A new scientific field trial is underway off the coast of Alicante, Spain, to evaluate an enhanced fishing technology that could help reduce the environmental footprint of bottom trawl fisheries while sustaining the catch performance that commercial fishers rely on.

The project will evaluate the performance of semi-pelagic trawl doors compared with conventional trawl doors. Designed to operate slightly above the seabed, semi-pelagic doors – also known as flying doors – have the potential to reduce direct contact with the seafloor and limit sediment disturbance while maintaining the horizontal opening and stability required for efficient fishing operations.

This collaborative initiative brings together the General Secretariat for Fisheries of the Ministry of Agriculture, Fisheries and Food of Spain and the General Fisheries Commission for the Mediterranean (GFCM) of the Food and Agriculture Organization of the United Nations (FAO), with the participation of the Spanish Institute of Oceanography, which is leading the field activities.

©Ministry of Agriculture, Fisheries and Food of Spain on the left; ©IEO-CSIC on the right

A step towards sustainable trawling

To avoid potential discrepancies associated with comparing different vessels, a single commercial bottom trawl vessel is being used throughout the trial, first operating with semi-pelagic doors and then with conventional doors. Conducting both phases in immediate succession and in the same fishing grounds minimizes the effects of seasonal, environmental and spatial variability, ensuring a robust comparison between the two gear configurations.

The trial is particularly relevant to Mediterranean bottom trawl fisheries targeting commercially important species such as deep-water rose shrimp (Parapenaeus longirostris), European hake (Merluccius merluccius), red mullet (Mullus barbatus), broadtail shortfin squid (Illex coindetii), blue and red shrimp (Aristeus antennatus), Atlantic horse mackerel (Trachurus trachurus), mantis shrimp (Squilla mantis) and common pandora (Pagellus erythrinus).

“During the fishing operations, researchers will assess catch rates, catch composition, gear geometry, trawl door behaviour and operational efficiency. The objective is to determine whether semi-pelagic doors can reduce environmental impacts without compromising fishing performance or the practicality of day-to-day commercial operations”, explained Sergi Tudela, Fishery Officer and Coordinator of the GFCM Western Mediterranean Technical Unit.

The fisheries and oceanographic research vessel Emma Bardán, operated by the Spanish General Secretariat for Fisheries, plays a key role in the trial. The vessel will produce high-resolution maps of the seabed before and after trawling with both door types, providing a direct comparison of their effects on the marine environment. It will also monitor water clarity during fishing operations to assess how much sediment is disturbed by each type of trawl door.

The project is carried out under the GFCM MedSea4Fish programme and directly contributes to the implementation of the GFCM 2030 Strategy by providing scientific evidence to support the adoption of lower-impact fishing technologies. Its findings will help inform future fisheries management decisions aimed at balancing healthy marine ecosystems with productive and resilient fisheries across the Mediterranean.

Cover photo: ©Ministry of Agriculture, Fisheries and Food of Spain