Monitoring the generation and evolution of the sediment plume behind towed fishing gears using a multibeam echosounder

Abstract

O'Neill, F. G., Simmons, S. M., Parsons, D. R., Best, J. L., Copland, P. J., Armstrong, F., Breen, M., and Summerbell, K. 2013. Monitoring the generation and evolution of the sediment plume behind towed fishing gears using a multibeam echosounder. - ICES Journal of Marine Science, 70: 892-903.We compare optical and acoustic-based measurements of sediment concentration in plumes behind the otter door of a demersal trawl and behind the roller clump of a demersal twin trawl. Measurements were made using a LISST 100X and a RESON 7125 multibeam echosounder (MBES), and we demonstrate how the MBES can be used to reliably monitor and quantify the evolution of sediment plumes in the wake of towed demersal fishing gears. The MBES data detail the spatial and temporal decay of the plume size and the concentration behind the gear and also reveal significant differences in the behaviour of plumes in the wake of different fishing gear components. The results highlight the importance of being able to measure and understand the processes at work at the level of the individual gear components and also detail the range of conditions over which an acoustic-based MBES technique can be applied to monitor such dynamics and to assess the impact of fishing on the seabed and on the marine environment. © 2013 International Council for the Exploration of the Sea.