62 
Fishery Bulletin 11 6(1) 
Table 1 
Number of samples (n), geographic regions, gear used, collector (when known) and collector’s affiliation for collec¬ 
tions of 6 gadid species sampled in this study: saffron cod (Eleginus gracilis), navaga (E. nawaga), Pacific tomcod 
(Microgadus proximus ), Pacific cod ( Gadus macrocephalus), walleye pollock (G. chalcogrammus), and Arctic cod 
(Boreogadus saida). Asterisks denote specimens originally identified in the field as saffron cod, but were later 
re-examined. 
Species 
Scientific name 
n 
Geographic region 
Latitude 
Longitude 
Saffron cod 
Eleginus gracilis 
30 
Chukchi Sea 
66.91°N 
162.55°W 
41 
Gulf of Alaska 
57.73°N 
152.51°W 
Nawaga 
Eleginus nawaga 
81 
Barents Sea 
69.04°N 
57.87°E 
Pacific tomcod 
Microgadus proximus 8 
Puget Sound 
47.7UN 
122.52°W 
15 
Prince William Sound* 
60.87°N 
147.19°W 
Pacific cod 
Gadus macrocephalus 5 
Puget Sound 
48.40°N 
124.41°W 
8 
Unimak Pass 
54.45°N 
164.99°W 
Walleye pollock 
Gadus chalcogrammus 6 
SE Bering Sea 
55.67°N 
163.33°W 
Arctic cod 
Boregadus saida 
39 
Chukchi Sea 
66.90°N 
162.59°W 
14 
Chukchi Sea* 
66.90°N 
162.59°W 
Species 
Date 
Gear 
Collector 
Affiliation 
Saffron cod 
9/11 
jig 
A. Whiting 
Native Village of Kotzebue 
6/7/2013 
rod and reel 
E. Munk 
NOAA Fisheries 
Navaga 
7/13 
trawl 
N. Chernova 
Russian Academy of Sciences 
Pacific tomcod 
3/1997-8/1999 
beach seine 
M Canino 
NOAA Fisheries 
7/12 
beach seine 
M. Arimitsu 
U.S. Geological Survey 
Pacific cod 
3/13 
beach seine 
M. Canino 
NOAA Fisheries 
3/13 
trawl 
M. Canino 
NOAA Fisheries 
Walleye pollock 
9/15 
trawl 
W. Strasburger 
NOAA Fisheries 
Arctic cod 
4/12 
jig 
A. Whiting 
Native Village of Kotzebue 
4/12 
jig 
A. Whiting 
Native Village of Kotzebue 
template. Fluorescent primers labeled with an IRDye 
infrared dye (10 pg/mL; Integrated DNA Technologies, 
Inc., Coralville, IA) were included in the reactions. The 
amplification profiles for each locus were the following: 
denaturation at 95°C for 5 min; 20 touchdown cycles 
at 95°C for 30 s, annealing temperatures ranging from 
62 to 52°C (touchdown) for 30 s (decreased 0.5°C per 
cycle), and 72°C for 30 s; then 15 cycles of 95°C for 30 
s, the lowest annealing temperature (55°C) for 30 s, 
and 72°C for 30 s, and a final extension at 72°C for 5 
minutes. 
Approximately 1 pL of amplified PCR product and 
stop buffer (95% formamide, 0.1% bromophenol blue) 
was loaded onto a 0.25 mm 6% acrylamide gel (PAGE- 
PLUS™, Amresco, Solon, OH) and fragments were 
separated in lx TBE buffer (0.09 M Tris-Borate, 2 mM 
EDTA, pH 8) at 1500 V with a 4300 DNA Analyzer (LI- 
COR, Inc., Lincoln, NE). Electrophoresis times varied 
from 2 to 3 hours depending on allele sizes of the PCR 
product. The image of the PCR product was analyzed 
with SAGA, vers. 3.1 (LI-COR, Inc.) software. Two in¬ 
dividuals scored each gel separately and samples that 
differed in recorded allele size were genotyped a second 
or third time. 
Analysis of data 
Two collections of E. gracilis (one from the Chukchi 
Sea and another from near Kodiak Island, Alaska) were 
examined separately (Table 1). Collections of B. saida 
from the Chukchi Sea were combined for analysis as a 
single species as were collections of M. proximus (Prince 
William Sound and Puget Sound), and of G. macroceph¬ 
alus (Puget Sound and Unimak Pass) (Table 1). 
Allele frequencies and expected unbiased heterozy¬ 
gosities were estimated and genotype frequencies were 
tested for departures from Hardy-Weinberg expecta¬ 
tions with GENEPOP, vers. 4.5.1 (Rousset, 2008). Sig¬ 
nificance of multiple tests was confirmed with sequen¬ 
tial Bonferroni tests (Rice, 1989) and false discovery 
rate (FDR; Benjamini and Hochberg, 1995) corrections. 
Genotypes of individuals that produced deviations from 
Hardy-Weinberg expectations or apparent principal 
component analysis (PCA) outliers were reconfirmed 
by additional genotyping. 
Two genetic distances that are not strongly influ¬ 
enced by the numbers of alleles at a locus, but that 
are based on very different algorithms, were estimated. 
The standardized genetic differentiation measure G ' s ? 
