Top researchers with the Atlantic Salmon Federation (ASF) are trying to figure out why wild Atlantic salmon numbers are dropping dramatically once they leave their home rivers and head into saltwater.
Jonathan Carr, ASF’s Director of Research and Environment, recently presented his latest scientific findings at the Atlantic Salmon Ecosystems Forum in Orono, Maine. Scientists from across North America gathered to exchange information regarding the latest research on wild Atlantic salmon and their habitat.
Carr presented more than 10-years worth of research, using acoustic telemetry to track both juvenile salmon (smolt) and repeat-spawning salmon (kelts). The tracking of smolt began in 2003 on the Miramichi and Restigouche rivers in New Brunswick and the Cascapedia river in Quebec, after a decade of developing the technology required to track fish in the ocean.
“Every year we gather new bits of information so it’s very important to track over time, “said Carr. “Our research has shown that freshwater survival in those rivers for outgoing smolt is good, but there is high mortality in the estuary and bay areas.”
Carr and a team of researchers are launching new studies to try to figure out what is causing these high mortalities. The team will be tracking striped bass as well to see if they are found in the same areas as smolt. They will also be looking at the stomach contents of the striped bass to determine what percentage of smolt may be in their diet. The study is a partnership among ASF, the Department of Fisheries and Oceans Canada (DFO) and the Miramichi Salmon Association.
“We’ll also be looking at the potential impact cormorants may have on smolt survival in the Restigouche estuary and Chaleur Bay region,” said Carr. “We ran an aerial survey over the colonies last year looking for eggs and nests. Using visual bird surveys, population abundance and size of out-migrating smolt, we can estimate what percentage of the cormorant diet may be composed of salmon smolt in that region.”
Partners involved with the cormorant study include the Restigouche River Watershed Management Committee, Gespe'gewaq Mi'gmaq Resource Council, DFO, and Institut national de la recherche scientifique.
In 2014, Carr and the team will use pit tags, which are inserted in smolt, to determine if the birds may be eating the fish. They then search areas where cormorant populations are located, seeking out the pit tags using metal detectors.
“Being able to address the problems of high mortality that are close to home improves our chances of success in restoring Atlantic salmon,” said Carr.
ASF researchers will be back in the field tracking salmon beginning in May of this year.