A team of researchers is launching a conservation effort for the Chinook salmon from the Alaskan Bristol Bay.
For their study, published in the journal Science Advances, the researchers attached a chemical signature tracker to the salmon's otolith, a bone in their ear. Using the chemical tracker, the researchers will observe the salmon's movements for the first year of their lives.
"Each fish has this little recorder, and we can reveal the whole life history of the fish from the perspective of the otolith. Each growth ring is a direct reflection of the environment the fish was swimming in at the time it was formed," study lead author Sean Brennan, a postdoctoral researcher in the University of Washington's (UW) School of Aquatic and Fishery Sciences, said in a press release.
Brennan conducted the study as a doctoral student at the University of Alaska, Fairbanks (UAF).
"Alaska is a mosaic of geologic heterogeneity," he said. "As long as you can look at a geologic map and see rocks that are really different, that's a good potential area."
The researchers' tracker is made up of isotopes taken from the strontium element, which can be found in bedrock. According to the release, how the chemical tracker reacts with the salmon's surroundings will tell the researchers where the fish is.
"This particular element and its isotopes are very strongly related to geography," study co-author Matthew Wooller, director of the Alaska Stable Isotope Facility at UAF, said in the release. "It is a really good marker for where animals have been and whether they move around in their environment."
