Audun Rikardsen (foreground) with tagged salmon just before release. (Photo: Mark Renkawitz, NOAA)
Satellite tags disclose data of Atlantic salmon's conditions at sea
Monday, February 13, 2012, 06:20 (GMT + 9)
Scientists are learning where adult Atlantic salmon go in the ocean and what environmental conditions they experienced thanks to satellite tags.
The fish are tagged and released near Nuuk, Greenland; the archival tags record information for months and then pop-off or dislodge from the fish. The tags transmit data about water depths, ocean temperatures and sunlight levels felt by the fish.
Researchers then use these data to re-create salmon migration routes and learn about the oceanographic conditions the fish experienced when traveling to their natal rivers to spawn.
The Greenland satellite tagging project is led by Tim Sheehan and Mark Renkawitz at the National Oceanic and Atmospheric Administration's (NOAA) Woods Hole Laboratory of the Northeast Fisheries Science Centre (NEFSC).
|Researchers insert the PSAT (pop-off satellite tag) to a salmon via a brief surgical procedure which anesthetizes the area. (Photo:Mark Renkawitz, NOAA)
Last September, the team attached tags to 17 salmon off Greenland's coast; 10 remain attached to the fish and are programmed to dislodge on 1 April, as the tag detachment apparatus relies on being in saltwater and there is a very low likelihood that any tagged fish will have returned to their natal river by this date.
Data from a tag attached during the pilot project in 2010-11 has given a picture of where this fish travelled during its nearly eight months at sea. When coupled with the water temperature and depth data, researchers will better be able to tag fish and refine the quantity of data obtained.
While Atlantic salmon used to be found in rivers throughout New England, Maine is now the only regional state with wild salmon populations, and though increasing numbers of smolts are entering the ocean via the Gulf of Maine, few are returning, and scientists want to know what is happening to them while at sea.
“Salmon are dying in the ocean at an increased rate. This project allows us to study the migration of these pre-spawning adults from their feeding grounds off Greenland to their natal rivers in both North America and Europe”, Renkawitz said.
"What we learn from this project, coupled with other related projects, will provide a much better picture of what oceanographic conditions are important for salmon survival and how large-scale ecosystem level changes over time have influenced the trends we are seeing”, Renkawitz continued.
Advances in genetics and tagging technology will one day show where an individual fish came from – perhaps down to its specific river. Genetic information is collected and added to the database when each fish is tagged.
As the tag technology advances and tags are made smaller, the NEFSC team hopes to tag even more salmon.
"Each project adds another piece to the puzzle", Sheehan added. "What we learn will help us better understand the global picture for salmon and for other fishery resources.”
By Natalia Real
Photo Courtesy of FIS Member National Oceanic and Atmospheric Administration NOAA/NMFS