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Effects of climate induced temperature change on marine coastal fishes.

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Cod stocks reduced by climate induced temperature changes

In recent months, the EC has imposed quotas on the trawling of white fish, in particular Cod, Herring, and Haddock. Whereas these restrictions have been imposed for reasons of over fishing, another underlying reason may be also to blame - climate induced temperature change.

Climate Change and Environment

A scientific study conducted in the eastern and western Atlantic Ocean from 1984 to 1996 studied the oceanic climatic change and its direct and indirect impacts on Cod growth conditions. The objectives of this study were to yield specific information regarding the population distribution of Cod and Eelpout, and any correlations these factors had with climatic fluctuations. The two species were chosen because Cod is an offshore species and Eelpout is a costal species. Thus having two different territories within one oceanic environment enabled the scientists to identify historical populations and growth effects imposed by climatic induced temperature. Four fishing grounds in the North Sea, Barents Sea, Baltic Sea and Norwegian Sea were selected for study, whilst stable and controlled results were derived from laboratory studies. The results from the latter environment demonstrated that optimum Cod growth is in conditions of 12 Celsius. Lower temperatures saw a decline in growth rates, but with higher temperatures, these growth rate reductions are even higher. Furthering the correlated evidence, analyses of Atlantic Cod in the North Sea and Barents Sea resulted in two independent effects on population growth for Cod in the Barents Sea as opposed to Cod in the North Sea. This then enabled scientists to attribute the rise in climatic temperature impacting Cod populations in the Atlantic Ocean. Similar investigations into Haddock and Herring resulted in collaborative information, which suggests that oceanic temperatures increases have a direct and negative effect on the population of white fish in general. These results combined with so called "over fishing" by the fishing industry, may therefore indicate that it will be many years before Cod stocks return to a sustainable fishing level.

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