Recovering Lost Crab Pots of the Salish Sea

In the low light of the underwater environment, towering sea anemones sway in the currents and shrimp seek out the brightness of the ROV's subsea lights. In contrast to this beauty are the traces of human impact; from barren seafloor caused by siltation, to old plastic pipes sticking up haphazardly from the sediment, to lost fishing gear being pulled away from shore by the tides. Unintentionally adding to this marine debris is the crabbing industry, which is fundamentally ingrained in the culture of those who live on the Olympic Peninsula in Washington State. Derelict fishing gear, such as lost crab pots, continue to trap and kill marine life with no one to retrieve them  (Drinkwin, 2016, pp. 6–9) . The growing byproduct of recreational and commercial crabbing are lost, abandoned, and discarded crab pots, which present mounting concerns among fishermen, conservationists, and politicians alike.  Derelict crab pots left on the seafloor are responsible for the decline of marine biodiversity and negative economic impacts in many coastal communities.

It is estimated that over 12,000 crab pots are lost annually in Washington waters of the Salish Sea, killing nearly 180,000 legal-sized male Dungeness crabs (Cancer magister) each year ( Antonelis et al. 2011 ), among other species. Organizations such as the  Northwest Straits Foundation  are working to tackle this challenge on a large scale and have already removed thousands of crab pots. However the expensive nature of these recovery efforts makes it so that their work only covers high traffic areas which can leave out certain parts of the Puget Sound. This is why community-driven recovery methods can contribute towards solving this ocean conservation challenge. This StoryMap presents ongoing research using an alternative, low cost recovery method by implementing an underwater ROV (Remotely Operated Vehicle), Geographic Information System (GIS) mapping, and community partnerships to recover lost crab pots in coastal areas.

The Jefferson MRC is part of the Northwest Straits Marine Conservation Initiative (which includes NW Straits Commission, NW Straits Foundation, and seven local Marine Resources Committees) and serves as an advisory group to the Jefferson Board of County Commissioners. The MRC also engages in hands-on marine stewardship projects with community partners, such as the Sea Dragons, to restore and protect the marine and nearshore environments of East Jefferson County. 

The Sea Dragons, a student-run underwater robotics team, is based out of Port Townsend, Washington. Their work involves designing underwater ROVs that specialize in technology-based environmental solutions. Most recently, the Sea Dragons through Applied Education Foundation were awarded a  NOAA DEIA Ocean Exploration Education Grant  to engage more students on the Olympic Peninsula in local derelict crab pot recovery efforts. Together the Sea Dragons and Jefferson County MRC are tackling the common marine conservation issue of locating and recovering lost crab pots.

Thanks to services provided by Coastal Sensing and Survey, surveying was conducted in the research sites. As the sonar was towed behind the research vessel, it emitted pulses of sound that bounced back to a receiver. After processing this data through display software, the features below the sonar were mapped. Within the visual display, you can see where crab pots are located in real time based on their unique shape and size. The sonar allows each crab pot to receive a geolocation based on their latitude and longitude. 

It’s also interesting to note the similarities and differences between the state of both crab pots. The first trap recovered was resting on the ocean floor while still very intact, while the second was stuck in sediment and quite dilapidated. However, both pots had their rot cords degraded. While this should have theoretically freed all the crabs, the door on the sedimented crab pot was forcibly stuck shut, and so it remained a problem for crab populations until the ROV removed it.

Field work in an ocean environment is always tough and this research was no exception, with the team battling low tides and bad weather while having to troubleshoot a ROV leak aboard a rocking boat. Safety was always the priority, but it did lead to some disappointing moments - like when a located crab pot was left behind due to the threat of emerging white caps. Floating debris like seaweed and fishing line is always a concern, because when it gets caught in the thrusters it can slow down the operations by requiring someone to manually remove the blockage. Other notable limitations were from the summer algal blooms that reduced visibility, and the strong currents that at times overpowered the ROV. Currently the ROV is also restricted from reaching certain depths due to its tether length, although improvements are already in the works.

These challenges are typical of any ocean fieldwork and served as a necessary step in both the experimental and engineering process. The team was able to efficiently adapt while in the field and are better prepared for future obstacles. One initial problem encountered was that the compass was displaying the wrong directions due to interference from the ROV’s battery. After this issue was recognized, a new digital compass was installed so that the ROV could navigate effectively in the subsequent dives. The team also continuously upgraded their methodology throughout the project. Once the benefits of small boats were fully discovered, it instead became simpler and more successful for the ROV to dive down the anchor line of a more maneuverable vessel.

Ultimately the team persevered - piloting their ROV from a variety of watercrafts to cope with the demanding conditions. Beneath the waves revealed a serene world; one where sea anemones swayed in the currents, crabs scuttled through the murk, and dogfish cruised lazily by. In addition to the thrill of recovering lost crab pots, those who worked on the project came away awestruck by the beauty of our marine ecosystems. The videos and data collected through this work will continue to serve as educational tools to teach communities about the destructive impacts of lost crab pots while inspiring others to get involved in marine stewardship. 

This work is ongoing. The Sea Dragons and the Jefferson County MRC will continue working together to enhance the ROV’s capabilities for operating at even greater depths, removing pots in other locations across East Jefferson County, refining ROV survey methods for pots with unknown locations, and eventually, advising other communities with access to a robotics team and interest in adopting similar efforts. To get involved contact the  Jefferson County MRC .