Comparison of a Remotely Operated Vehicle and a Submersible for Estimating Abundance of Demersal Shelf Rockfishes in the Eastern Gulf of Alaska

Abstract

A miniROVER MKI remotely operated vehicle (ROV) and the submersible Delta were compared for effectiveness in collecting abundance information on demersal shelf rockfishes, Sebastes spp., by means of strip transect sampling, in the eastern Gulf of Alaska. We attempted to run 18 transects with the submersible and 15 transects with the ROV. Seventeen submersible dives and seven ROV dives were completed; one submersible dive was aborted because of sea conditions, and eight ROV dives were aborted because of snags on bottom or other difficulties related to the rugged terrain. The ROV was effective only for covering transects in areas of low relief, such as soft bottom, cobble, and flat pavement. The ROV was not effective in high-relief, rocky areas typically inhabited by demersal shelf rockfishes. The submersible worked well in both low- and high-relief terrain. The submersible's utility for collecting information on demersal shelf rockfish abundance would be increased by using line transect rather than strip transect methods. We conclude that the miniROVER ROV is not useful for transects in high-relief habitats. However, given its lower cost, a ROV may be a preferred tool for surveys of organisms inhabiting soft- or flat-bottom areas.