Updated 11:29 AM EDT, Tue, Jun 16, 2020

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Ear Bone Can Help Revealing the Salmon History, New Study Finds


(Photo : REUTERS/ANDY CLARK) A sockeye salmon scurries through shallow water in the Adams River while preparing to spawn near Chase, British Columbia northeast of Vancouver.

Scientists developed a technique that allowed them to trace the birthplace of Chinook salmon and learn about the first year of its life. The technique can be used to provide more understanding on the behavior of other species and how location affects the fish's survival.

By taking advantage of chemical traces called strontium in the tree-like growth patterns found in salmon ear bones, researchers can precisely trace a salmon's life history, from the tiny tributary it was born in to the open ocean. 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.

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Salmon ear bones, called otoliths, grow differently than the bones in your body do.

"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," said lead study author Sean Brennan of the University of Washington.

In this case, Brennan and his colleagues mapped where the element strontium is found over a large area, and then matched the chemicals found in the ear bones to places on the map.

These location-linked chemical cues are particularly useful when studying migratory animals like salmon. Because they're tough to keep track of, figuring out which habitats they use and need to survive is a major challenge for conservation efforts.

This tracking technique is not specific to salmon, according to Brennan. It can be used to trace and study a wide range of animals.

Details of the study were published in the journal Science Advances.

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