Gaze upon the rolling deep

(Fish is plentiful and cheap)

As the sea my love is deep!

Said the Yonghy-Bonghy-Bó.

Edward Lear



THE sea is still deep, and fish may still be relatively cheap, but it costs much more than it used to. And it is far from plentiful.

This has become a commonplace. People have long been told that the North Sea is fished out and that the waters of the North Atlantic closest to Europe now produce only a fraction of the bounty of the 1940s. Books, articles and reports regularly record the decline. In 2004, for instance, a British royal commission described in bleak detail the collapse of north-east Atlantic cod, of North Sea hake and plaice, and of other species discarded as “bycatch” and thrown back dead into the sea in huge numbers.

Americans have heard similar stories. An authoritative report from the Pew Oceans Commission told them in 2003 that, of the American fish populations that had been assessed, 30% were being overfished, many of them unsustainably. Books like “Cod”, by Mark Kurlansky, have eloquently described how the fishing grounds that stretch from the shallow waters off Newfoundland south to Georges Bank, once considered the richest in the world, have come to be commercially moribund. Governments, though slow to respond, have not been wholly blind to the changes. Canada's closed the Grand Banks in 1992. Fishermen themselves have seen the evidence, and not just there. In the 1970s, for instance, West Coast trawlers were landing 11,000 tonnes of bocaccio a year. In 2001, just before the fishery was closed, the catch was 214 tonnes. It will take at least 90 years, say scientists, for the stocks to recover.

And overfishing is not just a problem of northern fisheries. A paper published in Nature in 2003 carried 13 charts showing the catch per 100 hooks in different fisheries from the temperate Pacific to South Georgia in the southern Atlantic, and from the Gulf of Thailand to the St Pierre Bank off Labrador. Each chart displayed a similar precipitous descent in the catch from the start of industrial fishing, some time before 1960, to a virtual plateau between 1980 and 2000. “Our analysis”, said the authors, Ransom Myers and Boris Worm of Dalhousie University in Canada, “suggests that the global ocean has lost more than 90% of large predatory fishes.” These are the ones, cod, groupers, salmon, tuna and so on, that everyone likes to eat.

An even gloomier assessment came in an article by 14 academics in Science in 2006. The accelerating erosion of biodiversity, often associated with overfishing, presaged a “global collapse” to the point, in 2048, where all species currently fished would be gone, they said.

The mackerel-crowded seas?

Even many scientists who are alarmed by the evidence of overfishing find such conclusions controversial. Most non-scientists are unmoved. For a start, fish appears to be in plentiful supply. Even cod is available; over 7m tonnes of cod-family (Gadidae) fish are caught each year. Sushi bars have spread across the world. To cater for the aversion to red meat, and a new-found need for omega-3 fatty acids, fish dishes are on every menu, even in steak houses. Supermarkets and restaurants boast of “sustainable” supplies, and sandwiches are reassuringly labelled “dolphin-friendly”, however threatened the tuna within them may be. Best of all, for the ethical consumer, fish are now farmed (see article). Salmon has become so plentiful that people weary of its delicate taste.

Moreover, fishermen themselves seem sceptical of any long-term scarcity. They clamour for bigger quotas and fewer restrictions (except on foreign competitors), and complain that the scientists are either ignorant or one step behind the new reality. Those with long memories can cite previous collapses that have been followed by recoveries. And, in truth, not all collapses are due solely to overfishing: the sudden crash of California's sardine industry 60 years ago is now thought to have been partly caused by a natural change in the sea temperature.

Plenty of figures seem to support the optimists. Despite the exploitation round its coasts, Britain, for instance, still landed 750,000 tonnes of Atlantic fish in 2006, two-thirds of what it caught in 1951; even cod is still being hauled from the north-east Atlantic, mostly by Norwegians and Russians. Some British fishing communities—Fraserburgh, for example—are in a sorry state, but others still prosper: the value of wet fish landed in Shetland, for example, rose from £21m in 1996 to £54m ($33m-99m) in 2006. Earnings from fishing in Alaska, in whose waters about half of America's catch is taken, rose from less than $800m in 2002 to nearly $1.5 billion in 2007. And for the world as a whole, the catch in 2006 was over 93m tonnes, according to the UN's Food and Agriculture Organisation, compared with just 19m in 1950 (see chart). Its value was almost $90 billion.

The main reason was that fishermen were still able to exploit their relatively new ability to find and catch their prey. Most underwater creatures had little to fear from man until 1873, when the first steam-powered whaling ships, armed with explosive harpoons, were launched. Whales were then ruthlessly pursued, several species almost to extinction, until hunting was banned in the 1980s.

The steam-powered trawler came next, in 1881. When fitted with an otter trawl, invented in 1892, it enabled fishermen to haul in six times the catch of a sailing ship. Soon came filleting machines, echo-sounders and spotter planes. Then Clarence Birdseye, an American fur-trapper turned inventor, developed a system for freezing fish. This gave the world the fish finger and launched the factory ship that sailed far from home and processed the catch from huge trawlers on the high seas.

Next came the cold war, whose main casualty may have been fish. The technology designed by America's Office of Naval Research developed to find the Soviet Union's submarines and hide NATO's was soon put to use in the pursuit of haddock, herring and every other kind of underwater prey. After that came satellites and with them global positioning systems and thermal images, enabling fishermen to find the places where warm and cold waters collide, which is where plankton flourish and fish gather. Now an array of technology—acoustic fish-finders, broad-swathe mapping of the seabed, computerised track plotters and so on—make it possible to find most fish bigger than a man's forearm.

