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Our Dying Planet
An Ecologist's View of the Crisis We Face
By Peter F. Sale
UNIVERSITY OF CALIFORNIA PRESS Copyright © 2011 The Regents of the University of California
All rights reserved.
We have always been fishermen. Fishing extends far back into our human past, and as our last remaining hunter-gatherer activity it ties us to that past in a tangible way. We capture wild aquatic organisms for personal use and to trade with other people. Most, but not all, of these fishery products are used for food. A trout fisherman on a Scottish stream who ties his own flies and approaches his sport with a quasi-religious fervor may have very little in common with the Malaysian peasant who fossicks at low tide for edible shellfish and crabs to feed her family, but both are part of fishing. So too are the giant multinational corporations, with their fleets of factory trawlers, their thousands of miles of longlines and nets, and their flash-frozen tuna air-lifted from deck to jet to Japan. Fishing is a vast global enterprise with a sophisticated array of technology and millions of people all engaged in extracting aquatic organisms from rivers, lakes, and oceans, trading them around the world, and consuming them in many different ways.
While we have always fished, we seem also to have usually overfished, leading to the reduction and sometimes the loss of formerly valuable fishery resources. Until recently, the consequences of such overfishing were generally local and temporary. Now, for the first time in human history, we face the possibility of widespread, essentially permanent collapse of the most important fisheries around the globe. Our continuing tendency to overfish is surprising given the investment in fisheries management around the world; on the surface, it does not seem to be that difficult to manage catch so that it does not exceed the capacity of the fished populations to supply.
Coastlines throughout the world provide scattered evidence of ancient fishing successes in the form of aboriginal middens—large piles of shells, bones, or other debris resulting from the capture, butchering, and presumably eating of the catch over many days and years by members of past cultures. In many middens, the size of the shells and bones varies with depth, with the largest buried deep in the oldest layers and the smallest occurring in the younger layers near the surface. This is evidence of ancient overfishing. The sizes of organisms being caught declined over time because, in all probability, the fishing was sufficiently intense to lower the life expectancy of the fished species. They lived less long, on average, before being caught and no longer reached the sizes they had in past years. And while we cannot tell this from examining a midden, it is very likely that as they became smaller over time, the animals being caught also became less common and harder to catch. Ancient fishermen often overfished and at some point had to search for new fishing grounds.
Most fish are remarkably fecund animals, producing thousands, sometimes millions, of eggs in a lifetime. Most also reproduce through external fertilization so that the female matures a clutch of eggs within her body before mating with a male. Most fish also grow in size throughout life, and because eggs take up space in the body cavity before they are laid, older, larger females are markedly more fecund than youngsters. Many fish also live for decades if not caught first. These life-history characteristics mean that fish populations can be remarkably productive, able to replenish their numbers rapidly following a decline in population size. The relative lack of parental care and the small size of newly hatched fish ensure that fish breeding success is strongly dependent on environmental conditions and a certain amount of luck—a fish population of a given size can produce an enormous cohort of young fish one year and far fewer the next.
Fishing is currently big business and vital to our food supply. The United Nations Food and Agriculture Organization (FAO) reports that, according to 2008 data, fishing provides 15.3 percent of the animal protein needs of the human population worldwide, or about 16.7 kg of fish per person per year. Commercial fishing directly employs about 44 million people and brings about 92 million metric tons of product to market every year, while aquaculture provides an additional 51.7 million metric tons. These fishery products are worth about US$91.2 billion and $78.8 billion per year, respectively, and the international trade in fishery products exceeds $92 billion per year. Adding in so-called illegal, unreported, and unregulated catches and the fish caught by recreational fishermen and by artisanal fishermen to feed their families around the world further increases the total tonnage of fishery species captured to 130 million metric tons per year.
The FAO also reports that the total world catch has been declining at the rate of about 0.7 million metric tons per year since about 1988, despite increases in fishing efforts. Globally, fishing is still very big business, but fisheries are failing to provide as they used to.
The decline in total commercial catch is one of several signs that our tendency to overfish is pushing us up against firm limits and that future catches may become far less bountiful than they have been. In this chapter we will look at fishing, sustainable fishing, and overfishing. We'll get into the science behind fisheries management and the reasons why management so often fails. I hope you'll become more aware of what takes place to make those fish available in grocery stores, and that you will appreciate the need to fish much more sustainably than we currently do. Along the way I will also touch on the more general problem of overuse of natural resources.
THE COD FISHERY OF THE NORTHWEST ATLANTIC
When John Cabot returned to England in 1497, he brought with him tales of plentiful Atlantic cod (Gadus morhua) of such size and abundance that catching these fish was simple. There were even claims that the fish were so abundant as to impede the progress of ships. Southern Europeans came to refer to the lands Cabot had found as Baccalaos, from the Spanish bacalao, the cod. The Portuguese had commenced fishing for cod off Newfoundland by 1501, followed shortly by the French and Basques. This commercial cod fishery was to last for almost five hundred years.
