Scientists have cracked the mystery of tracking the birthplace and migration of Chinook salmon though a chemical signature on their ear bones. The new findings published this week in Science Advance journal that shows where they spent their first year of lives and their evolution.
Through the growing stages of the fish, an ear bone called “otolith” builds up layers, with a chemical signature. Scientists will then compare the chemical signature of the otolith and the water in which it swims. The chemical signature is formed from the isotopes, found in bedrock. Strontium is dissolved into water, when water comes in contact with the rock. The element is then deposited into the otolith of the host fish.
“Each fish has this little recorder, and we can reveal the whole life history of the fish from the perspective of the Earth,” said Sean Brennan, a post doctoral researcher at the University of Washington’s School of Aquatic and Fishery Sciences.
The chemical signature remains as a permanent unchanged tag that can reveal the location of the fish in the river at a specific time. The research was carried out in Nushagak River which is home to more than 200,000 fishes in summer. Their eggs hatch in spring, the young salmon spends the first year in the river, and migrates to the Pacific and Bering Sea, after it is fully grown.
Ecologist at the U.S Geological Survey and the study’s co-author Christian Zimmerman stated that it was science responding to societal issue and need. Scientists aim to study salmon productivity and how freshwater habitats influence the ultimate number of salmon. Researchers are set to analyze traces of strontium in the teeth and feather of various species to migration patterns and patterns of survival.[ Via ]