There goes that Leviathan

The biggest ones have been the first to go. As a result, in over-exploited waters the fish tend to be smaller and younger. Among those caught in the Pacific, the average length of an English sole fell from about 34cm in the 1960s to 30cm in 2002, a Pacific barracuda from nearly 80cm in the 1950s to 65cm in 1970, a bocaccio from over 50cm in the 1970s to nearer 45cm in the 1990s. Whereas record-sized cod 2 metres long and up to 96kg (211lb) in weight were recorded in Massachusetts in the 19th century, and an average of 4.5kg per fish was common in living memory, a big cod is now a rarity in the north-west Atlantic. And when the big fish are gone, smaller varieties become the new catch. “Fishing down” the food web, as the practice is known, resulted in the average length of fish caught off the west coast of Newfoundland falling by a metre between 1957 and 2000, according to an article by Daniel Pauly and Reg Watson, of the University of British Columbia's Fisheries Centre, in Scientific American in July 2003.

When stocks of familiar fish are exhausted in familiar fishing grounds, man turns towards new fish in new places. Distant-water ships from such countries as Taiwan, South Korea and Russia have been ploughing far-flung oceans ever since the art of freezing fish became simple. “Klondikers”, huge factory ships from eastern Europe, started to turn up in foreign waters in the 1990s. Spanish boats, following the traditions of the medieval Basques, fish all over the world. Ships from Bulgaria, China, Japan, Mexico, Poland and Romania can all be found far from home.

Magnum Photos

Ever smaller, ever rarer

There they set about repeating what they have done in their own waters. Having caught almost all the northern bluefin tuna in the Mediterranean and many of the fish off other coasts, the countries of the European Union, for example, have negotiated rights to fish in coastal waters off west Africa. Now stocks of octopus, lobsters, tuna and other fish in this part of the Atlantic are dangerously low, contributing to the impoverishment of local fishermen. As a result, many are said to be driven to such desperate measures as eating bushmeat from endangered animals and setting sail in open boats in the hope of illegally settling in Europe.

Rich-country consumers of Senegalese shrimps or Omani lobsters are no doubt delighted with their entrées. Others may need a little encouragement to buy fish hitherto unknown to them. Many species are therefore renamed for the retail trade: bocaccio, a kind of rockfish, becomes Pacific red snapper, Patagonian toothfish becomes Chilean, or Australian, sea bass, and dogfish becomes rock salmon.

Creeping things innumerable

In British fish-and-chip shops pollock and coley are increasingly used in place of cod, and in American fast-food outlets Alaska pollock has become the staple. But in 2008 stocks of Alaskan pollock shrank by half, leaving what is believed to be the world's largest food fishery poised on the brink of collapse. This could be a natural fluctuation. So could the disappearance of chinook salmon from the waters off California and Oregon last year; the population during the spawning season was 88% below its all-time high in 2003.

Most fish-watchers, however, are uneasy. They see too many signs of overfishing, and too few of recovery. One of the most recent objects of concern is a small, shrimp-like creature called krill, which is now being fished in a big way. Krill spend their days in the depths of the sea, rising at night in what they believe to be the safety of darkness to snack on phytoplankton. In fact, they are likely to be hauled out by fishermen, especially if they are in the waters of Antarctica. Krill do not end up on plates in restaurants, except perhaps in Japan or Russia, but they are increasingly in demand for their fatty acids, for their enzymes (used in medicine), for feeding to farmed fish, especially to give the flesh of salmon a pink appearance, and for use as fish meal. And now a technique has been developed that enables trawlermen to process them at sea before their enzymes decompose. This means ships can stay longer away from port and multiply the size of their annual catch many times.

What are the wild waves saying?

No one thinks krill are yet endangered, but no one fully understands them. It is known, however, that many whales and seals and penguins live on them. And it is known that the plankton they eat cling to the underside of packed ice, ice that may start melting as temperatures rise. The fear is that devastating the krill population will set in train a series of changes that will affect other creatures.

This is, after all, what is happening in other places, though usually the changes start at the apex of the food web. Typically, this is a fish-eat-fish affair, with vegetarians like krill taking their place at the bottom (phytoplankton are plants, whereas zooplankton are animals). Thus the relentless hunting of big sharks off the United States' Atlantic coast has rendered them unable to “perform their ecosystem role as top predators”, in the words of Julia Baum of Dalhousie University. The upshot is a huge increase in the numbers of their prey, notably ray, skate and smaller sharks. Cownose ray, which may grow to be over a metre in width, are increasing by about 8% a year. With some 40m of them now looking for food off the East Coast, the shellfish they eat, such as scallops, oysters and clams, have been devastated.

One lesson here is that no species should be fished to the point where the ecosystem is unbalanced. That conclusion hardly requires the fish-fed brain of Jeeves. Another is that, to maintain a balance, big “apex” fish may be as important as small. Many fish take years before they are mature enough to spawn: cod, three or four, sturgeon 20, orange roughy 32. And they may be long-lived: cod can survive to 30, if they are lucky, and sturgeon to 100. Kill the fish at the top and you may get an explosion of smaller ones below, gobbling up much more food than would be eaten by a few big fish of the same total weight. And big fish provide more and better-quality fry. Take the big and leave the young, a common principle of fisheries managers eager to rebuild stocks, may therefore be a mistake. If so, it is not their only one.