Aarhus Universitets segl

Peter Grønkjær

Professor, Lektor

P. Grønkjær
Se relationer på Aarhus Universitet


Link to my CV


I study the processes that lead to change in fish populations - in order to improve predictions of how fish populations will respond to human exploitation and climate change.


Fish earstones (otoliths) contain information about the age of fish but also their metabolic rates and their diets. By analyzing carbon and nitrogen isotopes of earstone protein, I examine changes in diets of fishes driven by fishing and climate change over the last 100 years. I also analyze carbon isotopes in the earstones to gain knowledge of the metabolism of fish and how the metabolism is influenced by changes in ocean temperatures, food and stress factors.


My research has shown that the long-term catch from a fish population is determined by its position in the food web, and that the position changes in relation to climatic factors.

I have developed a method to document historic and contemporary food webs by analyzing earstones from research cruises, museum archives and kitchen middens. This enables me to map out positions of fish in the food web with very high temporal and spatial resolution, and to explore how food webs change in relation to climate and fisheries. The results show that there have been massive changes in the fish diet during the last 80 years as a direct response to climate changes and fishing.

Furthermore, my analysis of fish metabolic rates show that the increasingly warmer temperatures in the coastal habitats of juvenile cod increases their metabolic rate to a point where they can no longer survive in these important habitats.


I collaborate with a wide range of reseachers from physical oceanography over animal physiologys to molecular ecology.
The new methods I have developed has been developed in collaboration with researchers from Taiwan, France and UK.


Twitter @petergronkjaer

Grønkjær FishEco Lab

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