Hundreds of representatives of countries involved in bluefin tuna fishing, international organisations and NGOs met here Friday on how to improve catch controls and protect endangered species.

A report released last month warned that more than twice as many tonnes of Atlantic bluefin tuna were sold last year compared with official catch records for this threatened species.

This "bluefin gap" occurred despite enhanced reporting and enforcement measures introduced in 2008 by the 48-member International Commission for the Conservation of Atlantic Tunas (ICCAT), which sets annual quotas by country, it said.

Trade figures showed that real catches of bluefin in 2009 and 2010 totalled more than 70,500 tonnes, twice ICCAT's tally for those two years, according to the report compiled by the Washington-based Pew Environment Group.

In 2010, the target quota -- 12,900 tonnes for fish caught in the Mediterranean and Northeastern Atlantic -- fell for the first time within the panel's recommended range.

But the new report, released ahead of the nine-day ICCAT meeting in Istanbul which is attended by delegates from member countries, implies the industry has circumvented the catch limits and tougher compliance measures.

"The follow-up of catches is a key issue," ICCAT executive secretary Driss Meski told AFP on Friday.

"We are thinking about how to set up an electronic document that will follow the product from catch to consumer. We are doing a feasibility study and we will submit it."

ICCAT will also propose how to better protect other species, said a delegate who would not be named.

"We're talking about catch quotas or technical measures like a cap on the number of boats. And generalluy speaking we're following scientific recommendations," he added.

Meski confirmed that the parties involved in the Istanbul talks will discuss quotas.

The delegate said he also expected proposals on how to protect sharks which ICCAT sees as collateral victims of tuna fishing.