The scallop fishery includes a limited number of vessels. About 350 boats harvest scallops using a specially-designed dredge to scrape the animals off the sea bottom. A far smaller number of boats harvest scallops using a trawl net. Both methods are known to cause harm to sea turtles. Scallops are fished in large beds 30-100 meters deep along the continental shelf from the shoreline to the outer boundary of the U.S. Exclusive Economic Zone (out to 200 miles) in an area extending from North Carolina to Maine. The fishery operates throughout the year in the waters of the mid-Atlantic and southern Georges Bank, but sea turtles are most likely to be encountered from May through November. Only a decade ago, scallop landings were reduced due to overfishing. As a result of area closures to manage stocks, however, scallop numbers have grown significantly in recent years.
In 2001, as closed areas were re-opened, fishery observers began to report increased sea turtle capture. Until that time the National Marine Fisheries Service (NMFS) thought accidental turtle capture, or bycatch, in scallop gear was infrequent and not problematic. In 2003, NMFS estimated that 96 turtles of three species (loggerheads, Kemp’s ridleys and green turtles) were taken in the dredge fishery. However, in the following year the estimate was revised upward to 749 loggerheads. Today, the estimated biennial capture of sea turtles in the dredge component of the fishery stands at 929 loggerheads, of which 595 animals are either killed or seriously injured. Furthermore, NMFS estimates the trawl portion of the fishery captures 308 loggerheads biennially, with 40 mortalities. Adult and immature loggerheads predominantly are caught, but infrequent interactions with Kemp’s ridleys, greens and leatherbacks also are reported.
The standard 15-foot dredge frame weighs about 4,500 pounds. As it is slowly towed, the frame holds the dredge bag for the scallops open and near the bottom, while the cutting bar on the back of the frame hovers inches above the sea bottom. Sometimes turtles are run over by the dredge or lodged in the gear, which results in severe injury or death. Sea turtles can be swept into the bag and hit by large debris such as rocks; others are captured in the bag during haul-back from the water. When the bag emptied onto the deck, it is dropped from some height and then hit with the dredge frame to facilitate shucking of the scallops. Turtles caught in the bag are at risk from the fall itself and also from falling gear and debris.
Researchers believe loggerheads may be attracted to scallop boats because of the discarded chum and bycatch around the boats, which includes scallop parts, horseshoe and other crabs, whelks and fish caught by accident. The fate of 80 loggerheads recorded by trained observers from 1996 to 2007 reveals the risks associated with interactions between sea turtles and scallop boats. Six turtles were freshly dead or died onboard; 34 turtles were alive but injured; 22 turtles were alive and uninjured; and the remaining 18 turtles were alive, but their conditions were unknown. Many of the 34 injured turtles had cracks in their carapace and/or plastron, with blood and soft tissue damage. Sea turtles injured on scallop boats are simply returned, untreated, to the water.
To date, experiments to reduce injuries to sea turtles caused by scallop dredge operations have been relatively limited. NMFS has expended major effort addressing sea turtle interactions with the dredge bag, but little attention has been paid to the dredges themselves. Since August 2006, the agency has required scallop fishermen to insert mats of vertical and horizontal chains at the opening of the bags in an effort to prevent turtles from entering. Chain mats can reduce turtle interactions with the submerged bags and prevent them from being captured as the bag is hauled out, thus reducing injuries that can occur on deck. The chain mats also prevent the capture of turtles that are hit or run over by the dredge, which actually serves to mask the effects of the dredges by not bringing these animals to the surface. Because of this, sea turtle interactions with dredges probably are underestimated significantly.
Research conducted in 2004 identified the need to determine how dredges kill and injure sea turtles, since these interactions occur at the bottom of the sea and cannot be observed from onboard vessels. Some work has been done with turtle models to determine whether modifications to the dredge frame will deflect turtles, but no footage of actual turtle interactions with dredges has been obtained to assist in developing new designs.
A smaller number of fishermen fish for scallops with trawls rather than dredges; however, trawl boats tend to have higher rates of turtle interactions than dredge boats. Turtles captured in these wide-mouthed nets drown when they are unable to surface to breathe. As with other trawl fisheries, animals released alive can subsequently die as a result of physiological changes brought on by forced submergence.
In 2001, NMFS committed to addressing the capture and mortality of sea turtles in numerous U.S. trawl fisheries in the Atlantic and Gulf of Mexico by requiring widespread use of turtle excluder devices or TEDs. These two-dimensional net inserts have large escape openings that typically prevent the capture of sea turtles in trawl nest. In May 2007, the agency announced it would propose a TED rule in its published Advance Notice of Proposed Rule Making; however, to date NMFS has not done so. CCC is urging the agency to propose a comprehensive TED rule for public comment as soon as possible and no later than September 1, 2008.
The Endangered Species Act (ESA) prohibits fishermen from interacting with sea turtles and other endangered species. If a federally-managed fishery interacts with turtles or other protected species, NMFS is required to complete an ESA consultation as a Biological Opinion. These Opinions are supposed to take all information into account and make a determination as to whether anticipated or known levels of incidental capture jeopardize the species’ continued existence. If they find there is no jeopardy, NMFS then authorizes an Incidental Take Permit, which establishes the number of interactions the fishery is permitted to have with turtles. If jeopardy is found, NMFS has the authority to close the fishery or require fishermen to adopt measures to mitigate its effect, such as area closures or effort reduction. NMFS has considerable discretion and, in recent years, has permitted the scallop fishery to interact with hundreds of loggerheads annually. In response, the conservation community has brought several lawsuits to reduce the fishery’s impact on endangered sea turtles, but the courts have not found in the plaintiffs’ favor.
The latest requirements for the fishery were established in a March 2008 Biological Opinion and include new time and area closures for the entire fishery on a rotational basis. While he industry has threatened to sue NMFS for establishing these restrictions, the conservation community has expressed interest in taking NMFS to court for failing to provide sufficient safeguards.
While the important debate about the scallop fishery and sea turtle safeguards continues, it must be remembered that this problem is only a part of the larger issue of the cumulative impact of U.S. fisheries on these endangered species. For many years, as new data on turtle capture have become available, NMFS has increased the number of sea turtles all the fisheries are permitted to capture, injure and kill. NMFS’s failure to address cumulative mortality, especially with regard to loggerhead populations, is undermining decades of work to reduce incidental capture and help these animals recover their numbers. Since the establishment of our Fisheries Policy Program in 2006, CCC has advocated for reductions in the number of sea turtles allowed to be killed or injured in U.S. Fisheries, and we have supported the development of new fishing gear that will reduce the number of interactions with turtles. Currently, we are working to put in place a comprehensive rule requiring TEDs in all fishing trawls.