Genetic Variation in Atlantic Cod (Gadus morhua) Throughout Its Range

Abstract

The amount of genetic differentiation between stocks of Atlantic cod (Gadus morhua) was estimated from electrophoretically detectable protein loci expressed in skeletal muscle and liver. Variant alleles at 13 of these loci were detected among nine samples covering most of the species range: North America, Greenland, Iceland, Barents Sea, Norwegian coastal waters, the North Sea, and the Baltic Sea. A very low amount of genetic differentiation was observed among stocks. Only two loci (LDH-3 and PGI-1) showed large statistically significant heterogeneity of allele frequencies between samples. Standard genetic distances (Nei) between these samples based on 10 variable loci ranged from 0.00015 to 0.01072 with Baltic cod as the genetically most divergent sample. There was a highly significant correlation between genetic and geographic distance for the samples from the Atlantic suggesting that a substantial gene flow has occurred between these stocks with geographic distance being an inhibiting factor. The relatively larger genetic distance between the Baltic cod and other stocks may reflect isolation resulting from geographic and perhaps ecological barriers. However, the absolute amount of genetic differentiation in the Atlantic cod appears to be very low throughout its range.

To Adapt or Not Adapt: Assessing the Adaptive Capacity of Artisanal Fishers in the Trondheimsfjord (Norway) to Jellyfish (Periphylla periphylla) Bloom and Purse Seiners

“…Trondheimsfjord supports a local, self-recruiting cod stock, which traditionally has been the keystone species in the ecosystem and has sustained local fishermen for their livelihood for centuries (Dahl 1899;Mork, Reuterwall et al 1982;Mork et al 1985). Outside the spawning season cod are dispersed throughout the fjord, but aggregate on the spawning grounds in the innermost parts of the fjord in spring (March-May), when the annual spawning fishery takes place (Dahl 1899).…”

Phylogeographic mitogenomics of Atlantic codGadus morhua: Variation in and among trans‐Atlantic, trans‐Laurentian, Northern cod, and landlocked fjord populations

“…Early studies of hemoglobin protein markers found significant frequency differences among geographic locations (Cross & Payne, 1978; Frydenberg, Møller, Nævdal, & Sick, 1965; Gjøsæter, Jørstad, Nævdal, & Thorkildsen, 1992; Møller, 1968; Sick, 1965a,b), although selection and temperature differences have since explained many of these results (Jamieson & Birley, 1989; Mork & Sundnes, 1985). Trans‐Atlantic differences are evident in protein loci (Jamieson, 1967; Mork, Ryman, Ståhl, Utter, & Sundnes, 1985), mitochondrial cytochrome b (Carr & Marshall, 1991a; Sigurgíslason & Árnason, 2003), and nuclear DNA markers (Pogson, Mesa, & Boutilier, 1995), although results at local scales remain ambiguous. Extensive mtDNA analyses have found little or no structure in waters off the coasts of eastern North America (Carr, Snellen, Howse, & Wroblewski, 1995), Iceland (Árnason, Pálsson, & Arason, 1992; Árnason, Petersen, Kristinsson, Sigurgíslason, & Pálsson, 2000), the Faroe Islands (Sigurgíslason & Árnason, 2003), Norway (Árnason & Pálsson, 1996), and the Baltic Sea (Árnason, Petersen, & Pálsson, 1998).…”

Phylogeography and demographic history of Atherina presbyter (Pisces: Atherinidae) in the North-eastern Atlantic based on mitochondrial DNA

“…Almada et al 2008;Blanquer et al 1992;Debes et al 2008;Domingues et al 2007aDomingues et al , 2008Magoulas et al 1996;Mork et al 1985;Nesbo et al 2000;Stefanni et al 2007). Much emphasis has been placed on the Atlantic-Mediterranean transition (see Patarnello et al 2007 for a review), but the eVectiveness of this barrier varies greatly when diVerent species are analyzed (e.g.…”