BIM has combined resources to fast-track fishing gear development using side-scan sonar to create an enhanced image of the seabed. Photo: BIM
Among the key challenges facing Irish fisheries are the need to: reduce unwanted catches to meet the requirements of the EU landing obligation; and reduce the impacts of bottom trawling to improve protection of biodiversity, marine habitats and carbon stores.
These challenges are driving research in to novel gear modifications that require rapid development and assessment.
Historically, fishing gear has been developed by trial and error which takes time and has a financial cost. Scale models of trawls may be deployed in specialised flume tanks to study the effects of modifications in a simulated environment and while this is an efficient means of gear development there is considerable expense involved.
Side-scan sonar is typically used to create an image of the seabed for detection, identification and mapping of underwater objects and bottom features. BIM use side-scan sonar to search for seed mussel during the annual seed mussel survey and other aquaculture and inshore research. The aim of the recent trial in the Irish Sea off Skerries was to demonstrate that BIM’s side-scan sonar technology and expertise could be put to good use visualising and assessing fishing gear modifications.
The study was facilitated on board BIM’s research vessel T Burke 2 by Nicolas Chopin (side-scan sonar expert) and John Murphy (Skipper) and on board the fishing vessel Ocean Breeze by Ciaran Powell (Skipper). Matthew McHugh and Martin Oliver provided technical support and flew drones to capture some wonderful aerial images. Thanks to the close collaboration of all involved we managed to achieve our aim as well as develop some new gear modifications to reduce unwanted fish catches in Nephrops (langoustine) trawls. Further work is needed to quantify differences in catches using the new gear modification and to achieve more consistent side-scan sonar imagery. The results of this study suggest that the technology could be further used in the development of modifications to reduce seabed impacts by for example reducing the bottom contact of trawls.
This project was supported under the European Maritime Fisheries Fund
The report is available to read here