
Table 4. Frequencies of organochlorine residues (as frequency indices*) in eggs of Alaskan seabirds, 1973-76 
. by species and collection site. 



: Species? ; 
Region and collection site CL NF F-tSP LSP D-cC PC R-fC ACG G-wG MG B-lIK ArT AIT CM T-bM AM HP TP Total 
Gulf of Alaska 
Copper River Delta 0.385 0.385 
Hinchinbrook Island 0.638 0.469 0.815 0.641 
Middleton Island 0.678 0.554 0.285 0.538 0.518 
Barren Islands 0.769¢ 0.577¢ 0.692¢0.712 0.707 
Amalik Bay 0.446 0.446 
Kodiak Island 0.923¢ 0.602 0.554 0.490 0.2316 0.692 0.573 
Ugaiushak Island 0.308¢ 0.586 0.407 0.359 0.442¢ 0.692¢ 0.671 0.545 
Semidi Islands 0.505 0.385¢ 0.715 0.527 0.573 
Shumagin Islands 0.515 0.628 0.558 
Aleutian Islands 
Bogoslof Island 0.513¢ 0.462 0.477 
Buldir Island 0.769 0.601 0,462¢ 0.308¢ 0.654¢ 0.718¢ 0.308¢ 0.240 0.508 0.538° 0.538 0.542 
Attu Island 0.590 0.590 
Bristol Bay ; 
Round Island 0.397 0.538¢ 0.454 
Shaiak Island 0.513¢ 0.667¢ 0.513¢ 0.369 0.667 0.546 
Pribilof Islands 
St. George Island 0.705 0.636 0.601 
St. Paul Island 0.431 0.515 0.473 
Seward Peninsula 
Bluff Seabird Cliffs 0.453 0.462 ().457 
King Island 0.515 0.515 
Totals 0.923 0.559 0.769 0.601 0.396 0.645 0.385 0.308 0.532 0.554 0.442 0.231 0.590 0.501 0.385 0.442 0,508 0.662 0.677 0.540 


aComputed as total occurrences/possible occurrences. Total occurrences = number of times any of the 13 organochlorines were detected in eggs from that 
region; possible occurrences = number of clutches from that region x 13 chemicals. 
bC], = common loon: NF = northern fulmar; F-tSP = fork-tailed storm-petrel; LSP = Leach’s storm-petrel; D-eC = double-crested cormorant; PC = 
pelagic cormorant; R-f{C = red-faced cormorant; ACG = Aleutian Canada goose; G-wG = glaucous-winged gull; MG = mew gull; B-IK = black- 
legged kittiwake; ArT = arctic tern; AIT = Aleutian tern; CM = common murre; T-bM = thick-billed murre; PG = pigeon guillemot; AM = ancient 
murrelet; HP = horned puffin; TP = tufted puffin. 
cSample includes less than 5 eggs. 
Cliffs) and at the Copper River Delta and Amalik Bay, 
where only glaucous-winged gull eggs were collected 
(Table 4). Again, however, this overall pattern did not 
apply to all species represented at the various sites. 
Residue Concentration 
Within species, there were often significant differences 
among regional means for DDE and PCB's (Table 5); 
mean residue concentrations for other chemicals were 
tested only among selected species and for the collection 
sites where adequate samples were available. Means were 
usually higher in the samples from the Gulf of Alaska and 
lower in those from the Aleutian Islands and Bristol Bay 
than in those from the other two regions. However, mean 
concentrations of both DDE and PCB’s in glaucous-winged 
gull eggs from the Aleutian Islands were significantly 
higher than those from the Gulf of Alaska. Differences 
among the other regions were not consistent, probably in 
part because all of the species usually were not collected at 
each nesting colony. 
Mean concentrations of DDE and PCB’s for each species 
were usually of the same order of magnitude (Table 5 and 
Appendix III), but in black-legged kittiwake the level of 
DDE was consistently much the lower—usually about 
one-tenth that of PCB's. 
Mean concentrations of DDE (5.16 ppm) and PCB's 
(3.55 ppm) were higher in glaucous-winged gull eggs from 
Bogoslof Island than in any other samples we analyzed 
(Appendix III). These chemicals were also somewhat 
higher in black-legged kittiwake (0.089 ppm DDE; 
0.931 ppm PCB's) and fork-tailed storm-petrel (0.602 ppm 
DDE; 1.69 ppm PCB’s) at Buldir Island than at the other 
sites where eggs of these species were collected. However, 
concentrations of DDE (0.119 ppm) and PCB’s (0.126 ppm) 
were relatively low in common murres (Table 6), the only 
other species represented from Bogoslof Island. In thick- 
billed murre (PCB’s only, 0.090 ppm) and tufted puffin 
(0.135 ppm DDE; 0.395 ppm PCB's; see also Appendix 
III), residue levels were lower at Buldir Island than else- 
where. (Because the sample sizes for some species were 
small, not all of these differences could be tested statisti- 
cally; however, they indicate a pattern of relatively high 
residue levels in some species at Bogoslof and Buldir is- 
lands and lower levels in other species nesting there.) 
Among the sites where at least five samples per species 
were collected, mean DDE concentrations for glaucous- 
winged gull eggs were highest at Kodiak Island, the 
Semidi Islands, and Middleton Island and lowest at the 
Copper River Delta, Hinchinbrook Island, the Shumagin 
Islands, and Ugaiushak Island (Table 6). In black-legged 