Initially, fishing off Newfoundland was an entirely ship-based operation. Ships sailed from Europe in the spring, fished intensively, salting down the catch in barrels, and returned home to the markets. But early on, the British, French, and Basques established shore camps where they could land the catch, salt it, and air-dry it. It was then packed dry for transport to the European markets; as a lighter product it was more economical to ship and, as a less heavily salted product, it was preferred by the public. To this day, many Europeans along the Mediterranean coast prefer dried, salted cod to the fresh product.
The colonization of Newfoundland was a direct consequence of the growing commercial fishery. Initially it involved the construction of seasonal dwellings for the people who worked the fishery, processing the catch for shipment home. Gradually, seasonal dwellings became year-round homes as investments in real property began to require guarding it through the winter, but it was always the cod industry sustaining the development. Wars in Europe altered the overall fishing effort and the countries involved in the trade, and periodically the cod stocks failed, but on average the overall harvest grew year by year. As early as 1683, the problem of "overcapacity" was recognized by the Colonial Office in London—an excess demand for fish had fueled development of excess capacity (too many ships and nets) to catch them, and fishery stocks were failing.
Farther south, the Gulf of Maine cod fishery was "discovered," and Cape Cod named, by the crew of the Concord, a British ship sent to the New World to hunt for supplies of sassafras in 1602. Fishing vessels followed soon after, using the shores and the offshore islands of the gulf as suitable fish-drying sites. Fishing, and a Europe-based industry using seasonal dwellings on suitable shorelines, was well established by the time the first colonial settlements were being established in New England in 1620. However, the industry quickly became an American-based one, as local populations took up fishing, first in their immediate vicinity, and later in larger vessels venturing as far afield as the Grand Banks and northern Newfoundland. This was in contrast to the situation farther north, where the local Newfoundland and Nova Scotia populations operated inshore fisheries from smaller vessels and left the offshore fishery on the Grand Banks and the Labrador coast to be operated by larger vessels whose home ports were mostly in Europe. By the start of the eighteenth century, the Grand Banks fishery included vessels from England, France, Spain, and Portugal along with vessels from New England.
The cod trade grew so important that it became a vital source of foreign exchange for the developing American and Canadian colonies. It was incorporated into a profitable transatlantic trade in which the vessels that shipped dried cod to Europe returned with African slaves for the West Indies and southern American colonies, stocking up with sugar and salt in the West Indies before moving again to the fishing grounds of New England and the Grand Banks. Simultaneously, some vessels shipped the lower-quality fish south to feed the slaves in the West Indies and transported sugar back to Europe.
In these early days, fishing was done by hand-line from the decks of the vessel. Beginning in the nineteenth century, however, new methods were developed. Cod seines, gill nets, and cod traps were used to a limited extent in coastal waters, and small dories began to be carried by the offshore vessels so that hand-liners could spread out over a wider area to fish. By the 1850s, longlines with hundreds of hooks began to replace hand-lining in the offshore fishery, but it was at the start of the twentieth century, with the arrival of trawling, that fishing methods made a major advance in effectiveness.
The otter trawl was introduced to the U.S. Atlantic seacoast in 1908 but was not used in Newfoundland waters until 1935. An otter trawl consists of a large baglike net that can be dragged across the seafloor, with two large otter boards, or doors, mounted on the towing lines at the ends of the trawl's wings—the outer corners of its mouth. The doors can be as big as garage or barn doors and may each weigh 1,000 kg in commercial trawls that have mouths 100 meters wide. The doors are rigged so that hydrodynamic forces tend to move them outward, spreading the wings and pulling the mouth of the net open. Floats or kites lift the headline of the net to keep the mouth open vertically, and the footline is weighted and protected in various ways to keep the net in close contact with the substratum. The otter trawl proved to be very efficient at catching cod and other groundfish, and trawling became the principal method of capture in this fishery.
In addition to the introduction of trawling technology, the twentieth century saw increased use of steam and diesel power, of refrigeration and flash-freezing, and of long-distance rapid transport to market by truck, train, and plane. The result was that the Northwest Atlantic fishery was presented with an ever-expanding market and the temptation to continue to expand the fishing effort to supply the demand.
