Assessing the use of a camera system within an autonomous underwater vehicle for monitoring the distribution and density of sea scallops (Placopecten magellanicus) in the Mid Atlantic Bight
The views and opinions expressed or implied in this article are those of the author (or authors) and do not necessarily reflect the position of the National Marine Fisheries Service, NOAA. Abstract The sea scallop (Placopecten magellanicus) fishery in the Atlantic is assessed during annual surveys by using both dredging and surface deployed imaging techniques. In this pilot study in the Mid Atlantic Bight, we used an autonomous underwater vehicle (AUV) to photograph the seafloor and to evaluate its use for determining scallop density and size. During 22 surveys in 2011, 257 km of seafloor were photographed, resulting in over 203,000 color images. Using trained annotators and photogrammetric software, we determined scallop density and shell heights for 15,252 scallops. The inshore scallop grounds near Long Island (at depths <40 m) had a density of 0.077 scallops per m2, whereas the inshore grounds of the New York Bight had a density of 0.012 scallops per m2. Shell heights derived from images were found to agree well with measurements from scallops collected with a commercial dredge. We show that images obtained with an AUV can be used to reliably estimate both density and shell height consistent with direct sampling from the same area. Moreover, side scan sonar images obtained with an AUV can be used to detect dredge scars and, therefore, can provide a simultaneous, relative estimate of fishing effort in that area. AUVs provide a highly accurate suite of data for each survey site and therefore allow the design of experimental studies of fishing practices. The sea scallop (Placopecten magellanicus, Gmelin 1791) of the MidAtlantic Bight Atlantic fishery has been commercially active for over 100 years, and in recent years has consistently ranked in the top five most valuable domestic U.S. fisheries at around a half billion dollars (NMFS, 2009 2013) To promote the sustainability of the sea scallop fishery, the National Marine Fisheries Service (NMFS) monitors the fishery annual ly through a combination of survey approaches (Stokesbury et al. 2004; Kelly1; DuPaul and Rudders2; NEFSC3;