Reducing Sea Turtle Bycatch in Northeast Fisheries
We are working with fishermen to make squid, shrimp, and sea scallop gear less likely to capture sea turtles.
All sea turtles in U.S. waters are listed under the Endangered Species Act and some fisheries are a significant threat to them. Our research helps find ways to modify gear that maintains target catch, but reduces the likelihood of catching sea turtle species such as loggerheads or leatherbacks.
Low-Profile Gillnet Research
Bycatch of loggerhead sea turtles in sink gillnet fisheries is one of the most significant threats to their recovery. Our gear research team works with fishermen to test fishing gear that is designed to reduce the bycatch of sea turtles.
In the northwest Atlantic, the sink gillnet is one type of fishing gear that threatens loggerhead turtle recovery (PDF, 12 pages) From 2012 to 2016, 705 (141 annual average) loggerheads were estimated to be incidentally caught in sink gillnet fisheries in Georges Bank and the Mid-Atlantic. Of these, 557 (approximately 112 annual average) were fatal. Other protected animals such as leatherback turtles, Atlantic sturgeon, and cusk (a candidate species for protection under the Endangered Species Act) are also at risk of entanglement in sink gillnet fisheries. NOAA Fisheries is working to minimize bycatch of these endangered animals in this gear type.
The lucrative Mid-Atlantic sink gillnet fishery mainly targets monkfish, and occurs in an area also used by loggerhead sea turtles. Several years of research had demonstrated that an experimental, low-profile gillnet reduced the bycatch of Atlantic sturgeon while maintaining acceptable landings of target catch. However, results for sea turtle bycatch were inconclusive.
From February through March 2021, our gear team tested an experimental low-profile gillnet along with a traditionally fished net. They found that the experimental net reduced turtle catch by approximately 68 percent compared with the control net. As part of that work, underwater cameras recorded the nets in action, and also grabbed what may be the first known video of sea turtles interacting with the nets.
NEFSC Gear Research Series: Going Low to Reduce Sea Turtle Bycatch
Working with fishermen across the East Coast, Northeast Fisheries Science Center researchers tested a new fishing gear design that reduces the chance of catching sea turtles in gillnets. Luckily they had underwater cameras to see how it works!
We will conduct more research to further test the target catch efficiency of the low-profile net before it is fully introduced into the fishery. However, for gillnet fisheries that occur where loggerhead bycatch is a concern, this work shows a promising way to mitigate risks posed to these turtles while maintaining fishery catch.
Trawl Gear Research
Turtle excluder devices are already used in shrimp trawl nets to reduce the capture of sea turtles and other large non-target species. Our trawl gear research is further improving results where TEDs are presently used, and finding ways to reduce sea turtle bycatch in other trawl fisheries in the region.
We are focused on a new design for squid trawls using a sorting grid made from cables sewn into the net. This design was developed by NOAA Fisheries’ Southeast Fisheries Science Center. Experimental work is ongoing to test how adding the cable grid affects catch and bycatch rates, and how vessel size affects the gear’s performance.
Image
Sea Scallop Dredge Research
Historically, sea scallop vessels using dredges incidentally caught sea turtles, in particular loggerhead turtles and Kemp’s ridley turtles. To reduce this bycatch, we worked with the sea scallop industry to develop and implement a modified scallop dredge, which eliminates much sea turtle bycatch.
The U.S. Atlantic coast provides habitat and essential feeding grounds for both Atlantic sea scallops and loggerhead sea turtles. Because of this, there have been numerous recorded interactions (PDF, 18 pages) between the scallop fishery and loggerhead sea turtles. These interactions have been mostly reported by fisheries observers on scallop dredge vessels (PDF, 22 pages) operating in the mid-Atlantic. Observer data report interactions between sea scallop gear and loggerhead sea turtles and, less frequently, Kemp’s Ridley sea turtles.
Scallop dredges target sea scallops lying on the top layer of seafloor. When dredges are pulled across the ocean bottom, they can also capture or injure sea turtles in their path. Sea turtles captured in the dredge bag can also be injured by rocks or other debris that gather in the bag. When the bag is emptied, captured turtles may be harmed when they are dropped on the boat deck, or by the weight of the dredge. To reduce this risk, we needed to keep turtles from getting into the bag to begin with.
Our gear research team worked with the scallop industry to develop chain mats and Turtle Deflector Dredges that reduce the probability of the dredge catching a sea turtle. The Atlantic sea scallop fishery now requires vessels to use TDDs, which deflect turtles over the top of the dredge frame. When fishing for scallops in some federal waters from May 1 to November 30, fishermen must use chain matting and TDDs to reduce the likelihood of capture and injury to sea turtles.
In the Northwest Atlantic, estimated visible contacts between loggerhead turtles and dredge gear have decreased from 218 loggerhead turtles per year in the early 2000s to one animal in 2014. Our work on Turtle Deflector Dredges was able to reduce sea turtle mortality by 36% compared to standard dredges. Turtles continue to be observed in the area, so this drop in both observed interactions and reduced mortality is most likely because of TDDs.