Crab pot clean up
Photos by Evan Krape | Video by Paul Puglisi and Ally Quinn March 18, 2020
UD, Delaware Sea Grant and DNREC lead clean-up of the Delaware Inland Bays
Delaware Sea Grant’s Kate Fleming and the University of Delaware’s Art Trembanis went out in Rehoboth Bay in 2019 with a side-scan sonar to conduct exploratory surveys in 100 acres of Rehoboth Bay to search for submerged derelict crab pots, or pots that have been lost or abandoned beneath the surface of the water.
They found 160 of these derelict crab pots, with over half of those found residing in Bay Cove, a section of the bay near Dewey Beach. These initial results showed that derelict crab pots posed a problem for the Delaware Inland Bays.
In 2020, Fleming, Trembanis and their team were able to do a more intense study and clean-up of the area. This activity was funded and coordinated by the Delaware Department of Natural Resources and Environmental Control (DNREC), which has an active community-based removal grant with the National Oceanic and Atmospheric Administration (NOAA) Marine Debris Program.
In January, representatives from UD, Delaware Sea Grant and DNREC spent time on the water locating and removing 114 derelict crab pots from Bay Cove and Love Creek.
“The clean-up effort went really well, and I’m pleased with the outcome,” said Fleming, a coastal ecology specialist for Delaware Sea Grant. “It was a huge coordinated effort. It went smoothly, and we were able to not only get pots up but learn something about their potential impacts, too.”
Crab pots become derelict for a variety of reasons. Boats run over crab pot lines, severing the pots from their marker buoys. Pots can be lost during storms. Improper rigging or using lines that have been degraded can increase line breakage rates. There is also some abandonment, where people don’t come back to their pots after they’ve been set.
Delaware’s Inland Bays permit only recreational crabbing — with the exception of one spot in Little Assawoman Bay — and the crab pot season runs from March 1 to Nov. 30. During the season, DNREC Enforcement officials do a significant amount of work to minimize pots from becoming derelict, but there are inevitably pots that get separated from their marker buoys.
These lost pots pose a variety of problems for an area. They can cause damage to boat propellers and they have the potential to “ghost fish,” trapping sea creatures that die and re-bait the pots.
“When harvestable crabs are caught by derelict pots, it can result in lost catch opportunities,” said Christy Kehoe, the Mid-Atlantic regional coordinator for the NOAA Marine Debris Program. “Recovering derelict crab pots and other debris from this area can help to reduce the mortality of crabs, fish, and other species inadvertently trapped in derelict pots.”
Pinpointing crab pots
In December 2019, Trembanis, associate professor in UD’s College of Earth, Ocean and Environment (CEOE), and members of the Coastal Sediments Hydrodynamics and Engineering Lab (CSHEL) used side scan sonar to identify 322 derelict crab pots in Bay Cove and 169 pots in Love Creek.
“The numbers were frightening when we went out almost a year ago last February, and it became more so when we did the fuller surveys in December,” said Trembanis.
Kari St. Laurent, a research coordinator and environmental scientist with Delaware Coastal Programs who participated in the crab pot removal and served as the grant manager for the project, said the numbers show that crab pots are a significant problem for the Delaware Inland Bays.
“I think this whole project has confirmed that there really are a substantial amount of derelict crab pots out there,” said St. Laurent. “To me, that shows it’s a pretty ubiquitous and consistent problem that’s being experienced in that ecosystem.”
Once the CSHEL lab identified the pot locations, Hunter Tipton, a Master’s level student in CEOE and a member of the CSHEL lab, uploaded those waypoints onto the side-scan sonars of the boats participating in the January clean up, allowing the crews to use those points to locate the crab pots in the bay.
Crab pot clean up
The clean-up took place over three days, with two of the days focused on Bay Cove and one focused on Love Creek. On the day with the most participants, there were six boats out on the water including the DNREC enforcement boat helping to transfer pots to and from shore. The crew was also joined by David Beebe, a local oysterman who provided the use of a hose on board his boat, and Rich King of Delaware-Surf-Fishing.com.
Because the bay is so shallow, when the boats got close to a waypoint location, crew members were able to throw grappling hooks or use boat hooks to manually haul the pots on to their boats where they were cleaned and recorded.
Getting the pots onto the boats was not always easy, as the pots were heavy and sometimes filled with sediment.
Once on board, participants recorded information such as the pots’ weight, the pot type, pot material, whether the pot had a bycatch reduction device attached and the condition of the pot, among other information.
To learn about the potential species that can be captured and killed in the pots, they also documented pots that were ghost fishing and what deceased animals they found inside, including blue crabs, remnants of diamondback terrapins and dead oyster toadfish.
The team found about 20 pots in good enough condition that they are going to use them in future outreach and education programming.
They also tested different methods of collecting pots to see what worked best. For instance, the DNREC enforcement boat without side-scan sonar worked alongside a boat equipped with side-scan sonar. The boat with the sonar went in front and marked the pots with the enforcement boat trailing behind and collecting the pots.
Fleming said that it was great to be able to test out methods on the water and get people experienced in the process of pulling pots.
“Now that we have a group of people that have gone through this process, we are better positioned to attempt to leverage the assistance of the public in a way that is safe and controlled and helpful,” said Fleming.
Fleming, Trembanis and other researchers have conducted a post survey of Bay Cove to see what the area looks like now that they’ve removed a significant number of crab pots and are still analyzing the results.
They are also hoping to leverage the information they’ve collected to develop outreach and education materials about the ways the public can minimize pot loss as well as the environmental impacts of lost pots.
Because the Delaware Inland Bays mostly only allow for recreational fishing, Fleming said recreational boaters and crabbers are the targeted audiences for outreach and education, and there may be opportunities to leverage support from these groups.
“With funding, we’d like to do more removal work in the inland bays in future years, and we’d like to rally the assistance of the recreational fishing and boating community to do it,” said Fleming.