Since the 1960s, surface longlines have killed tens of thousands of fish and other animals in the Gulf of Mexico each year, most of them unintentionally. Now more selective alternatives are available. A pilot program is testing greenstick gear and swordfish buoy gear, which should reduce unwanted catch and keep fishermen in business.
The Gulf of Mexico provides essential habitat for a variety of species, including western Atlantic bluefin tuna, which are severely depleted. These tuna rely on the Gulf as their only known spawning ground; blue and white marlin and sailfish are also believed to spawn in these waters. In addition, endangered species such as leatherback sea turtles depend on the Gulf’s rich offshore waters for food.
Since the 1960s, fishermen using surface longlines for yellowfin tuna and swordfish in the Gulf have unintentionally caught and killed these and approximately 80 other species. This fishing gear consists of a main line averaging 30 miles long connected to buoys that suspend approximately 750 baited hooks near the surface. These hooks often remain unattended in the water for up to 18 hours, resulting in high mortality of ocean wildlife. Making matters worse, the 2010 BP oil spill disaster—which contaminated important Gulf habitat with about 172 million gallons of oil and 1.8 million gallons of dispersants—caused injury to bluefin tuna and other marine wildlife while exacerbating the decades-long problems caused by surface longlines.
Early in 2012, researchers with the Florida-based Nova Southeastern University Oceanographic Center initiated a pilot program to determine whether highly selective greenstick gear and swordfish buoy gear are environmentally and economically viable alternatives to surface longlines in the Gulf of Mexico.
Greenstick gear consists of a 35- to 45-foot fiberglass pole that tows a 500- to 800-foot main line. (The pole is usually green in color, hence the name.) Up to 10 artificial squid lures are individually attached to this main line and pulled across the surface of the water to attract yellowfin tuna. Once a fish is hooked, fishermen quickly bring it to the boat so that they can release any unintentional catch immediately in good condition. Because of the way the gear is fished, tunas account for the vast majority of greenstick catch.
Swordfish buoy gear consists of a single piece of heavy fishing line attached to one or two baited hooks on one end and a flotation device (buoy) equipped with a light on the other end. Generally, one vessel will use 12 to 15 of these free-floating gears at a time. The buoys, which are deployed at dusk, are set in a straight line. When a fish takes the bait, it drags a buoy out of line, indicating that it has been hooked, so the fisherman can quickly retrieve the fish and make a decision to retain or release it.
Researchers from the pilot program are working with commercial fishermen, including surface longliners, from Louisiana, the Florida Panhandle, and Madeira Beach, FL, to install and use these gears in the Gulf of Mexico for one year. Initial results indicate that the new equipment could provide a potential solution to the decades-old problem posed by surface longlines. The new equipment is proving to be more effective at reducing unintentional catch, and increasing catch rates for each successive trip suggest that fishermen are using it more efficiently over time. In addition, researchers have recorded no interactions with bluefin tuna or sea turtles. If adopted throughout the Gulf, these more selective fishing methods could provide significant environmental advantages while also maintaining economic benefits to the region.
Data collection for the pilot program is scheduled to conclude in May 2013. If the program demonstrates that greenstick gear and swordfish buoy gear are viable alternatives to surface longlines in the Gulf, restoration funds from the Deepwater Horizon oil spill could be used to help fishermen make the transition from surface longlines to more selective gear. Such a transition would mean the end of a wasteful fishing practice and a new beginning for fishermen in the Gulf of Mexico.