A new report commissioned by commercial fishermen has destroyed the myth that the reason why fish stocks are so low has little to do with climate change

http://www.marlab.ac.uk/FRS.Web/Uploads/Do...20Fisheries.pdf

If cod had been fished during 1988-2001 so that it produced the maximum sustainable
yield, could have been approximately 260,000 tonnes, which would have sustainably
supported a fishery during that period of 180,000 tonnes each year.

This result is very clear and worth repeating. Even given the warming in the North
Sea that happened between 1988-2001, and all the observed changes in the food-
chain, if we had fished cod at a lower level the ecosystem could possibly have
sustained a spawning stock of 260,000 tonnes. In actual fact over this period the
spawning stock size decreased from 150,000 tonnes to less than 50,000 tonnes.


Recent tagging studies by FRS, using tags which record the temperature cod have
been living in between release and recapture, clearly show that North Sea cod a) do
not move very far during their life time, often tolerate warm temperature in the
southern North Sea without moving away from the area, c) have ample cooler
grounds to move to in the northern North Sea if they needed to, but they do not
move.

The reason that we do not have this size of stock is
due to the high fishing pressure we have subjected the stock to. Cod is
not moving north; rather we are fishing out the southerly components of
the stock. There still remain large areas of potential habitat for North Sea
cod at suitable temperatures. We can not blame climate for the decline
of North Sea cod. he following is extracted from the report