123 
Abstract— Even-year pink salmon (On- 
corhynchus gorbuscha) populations from 
the Russian Far East and Japan exhibit 
genetic structure that reflects their 
geographic relationships. Extension of 
genetic analysis to include data from 
Bering Sea and northern Gulf of Alaska 
populations shows a combined genetic 
structure with three prominent group- 
ings that correspond to the three 
North Pacific Ocean basins — the Sea of 
Okhotsk, the Bering Sea, and the Gulf 
of Alaska — and that are consistent with 
geographic, geologic history, and ocean- 
ographic features. Analysis of 35 Asian 
collections at 39 variable allozyme loci 
(54 total) allowed examination of pop- 
ulation structure of even-year pink 
salmon. Although most (98.5%) of the 
genetic variation occurred within collec- 
tions (populations), the 1.5% attribut- 
able to among-collection divergence was 
sufficient to detect population structure 
and provide a basis for some stock sep- 
aration. Differences between western 
Kamchatka populations and eastern 
Sakhalin Island populations indicate 
that little gene flow occurs between 
those regions and argues against an 
interregional fluctuating stock model. 
Manuscript accepted 22 August 2000. 
Fish. Bull. 99:123-138 (2001). 
Analysis of contemporary genetic structure of 
even-broodyear populations of Asian and western 
Alaskan pink salmon, Oncorhynchus gorbuscha 
Claire Noll 1 
Natalia V. Varnavskaya 2 
Evgeny A. Matzak 3 
Sharon L. Hawkins 1 
Victoria V. Midanaya 2 
Oleg N. Katugin 3 
Charles Russell 1 
Natalya M. Kinas 2 
Charles M. Guthrie III 1 
Hiroshi Mayama 4 
Fumio Yamazaki 5 
Bruce P. Finney 6 7 
Anthony J. Gharrett 17 
E-mail address (for A J. Gharrett, contact author): ffajg@uaf.edu 
Pink salmon ( Oncorhynch us gorbuscha ) 
are the most abundant Pacific salmon 
species and spawn along most of the 
Pacific rim coastline north of 40°N 
latitude (Heard, 1991). The species is 
unique among salmonids in having a 
determinate life cycle. Adults return 
to their natal streams to spawn at 2 
years of age, which has resulted in 
separate broodlines in even and odd 
years (Heard, 1991). Most of the range 
supports spawning runs of both brood- 
lines, although they may differ in num- 
bers. The southern part of the North 
American Pacific coast has only small 
even-year runs; and in western Alaska, 
even-year runs are much more abun- 
dant than odd-year runs (Heard, 1991). 
The pattern of a numerically dominant 
broodline in many areas has changed 
since early this century, perhaps in 
response to changes in fishing inten- 
sity (Takagi et al., 1981) or climate 
cycles (Mantua et al., 1997). Optimum 
management and conservation of the 
pink salmon resource requires thor- 
ough knowledge of their biology, includ- 
ing population structure, relationships 
among populations, and the extent of 
genetic exchange among local popula- 
tions and between geographically dis- 
tinct regions. Genetic divergence among 
groups of salmon also may provide a 
basis for stock identification by fish 
managers (Beacham et al., 1985; Pella 
and Milner, 1987). 
Although DNA-based analyses have 
become available in recent years (e.g. 
Park and Moran, 1994), allozyme anal- 
ysis remains a powerful method for 
pink salmon studies because they ex- 
hibit variability at a number of loci. 
From allozyme data, marked broodline 
differences have been demonstrated be- 
tween pink salmon populations from 
the Russian Pacific coast (Gagalchii, 
1986; Glubokovsky et al., 1989; Kar- 
tavtsev, 1991; Zhivotovsky et al., 1989; 
Kartavtsev et al., 1992) and from the 
North American Pacific coast (Aspin- 
wall, 1974; McGregor, 1983; Beacham 
et al., 1988). Although based on few 
allozyme loci, genetic divergence with- 
in each broodline also has been ob- 
served among pink salmon collections 
from many regions of Russia (Gagal- 
chii, 1986; Glubokovsky et al., 1989); 
1 National Marine Fisheries Service, Auke 
Bay Laboratory, 11305 Glacier Hwy., 
Juneau, Alaska 99801-8626. 
2 Kamchatka Scientific Research Institute 
of Fisheries and Oceanography, Kamchat- 
NIRO, Petropavlovsk-Kamchatsky 683602, 
Kamchatka, Russia. 
3 Pacific Research Fisheries Centre (TINRO- 
CENTRE), 4 Shevchenko Alley, Vladivo- 
stok 690600, Russia. 
4 Hokkaido Salmon Hatchery, Fisheries 
Agency of Japan, 2-2 Nakanoshima, 
Toyohira-ku, Sapporo 062, Japan. 
5 Hokkaido University, Laboratory of Genet- 
ics and Embryology, Faculty of Fisheries, 
Hakodate 041, Japan. 
6 Institute of Marine Science, University 
of Alaska Fairbanks, Fairbanks, Alaska 
97735. 
7 Fisheries Division, University of Alaska 
Fairbanks, 11120 Glacier Hwy., Juneau, 
Alaska 99801. 
