Loss of “prey fish” may starve oceans

Scientists are finding evidence of widespread malnutrition in commercial and recreational fish, marine mammals and seabirds because of the global depletion of the small “prey fish” they need to survive, according to the oceans campaigning group Oceana. Prey fish underpin marine food webs and are being exhausted by heavy fishing, demand for aquaculture feed and climate change, Oceana said.


“We have caught all the big fish and now we are going after their food,” said Margot Stiles, an Oceana marine scientist. “Until recently it has been widely believed that prey fish are impossible to overexploit because their populations grow so quickly. We are now proving that untrue as the demands of commercial fisheries and aquaculture outpace the ocean’s ability to provide food for us and itself.”


In a report, Hungry Oceans: What Happens When the Prey is Gone?, Oceana said that seven of the top 10 fisheries in the world target prey fish. These fisheries have emerged as populations of bigger fish have become overexploited and depleted. The report concludes that the impacts of fishing activity over the past decades has been so great that nearly all prey fisheries now cannot withstand increased pressure.


Hungry Oceans also found that aquaculture is increasingly the driver behind overfishing of prey fish, as salmon, tuna and other carnivorous farmed fish become the fastest growing seafood products in the world. Changing ocean temperatures and currents caused by climate change also make prey fish populations more vulnerable.


The study coincided with the release of the biennial State of the World Fisheries and Aquaculture report by the United Nations Food and Agriculture Organisation (FAO). The FAO concludes that 80% of all marine fish stocks are fully exploited, overexploited, depleted or recovering from depletion, including stocks of the seven largest prey fisheries.

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