Estimating Abundance of Derelict Lobster Pots in New England Using Side-Scan Sonar
The NOAA Marine Debris Program partnered with the Massachusetts Division of Marine Fisheries to address challenges associated with identifying lost and abandoned lobster pots, and to improve derelict pot density and impact estimates in Massachusetts waters.
Type of Project: Fishing for Energy
Project Dates: December 2015 - November 2016
Who is involved?
This project was funded through the Fishing for Energy partnership between the NOAA Marine Debris Program, Covanta, and Schnitzer Steel Industries, and administered by the National Fish and Wildlife Foundation (NFWF). The Massachusetts Division of Marine Fisheries (MA DMF) evaluated the accuracy of side-scan sonar methods in detecting lost and abandoned lobster pots, and conducted a pilot density assessment to improve upon derelict pot density estimates.
What is the project and why is it important?
Derelict commercial and recreational fishing gear can have numerous ecological and economic impacts including damage to habitats, entanglement of marine species including seabirds and marine mammals, the creation of navigational hazards, and ghost fishing, which can result in lost catch opportunities and financial losses for fishers. In Massachusetts waters, the cost to replace lost pots is between $676,000 and $1,587,000 per year, and those lost pots are estimated to continue to catch and kill 3.6 lobsters per pot annually in Buzzards Bay and 4.8 lobsters per pot in Cape Cod.
To improve derelict pot density and impact assessments, the MA DMF evaluated the accuracy of side-scan sonar in identifying derelict lobster pots and conducted a pilot survey in Massachusetts Bay. To evaluate side-scan sonar techniques, lobster pots were set on both complex (rocky) and featureless (sandy/muddy) seafloor surfaces and then used to determine the associated detection rate using side-scan sonar methods. In addition, the MA DMF conducted a density survey using side-scan sonar in a section of Massachusetts Bay. The results of these surveys may enable the MA DMF to develop accurate derelict pot density estimates and to estimate the impacts of ghost fishing to both marine animals and the fishery, which sees economic impacts. These results may also inform stock assessments for affected species as well as encourage the lobster fishers to employ strategies to prevent pot loss or implement recovery programs.