Mitochondrial DNA sequence variation and genetic stock structure of Atlantic cod (Gadus morhua) from bay and offshore locations on the Newfoundland continental shelf

Mitochondrial DNA sequence variation and genetic stock structure of Atlantic cod (Gadus morhua)... Bay cod, Atlantic cod (Gadus morhua) that over‐winter in the deep‐water bays of northeastern Newfoundland, have historically been regarded as distinct in migration and spawning behaviour from offshore (Grand Bank) cod stocks. To investigate their genetic relationships, we determined the DNA sequence of a 307‐base‐pair portion of the mitochondrial cytochrome b gene for 236 adult cod taken from the waters off northeastern Newfoundland, including fish found over‐wintering and spawning in Trinity Bay. Although 17 genotypes were found, a single common genotype occurs at a frequency of greater than 80% in all samples, and no alternative genotype occurs at a frequency of greater than 3%. Genotype proportions did not differ significantly among samples. Measures of genetic subdivision among sampling locations are nil. Cod over‐wintering in Trinity Bay are not genetically distinct from offshore cod. In combination with tagging and physiological studies, these data suggest that there is sufficient movement of cod between bay and offshore locations to prevent the development or maintenance of independent inshore stocks. Adult cod that over‐winter in Trinity Bay appear to represent an assemblage of temporarily nonmigratory fish that have become physiologically acclimated to cold‐water inshore environments. The pattern of genetic variation in northern cod suggests a recent population structure characterized by extensive movement of contemporary individuals superimposed on an older structure characterized by a bottleneck in the population size of cod in the north‐western Atlantic. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Molecular Ecology Wiley

Mitochondrial DNA sequence variation and genetic stock structure of Atlantic cod (Gadus morhua) from bay and offshore locations on the Newfoundland continental shelf

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Publisher
Wiley
Copyright
Copyright © 1995 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0962-1083
eISSN
1365-294X
DOI
10.1111/j.1365-294X.1995.tb00194.x
Publisher site
See Article on Publisher Site

Abstract

Bay cod, Atlantic cod (Gadus morhua) that over‐winter in the deep‐water bays of northeastern Newfoundland, have historically been regarded as distinct in migration and spawning behaviour from offshore (Grand Bank) cod stocks. To investigate their genetic relationships, we determined the DNA sequence of a 307‐base‐pair portion of the mitochondrial cytochrome b gene for 236 adult cod taken from the waters off northeastern Newfoundland, including fish found over‐wintering and spawning in Trinity Bay. Although 17 genotypes were found, a single common genotype occurs at a frequency of greater than 80% in all samples, and no alternative genotype occurs at a frequency of greater than 3%. Genotype proportions did not differ significantly among samples. Measures of genetic subdivision among sampling locations are nil. Cod over‐wintering in Trinity Bay are not genetically distinct from offshore cod. In combination with tagging and physiological studies, these data suggest that there is sufficient movement of cod between bay and offshore locations to prevent the development or maintenance of independent inshore stocks. Adult cod that over‐winter in Trinity Bay appear to represent an assemblage of temporarily nonmigratory fish that have become physiologically acclimated to cold‐water inshore environments. The pattern of genetic variation in northern cod suggests a recent population structure characterized by extensive movement of contemporary individuals superimposed on an older structure characterized by a bottleneck in the population size of cod in the north‐western Atlantic.

Journal

Molecular EcologyWiley

Published: Feb 1, 1995

Keywords: ; ; ; ;

References

  • Gene flow and lack of population differentiation in Atlantic cod, Gadus morhua L., from Iceland, and comparison of cod from Norway and Newfoundland
    Árnson, E.; Pálsson, S.; Arason, A.
  • The direction of hybridization between species of north American deer (Odocoileus) as inferred from mitochondrial cytochrome b sequences
    Carr, SM; Hughes, GA
  • A direct approach to the measurement of genetic variation in fish populations: Applications of the polymerase chain reaction to studies of Atlantic cod (Gadus morhua
    Carr, SM; Marshall, HD
  • Geographic variation in Atlantic cod, Gadus morhua, off eastern North America: a biochemical systematics approach
    Cross, TF; Payne, RH
  • The Cod Fisheries
    Innis, HA
  • Discrimination of the stock complex of Atlantic cod (Gadus morhua) off southern Labrador and eastern Newfoundland, as inferred from tagging studies
    Lear, WH
  • Mechanisms of Migration in Fishes
    Lear, WH; Green, JM
  • Molecular Evolutionary Genetics
    Nei, M.
  • The bottleneck effect and genetic variability in populations
    Nei, M.; Maruyama, T.; Chakraborty, R.

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