We find it hard to believe these descriptions of extraordinary past abundance because it has been so long since such scenes were commonplace. It is a human trait to give greater weight to personal experience than to others’ descriptions. The result, as I described in the opening of this book, is an intergenerational shift in the way we perceive the world. Science is particularly susceptible to these shifting baselines, as scientists work at the forefront of knowledge and are always in hot pursuit of the latest ideas.
Many journalists asked me why these old fisheries statistics had been ignored for so long after we published Ruth’s study on the decline of UK trawl fisheries. It perplexed them. The answer is that old figures were thought to be no longer relevant to the question that fisheries scientists are asked: How many fish is it safe to catch next year? The answer to that depends on how many fish there are at the moment, which is usually settled by the latest survey, not by reaching back decades or centuries. But it is only by going back many years that a full perspective can be gained on the fortunes of fish stocks and so a judgment reached about their sustainability.
The balance of power between fishers and their quarry has been lopsided in favor of the hunters for the best part of 150 years. We have established regulations in the last few decades to restrain fishing power, but they have failed to give most species the time and space they need to reproduce. Life is extraordinarily dangerous for fish that are caught or killed alongside the target, or “bycatch” species, as they are called. Fishing intensities are now so high that, once some species reach a level at which they can be caught, their chance of death from fishing in any given year ranges from 30 percent to 60 percent, or more.
Every year, estimates suggest, trawlers sweep an area of seabed equivalent to half of the world’s continental shelves.11 Together with dredgers like the Clyde’s scallop boats, they have transformed life on the seabed, converting three-dimensionally complex habitats rich in coral, sponge, sea fan, and seaweed into endless, monotonous expanses of shifting gravel, sand, and mud. While trawls and dredges decimate the ocean floor, the hand lines of old have evolved into longlines. The length of hook-studded longlines set every night in our seas is enough to wrap around the world five hundred times over.
Although the scale of the ocean is hard for the human imagination to grasp, life is concentrated into the surface layers, continental margins, and other hot spots where nutrient-rich currents well up to the surface. We focus our fishing on these places, to devastating effect. Even migratory species such as tuna and swordfish, which undertake oceanic odysseys of tens of thousands of miles each year, can be intercepted in a few areas of particular importance to them, such as feeding and breeding grounds.
Throughout history, fishing has followed a familiar pattern. At first we meet all our needs from local sources. But we eventually reduce the populations, and so to sustain catches, we have to develop better ways to outwit the fish, or they move to places that have been less exploited or switch to less favored species. James Bertram recognized this tendency as early as 1873, when he lamented: “We are continually, day-by-day despoiling the waters of their food treasures. When we exhaust the inshore fisheries we proceed straightaway to the deep waters.”12
This pattern can be read in the changing fortunes of the UK trawl-fishing fleet. From 1889 to the outbreak of World War I, British trawlers fished mainly on home grounds. Landings per unit of fishing power fell steeply as those stocks were depleted. After the war people undertook long voyages, to Iceland, the Arctic, and West Africa, in search of virgin stocks, and landings per unit of power climbed. Rewards from fishing fell off steeply in the 1960s, as these grounds became depleted. This loss was compounded in the 1970s by the enlargement of sovereign waters and the establishment of exclusive economic zones that reached out two hundred nautical miles, forcing boats back to home grounds again, where the fishing hauls were greatly reduced.
