Demersal trawl exclusion devices to eliminate bycatch of cetaceans and sharks in demersal fisheries

This solution is advanced by:

Bycatch of cetaceans and sharks remains a significant challenge in demersal trawl fisheries, particularly in pair trawling operations where interactions with common dolphins can occur. These interactions may result in injury or mortality of protected species and create operational challenges for the fishing sector.

The MarineGuardian demersal trawl exclusion devices aim to reduce and eliminate bycatch of cetaceans and sharks by integrating Cetacean Excluder Device (CED) into demersal trawl configurations, while maintaining effective fishing operations.

The challenge

Pair trawling in demersal fisheries can attract cetaceans such as common dolphins, increasing the risk of unintended capture. Once inside the trawl, cetaceans and sharks may be unable to escape standard gear configurations, leading to injury or mortality and raising conservation and compliance concerns.

Reducing bycatch in these fisheries requires specialised exclusion devices that can safely separate and release unwanted species without compromising target catches or fishing efficiency.

Common dolphin – Source: https://www.fisheries.noaa.gov/species/short-beaked-common-dolphin

The solution

This MarineGuardian solution focuses on testing Cetacean Excluder Device (CED) adapted to demersal pair trawl fisheries.

The devices are designed to:

  • Guide cetaceans and sharks towards escape openings
  • Allow safe separation and release of unwanted species during fishing operations
  • Maintain retention of target species

The solution combines gear design, operational testing and behavioural observation to optimise exclusion performance.

Cetacean excluder devices examples

Development and progress

The development of demersal trawl exclusion device follows a stepwise experimental approach:

  • Design and construction of a suitable CED prototype for the pair trawl fishery has started in the autumn 2025
  • At-sea testing is scheduled to start in the second part of 2026, onboard a research vessel
  • Sub-sea video monitoring will be used to assess device performance and evaluate the separation and release of cetaceans and sharks

Expected impact

The demersal trawl exclusion device is expected to contribute to:

  • Reduced bycatch and injury of cetaceans and sharks
  • Increase sustainability of demersal trawl fisheries
  • Improved coexistence between fisheries and marine wildlife