The utilitarian argument may be extended to point out that benefits to humankind may be obtained not only from individual species but from biodiversity itself. The health of the planet may depend not so much on individual species but on the interaction between them, perhaps especially involving the vast numbers of microbial species in the soil. But quite how this may be so is not understood, and scientists’ opinions have differed on whether a high level of biodiversity assists the working of the global ecosystem.
Quite different is the aesthetic argument more favoured in Europe that biodiversity should be preserved for our pleasure. We should look after species in the same way that we look after works of art – a loss may be afforded economically, but it is always to be regretted. If we grow to love our ecosystems, then that very familiarity will help to save them, even if it does mean that we try hard to preserve the glamorous species and ignore the dull ones.
Finally, there is a purely moral supposition that humankind has a duty of global stewardship. Upon this argument may depend the survival of those unfortunate species that we find neither useful nor pretty.
The problem with these arguments is that we don’t really know what we are talking about. There are probably something less than 10 million species, although estimates range hugely between around 3 and 100 million, according to a 2003 report by the British Royal Society.4 Only 1.7–1.8 million of these species have names, and even this figure is uncertain because there is no central catalogue and many species are certain to ‘exist’ only as synonyms. Most plants and vertebrates are named, but there are perhaps seven more insects for each of the million with a name already, while only 100,000 of the world’s estimated 1.5 million fungi species are named. Still less is known about marine micro-organisms and microbes in the soil, the numbers of which cannot be estimated by the methods used for larger species. Then, within species, even many of the large and obvious ones, there are high uncertainties as to population numbers and trends. So when the 2002 World Summit on Sustainable Development set a target for the reduction of biodiversity loss, it did so despite the fact that ‘[n]o sound scientific basis currently exists for assessing global performance against this target’:5
Small wonder, then, that some species finds turn out to be previous losses (such as the Cypriot mouse). Others go straight from unknown on to the endangered lists. With so many species unknown, and the populations unknown of many of those we do know, it can only follow that estimates of rates of species loss and endangerment are little better than guesses. As the Royal Society confesses, ‘The fate of organisms that have not yet been recognized by science cannot be measured.’ Extravagant claims for annual losses of species in the tens of thousands attributed to Al Gore and Ed Wilson can most charitably be explained as fractions derived from the absolute maximum possible number of species on the globe.6
This ignorance makes it hard to direct conservation efforts appropriately. But there is another factor that may make them irrelevant altogether. Scientists have little idea of how many species we can afford to lose, not only because of the uncertainties in their estimates of species numbers and populations, but because of the fundamental nature of evolution.
The trend in biodiversity has been an upward one for millions of years as species achieve closer adaptation to their habitats. This raises a logical conundrum with practical consequences for our efforts to contain the damage we are doing to the Earth’s biodiversity. If biodiversity always tends to the maximum, it becomes meaningless to talk about an optimum level of biodiversity. And if there is no optimum level, there’s less point in fretting about loss of biodiversity when this is something that only temporarily sets back nature’s ‘aim’. We cannot logically say that we can afford no loss of biodiversity, except to the extent that the loss of one species might have a detrimental impact on connected species. Of course, it would be a shame if, amid the general carnage, we were to lose one species that held the balance of a whole ecosystem, or that might have offered us some miracle medicine.
Our modern successes in agriculture, industry and spreading our own species have so far killed off species equivalent to 100,000 years’ worth of evolution. But does it matter? For utilitarian purposes, the answer is no. We need only a tiny fraction of species to support our lifestyle. Even on a higher plane, it is not clear that maximum biodiversity is necessarily a good thing – the strength of interaction between pairs of species may matter more, according to the population biologist Robert May. So our main reason to fear the loss of biodiversity may be sentimental. As the newspaper pictures remind us, we just like sharing our world with polar bears and Dartford warblers.
Setting aside dilemmas over which species to save and why, the problem of conservation is a practical one. The major environmental causes of biodiversity loss are over-harvesting, pollution, climate change, aggressive species invasions and human settlement. But they all come down to loss of suitable habitat. In the 1960s, Ed Wilson developed a ‘theory of island biogeography’, which shows how the number of species sustainable within a given area depends on that area. The theory predicts how many species we can expect to find on an island (or other area of habitat that is in effect isolated) of a given size. It also predicts how diversity will be lost if the habitat is reduced. Roughly, if an isolated habitat is cut to a tenth of its former size, it will be able to support only half the species it used to. The theory also shows how fragmented areas that look like a sustainable habitat on a map may not suffice if the species in question will not cross from one area to the next.
This is a major reason why, even in the admission of scientists, many conservation efforts have been unsuccessful to date. The areas devoted to wildlife have been too small and too broken up. Even the vast national parks of North America are proving too fragmented for some species, whose decline, though slowed, has followed the pattern predicted by Wilson’s theory.