Geographic expansion and substitution of species has served fishers well for most of history. In the nineteenth and early twentieth centuries, the U.S. oyster fishery worked its way around American estuaries in sequence, moving south from New York and north from San Francisco, exhausting stocks along the way. But fishing has spread ever wider and deeper in the last century, until it has today reached the limits of the oceans. After World War II, Japanese longline boats took to the high seas and fanned out across the world’s oceans, and by the 1970s were fishing almost everywhere. Soviet fishing boats targeted deep seamounts one after another from the 1960s and 1970s. They have been joined today by fleets from Spain, Taiwan, Sri Lanka, China, and other countries, and they have diversified from tuna and swordfish, to sharks, mahi-mahi, opah, and high-value deep-sea beasts such as the six-foot-long Chilean sea bass found in the freezing depths of the southern ocean. Boats now pursue fish to the edges of polar ice shelves and ten thousand feet into the abyss. The impact of the fishing industry goes even deeper than the maximum limits of our gears.13 Animals that migrate up and down from underlying layers are also caught, and the palls of mud thrown up by trawls settle farther down. Estimates suggest that most of the world’s major fishery species have been reduced in numbers by 75 percent to 95 percent or more. Figures compiled by the UN Food and Agriculture Organization, the FAO, show that two thirds of the species we have fished since the 1950s have experienced collapse, and the rate is accelerating.14 It doesn’t take a genius to see that with a track record like this we are squandering life.
Life begins at forty, so the saying goes, but for most of us our reproductive years are behind us by this time (although wealthy old men seem to buck the trend!). For fish and shellfish, however, life really does get better with age. Big, old, fat fish produce far more offspring than their young, lithe, and smaller brethren. Their size and experience give them an edge. Their eggs are better provisioned than those of small fish, so more of them survive the dangers of early life. But fishing has dismantled the dominion of the old in the span of a century or two, and evolution has begun to work in a different direction.
A universal rule of fishing is that when you exploit a population, the average size of the animals gets smaller. Most fishing methods are size-selective, which is to say that they catch animals whose bodies or mouths are larger than the size of a mesh or a hook. Even hand-gathered fish and shellfish are susceptible, as people tend to pick out the largest and juiciest ones first. Over time, therefore, fishing alters the balance between young and old in a population. Modern-day fishers are not the first to have caused their quarry to become smaller. You can read the signals of increasing fishing intensity in the ancient shell middens of California: Mussels fell in size by over 40 percent between ten thousand and two hundred years ago, while the average red abalone eaten decreased from nearly eight inches long to under three inches.15
Evolution works to maximize the number of descendants that an animal leaves behind. Where the risk of death from fishing increases as an animal grows, evolution favors those that grow slowly, mature younger and smaller, and reproduce earlier. This is exactly what we now see in the wild. Cod in Canada’s Gulf of St. Lawrence begin to reproduce at around four today; forty years ago they had to wait until six or seven to reach maturity. Sole in the North Sea mature at half the body weight they did in 1950.16 Surely these adaptations are good news for species hard-pressed by the onslaught of fishing? Not exactly. Young fish produce many fewer eggs than large-bodied animals, and many industrial fisheries are now so intensive that few animals survive more than a couple of years beyond the age of maturity. Together this means there are fewer eggs and larvae to perpetuate future generations. In some cases the amount of young produced today is a hundred or even a thousand times less than in the past, putting the survival of species, and the fisheries dependent on them, at grave risk.
Over the course of decades, climate cycles like the North Atlantic oscillation shift the probability that young will survive up and down. Many species have adapted by developing long lives and can reproduce many times. The
y maximize the chances that some of their young will make it by hedging their bets this way. Excessive fishing ramps up the risk of reproductive failure and population collapse by contracting the number of years over which species can reproduce. Fishing drives up the risk of population crashes today by pushing evolution in a direction counter to that of the environment, and in doing so, unravels adaptations developed over thousands of years. Long-term surveys of marine life off the coast of California show that the species we catch now have more variable replenishment than ones we don’t.17
Intensive exploitation over long timescales leads to the progressive loss of larger animals. This phenomenon is so pervasive that it has been given a name: “fishing down the food web.” It is brother to the process of sequential overexploitation—the removal of species in sequence from large to small, predator to prey, high to low value—as they tend to go hand in hand. We begin with the pursuit of large and valuable animals. Big species are often predatory by nature, and as a consequence have firm, succulent flesh that we prize. As predators they tend to be bold and voracious, and they readily succumb to the lure of a baited trap, hook, or net. When they have been depleted we switch to smaller, less-favored, lower-value species.18
Where once vast sawfish churned the waters of estuaries in the southern United States, now much smaller fish raise puffs of mud as they feed in the shallows. When rich new cod-fishing grounds were discovered on the Rockall Bank off Scotland’s west coast in the 1860s, one report said, “The crews caught the fish as fast as they could bait and haul and it is stated that when any of the cod broke from the hook, great monstrous sharks as blue as if painted with a brush darted round the ship’s side and swallowed them in an instant.”19 Today the blue sharks are almost gone, and the cod has been humbled.
