Publication Abstract

Acoustic seabed classification: identifying fish and macro-epifaunal habitats

S.M. Freeman, M. Bergmann, H. Hinz, M.J. Kaiser, J. Bennell and S. I. Rogers

Increasing use of seabed resources and the effects of fishing on the seabed requires an urgent need to assess the extent and diversity of those habitats affected. Traditional techniques of site-specific sampling do not adequately map the extent of seabed habitats and prone to overlooking uncommon habitats. Assessing the utility of remote sampling techniques such as swath bathymetry and acoustic ground-discrimination systems is important because they provide a predictive basis for better-targeted benthic sampling. Acoustic surveys were conducted in conjunction with traditional biological sampling methods at eight study sites selected for differences in demersal fish abundance, in the Irish Sea. Using a 2-m and 3-m beam trawl, distinct fish and macro-epifaunal assemblages were identified. These were strongly associated with acoustically distinct habitats identified using QTC VIEW™. Sidescan images provided detailed information on surface texture and gross substrata types, whilst sediment samples were used effectively to ground-truth acoustically distinct habitats. An index of habitat complexity was correlated with acoustic data, which provided an effective assessment method for mapping the spatial extent of fish and macro-epibenthic habitats.

Reference:

S.M. Freeman, M. Bergmann, H. Hinz, M.J. Kaiser, J. Bennell and S. I. Rogers, 2002. Acoustic seabed classification: Identifying fish and macro-epifaunal habitats. ICES Copenhagen, CM2002: K:08, 28pp.