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Marine Ecology Progress Series

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MEPS 410:177-195 (2010)  -  DOI:

Fine-scale spatial and temporal genetic structure of Atlantic cod off the Atlantic coast of the USA

Adrienne I. Kovach1,*, Timothy S. Breton2, David L. Berlinsky2, Lorraine Maceda3, Isaac Wirgin3

1Department of Natural Resources and the Environment, and 2Department of Biological Sciences, University of New Hampshire, 46 College Road, Durham, New Hampshire 03824, USA
3Department of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, New York 10987, USA

ABSTRACT: Atlantic cod Gadus morhua in US waters are currently managed as 2 stocks: (1) a Gulf of Maine stock and (2) a Georges Bank and south stock. This designation is decades old and warrants re-evaluation in light of concerns that fisheries management units may not reflect biologically meaningful population units. In this study, we used 10 microsatellite loci, the PanI locus, and 5 single nucleotide polymorphism markers to characterize the population genetic structure of cod in US waters. We found significant differentiation among temporally and spatially divergent populations of cod (global FST = 0.0044), primarily stemming from 2 potentially non-neutral loci, and evidence for a population structure that strongly contradicts the current 2-stock management model. This genetic structure was stable over a 5 yr period. Our results indicate that cod in US waters are broadly structured into 3 groups: (1) a northern spring-spawning coastal complex in the Gulf of Maine (GOM), (2) a southern complex consisting of winter-spawning inshore GOM, offshore GOM and sites south of Cape Cod, Massachusetts, and (3) a Georges Bank population. The strongest differentiation occurs between populations in the northern and southern complex (mean FST = 0.0085), some of which spawn in the same bays in different seasons. By means of mixture analysis, young-of-the-year fish sampled on juvenile nurseries were assigned to the spawning complex of their origin. Our findings contribute to a growing body of knowledge that Atlantic cod and other marine fish populations are structured on a finer scale than previously thought and that this structure supports biocomplexity and locally adapted populations. As such, it may be warranted to re-evaluate current management units and tailor management plans toward this finer scale.

KEY WORDS: Atlantic cod · Microsatellite DNA · Single nucleotide polymorphism · Population genetic structure · Stock identification · Gadus morhua

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Cite this article as: Kovach AI, Breton TS, Berlinsky DL, Maceda L, Wirgin I (2010) Fine-scale spatial and temporal genetic structure of Atlantic cod off the Atlantic coast of the USA. Mar Ecol Prog Ser 410:177-195.

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