In all but the most extreme environments, the web of life is highly complex. Animals and plants interact in a multitude of ways. They hunt or hide from each other, or use the living space others create. When species are reduced in numbers or removed, the effects cascade on others through the web of life, with unpredictable consequences. We know from farms that simplified ecosystems suffer problems. Reducing diverse plant communities to a handful of species raises the likelihood that there will be outbreaks of pests and diseases. On land we control these unwanted effects with chemical sprays or elaborate husbandry. We have no such recourse when things go wrong in the sea.
Think of life as a game with many players. Some players fulfill similar roles, and circumstances dictate their fortune. One set of conditions will favor one species or group of species. Fortunes shift when circumstances change, and others take their places. But the role itself endures. Ecosystems with a higher diversity of species and greater complexity have the resilience to adapt when the environment shifts. Those that have lost species, due to overfishing or other forces such as pollution, will be less able to cope.
The Firth of Clyde, where this chapter began, offers a bracing illustration of what can go wrong. This narrow arm of the sea penetrates sixty miles into southwest Scotland, ending where mountains shade the head of Loch Fyne. In the eighteenth century its banks and bays abounded with fish, shellfish, whales, and porpoises, none more abundant than the herring, which migrated each year into the loch to breed. One eighteenth-century traveler marveled at how, when the herring shoals came in, the sea seemed to consist of two parts fish, one part water. Huge basking sharks and whales feasted upon plankton that bloomed in the tide-churned waters while packs of hunters savaged the herring. Such abundance and vitality attracted a lively fishery. Henry Beaufoy, a British member of Parliament, described the fishing in 1785:
On conversing with [one of these fishermen], he gave me accounts of the quantities of fish he catched, that appeared altogether incredible; for one article, he assured me, that when he baited his small line for the smaller flat fish, which line contains 400 hooks, it was not at all an uncommon thing for him to take in, at one haul, 350 fish from the 400 hooks. These consist of turbot, soal, and large fine flounders, about two or three pounds weight each. As to skait, he said he seldom fished for them, as they are not a salable article there; but he could easily fill his boat with them, when he chose it, at one haul of his lines—and from the accounts of other people, I had no reason to doubt the man’s veracity.20
Nets and trawls were introduced in the late nineteenth century that could touch bottom on the shallow spawning banks at Ballantrae upon which herring laid their eggs in the southern Firth of Clyde. The herring fishery there collapsed within a couple of decades. This catastrophe spurred fishers to establish a ban on bottom trawling throughout the Firth of Clyde that stood until the early 1980s. Landings of many bottom fish held up well while it was in place, although herring and saithe, a relative of cod, were wiped out in the 1960s and 1970s through the invention of electronic fish finders and midwater trawls.
With the herring gone, pressure then mounted from prawn trawlers to open up the closed areas. Following repeal of the ban in 1984, cod, plaice, haddock, whiting—in fact, all of the Firth’s productive fisheries—declined to virtually nothing within twenty years. Today the seabed is barren, and the only fisheries left are for prawns and scallops, and even they are overfished. It is a marine wasteland.21
We can glimpse the endpoint of overfishing in the Firth of Clyde, a time when nothing worth catching is left. Unfortunately, this story is far from unique. The combination of increased fishing power and dwindling areas of refuge is repeated in all of the world’s seas and oceans. The Firth of Clyde gives us a stark vision of a future without fish.
