A global concern is the expansion and uncontrolled development of high seas longline fisheries during the last 20 years. A longline consists of a single monofilament line, that may be up to 10 to 120 km long. From this “main line” dangle hooks every 20 to 50 meters, baited with squid, fish, or shark, which are connected to the main line by means of a gangeon and a pressure clip. The line is set at the desired depth by means of buoys. It is estimated that around the world longliners set from 5 to 10 billion hooks per year. This is approximately 5 million hooks a day, or 160,000 km of line.
The target species of this fishery includes large pelagic fish, such as billfish (sailfish, swordfish, and marlin), tunas (yellowfin, black tuna), mahi mahi (Coryphaena sp), and sharks.
Unfortunately, this fishery is out of control, particularly in the Eastern Pacific. Some populations of fish which constitute the target species, and which should enjoy efficient management, currently suffer from over fishing. Sharks are captured under an industrial fishing effort, only to harvest their fins and discard the bodies at sea. Furthermore, this type of fishing captures many other marine species, some endangered, such as sea turtles. Leatherback turtles are on the verge of extinction in the Pacific Ocean, and longline fisheries have been pointed out as the culprit.
Download a report describing swordfish longline fisheries in South America, including sea turtle interactions and recommendations for management, elaborated by Randall Arauz, under consultation by James R. Spotila, Drexel University, 1999.
PRETOMA activities with local Costa Rican longline fishermen to promote biological research, management, and responsible fisheries:
Study on the impact of the mahi mahi longline fishery on shark and sea turtle populations in the Exclusive Economic Zone (EEZ) of Costa Rica. Together, Papagayo Seafood S. A. And Nutria Marina S.A. collaborate with PRETOMA in the development of technologies and guidelines for responsible fisheries.
Through the collaboration of the University of Hawaii, research is being carried out to evaluate post hooking mortality using satellite telemetry. Under this same framework, a project is being prepared to test “blue bait”, which has the potential of reducing the capture of sea turtles dramatically.