Taxonomic debate complicates Bluefin Tuna trade ban

[Guest guest]

Salim Ali himself wrote to Sidney Dillon Ripley complaining about taxonomy :

 

" My head reels at all these nomenclatural metaphysics! I feel strongly like

retiring from ornithology, if this is the stuff, and spending the rest of my

days in the peace of the wilderness with birds, and away from the dust and

frenzy of taxonomical warfare. I somehow feel complete detachment from all

this, and am thoroughly unmoved by what name one ornithologist chooses to

dub a bird that is familiar to me, and care even less in regard to one that

is unfamiliar ----- The more I see of these subspecific tangles and

inanities, the more I can understand the people who silently raise their

eyebrows and put a finger to their temples when they contemplate the modem

ornithologist in action. "

—Ali to Ripley, 5 January 1956

 

 

*Scientific American Magazine*

<http://www.scientificamerican.com/sciammag>- March 4, 2010

*

 

The Deadliest Catch: A Proposed Trade Ban Could Take Bluefin Tuna off the

Menu

 

New DNA " fingerprint " techniques could aid this month's push for an

international trade ban

*

 

By Michael Moyer

 

This January a 511-pound monster of a bluefin tuna sold at Tokyo’s Tsukiji

fish market for $175,000—by far the highest price paid for a fish in nine

years. By that afternoon, customers at Kyubey, a Michelin-starred restaurant

a stone’s throw from the market, were dining on the tuna’s fatty belly, or *

toro*, the most opulent and rich cut from the most valuable fish in the

world.

 

Japanese diners could soon face much higher bills for bluefin. This month a

meeting of the Convention on International Trade in Endangered Species

(CITES) in Doha, Qatar, is slated to consider a proposal to ban all

commercial trade of the Northern bluefin, *Thunnus thynnus*, grouping it

with megafauna superstars such as the white rhino and the Asian elephant.

Japan imports about 80 percent of the total bluefin catch in the Atlantic

and Mediter­ranean, even as those stocks have plummeted to such paltry

levels that many scientists speculate that the fish could be headed for

extinction.

 

Never before has such a commercially important animal been subject to an

international trade ban, and proponents have braced for furious opposition.

To qualify for a complete trade ban, CITES requires that the population of a

species must have declined to less than about 20 percent of its historic

population size or have suffered from an extremely high recent rate of

decline. And although it is no simple task to measure the total size of a

population that wanders from the Mediterranean to the Gulf of Mexico over

its decades-long life span, recent scientific committees organized by the

United Nations Food and Agriculture Organization and the International

Commission for the Conservation of Atlantic Tunas (ICCAT) agree that the

Northern bluefin meets the criteria.

 

Another condition of a CITES listing is that enforcement inspectors must be

able to identify the tuna—a task that turns out to be almost as difficult as

measuring the population. There are three species of bluefin tuna—Northern,

Pacific and Southern—and even trained taxonomists have trouble

distinguishing Northern bluefin from its Pacific cousin.

 

The problem extends all the way to the plate. Late last year a team of

researchers from Columbia University and the American Museum of Natural

History examined 68 samples of tuna smuggled out of sushi restaurants in New

York City and Denver. They found that 19 of 31 restaurants either could not

identify or misidentified the species of tuna they were serving—for example,

replacing bluefin with bigeye (or vice versa). Of the nine samples of fish

advertised as “white tuna,” they discovered that five were not tuna at all

but rather escolar, a fish banned as a health hazard in Italy and Japan

because it contains indigestible wax esters that can cause diarrhea.

 

Traditional DNA analysis techniques could not identify the various species

of tuna; the fish are too genetically similar. Instead the researchers

introduced a new approach. Conventional DNA “barcoding” techniques break

apart DNA sequences into a jumbled bag of base pairs, then compare how

similar the bag is to a reference bag. The new approach looks at the order

of nucleotides in a DNA sequence at a specific location on the genome. The

approach enables positive identification of any tuna sample—even one that is

sitting on a bed of rice.

 

“Some sort of DNA-based identification will be a critical component for

making CITES an effective regulation,” says Jacob Lowenstein, one of the

co-authors of the research. “This will probably in the short term become the

standard tool for regulatory bodies.” And even if the CITES proposal fails,

there will still be much to enforce. ICCAT is charged with setting bluefin

catch quotas in the Atlantic and Mediterranean, and by most accounts it has

done a terrible job of it. “ICCAT was convened and established in the 1960s

because of widespread concern by tuna fishermen over the decline of bluefin

tuna,” says Carl Safina, president of the Blue Ocean Institute. “Since its

inception the bluefin population has done nothing but go down.”

 

Even though ICCAT sets catch quotas far higher than the recommendations of

its own scientific advisory board, poaching and smuggling are still rampant.

In 2007, for instance, ICCAT had set the quota for the Eastern Atlantic and

Mediterranean at 29,500 metric tons of bluefin, even though scientists had

recommended that ICCAT shut down the Mediterranean fisheries for two months

during spawning season and limit total catch to less than 15,000 metric

tons. Fishermen caught an estimated 61,000 tons, most of it in the

Mediterranean spawning grounds. Says Safina, “It’s an all-out war on the

fish at the moment.”

 

http://www.scientificamerican.com/article.cfm?id=the-deadliest-catch & print=true