Detection and characterisation of derelict creel fleets to evaluate marine megafauna entanglement risk in Scottish waters: CreelMap Final Project Report Scottish Marine Environmental Enhancement Fund (SMEEF) projects 502257 / 502492

Creel fisheries, using fleets of baited pots or ‘creels’ to catch Nephrops, lobsters and crabs, are an important component of the inshore, and to a lesser extent offshore, Scottish fishing sector.
Unfortunately, this fishery has also been implicated in accidental lethal entanglements of marine mammals and other megafauna, notably minke whales, humpback whales and basking sharks. It is not clear how much of this impact is caused by creel fishing gears (fleets) that are actively fishing and regularly tended, vs. fleets that have been lost due to storms or interactions with other fishers. Loss rates of creels are poorly characterised but anecdotal records suggest they may be considerable. Once fleets of creels are lost, there is little information about the entanglement risks they continue to pose (in addition to wider concerns about damage to sensitive habitats and chemical pollution as they slowly degrade). To address ongoing impacts of creel fisheries on species of conservation concern in Scotland, it is essential to understand the distribution and configuration of, and risks posed by, derelict
creel fleets. The CreelMap project sought to evaluate a combination of different towed side-scan sonar (SSS) systems and in-situ observations by Remotely Operated Vehicle (ROV) to assess whether these tools can efficiently detect and locate derelict creel fleets, an essential first step towards considering potential recovery. Several different kinds of SSS systems were tested by towing them behind the SAMS research vessel Seol Mara in inshore waters adjacent to the Scottish Association for Marine Science (SAMS) in western Scotland, between August 2023 – May 2024. A subset of likely survey targets was subsequently observed directly through deploying an ROV during December 2023 – June 2024, again from RV Seol Mara. Results revealed that SSS systems operating at frequencies ≥500 kHz) were able to reliably identify creels, and when operated at higher frequencies could discriminate groundlines.