The Connecticut River historically represented the southernmost extent of the North American range of Atlantic salmon (Salmo salar), but the native population was extirpated 200 years ago by dam construction. An extensive restoration effort has relied upon stock transfers from more northerly rivers, especially the Penobscot River (Maine). Recent work has shown differences in age structure between donor and derivative populations. Here we focus on a related life-history trait, the timing of the adult migration. We examined 23 years of migration timing data collected at two capture locations in the Connecticut River drainage. We found that both dates of first capture and median capture dates have shifted significantly earlier by about 0.5 days·year1. To conclude whether this is a consequence of local adaptation or a coast-wide effect, we also quantified changes in migration timing of more northerly stocks (in Maine and Canada). We found that the changes in migration timing were not unique to the Connecticut River stock and instead observed coherent patterns in the shift towards earlier peak migration dates across systems. These consistent shifts are correlated with long-term changes in temperature and flow and may represent a response to global climate change.
Anadromous Atlantic salmon Salmo salar from 12 rivers in Maine, 3 rivers in New Brunswick, and 2 rivers each in Nova Scotia, Quebec, Newfoundland, and Labrador as well as 2 landlocked strains in Maine (N ϭ 3,863) were genotyped at 11 microsatellite loci. Fish in the drainages of Maine's Kennebec and Penobscot rivers were genetically similar to those sampled from the 8 rivers recently listed as containing an endangered distinct population segment under the United States' Endangered Species Act. Genetic distance estimates confirm that Maine's Atlantic salmon, both landlocked and anadromous, represent a discrete population unit, genetically as independent from any Canadian population as the Canadian populations are from each other. Within Maine, the anadromous and landlocked populations were statistically distinct. Anadromous Atlantic salmon were more genetically similar among year-classes within rivers than among rivers, as would be expected if the river is the unit of population. The effective number of breeders estimated within each river is larger than the number of adults estimated from samples and redd counts over the 10-year period from 1991 to 2000. subsistence and commercial fishery resource for both native North Americans and European settlers through the beginning of the industrial revolution. The Atlantic salmon was nearly extirpated from New England in the 19th century, when habitat loss resulting from dam construction and logging
Electrophoretic examination of 56 wild Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) from the Stewiacke River, Nova Scotia, revealed one individual believed to be a hybrid between these two species. The possibility of loss of the genetic integrity of each species is considered. A long history of sympatry between Atlantic salmon and brown trout in Europe may have prevented the formation of hybrid swarms as occurred in western North America following introduction of nonindigenous Salmo.Key words: electrophoresis, introgression, enzymes, genetic interaction
Water velocity and depth preferences of spawning Atlantic salmon (Saltno salar) in four rivers in Maine were measured dnring October in 1975--1977. Female Atlantic salmon constructed redds in water with a mean depth of 38 -+ 0.8 cm. Mean water velocity measured 12 cm above the substrate was 53 ___ 1.3 cm/sec. Management implications of water depth and velocity requirements of spawning salmonids are discussed.
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