Sme et al.: Identification of Eleginus gracilis by means of microsatellite markers 
67 
Table 4 
Summary of results of a series of tests (Piry et al., 2004) that assigned each fish to 1 of 7 species groups: 
saffron cod (Eleginus gracilis) of the Chukchi Sea (CSC), saffron cod of the Gulf of Alaska (GSC), navaga 
(E. nawaga) (NAW), Pacific tomcod ( Microgadus proximus) (PTC), Pacific cod ( Gadus macrocephalus ) 
(PCO), walleye pollock (G. chalcogrammus ) (WPO), and Arctic cod ( Boreogadus saida) (ACO). n=the 
number of individuals of each group. For all results from the assignment tests, see Supplementary 
Table 2. 
n 
Species group 
Assigned to 
CSC 
GSC 
NAW 
PTC 
PCO 
WPO 
ACO 
30 
CSC 
29 
l a 
0 
0 
0 
0 
0 
41 
GSC 
0 
41 
0 
0 
0 
0 
0 
81 
NAW 
0 
0 
81 
0 
0 
0 
0 
23 
PTC 
0 
0 
0 
23 
0 
0 
0 
14 
PCO 
0 
0 
0 
0 
14 
0 
0 
6 
WPO 
0 
0 
0 
0 
0 
6 
0 
53 
ACO 
0 
0 
0 
0 
0 
l b 
52 
a 83% GSC/ 17% CSC. 
b 55% PCO/ 44%. WPO/1% ACO. 
notable instances were 14 aberrant genotypes included 
in a collection of E. gracilis from the Chukchi Sea and 
another 15 in a collection of E. gracilis from Prince 
William Sound. In both instances, it was possible to 
re-examine the individual specimens; the former were 
re-identified as B. saida and the latter as M. proximus 
(Table 1). Both sets of re-identified individuals were 
included with their correct species in the analyses pre¬ 
sented here (designated as ‘+’ and ‘x’, respectively in 
Fig. 1). Assignment tests correctly reassigned all of the 
other gadids except one Arctic cod. 
In these analyses, the two collections of E. graci¬ 
lis, and the collections of M. proximus, and E. nawa¬ 
ga were all distinct from each other (P<0.0001). The 
degree of their divergences mostly exceeded those 
observed between S. aleutianus and S. melanostictus 
(Gharrett et al., 2005) and each of the collections clus¬ 
tered separately in PCAs. It is notable that misidenti- 
fied individuals of Prince William Sound M. proximus 
were collected at the same site with E. gracilis, but 
were genetically distinct from them. Clearly, some field 
identifications, even by trained personnel, are chal¬ 
lenging (cf. Teletchea, 2009). It is unlikely that they 
represent two sympatric populations of a single marine 
species—populations that are so strongly different ge¬ 
netically. Although it could be argued that the genetic 
differences between the collections of E. nawaga and E. 
gracilis could result from divergence over the large dis¬ 
tance that separates them, the very large divergences 
in allele frequencies, as well as similar differences in 
allele size ranges at Elgrll and Elgrl4, are more con¬ 
sistent with their being distinct species. More complete 
information on the modern Arctic distributions of the 
two species of Eleginus, and the location of the historic 
contact zone between them, would contribute to re¬ 
solving their systematic status, as would independent 
data, such as mitogenomic sequences of E. nawaga 
and E. gracilis, coupled with morphological characters 
(Teletchea, 2009). 
Acknowledgements 
Funding was provided by the U.S. Department of In¬ 
terior (Bureau of Ocean Energy Management Agree¬ 
ments M12AC00009 and M12AC00009), the U.S. De¬ 
partment of the Interior (Fish and Wildlife Service 
Agreements 10-CIAP-010 and F12AF00188), the De¬ 
partment of Energy (award no. DE-FC09-07SR22506), 
and the Russian Federation for Fundamental Investi¬ 
gations (Grantl5-04-02081, Gostema no. 01201351186). 
This article is contribution EcoFOCI-0896 to NOAA’s 
Ecosystems and Fisheries Oceanography Coordinated 
Investigations program. 
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