* Business owner tracks bluefin tuna population
* Fishing nations meet in Paris to discuss catch quotas
* Data helps to establish global fishing quotas
By Claude Canellas
PERIGUEUX, France, Nov 17 (Reuters) - Jean-Claude Rignal once helped sport fishermen detect their prey. Now he helps to establish fishing quotas for the endangered bluefin tuna by tracking them from the cockpit of a Cessna 337 plane.
His transition started a few years ago, he said, when fishing limits started to rob his small business of a key revenue stream -- private fishermen with no time to hunt for fish in the Mediterranean Sea.
"We almost had to shut down in 2006 when the quotas were set up (in France), as our main activity was tracking fish schools for private fishermen," said Rignal, a pilot.
Now his firm, which operates six small planes and one helicopter from an air base in southwestern France, works for the French government and the International Commission for the Conservation of Atlantic Tuna (ICCAT).
"I guess the hunters have become gamekeepers," Rignal joked.
Last summer, Rignal's team spent more than 100 hours in the air gathering data on the Atlantic bluefin tuna, which inhabits the Mediterranean and whose numbers have dropped more than 80 percent since 1970 due to overfishing, Western scientists say.
Their findings will be at the heart of talks among 48 fishing nations that began in Paris on Wednesday with the aim of forging a deal on catch quotas for the endangered fish by Nov. 27.
A bluefin tuna can weigh up to 650 kg (1,430 pounds) and a single specimen can fetch up to ${esc.dollar}100,000. [ID:nLDE6A81GJ]
ICCAT countries limited the global catch of Atlantic bluefin tuna to 13,500 tonnes this year, down from 19,950 in 2009.
France, Spain and Italy catch most of the fish consumed in the world, and Japan imports about 80 percent of the haul.
Environmental groups say the quotas are so widely flouted as to be of little use, and scientists say fishermen systematically underreport their catch.
That could all create more work for Rignal, whose data on bluefin tuna can serve as a reality check for scientists and countries campaigning for looser fishing curbs. He has already expanded his team, adding a pilot and a scientific observer.
Flying through the air space of dozens of countries can create complications. "Libya refused to grant permission to fly over its zone at the last minute," said Rignal.
"We also had problems with Turkey, but Ankara finally agreed thanks to the work of French diplomats."
Rignal's main business is tracking fish populations, but his planes also conduct observation missions over forest fires and oil rigs. His next mission?
"It would be tracking marine mammals (such as whales). We have responded to the call for bids and we are optimistic." (Writing by Nick Vinocur; editing by Mark Heinrich)
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