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Historical changes in length of the Baltic cod

Researchers Henrik Svedäng and Sara Hornborg investigate in an article why the Baltic Sea almost completely lacks larger cod. They compare the Baltic cod stock with Öresund where there are cod in all sizes. One explanation may be that in Öresund, trawling has been forbidden since the 1930s. The Baltic cod stock, on the other hand, is exposed to a heavy fishing pressure with bottom trawling that focuses on the larger cods.

As the largest predatory fish, cod has an important function in the Baltic ecosystem. Without growth of larger individuals, space for other species with unbalance as a consequence is left.
The researchers argue that the allowable fishing quotas are not sufficiently low for the cod to recover. A much more restrictive management of the Baltic Sea is needed, with a dramatically reduced fishing pressure.

Read the article by Henrik Svedäng and Sara Hornborg, here: Historic changes in length distributions of three Baltic cod (Gadus morhua) stocks: Evidence of growth retardation.
The article was published in spring 2017.