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The curse of the swim bladder

Harald Franzen
September 30, 2016

Nobody is trying to catch or kill vaquitas - yet they are on the verge of extinction. Now, an international agreement to crack down on trafficking to a fish species, the totoaba, may save the world's smallest porpoise.

 Vaquitas in the ocean
Image: Gemeinfrei

At the CITES conference in South Africa, countries have adopted a proposal from Mexico that could help to change the fate of the world’s smallest porpoise by banning international trade of a fish species native to the Gulf of Mexico, the totoaba. 

The fish is under significant pressure due to increased demand for its swim bladders in China and Hong Kong. This threatens not only the totoaba, but also the vaquita, which happens to share the fish's habitat.

The adorable vaquita is already the most endangered species of cetacean in the world. The less than 1.5-meter (5-foot) long porpoise has black rings around its eyes and a black line along its mouth - making it seem to be constantly smiling. Although a 1997 survey found 567 of the animals in the Gulf of California, the most recent count by the InternationalCommittee for the Recovery of the Vaquita (CIRVA) concluded last year that only about 60 animals were left - and that this number is likely to keep dropping.

"We are watching this precious native species disappear before our eyes," Lorenzo Rojas-Bracho, the chair of CIRVA, said at the presentation of the group's findings.

Vaquitas are protected and nobody is hunting them. Their fate, however, is inextricably linked to that of another animal that shares its only habitat in the Gulf of California: the totoaba.

That darned swim bladder

Although the totoaba fish is nowhere near as cute as the vaquita, it has other attractive features.

The animals used to be abundant in the Gulf of California, but intense fishing took its toll. Commercial fishing of Totoabas was only banned 1975. But that doesn't keep poachers from catching the fish illegally.

But these days, fishermen are no longer interested in filets - instead, the swim bladder has become a hot commodity.

Like so many other body parts of endangered animals, the bladders are considered a delicacy in China. The conservation group Defenders of Wildlife estimates that the bladders are sold for more than $4,500 per pound (9,000 euros per kilogram) in China.

As a result, local fishermen can make more money in just a few weeks of illegal fishing than they would make fishing legally all year long.

It is not surprising that this has helped push the totoaba to the brink of extinction - and the vaquita, along with it.

 A vaquita and a totoaba
Vaquitas are around the same size as totoaba fish and often get caught up in gill netsImage: picture-alliance/AP Photo/Omar Vidal

Fates intertwined

So what do the totoaba and vaquita have to do with each other? Totoabas are about 2 meters long - in other words, slightly larger than Vaquitas, but not by much.

As a result, the same gillnets used to poach totoabas almost invariably catch vaquitas as well. And since vaquitas are marine mammals that need to come up for air occasionally, they typically drown after getting entangled in the fishing nets.

"We have lost 80 percent of the species in only four years," Barbara Taylor, a conservation biologist at the US National Oceanic and Atmospheric Administration (NOAA) Southwest Fisheries Science Center recently explained in an interview.

"There's a tremendous amount of ongoing dangers, and despite heroic efforts by the government of Mexico to ban gillnet legal fishing, illegal fishing is still an enormous threat and it isn't contained yet."

Part of what makes it so difficult to protect both species is that they both only live in one place on earth - the Gulf of California - and the vaquitas only even within a small area of the gulf.

Drastic measures

As the situation is dire, CIRVA has proposed drastic measures.

These include a permanent ban on all gill nets in the area (for now, there is only a two-year ban in place), efforts to remove gill nets from the vaquitas' range, and the development of gillnet-free fisheries.

But one proposal is highly-controversial - even among conservationists. The group proposes an "ex-situ" conservation approach, which means that a number of the vaquitas would be captured and taken to breeding areas, where they would be protected from the deadly gillnets.

Such an approach is risky since there are so few animals left, and nobody has ever kept the shy creatures in captivity. Nobody knows how they would cope with being handled, or with those dramatically different living conditions.

Even the authors of the report agree that this would be a risky move, writing that removing the nets and preventing poaching should take priority.

One thing everyone agrees on, however, is that if decisive action isn't taken right now, there will be no vaquitas left to save in a decade's time.

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