When Ruth Thurstan and I published our research on the Clyde in 2010 many fishermen and others familiar with the area agreed with our conclusion. Indeed, we thought the sorry state of Clyde fisheries was, to paraphrase Jane Austen, a truth universally acknowledged. But industry leaders were not pleased. The heads of two Scottish fishing organizations between them were reported in one newspaper deploying the three favorite tactics of those in denial: attack the science; slander the scientists; and blame something else (pollution, seals, and climate change were the straws they clutched).22 If the consequences of their denial were not so devastating, I would have found more humor in their last comment: “We don’t need to do much about this report.… [W]e are letting proper marine scientists rubbish it for us.”
Two sea anglers who were interviewed for the same piece were not afraid of saying what everyone who lives there recognized. “There’s only mackerel left,” one said, “and then only in the summer. You used to see people angling from the beach at the West Bay there, even at night. There’s no point now, because there’s nothing to catch.” The other said: “It’s not a one-man-band or a guy with a rod that’s causing the problem. And it’s not down to the Clyde being dirty—it’s cleaner now than it was in the seventies—it’s the trawlers.”
Over the years I have come across spectacular levels of denial among fishing industry representatives. In parliament and senate buildings and committee rooms across the world I have seen them dig their heels in to resist regulations that could help fish stocks recover. Politicians too willingly believe their claims that greater regulation would cause unnecessary hardship. In reality, failure to acknowledge and deal with the problem represents a far more serious risk to their livelihoods. The relationship between politicians and the fishing industry in the European Union has become like that of a doctor assisting the suicide of a patient. For the last twenty-five years politicians have given the industry a one-third larger catch quota on average than scientists have recommended as safe.23 The only outcome possible from such a policy is the collapse of fish stocks and the fishing industry. If you don’t believe me, imagine a farmer who takes ten more sheep to market each year than his flock produces. You can’t cheat nature, however good you may be at spinning a story.
To close this tale of demolition, allow me to return to the Atlantic bluefin tuna, for this majestic fish has recently become emblematic of the worst of humanity’s destructive tendenc
y. Their abundance has declined by at least two thirds since 1970, and the total decline over the course of the last century is probably closer to 95 percent. By the 1970s, bluefin tuna had already disappeared from the North Sea, perhaps the result of the decimation of a highly migratory subpopulation of the species.24 By the 1980s, the Black Sea population was all but gone, and it is now considered extinct. This is a species that, by any metric, we have taken from abundance to the verge of extinction. The scientific evidence is unequivocal. Yet the badly misnamed International Commission for the Conservation of Atlantic Tunas continues to award its members catch quotas far above those that would enable this fish to recover.25 Corporate greed has triumphed over human decency.
Daniel Pauly, a charismatic fisheries scientist from Canada’s University of British Columbia, describes world fisheries as a giant Ponzi scheme. Fraudsters in this type of scam pay investors from the capital in a fund rather than from the returns made on their investments. Ponzi schemes collapse when the flow of new capital dries up. Since the nineteenth century, when fisheries were first industrialized, landings have been sustained by fishing ever farther afield, and deeper. The fishing industry has been dependent on a constant input of new capital. Whenever fish began to run out, fishers moved on or switched to other species. Over time fisheries have eaten up their capital stocks rather than lived within the limits of annual production. But fisheries are now failing because, like in a Ponzi scheme, they are running out of new capital. We now hunt fish to the farthest limits of the oceans, and to depths where productivity slows to a trickle. There is nowhere else to go and few species worth eating remain untouched by fishing. The solution is not for a handful of people to stop eating fish. We need to set up new regulations and police them well. But I will return to this later on in the book, when it comes time to consider solutions.
The Ocean of Life Page 6