By Marcel Evans
The second-most-common catch on Costa Rica’s longline fisheries in the last decade was not a commercial fish species. It was olive ridley sea turtles. These lines also caught more green turtles than most species of fish.
These findings and more, reported in a new study in the Journal of Experimental Marine Biology and Ecology, indicate that the Costa Rican longline fishery represents a major threat to the survival of eastern Pacific populations of sea turtles as well as sharks
The researchers argue that time and area closures for the fisheries are essential to protect these animals as well as to maintain the health of the commercial fishery.
The research was conducted by a team from Drexel University, the Costa Rican non-profit conservation organization Pretoma and a U.S. non-profit working in Costa Rica, The Leatherback Trust.
The researchers used data from scientific observers on longline fishing boats who recorded every fish and other animal caught by the fishermen from 1999 to 2010 and the locations of the captures and fishing efforts. Those data provided the basis for a mathematical analysis of the fishery resulting in maps of geographic locations and estimates of the total number of captures of sea turtles in the entire fishery.
The most commonly targeted fish, mahi mahi, is one of the most common species caught in the Costa Rican longline fishery.
But the researchers were surprised by their finding that olive ridley turtles, internationally classified as vulnerable, were the second-most-common species caught. More....