New Methods Will Help Assess Growth, Age Of Baltic Sea Cod

By on February 19, 2016
Dr. Karin Limburg with a cod caught in Iceland. (Credit: Environmental Science and Forestry)

Oxygen depletion in the Baltic Sea has made it more difficult for researchers there to assess the age of cod. This is because the main method for judging their age involves using otolith bones, or fish ear bones, that carry markers of conditions in which the fish live.

Because of the change in oxygen conditions, researchers at the State University of New York (SUNY) are having to find new ways to monitor the age and growth of Baltic Sea cod. Their new plan is to use historical data combined with more hands-on surveys of the fish relying on tracking tags and chemically-induced markings on cod otoliths.

This chemical method is more accurate for tracking growth than external methods because those can reflect only the conditions the cod is in upon being captured. Chemical markers, by contrast, stay with a fish internally over its entire lifetime and allow scientists to assess its growth and age no matter what state it is caught in.

SUNY scientists are joining with others already working in the region to assess the state of cod stocks in the Baltic Sea. Their efforts will be funded by Baltic Sea 2020, a foundation whose goal is to improve the health of the sea by 2020.

Top image: Dr. Karin Limburg with a cod caught in Iceland. (Credit: Environmental Science and Forestry)

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