ANKARA, Turkey - Half of the 48 countries that fish the Atlantic did not report any shark catches in 2009, a sign that they are failing to adequately assess the impact of fisheries on threatened shark species, an environmental advocacy group said Tuesday.

Oceana called on the International Commission for the Conservation of Atlantic Tunas (ICCAT), which is meeting in Istanbul, to require that endangered or particularly vulnerable shark species, including porbeagle and silky sharks, are thrown back if they are caught in nets.

"Protecting the ocean's top predators is not a luxury, but a necessity," said Elizabeth Griffin Wilson, senior manager of marine wildlife at Oceana. "The fishing countries of the Atlantic can no longer ignore that shark populations are being decimated by ICCAT fisheries."

The ICCAT only has protections in place for bigeye thresher, hammerhead and oceanic whitetip sharks, Oceana said. The group urged ICCAT to establish catch limits for blue and shortfin mako sharks and require compulsory reporting of catch data of sharks.

Most shark species in the Atlantic are vulnerable to overfishing because of their exceptionally low reproductive rates, the group said.

"It is time to stop putting short-term financial interests before the long-term health of our oceans," said Griffin Wilson.

The conference also focuses on how to monitor illegal catches of Atlantic bluefin tuna, prized for its tender red meat, which has been severely overfished to feed the sushi market across the globe. The European Commission is expected to propose electronic surveillance to monitor the catches of bluefin tuna via a system that assigns a barcode to every fish, allowing it to be followed from catch to consumer.

The Pew Environment Group has said an electronic system would close loopholes by adding real-time monitoring, facilitating enforcement, and providing a more accurate count of the amount of bluefin tuna caught each year.

Oceana also urged the ICCAT to address the overfishing of Mediterranean swordfish and the bycatch of numerous vulnerable species, including sea turtles, marine mammals and sea birds, that are being caught in these fisheries.