Climate changes will significantly reduce fishery yields

According to research from the University of California, Irvine, climate change could drive fishery yields down by 20 percent across the world ocean and by 60 percent in the North Atlantic before the year 2300.

The decline is primarily linked to a lack of ocean mixing. When the surface layer of ocean water is warm, it prevents the nutrients that have built up in the deep waters from rising to the surface.

The study authors explained that significant changes in ocean mixing would ultimately drive a decline in fish populations near the surface.

Many studies have confirmed that fisheries will be significantly less productive by the end of this century, but little research has investigated the fate of fisheries beyond 2100.

A team led by J. Keith Moore used modeling to predict the effects of climate change on fisheries under the condition that the rate of carbon emissions remains the same as it is today.

Currently, the Southern Ocean has such a successful amount of mixing that nutrients abundantly flow into other oceans.

But now, model simulations produced by the current study indicate that changing wind patterns and warmer ocean surface layers will cause an increased portion of nutrients to sink into the deeper layer of the ocean and become trapped there. The model showed that phosphate, for example, will become 41 percent less abundant.

The steep decline of mixing in the Southern Ocean will also be facilitated by a polar shift of nutrient upwelling into the Antarctic.

The study authors also established that ocean mixing will be particularly reduced in the North Atlantic. They explained that the long-term impact of these changes in ocean mixing will reduce fishery yields for at least a thousand years.

The study is published in the journal Science.

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By Chrissy Sexton, Earth.com Staff Writer