Groundtmthing Multibeam Bathymetric Surveys of Finfish Aquaculture Sites in the Bay d’Espoir Estuarine Fjord, Newfoundland

Abstract

Current and potential salmonid aquaculture sites in the Bay d’Espoir estuarine fjord on the south coast of Newfoundland were surveyed using multibeam SWATH sonar. In 1997, shallow sites were surveyed using the CSS Puffin EM3000POS/MV system, and deeper sites were surveyed in 1998 using the CCGS Creed hull mounted EM 1000. Sediment cores from representative areas were collected during this period and analyzed for organic matter content, and pore water ammonium and sulfate. We discuss the correlation between the sediment core profiles and the results of the side scan and sun-illuminated bathymetric imagery. Bay d’Espoir is a natural depositional area, and that, coupled with the unique backscatter properties of fish farm wastes, increases the difficulty of interpreting these multibeam sonar images. A fairly accurate broad scale characterization of sediment quality can be made from high-resolution images. However’, much of the fine scale detail and inherent variation of sediment characteristics associated with impacts from aquaculture cannot be determined from multibeam imagery.