Down the food chain

Abstract

Fisheries are increasingly targeting smaller and more unusual species as traditional targets decline and the demand for feed for farmed fish increases. Nigel Williams reports. Fisheries are increasingly targeting smaller and more unusual species as traditional targets decline and the demand for feed for farmed fish increases. Nigel Williams reports. As many flagship fish species become increasingly scarce as a result of over fishing, fleets are increasingly targeting species further down the food chain. A new report by the UN's Food and Agriculture Organisation, published last month, highlights growing concerns about future stocks of sea cucumbers, an echinoderm being increasingly sought by fishermen. It probably comes as a surprise to the Western world, where they are mostly a summer oddity on the sea-bed seen while snorkelling or diving. But in Asia they have long been a key ingredient in soups, stews and stir-fries and demand is growing. Countries like Indonesia, Papua New Guinea and the Philippines export large quantities of them to China and other Asian markets each year.“Scientists are finding evidence of widespread malnutrition in commercial and recreational fish, marine mammals and seabirds because of the global depletion of the small fish they need to survive” “Scientists are finding evidence of widespread malnutrition in commercial and recreational fish, marine mammals and seabirds because of the global depletion of the small fish they need to survive” According to the FAO report, sea cucumber stocks are under intense pressure throughout the world. Most high-value commercial species have been depleted. In a majority of countries reviewed and in the Africa and Indian Ocean regions, stocks are overfished. Likewise in the Asian Pacific region, the most sought-after species are depleted. “The fast pace of development of sea cucumber fisheries to supply growing international demand is placing most fisheries and many sea cucumber species at risk,” the report says. Sea cucumber management plans specific to local circumstances need to be developed, it says. These could include such measures as establishing catch quotas and minimum size limits, closures during breeding seasons and better monitoring of stocks. Sea cucumbers make a substantial contribution to the economies of coastal communities, being in some places the most economically important fishery and non-fin-fish export — highlighting the need to improve management and fishing practices, the report says. Asia and the Pacific are the top areas where sea cucumbers are caught with total regional production between 20,000 and 40,000 tonnes per year. But Ecuador's Galapagos Islands, the Seychelles and Newfoundland in Canada also have key fisheries. And a worry is that new markets are developing. In Spain, up until ten years ago, these animals were considered relatively worthless by Catalan fishermen, who had eaten them on board their boats but never brought them to market. But then chefs in Barcelona began to appreciate them and a Spanish market was created for them, the report says. While the FAO highlight the threat to sea cucumbers, a new report by the marine conservation organisation Oceana highlights the depletion of small prey fish on which the top ocean predators depend. “Scientists are finding evidence of widespread malnutrition in commercial and recreational fish, marine mammals and seabirds because of the global depletion of the small fish they need to survive,” according to the new Oceana report Hungry Oceans: What happens when the prey is gone? “We have caught all the big fish and now we are going for their food,” said Margaret Stiles, a marine scientist at Oceana. Four times as much of these small fish are brought to shore compared with half a century ago. According to FAO figures, most of this catch does not go directly to feed people but is processed to produce feedstuffs for farmed fish. The Oceana report coincides with the release of FAO figures that 80 per cent of all marine fish stocks are fully exploited, overexploited, depleted, or recovering from depletion, including stocks of the largest seven prey fisheries. Very few marine fish populations remain with the potential to sustain production increases, and more have now reached their limit than ever before, the report says. “Valuable fish like bluefin tuna are struggling and we can't expect the fishery to recover when we are stealing their food supply,” says Stiles. Hungry Oceans proposes a series of measures including a moratorium on new fisheries targeting prey species, conservative catch limits for existing fisheries, first priority for the needs of ocean predators, and stopping fishing for prey in predator-breeding hotspots. “Fisheries managers simply take prey for granted despite their critical role in the ecosystem,” said Stiles. “We need to act responsibly when taking prey from natural predators, with our eyes open to the consequences for the ocean and our own supply of seafood.” According to conventional wisdom, small, fast-growing fish are impossible to overfish because their populations are so large and grow so quickly, the report says. “Yet we are now seeing disquieting signs that conventional wisdom is wrong. Most significantly, scientists are reporting ocean predators emaciated from lack of food, vulnerable to disease and without energy to reproduce,” the report says. “Dolphins, striped bass, and even whales have turned up along coastlines around the world. Recreational fishermen are losing both their target fish — and their bait.” “For many prey species, humans have replaced their natural predators — the other fish, the sea birds, the marine mammals — all the species that depend on them for their existence,” the report says. “Unless the current trends are reversed we can look forward to a future with increasingly hungry oceans.”