Can DNA Barcoding Really Save Endangered Fish?

Preserving Nemo’s future might be one barcode scanner away, it turns out.

A group of clownfish is displayed at the 2011 Taiwan International Ornamental Fish Expo. (Photo: Pichi Chuang/Reuters)

Jun 24, 2013· 3 MIN READ
Richard Conniff is the author of House of Lost Worlds: Dinosaurs, Dynasties, and the Story of Life on Earth and other books.

There’s always been a kind of zen, a sense of serenity and connection to nature, about watching ornamental fish. That’s one reason more than 10 percent of American households keep fish tanks, ranging from goldfish bowls to vast, meticulously maintained saltwater ecosystems. But according to a new study in the journal Biological Conservation, this popular hobby may be causing some of the most beautiful species on Earth to become extinct.

The study looks at the trade from just one country, India, from 2005 to 2012, and it reports that dealers there exported 1.5 million freshwater fish in at least 30 threatened species, including a dozen that are endangered. Just within the red line torpedo barbs, a colorful species complex, more than 300,000 individual fish were shipped to the United States and a half dozen other countries.

Dealers probably took many times that number from the wild, the study suggests, counting those that died before they could be exported. Uncontrolled harvesting of these charismatic fish “during the last two decades is associated with severe population declines, and an ‘Endangered’ listing” on the IUCN Red List of Threatened Species.

Part of the problem with the trade has to do with limited or misguided regulation in India. When the Department of Fisheries in the southern Indian state of Kerala set out in 2008 to control the trade in red line torpedo barbs, the new study reports, it did so with little scientific advice. So it closed the trade in June, July and October, to allow the fish time to breed in peace.

But these species actually breed from October to March, when about 90,000 of the exported fish were taken. The regulations also encouraged collection of large spawning adults instead of juveniles. To compound the problem, the government of Kerala itself participates in a trade partnership with private industry to export the red line torpedo barbs.

Enforcement of existing regulations is often lax or nonexistent. The study notes, for instance, that exporters in April 2012 shipped to the United States hundreds of specimens of a rare species, the new Malabar loach (Mesonoemacheilus ramadevii), “known only from a single location inside the highly protected Silent Valley National Park,” also in Kerala. Kerala bills that park as “probably one of the most magnificent gifts of nature to mankind.” But dealers in the United States were soon offering some of its endemic species for sale at $3.58 apiece.

Co-author Michael F. Tlusty, of the New England Aquarium in Boston, says the new study is not intended as an attack on the ornamental fish trade, which gets 90 percent of its sales from captive-bred stock. Nor is it an attack on trade in wild-caught fish. If properly regulated, he says, that trade can be a way of “creating value for intact functioning ecosystems.”

The aquarium’s own Project Piaba encourages the trade under the slogan “Buy a fish, save a tree!” Cardinal tetras are abundant in the Brazilian Amazon, Tlusty explains, and catching them from the wild provides “69 percent of the local economy in an area the size of Pennsylvania in the middle of the Amazon.” They are a renewable resource.

But the conditions for a wild-caught trade vary from country to country, and species to species. India, in particular, has an abundance of small, fragmented habitats where it would be relatively easy for uncontrolled trade to wipe out an endemic species. (It’s also a sore point in India that where captive breeding programs for its species exist, they are generally concentrated abroad in Singapore, Hong Kong, and other centers of the ornamental fish industry.)

To clean up the business, the new study recommends a better system of digital data-tracking, with every shipment including the species name, capture location, size of the specimens, and the names of the collector and exporter. That system should also include communication between countries on both ends of the trade.

Right now, says Tlusty, overwhelmed customs inspectors in the United States tend to get a 70-page paper invoice and a few minutes to make sense of a large shipment that may include any of 1,800 fish species now commonly traded. Even a trained ichthyologist would struggle to make some of the finer species distinctions. Inspectors just get frustrated, or give up.

What’s needed, says Tlusty, is an electronic system that can compare the species listed on an invoice with a database of threatened and endangered species. That kind of system could also tip inspectors off to a problem. “This box says it contains 40 goldfish, but it’s too heavy to be just 40 goldfish.” The system could also alert inspectors to companies or countries that have caused problems in the past. So even if only a small percentage of shipments gets inspected, those inspections would be targeted to likely trouble spots.

Misidentifications and deliberate mislabeling are frequent problems (some shipments are simply labeled “ornamental fish”). So one recent study proposes using DNA barcoding to identify species quickly and economically. But barcoding can require killing a sample fish. So another study out this month in the journal Biological Invasions suggests instead that it’s possible to get a genetic identification for the species in a shipment just by sampling the water in which they have been swimming. Those kinds of inspections could take place on a highly automated basis.

One hitch for all of these proposals is that government inspectors, like other federal workers, are feeling intense budget pressure. On the other hand the aquarium fish trade continues to prosper, doing a $15-30 billion business annually worldwide. In keeping with the zen image of the hobby, trade associations frequently talk the talk about environmentally responsible practices. So maybe now the industry will step up and walk the walk.

Alternatively, the U.S. Fish and Wildlife Service could begin to encourage compliance by prosecuting pet stores and dealers. (It would be a relatively easy high school or college science project to get barcoding samples from the fish sold by local retailers, the way students now do barcoding studies to identify mislabeled species in the edible fish business.) The penalty under the Endangered Species Act for selling an endangered species can be as high as $50,000 and a year in prison per infraction—and that could make for some very expensive pet fish.