So what do we see when we look at the catch of cod? Detailed examination of the early fishery, region by region, reveals many examples of stock declines and resulting poor catches, but the solution was simply to expand to new fishing grounds. For example, a failure of the southern and southeastern inshore Newfoundland fishery in 1715 provided the impetus for expansion to the northeastern Newfoundland shore and for a progressive expansion of fishing on the Grand Banks. And with each shift to more distant fishing grounds there was a shift toward larger vessels and more fishing effort to cover the additional costs. The growth in the catch proceeded as the area being fished expanded, as technology advanced, and as markets opened up. By 1765, the total catch for Newfoundland, the Grand Banks, Georges Bank, and coastal waters was about 180,000 metric tons, supporting a brisk trade with Europe and the West Indies. Catches declined during the American War of Independence but then recovered. By the mid-1800s, the total catch of cod from the Northwest Atlantic was about 200,000 metric tons, but it increased further, reaching 260,000 by the early 1870s. By 1895, the Northwest Atlantic cod fishery was landing 420,000 metric tons, and it continued at about this level, fluctuating between 400,000 and 700,000 metric tons, through to the Second World War. By 1955, the catch had reached about 1,000,000 metric tons, and it peaked at about 1,900,000 metric tons in 1968. Thereafter, catches declined progressively, to about 500,000 metric tons in 1975 and 80,000 metric tons in 1990. The Canadian government closed the northern cod fishery in 1992 and all groundfishing in Canadian Atlantic waters in 1993. Since then, cod stocks have shown minimal recovery. A commercial fishery that had provided enormous economic and nutritive benefits over five hundred years was finished.
From the commencement of commercial fishing, there were local declines or outright failures in the cod fishery. With hindsight, it's possible to see that in a situation in which anyone with the funds to secure a vessel could join the fishery, there was always a tendency to overfish local cod stocks. In the 1600s and 1700s, fishing was restricted to those locations that were near to land or home ports. When fishing yield declined in those locations, it was possible to travel to new locations. The result was that diminished stocks often had a chance to recover, while the fishery was sustained commercially by turning to previously unfished stocks. However, once the fishery grew so large that all fishable locations in the region were being fished, the tendency to overfish still reduced stocks, but there was nowhere else for the fishing effort to go.
If fishermen were not inventive and had continued using hand-lines from relatively small boats, it is possible that the catch of cod would never have grown to the size it did, and the collapse of the 1990s would not have occurred. But that is not the nature of fishing. Fishermen are wily predators, always looking to innovate to capture their prey faster and more economically.
The collapse of the cod fishery provides three clear lessons. First, there is a profound difference between the local failures that occurred from time to time during the early years of the fishery and the final overall collapse. Second, the combination of growing demand and improving technology led to ever-expanding effort and ever-growing yield up until the eventual collapse. Third—but not evident from the information I've provided so far—the fishing effort acted in concert with other factors to bring about the decline in cod populations. To fully understand what happened, it is necessary to move beyond a focus on effort and catches to examine the myriad factors that determine how abundant a population of fish will be and how fishing changes that. To do this we have to dip into theory. It's not particularly complicated theory, so bear with me.
EFFECTS OF FISHING ON FISH POPULATIONS
Logic dictates that populations of fish (or other species) grow when more fish are born than are dying, and they decline when more fish die than are being born. Ideally, a population will remain at constant size if each female produces, on average, the number of offspring needed to ensure that exactly two of them will reach adulthood and breed in their turn. (Two are required because in most species of fish, as in other animals, 50 percent of offspring are males.) That a female cod spawns millions of eggs each year and can live up to twenty more years after reaching maturity at five or six years tells us that very few hatched cod eggs grow up to become adult spawning cod. There are lots of things that happen to kill cod, nearly always well before they reach sexual maturity. Only one of these is fishing, which principally kills older fish.
From the perspective of the fish, fishing is just one more form of predation—one more challenge in its struggle to survive and reproduce. When fishing commences on a previously unfished population, it increases the chance of mortality, with the result that fish live, on average, less long before they die. In addition, fishing is a size-selective form of predation that tends to have the greatest impacts on the larger and older members of the population. While Atlantic cod can live for twenty-five years or more, by the early 1990s fishing was so intense that most cod were being caught before they were seven years old.
Because of these basic facts, there are several consequences of starting to fish a population. First, because animals tend to die younger, the population tends to become smaller than it was before, because each individual is present for a shorter period of time. Second, because the animals tend to die younger, they have fewer seasons after reaching sexual maturity in which to spawn—two or three seasons versus as many as twenty seasons in the case of cod. The result is that each successful fish (one that reproduces at least once) produces fewer offspring over its (shortened) lifespan. Furthermore, because fish are more fecund when they are older, the actual reduction in the production of offspring is substantially greater than the reduction in the number of spawning seasons might suggest.
Excerpted from Our Dying Planet by Peter F. Sale. Copyright © 2011 The Regents of the University of California. Excerpted by permission of UNIVERSITY OF CALIFORNIA PRESS.
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