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Keeping Turtles out of Skimmer Trawl Nets in the South Atlantic and Gulf of Mexico: Turtle Excluder Device (TED) Testing
Credit: Blake Price, NOAA
Skimmer Trawl Vessel
Credit: Blake Price, NOAA
TEDs are an important management option for the Gulf of Mexico and South Atlantic skimmer trawl fishery, due to:
- minimal shrimp loss,
- greatly reduced bycatch, and
- the rarity of observed sea turtle captures in nets with TEDs that are properly constructed, installed, and maintained
Different TED configurations appear to perform better in some regions relative to others--no "one size fits all" configuration has been identified. NOAA Fisheries Southeast Fisheries Science Center's Harvesting Systems Unit is developing TEDs specifically for the skimmer trawl fishery.
Reducing Sea Turtle Bycatch: Tow Time Limits vs TEDs
Skimmer trawls are used in North Carolina, Florida, Alabama, Mississippi, and Louisiana.
Skimmer trawls have been exempt from turtle excluder device (TED) regulations since TED requirements were first implemented in the early 1990s. However, skimmer trawl vessels have been required to adhere to tow time limits (55 and 75 minutes, seasonally). Because skimmer trawl tail bags can easily be retrieved, tow time limits are seemingly a workable solution to significantly decrease potential sea turtle bycatch and mortality.
Unfortunately, past observations aboard commercial vessels indicate that tow times are often exceeded; thus, an increased risk of sea turtle mortality continues to exist in this fishery (Scott-Denton et al. 2006). Recognizing that tow time limits are difficult to enforce and often exceeded, NOAA Fisheries Southeast Fisheries Science Center's Harvesting Systems Unit was tasked with developing TEDs for the skimmer trawl fishery in 2007.
Since 2007, nearly 1,500 comparative tows have been conducted aboard commercial skimmer trawl vessels in NC, AL, MS, and LA. These studies assessed a multitude of TED:
- sizes and shapes
- flap configurations
- orientations (top or bottom)
Collectively, testing has been successful with minimal TED handling problems and minimal shrimp loss (~5%) observed (Price and Gearhart 2011).
In the summer of 2012, NOAA fishery observers found that many of the turtles captured in skimmer trawls are so small that they can pass through the 4" bar spacing that has been used for otter trawls and get caught inside the end of the net. Upon further investigation, NOAA scientists realized that this was particularly true for small Kemp's ridleys.
Testing in LA and NC during 2013 showed promising preliminary results with the use of reduced bar-spaced (3") TED grid. In addition to relatively minimal shrimp loss, we also observed about a 25% reduction in finfish bycatch. There were no interactions with sea turtles observed in the TED-installed nets during this testing. However, approximately 18 sea turtle captures were observed in control nets (no TED) throughout these studies. All 18 sea turtles were sampled and released alive in good condition.
NMFS will continue to TED testing with 3" bar-spacing as well as a collaborate with University of New Orleans on additional testing. Extensive industry training and outreach are scheduled for the 2014 season.
Updated: June 18, 2014