Ghost fishing gear, including lost and abandoned lobster traps, poses a serious challenge along the coast of Maine. These traps can scour and damage the seabed, become tangled with active fishing equipment, and continue catching lobster and other species long after they are lost, thereby reducing the number of lobsters available to harvest. Maine is the centre of the U.S. lobster industry, landing more than 80% of all American lobster. This represents close to 50 million kg a year and about US$500 million in dockside value. With almost 3 million trap tags issued annually, even a conservative estimate of 5% gear loss means that tens of thousands of traps are lost each year. Gear is lost for many reasons including vessel interactions, severe weather, strong currents, gear entanglement, vandalism, and the abandonment of end-of-life equipment.
Because retrieval efforts are led primarily by non-profit organisations with finite funding, it is essential that their time on the water is spent as efficiently as possible. Retrieval teams usually rely on reports from lobstermen and make exploratory passes with recreational fish-finder sonar in locations where lost traps are suspected. Divers must then locate traps in limited visibility before attaching a recovery line so the gear can be hauled to the surface.
New Tools for Improved Efficiency
To support more efficient and targeted recovery efforts, the General Oceans Foundation set out to test whether side-scan sonar could be used to detect and map ghost lobster traps across larger areas of the seafloor. Unlike fish-finder sonar, side-scan sonar can produce detailed seafloor imagery over a far wider search range.
For this pilot project, we partnered with Klein Marine Systems, a pioneer in side-scan sonar technology since the 1960s and now part of the General Oceans Group, who supplied the sonar system for the trials. Our field team included volunteer sonar specialist Vince Capone, who led the technical operations, and OceansWide, a Maine based organisation focused on the recovery and disposal of abandoned or discarded fishing gear.
The Autumn 2025 Pilot Survey
During Autumn 2025, the team spent several days surveying waters around Boothbay Harbor. We tested Klein’s 4900 side-scan sonar at different frequencies, ranges, depths, and over a variety of substrate types including mud, sand, and rock.
What We Found
These findings show that side-scan sonar can help retrieval teams work more efficiently. With clear maps highlighting where ghost gear has accumulated, divers can go straight to the hotspots, retrieve more traps at once, and avoid the time-consuming process of searching without direction.
Looking Ahead
Following the success of this pilot study, the Foundation is preparing for more extensive surveys in Spring 2026. We are also exploring ways to make data processing and interpretation more efficient, including the potential use of artificial intelligence to scan sonar imagery and highlight objects that may be lost traps. In parallel, we are investigating technological solutions that could further improve retrieval operations, particularly in areas that are difficult or unsafe for divers to access.
By combining proven marine technology with the expertise of local partners, we are working to reduce ghost gear, protect marine habitats, and support the long-term sustainability of Maine’s iconic lobster fishery.
Image: 1. Deploying the side-scan sonar from the boat. 2. Hauling up an abandoned lobster trap. 3. A juvenile lobster in a ghost trap. 4. The OceansWide team carrying ghost traps ashore for responsible disposal. 5. Side-scan sonar image showing a shipwreck surrounded by ghost lobster traps. 6. Sonar image showing active traps connected by a rope, surrounded by ghost traps.