Stocks of Atlantic salmon (Salmo salar), which have been steadily declining for the past few decades, are facing new challenges in the Gulf of Maine, where changing spring wind patterns, warming sea surface temperatures and new predators along altered migration routes are affecting their survival.
In a paper published online in the journal Fisheries Management and Ecology, Kevin Friedland and co-authors suggest post-smolts are entering an increasingly warmer coastal ocean, where they are facing mortality risks associated with a changing climate, such as changing distributions of potential predators. They also suggest Gulf of Maine salmon survival during their first months at sea is related to predation, possibly by populations of silver hake, red hake and spiny dogfish increasingly found along the salmon's extended migration routes in the western Gulf of Maine. Friedland is a researcher at the Narragansett Laboratory of NOAA's Northeast Fisheries Science Center, and is a member of the Center's Ecosystems Assessment Program.
Gulf of Maine Atlantic salmon are listed as endangered, and returns of these fish to rivers where they spawn have been low despite increased numbers of smolts entering the marine environment. The researchers examined a variety of data collected over decades, including spring wind patterns, Gulf of Maine currents, ocean circulation systems, historical tagging returns, migratory routes, and changes in potential predator abundances and distribution patterns. Models were used to consider how shifting climate and biological factors, under various scenarios, affected salmon recruitment and survival in the Gulf of Maine.
"This study had two primary goals. The first was to examine the effects of spring winds in the Gulf of Maine on the migration trajectory of post-smolts, since the route and length of migration could impact their mortality or survival," said Friedland. "The second goal was to look at the
|Contact: Shelley Dawicki|
NOAA Fisheries Northeast Fisheries Science Center