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Content archived on 2024-04-30

Reduction of adverse environmental impact of demersal trawls


The main objective is to asses methods to reduce the adverse impact of demersal trawls on benthic marine organisms through changes in net design and alternative methods of stimulation.

EU funded research has shown that commercial beam trawling has detrimental affects on the structure and composition of benthic communities in the North Sea, as does otter trawling for Nephrops in the Irish Sea. It appears that short-lived species are favoured while longer-lived species are more adversely affected, with the result that the disturbed communities may favour scavengers, and predators other than fishery target species. Reducing potential damage to longevous benthic invertebrates could result in more viable standing crops of prey for target species. This project seeks to find technical solutions whereby the adverse effects of demersal trawls on benthic organisms can be significantly lessened.

The work programme will therefore:

review alternative techniques that could reduce the adverse effects of demersal trawls on marine benthic organisms, and to identify, in co-operation with the fishing industry, those with most promise for further investigation.

investigate the practical feasibility of the identified alternative techniques with respect to the following criteria: reduction of fish/benthos by-catch, effectiveness, economy, and acceptability to the fishing /scientific community, and to refine selected alternatives, driven by the requirement that catch levels can be maintained with emergent new gear designs.

evaluate the impact of the modified gear by taking representative benthos samples prior to and after its passage along accurately demarcated transects. Results will be disseminated to the fishing industry and the scientific community, using appropriate paper documentation and a dedicated video / CD.

Modification to existing techniques and novel approaches will be explored both in liaison meetings with fisheries and scientific interests and in flume tank experiments, prior to a programme of planned sea trials. Approaches identified for study at this time (i.e. ahead of a planned review of this whole area of activity) include: changes in stimulation systems e.g. new chain arrangements, water jet injection and electrical stimulation, and changes in net design e.g. the incorporation of benthos release holes or separating panels. The practical feasibility of the most promising techniques (including considerations of equipment handling, durability and maintenance) will be investigated through sea trials. Effects on benthos mortality will be determined in the field by taking benthic samples before and after the passage of the gear. Recommendations will then be made on the most effective and acceptable solutions to these problems.

Call for proposal

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National University of Ireland, Galway
EU contribution
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University Road

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Participants (6)