Several years back, the Fisheries Agency of Japan began claiming that whaling is necessary to protect valuable fisheries. The agency argues that if we do not kill whales, they will eat millions of tons of fish that are rightfully destined for human consumption. Since some whale populations are increasing, and many fish stocks are falling, the agency's argument is seductive in its simplicity.

It is also the scientific equivalent of claiming that to save the rain forests we must cut down the tallest trees.

The real problem is that oceans are among the planet's most complex ecosystems and are probably the least understood. Yes, commercial fish catches are dropping, but whales could very well be part of the solution, not the problem.

One example of how ecosystems defy simplistic analyses was an attempt to increase fish catches on the Zambezi River, which flows from Zambia and through South Africa into the Mozambique Channel. Along one section of the river, fishermen decided to kill all the crocodiles, because crocs eat fish and they assumed that fewer crocs would mean more fish. Soon after the crocs were gone, however, fish populations began to shrink. It turns out that young crocs eat crabs, and crabs eat fish eggs. Without juvenile crocs to eat the crabs, the crustacean populations boomed and the number of fish eggs fell dramatically.

Faced with such a situation in Japan, some Fisheries Agency bureaucrats might argue that the African villagers should simply acquire a taste for crab. The wiser conclusion would be to realize that, regarding complex ecosystems, what we don't know can hurt us.

Thanks to our ignorance, the oceans are going to hell in a fish-basket, and killing a few whales or protecting a few fish species is not going to save them. Oceans and marine species are under assault on many fronts. As Denis Hayes, a founder of Earth Day, told the U.S. Commission on Oceans this month: "In a nutshell, we have been taking far too many good things out of the ocean, and we have been putting too many bad things into it."

Considering how much we depend on the oceans for food, shipping, recreation and inspiration, it is shocking how little we know about them. Counting stars and soaring off into space captures the imagination of landlubbers, but tallying fish and exploring the murky depths smacks more of the mundane. Yet relative to space, oceans are easily accessible and finite -- though nonetheless vast, covering more than 70 percent of the planet's surface and containing 97 percent of its water. Sadly, what we know about them is a mere fraction of what we do not.

Adding insult to ignorance, we treat our oceans like a bottomless sewer. Much of what we pour down our sinks, flush down our toilets, pump into our air, toss into our gutters, and dump into our bays and rivers ends up in our oceans. According to Reef Watch Marine Conservation, an India-based marine-resources awareness organization, each year we dump into our oceans three times as much waste as the weight of fish we take out.

This spring, Anne Platt McGinn, a senior researcher at the Worldwatch Institute in Washington, D.C., wrote a World Summit Policy Brief titled, "Healthy Oceans Key to Fighting Poverty." She notes: "Pollution, overfishing and land-based activities -- like deforestation, agriculture, freshwater diversions and industrial development -- all contribute to the degradation of valuable coastal habitats."

She adds that in developing nations, "70 percent of industrial wastes and 90 percent of sewage are released untreated into surface waters where they pollute aquifers, freshwater resources and coastal areas."

Not surprisingly, the toxins we cavalierly toss into our rivers and oceans come back to us in the fish and shellfish we eat. This does not stop us from gorging on marine resources, however, and our gluttony must awe the whales. McGinn writes: "Since the Earth Summit in Rio in 1992, scientists have recognized that overfishing has become the major driving force behind marine ecosystem collapse in many regions. The global fish catch has stagnated since 1990. Seventy percent of fish stocks are now fully- or over-exploited."

Aware, as we are, that fish stocks are shrinking worldwide, it would be reasonable to assume that fishers and governments were taking steps to protect such valuable resources. Such an assumption would be wrong. The race to catch an ever-dwindling number of fish goes on unabated, with improvements in technology ensuring greater and greater efficiency. In addition, commercial fishing continues to be "grossly wasteful," according to McGinn. "In the process of harvesting 85 million tons of fish each year, fishers routinely discard at least 20 million tons of bycatch -- unwanted fish and marine species that are usually killed," she reports. And these fishers are the law-abiding ones.

A June 4 news item in The Japan Times highlighted yet another problem: The criminally greedy who trade in illegal catches, further undermining our food future. According to the AFP-Jiji story, "nearly 75 percent of Russia's annual fish exports to Japan are illegal, earning poachers over 150 billion yen a year." As the subhead stated: "Russia loses big; Japan a ready buyer."

If Japan's Fisheries Agency really wanted to protect marine resources, it would long ago have demanded a crackdown on this grossly unsustainable practice of "midnight trading," in which hundreds of Russian boats offload illegal catches into the holds of Japanese couriers. The Fisheries Agency, however, is enmeshed in business-as-usual.

So what can we do about the pillaging of the seas? First, stop eating at crab and sushi chain-restaurants that tout rock-bottom prices. If the prices seem too good to be true, they are. More than likely you are eating "poached" fish -- and undermining the livelihood of legal fishers who work hard just to break even.

You can also educate yourself on the threats facing our oceans. To provide knowledge about the marine environment and help raise awareness of overfishing and pollution, the UN has a Web site at www.oceansatlas.org that is worth checking out, along with one created by The Worldwatch Institute at www.worldwatch.org and another that is operated by the World Resources Institute at earthtrends.wri.org

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In response to my last fortnightly column, on June 13, headlined " 'Dark Side' proved a lightning rod for readers' ire," a reader wrote, "So what now?" She's heard enough bad news about the environment and wants to know what people in Japan can do to help out. So here's a request to readers: If you know of any nongovernmental organizations, community groups, companies or individuals who want volunteers to work on environment-related projects, please let me know. All ideas are welcome, particularly opportunities available for foreigners who cannot speak much or any Japanese. Please send suggestions to the e-mail address below, and I will pass them on to readers in a future column.