In North Carolina, shrimp are harvested for both food and bait, primarily using trawl gear, though a small amount of shrimp is harvested using channel nets, shrimp pounds, and cast nets. Trawls of varying sizes and types are used in most South Atlantic states and are regulated to address user conflicts, reduce bycatch, and mitigate impacts on essential habitats. The two primary types of trawl gear are skimmer trawls and otter trawls.
How a Skimmer Trawl Works
Skimmer trawls derive their name from the way they skim along the surface of the water. They are primarily used to harvest white shrimp in both estuarine and ocean waters. Each skimmer trawl consists of two rigid frames mounted on either side of a vessel, with nets attached along the sides of the frames. Metal skids keep the frames elevated off the bottom as the nets are pushed through the water column.
One advantage of skimmer trawls is that the tailbag can be checked periodically while the nets continue fishing. This allows for higher bycatch survival rates compared with otter trawls and reduces the time needed to haul in the nets, thereby increasing operational efficiency. Although the use of skimmer trawls has grown in certain parts of North Carolina, they still account for less than 10% of the state’s total commercial harvest.
How an Otter Trawl Works
Otter trawls are named after the two otter doors, or boards, that hold the net open as it is towed behind a vessel. These trawls account for nearly 90% of North Carolina’s shrimp harvest. They are used to catch all three shrimp species, with gear specifications adjusted to target specific species and to operate effectively in different environments.
Because otter trawls make contact with the seafloor while being towed, they are known to have a more direct impact on habitats, particularly structured habitats such as oyster reefs, shell bottoms, and submerged aquatic vegetation (SAV). Of the approximately 2.1 million acres of estuarine habitat in North Carolina, the Division of Marine Fisheries estimates that 1.2 million acres are currently closed to bottom trawling. Many of these areas are designated as primary nursery areas or permanent secondary nursery areas, which remain closed year-round. However, seasonal trawling is permitted in habitats classified as special secondary nursery areas from September 1 through November 30.
Bycatch (the incidental take of non-target species) is also a concern in otter trawl fisheries, particularly for sea turtles and juvenile finfish. Each otter trawl tailbag must be fitted with two bycatch reduction devices and a turtle excluder device. The Marine Fisheries Commission recognizes the importance of collaborating with the shrimp industry to identify and evaluate gear modifications that further reduce bycatch in this fishery. Additionally, the development of a comprehensive shrimp observer program has been identified as a key priority to better quantify bycatch by season, gear design, and area.
Other Gears
Gears other than skimmer and otter trawls include float nets, channel nets, butterfly nets, shrimp pounds, and shrimp pots. These gears are much less common when compared with skimmer and otter trawl gears. However, their use has increased in recent years, primarily in the area along the coast from Jacksonville to Wilmington.
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