Scientists developed a technique that allowed them to trace the birthplace of Chinook salmon and learn about the first year of it's life. The technique can be used to provide more understanding on the behavior of other species and how location affects the fish's survival.
Researchers at the University of Alaska Fairbanks discovered a chemical signature on the ear bones, also known as otolith, of a Chinook salmon captured from Alaska's Bristol Bay region in 2011. They observed that the otolith grows layers as the fish grows, and these so-called growth rings persist throughout the life of the salmon.
The team found traces of the element strontium, which is usually found in bedrock and varies depending on location. The strontium got transferred to the salmon by getting trapped to its ear bones while it swims. Though the salmon travels across different waters, the researchers observed that the chemical signature remains the same, allowing them to rule out the exact waters where the salmon had travelled.
"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," Sean Brennan, study leader and a postdoctoral researcher in the University of Washington's School of Aquatic and Fishery Sciences, said in a press release. He completed the study as a doctoral student at the University of Alaska Fairbanks.
Using a river system that maps the variation of the strontium isotope, the researchers were able to trace the birthplace of the salmon, as well as the places it'd been to. They found that the Chinook salmon was born in the Nushagak watershed and stayed there for a year prior to migrating to the ocean.
The researchers believe that this technique could help them explain the declining population of the Chinook salmon. Such information can pave way in the development of efforts that can help conserve the species.
The study was published in the May 15 issue of the journal Science Advances.
