The Imperiled Giants of the Mekong

Ecologists struggle to understand—and protect—Southeast Asia's large migratory catfish

M. Jake Vander Zanden, Zeb Hogan, Peter Moyle, Bernie May, Ian Baird

Action Plans

Although much remains to be learned about the ecology of the migratory catfish inhabiting the Mekong, enough good science is now available to forge a strategy for the sustainable management of these inland fisheries. This broad survey of the problem isn't the place to detail prescriptions for better fisheries management, but we can at least outline what would be involved.

First, maintaining the connectivity between spawning grounds and nursing areas is absolutely critical, in part because many seasonal fisheries are based on the catch of migratory fish. It is important to avoid what happened on the Mun River, the Mekong's largest tributary in Thailand, where a dam blocked the upstream migration of many fish, especially catfish, most of which cannot navigate the ladder constructed to allow them to climb over this obstruction. Not surprisingly, the local catch of migratory species plummeted after construction of the dam. The resultant political fallout has been widespread and long lasting: Fishers protested, and eventually occupied, the dam site in 2000, and in 2001 the ongoing opposition prompted the government to consider removing the dam. In the end, authorities decided to operate the dam at reduced capacity (opening the massive flood gates for four months of the year), in hopes of bolstering stocks of migratory fish.

If the Mun River Dam is any indication, planners should be cautious about proposals for mainstream dams on the Mekong River, recognizing that no workable design yet exists to mitigate the harm these dams bring to migratory fish. Dams would also alter the natural variation in river flow, which is critical to maintain, because the behavior of migratory fish (and the people who depend on them for a livelihood) is closely tied to these seasonal changes.

Because the central governments have only limited presence in the rural areas where the fishing takes place, management of this natural resource must begin at the local level. But with fish migrating between Vietnam, Thailand, Laos and Cambodia, action at the local, or even the national level, is not sufficient. The fisheries of the Mekong need to be managed as a transboundary resource. And the authorities drafting the regulations need to be aware that in a mixed-species fishery such as this, slowly maturing species are especially vulnerable to over-exploitation—and thus to extinction. That is, regulations that are able to maintain the total catch in a multi-species fishery can nonetheless lead to severe declines among vulnerable groups, most notably large-bodied, migratory fish.

Ultimately, the preservation of such species must be considered not only as a matter of fisheries management but also as a conservation issue. The growing list of threatened migratory fish (P. gigas, P. sanitwongsei, P. hypophthalmus, P. jullieni, C. siamensis) demonstrates the need for precautionary actions to aid their conservation and for greater efforts to assess their status.

One option that acknowledges the shortcomings of typical approaches to fisheries management would be to pursue an idea recently championed by Harvard entomologist E. O. Wilson: conservation concessions. Adopting this tactic on the Mekong River would blend something similar to what can now be found on land in several places (including Guyana, Suriname, Bolivia, Peru and the Congo) with the situation in various marine protected areas. The idea is to purchase the right to fish commercially in a specified area but not to exercise it. These "fishing rights" would then become nonfishing rights: the power to halt large-scale commercial fishing in certain areas in favor of small-scale subsistence fishers—and fish. Some people living along the Mekong already use a similar tactic on a small scale, forbidding fishing in reaches of the river adjacent to their villages.

This strategy offers a direct method to protect these natural resources for the long term. If carried out effectively, conservation concessions have the potential to boost fisheries production elsewhere, by increasing the spawning stock while at the same time providing revenue to the governments that issue them, new jobs for fisheries officials (to enforce regulations within the concessions) and opportunities for community participation in their management. Such concessions could either be established with revenues from ecotourism or with funds from organizations such as the Asian Development Bank or the Global Environment Facility, which are both currently involved in large-scale projects in the Mekong River basin.

Whether or not such conservation concessions are quickly established, a complete moratorium on the catch of Mekong giant catfish, including those caught incidentally, is urgently needed. The remaining population simply cannot support a fishery at this time. What is more, the ban needs to extend to wild fish caught for artificial breeding. The Thai Department of Fisheries should breed existing captive stocks to supply the commercial aquaculture sector. The captive stocks should also be used to develop a breeding program that produces greater genetic diversity in the fish that are to be introduced into the wild. Even if this strategy fails, effective conservation measures in Cambodia may allow the wild population there to bounce back, and this "downstream" stock might then replenish other stretches of the river.

It's obvious that in some spots, notably in China and along some tributaries, the river ecosystem is deteriorating rapidly. But when considering the Mekong River as a whole, there is still ample reason to be optimistic. So far, the main channel of the Mekong river has not been dammed below China. This waterway remains relatively unpolluted, and fishers here and on many of the tributaries are still able to capture phenomenal quantities—some 16 percent of the world's total freshwater catch. The countries of the lower Mekong (Thailand, Laos, Cambodia and Vietnam) have shown resolve to work together for the sustainable development of their shared aquatic resources. Perhaps they can accomplish something that we have largely failed to do in North America: develop truly sustainable fisheries while protecting local biodiversity.

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