The answer is much bigger, better-located and better-regulated reserves. Ideally, we should focus on conserving habitat – then the species that live there will be saved automatically. But being the sentimental souls we are, we prefer to cherish glamorous species of rare orchid or the iconic panda. Fortunately, this is almost as good. If the Chinese succeed in saving the panda – despite the country’s galloping industrialization, conservation efforts are doing well, and recent fieldwork has shown there are more pandas than were thought – it will be because they saved enough of its habitat, and with it hundreds of other species without really trying.
It is the same in the heathland of the Thames basin. Should we care more about the Dartford warbler than that 50,000 people are housed? Perhaps not. But should we then support these people’s demand to be housed precisely where they fancy rather than somewhere else less critical to biodiversity? Again, perhaps not.
The Cod Delusion
‘Cod and oysters: tastes our grandchildren may not savour’ Guardian
On 3 November 2006, it was widely reported that the world’s entire commercial fishing stocks might be exhausted within our lifetimes. ‘Study: Seafood could disappear by 2048’, was how the Chicago Tribune led with the item. The paper neglected to say in which month of that year we’d have reached the bottom of the barrel. But it mourned: ‘Clambakes, crabcakes, swordfish steaks and even humble fish sticks could be little more than a fond memory in a few decades.’
Most of the major American newspapers ran variations of the story on the same day, prompted by a paper in the journal Science. Often they used the word seafood rather than fish stocks, bringing home the human implications as forcefully as they could. Most cited the doomsday year 2048, and some printed a dramatic downward graph of fish supplies crashing to zero.
Something running out plays well in the newspapers, especially when there’s nothing for people to see by which they might make a judgement on the matter for themselves. (It makes bad television for the same reason.) We can’t see the fish in the oceans. But it was all too easy to picture the suddenly emptied supermarket counters repl
enished with turnips rather than turbot. Consumers can be forgiven for feeling a little confused. Hardly had we got used to the message that we should eat more fish because its protein and omega oils were good for us than we were being told to stop in the name of environmental sustainability.
The science behind the story is more subtle and leaves room for hope. In 2003, Boris Worm and his colleagues at Dalhousie University in Halifax, Nova Scotia, had reported that 90 per cent of large predator fish, such as sharks, had vanished from the oceans since 1950. This was about conservation, not the human food supply; indeed if predators were down, their prey – and our food – might prosper. But Worm’s new paper in Science shows that this is certainly not the case. Worm and his team assessed a wide array of marine ecosystems and found them to be ‘rapidly losing populations, species or entire functional groups’ – that is to say, whole families of species.1 Both absolute fish numbers and diversity in terms of numbers of species showed heavy declines. The authors’ significant conclusion is that these two are bound up together such that over-fishing leads to loss not only of the species fished but of wider biodiversity, and conversely that reduced diversity in itself adds to the erosion of commercial fish stocks.
The results come from a statistical analysis of many previous studies, taking into account data gathered in different ways from different areas. In other words, it is not an analysis of directly collected scientific data, but an analysis of other people’s analyses, what the scientists themselves call a ‘meta-analysis’. This is not invalid at all, but it does leave the door open for sceptics to take issue, perhaps because a particular set of data is thought less reliable than others or because different data sets are not strictly cross-comparable. The papers had no difficulty finding scientists who did not support the study, one quoting a local professor who called it ‘just stupid’.
The Dalhousie authors themselves concede that some of the data they have used may be unreliable. Figures from the United Nations Food and Agriculture Organization (FAO), for example, are supplied by member nations, some of which may distort the information they provide in what they see to be their own interests.
The assumption factored into the projection of the data into the future – that fishing and marine conservation practices will continue unchanged – is more problematic, as is the fact that the apparent correlation between biodiversity and fish stocks is not proof of a direct connection. These are standard difficulties with scientific statistics that use present-day data to try to tell us what will happen in the future. Against this, the authors can, and do, claim that if enough surveys are taken into the reckoning, and all are found to fit the overall pattern, then it would be foolish to dismiss the major conclusion.
The more glaring loopholes – chinks of light for optimists in the fishing industry – lie beyond the terms of reference the scientists set for themselves. For a start, Worm and his colleagues focus their attention on areas where there is the most detailed data, which is to say where we fish already, and on the species that are ‘currently fished’. This seems at first like looking at a dug-out seam of coal and saying all the coal has run out. Fish are free to move within their ecological range, however, and so a loss in a monitored area can be taken to indicate a likely loss in other areas, although it is not a guaranteed loss.
Finally, the paper does not show the newspapers’ simple graph of fish stocks hitting rock bottom in 2048 (the future portion of which is an extrapolation based on a business-as-usual fisheries model). Instead it shows a different set of downward curves only to 2004, representing groups of species ‘currently fished’, which portend potentially less dire consequences.
