Why aren’t fish coming back?
By Mark Kurlansky
Mark Kurlansky is world-renown journalist, author, and winner of the James Beard Award for Writing. He has published 31 books in twenty-five languages, mainly on the topic of culinary anthropology and food sustainability. He’s working on two books, the first is about salmon and the second is “Bugless,” a young adult book about the crisis posed by disappearing insects.
Sustainable is an ever more complicated word. In the mid-1960s, when I was a kid working on commercial fishing boats in New England, the fishermen were constantly talking about the problem of over fishing. They were among the first to raise the issue. But they were primarily complaining about foreigners in their waters, especially Russians and Japanese. After 200-mile exclusions zones were declared by most countries in the 1970s, the problem of overfishing foreigners was solved. Then came a worse problem of overfishing local fishermen.
To be clear, the problem of overfishing is not a failure of fishermen, it is a failure of government. Fishermen fish and governments regulate. Management has been so faulty that fishermen have been talking about regulating themselves, which is an interesting possibility, but oversight would still be needed.
In 1994 when the most historically important fishery in the world collapsed, the northern cod stock on the Canadian Grand Banks, government started taking fishery management seriously, at least in the northern hemisphere. Exploitation of southern countries and the devastation of those previously only slightly fished waters became a major classically colonialist problem.
But in the north, particularly in North America and Europe, fishing became tightly regulated. One would imagine the fish coming back. But this has not happened. It’s turned out to be far more complicated than originally thought. To simply order fisherman to take fewer fish became a wasteful policy forcing fishermen to throw away their catch. Then came reduced efforts, limiting the number of days at sea, the size of nets, the power of engines. Closing down certain grounds for a number of years. Sometimes using a combination of these proved most successful.
There have been a few victories and a few improvements. Cod, we are told, has become once again abundant on the banks in the North Sea. But when the actual numbers are looked at, while they have increased, they are still at levels once considered disastrous, nowhere near the levels once considered natural. It is a problem that biologists call ‘shifting baselines’. We become accustomed to such low numbers that improvements that are far below what was once considered healthy are hailed as success. We are getting to a point where few people remember what it once was, and so the goals become obscured.
But why haven’t tightly regulated fish stocks returned to their historic levels? One of the most dramatic examples is Atlantic salmon, of which there are only about 1.5 million left in the world. The commercial fishing of Atlantic salmon has been brought to a nearly complete halt. And yet the population continues to dwindle. Ample smolt populations go to sea and yet the percentage of returns become less every year.
We have arrived at a point where a fishery that could be saved simply by good management would be extremely fortunate. The abused ocean is having difficulty sustaining life.
First there is pollution including the hydrocarbons leaked by an under-regulated oil industry. The ocean abounds in heavy metals and PCBs many of which accumulate in arctic regions vital for the food fish depend on. More than 12 million tons of plastics enter the ocean every year and will not decompose for centuries. They do break down into tiny pieces that are consumed by fish.
The number one problem keeping fisheries from attaining sustainable healthy populations is climate change. Carbon dioxide, the leading cause of climate change, is absorbed by water. About a third of the carbon dioxide in the air is absorbed by the sea, where it produces a chemical reaction that makes the water more acidic. Specifically it causes an increase in hydrogen ions and a decrease in carbonate. The lack of carbonate ions diminishes the ability for growth in shellfish, coral, and certain plankton. This is important food for fish that the ocean is no longer producing. The lack of carbonate also diminishes the ability of fish to detect predators, which upsets the balance of species.
This acidification is taking place not only in all the world’s oceans, but also in rivers and their estuaries. This means that anadromous fish, that reproduce and grow in fresh water but live at sea — such as salmon, striped bass, sturgeon, shad, river herring, and sea lamprey — are all in trouble.
Carbon dioxide is also causing a warming of air and water. This is a problem for a fish such as salmon that require cold water. But this warming is also causing ice to melt and making sea water less salty. Fish such as salmon and cod that take cues from temperature and salinity for the various stages of their life cycle including when to spawn are becoming confused. Climate change is rapidly changing the North Atlantic. It is diminishing capelin and zooplankton, vital food for larger species such as cod and salmon. Such larger species are lacking protein and sometimes do not have the strength to survive.
While we like to focus on the excesses of commercial fishermen, so many things that we do from driving cars to drinking from plastic bottles are endangering fish. We have many tasks besides fishery management to embrace if we are to have sustainable fisheries. And in the interconnected web of life, sustainable fisheries are imperative for the survival of the planet.
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