The Ocean's Prey Problem

Prey fish are the foundation of many marine animals" diets, and have been depleted to dangerously low levels due primarily to overfishing and climate change.
© Alfredo Wang

The food source upon which commercial and recreational fish, marine mammals and seabirds depend to survive is being steadily exhausted, according to a new report by Oceana, "Hungry Oceans: What Happens When the Prey Is Gone?" These so-called "prey fish" are the foundation of many marine animals" diets, and have been depleted to dangerously low levels due primarily to overfishing and climate change.

“We have caught all the big fish and now we are going after their food,” says Oceana marine scientist Margot L. Stiles. “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.”

The future of both commercial and recreational fisheries is threatened by the loss of prey fish, especially those that are currently rebuilding from depletion. Hungry Oceans identifies bluefin tuna, striped bass, Pacific salmon and Pacific halibut as key species dependent on prey fish.

Marine mammals and seabirds also depend on access to prey fish for their daily survival and for their young, including blue whales, humpback whales, penguins and terns.

Hungry Oceans proposes, among other conservation measures, a moratorium on new fisheries targeting prey species, catch limits for existing fisheries and giving top priority to ocean predators.

“Fisheries managers simply take prey for granted despite their critical role in the ecosystem,” says Stiles. “We need to act responsibly when taking prey from natural predators, with our eyes open to the consequences for the ocean and for our own supply of seafood.”

Source: Oceana.org