The Baltic Sea is not trapped in a “cod hostile” state. Stocks can recover if fishing effort is reduced, scientists conclude in a new study.

Overfishing, climate change and eutrophication are thought to have altered the functioning of the ecosystem in the Baltic Sea. Several factors now put a strain on the cod. A large sprat stock eats cod eggs. Eutrophication and a decreased inflow of oxygenated water is detrimental to the cod’s spawning.

In short, the Baltic Sea ecosystem has been considered to have reached a “cod hostile” state during the last three decades.

However, in a paper published this week in Marine Ecology Progress Series, scientists Massimiliano Cardinale and Henrik Svedäng argue that this is not the case. After more than two decades of low biomass, Baltic cod has recently recovered. Why? Because of reduced fishing, Cardinale and Svedäng conclude.

Svedäng said: “Our analysis shows that we have not come to the end of the road. Nature itself has refuted the theories that claim that the Baltic Sea is locked in a state where the cod cannot recover.”

The main reason that the eastern Baltic Sea cod has been recovering during the last few years, Svedäng said, is reduced fishing pressure. This can mainly be attributed to the fact that the Polish fleet was payed to stay in harbour for 18 months a few years ago.

Does this send a message to those who form the EU fisheries policy?
“Yes. If stocks are not far too overfished, there is a good chance for stock recovery if fishing pressure is reduced to ecologically sustainable levels.”

Axel Naver

Link: Read the full study (pdf)

Reference:
Cardinale M, Svedäng H: The beauty of simplicity in science: Baltic cod stock improves rapidly in a ‘cod hostile’ ecosystem state, Marine Ecology Progress Series, Vol. 425: 297–301, 201
doi: 10.3354/meps0909

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