Atlantic salmon are anadromous fish, meaning they are born in fresh water and migrate from rivers to the ocean after undergoing a number of distinct stages of development over several years. As smolts, the thin silver fish head to the ocean, usually between March and June, to begin a stage of enhanced feeding and growth. After several years at sea, adults return to the freshwater streams and rivers where they were born to reproduce.
At one time Atlantic salmon could be found in rivers throughout much of New England, but Maine is now the only state in the region with wild Atlantic salmon populations. While increasing numbers of smolts are entering the ocean via the Gulf of Maine, few are returning, raising questions as to where these fish are going and what is happening to them at sea.
"Shifting environmental conditions affect both the freshwater and marine habitats for Atlantic salmon, and are already a concern for salmon stocks at the southern end of their distribution range in both North America and Europe, "Friedland said. "Understanding the linkages between post-smolt survival and climate, especially ocean conditions, is critical and needs to be considered in the scientific basis for conservation planning and management actions."
Rising temperatures could exceed the tolerable limits for juvenile salmon and reduce the amount of habitat available for growth and development during their freshwater stages. Warming ocean temperatures in the Gulf of Maine, expected to occur in the decades ahead, could result in extirpation of salmon stocks from the southern end of the species' range.
|Contact: Shelley Dawicki|
NOAA Fisheries Northeast Fisheries Science Center