The Dalhousie research is both ambitious in scope and gloomy in tone, but predictions that we will run out of fish are nothing new. At the beginning of the last century, Britain reacted to depletion in the North Sea by sending its fishing fleets further north. Fifty years on, this led to a series of ‘cod wars’ with Iceland. Globally, though, the view was that there were plenty more fish in the sea. In the 1940s, even Rachel Carson, later to write Silent Spring, was emphasizing not man’s depredations but the ocean’s bounty in two books entitled Food from the Sea.
The global ocean catch grew from 19 to 85 million tonnes from 1950 to 1990, according to FAO figures, a growth factor rather greater than for the world population, accounted for by the fact that people are eating more fish than they used to. Since 1990, the catch has fallen slightly, and the ‘dream anticipated by policymakers in the 1970s’ of a harvest of 100 million tonnes seems beyond achievement.2 In 1997, the FAO warned that 60 per cent of commercial fish species were fully exploited, over-fished or depleted. By 2002, the figure was 75 per cent. National commissions warned of the worsening situation in American waters in 2003 and 2004. It now appears that the world reached a point of ‘peak fish’ around 1994, although the moment passed unnoticed, in marked contrast to ‘peak oil’, which we may be experiencing at the moment.
Assessment of the risk of losing a favourite food is not helped by a history of antagonism between conservation biologists and the fishing industry as well as the sheer complexity of the ecology. A US National Fisheries Institute spokesperson responded tartly to the Dalhousie findings: ‘Fish stocks naturally fluctuate in population.’3 Fishermen observe that warming oceans may be important, but this may simply be part of a denial mechanism by the fishing community to blame external factors rather than its own malpractice. There are frequent reports of exotic warm-water fish newly found in British waters, for example, while fleets have to go further north to find familiar species. But are the latter fish found in the north because they have migrated there due to climate change or because Iceland and Norway have better managed the resources off their coasts? It is impossible to say for sure.
For their part, policy makers often tread a middle line, which may be diplomatic but is perhaps not sustainable. In November 2006, for example, the International Commission for the Conservation of Atlantic Tunas cut quotas for Mediterranean bluefin tuna, but not by as much as the body’s scientists were recommending, prompting environmentalists to repeat warnings that the fish would soon vanish entirely from these waters. According to the headline in the Independent, it was the ‘Growth of sushi bars “driving tuna to extinction” ’.
How bad is it really? It seems likely that individual consumption of fish cannot keep growing as it has been doing, but there is no reason to believe that we will be fresh out of all fish by 2048. There are grounds for optimism on many fronts. Much of the increased global demand has been met by fish farming, or aquaculture, which now yields 40 million tonnes a year, up from just 13 million tonnes as recently as 1990. There are severe problems with aquaculture as it is presently practised, merely the least of them being that the product frequently tastes like blotting paper. Using grain and fishmeal for feed is highly inefficient. It can take 3 tonnes of ocean fish to make meal to feed one tonne of farmed fish. Chemical and genetic contamination of the marine environment is also an issue. But aquaculture is a young industry that is experiencing many of the historical difficulties of intensive agriculture all at once. Imagine the chaos and protest that would follow on land if acres of forest, heath and wetland were suddenly turned over to wheat and cattle. In principle, farmed fish offer a more sustainable source of protein than livestock.
It is possible, though always politically unpopular, to scale back sea fishing. Norway did this with its cod fleets in 1989 and found that stocks bounced back amazingly quickly, so that by 1992 it was possible to relax the restrictions. The short-term economic and social cost was considerable, but not as great as the cost of ignoring the problem, which is what happened in Newfoundland, leading to the extinction of cod there and the permanent loss of the vast industry they once supported. However, regulations and quota systems must be enforced if they are to be effective.
A fifth of the global catch – some 20 million tonnes a year – is unwanted or disallowed under quota rules and is simply thrown back in the se
a dead. Reducing this by-catch is a priority. Other efficiencies may be possible. At present, the harvesting of fish is allowed to proceed in an unconscionably crude way as Charles Clover illustrates in his book End of the Line with a dramatic comparison of how trawling might appear on land, indiscriminately killing and mangling as well as catching all kinds of animals. Fishing is an industry, not a romantic calling, and just as technology has helped us ruthlessly to track down ever more elusive stocks, so there may be technological means of selecting fish for harvest without damaging other species or the supporting ecosystem as much as we do now.
More and larger marine reserves would work not like safari parks but like game nurseries, providing refuge where depleted species could recover to sustainable levels so that we could then continue to harvest them from unprotected seas. Such reserves would also help to maintain the biodiversity upon which population levels of economically important species depend. As Worm notes: ‘there is no dichotomy between biodiversity conservation and long-term economic development; they must be viewed as interdependent societal goals’. Encouragingly, while fish stocks decline when biodiversity is lost, they can also recover rapidly when diversity is high, making the fisherman’s job easier once more.
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