 
Grand Total 440 48.9 31.1 60.5 Bare] 22.0 84.3 48.4 33.9 82.7 33.2 0.540 

‘In addition to compounds listed here, DDE was found in all samples and PCB’s were detected in all eggs except five glaucous-winged gull eggs from the 
Gulf of Alaska (i.e., they were present in 95.6% of the samples from that region). Endrin occurred in one black-legged kittiwake egg from the Gulf of 
Alaska. 
bOr trans-nonachlor, or both (see Methods). 
‘Computed as total occurrences/ possible occurrences. Total occurrences = number of times any of the 13 organochlorines were present in eggs from that 
region or species; possible occurrences = number of clutches from that region or species x 13 chemicals. 
currence was higher at Hinchinbrook Island, the Barren _ glaucous-winged gull was the highest of all sites for that 
Islands, Semidi Islands, Shumagin Islands, and Kodiak species, but frequencies of residues in northern fulmar and 
(Gulf of Alaska) and St. George islands than at most other —_ tufted puffin were the lowest for the various sites for those 
sites (Table 4). At certain sites the frequency of residue species; this combination produced a relatively high over- 
occurrence was different among the species represented; _ all index for the site. 
consequently the overall average for the site did not accu- Frequency of residue occurrence was low (<0.500) at 
rately reflect geographic differences among sites. For four sites where two or more species were cote ne 
example, at the Semidi Islands the frequency of residues in lof, Round, and St. Paul islands, and the Bluff Seabir 

