A towed camera sled for estimating abundance of juvenile flatfishes and habitat characteristics: Comparison with beam trawls and divers

Abstract

An inexpensive towed video camera sled was developed to provide abundance estimates for juvenile flatfishes and other benthic taxa, and to characterize habitat features. The camera sled was compared with beam trawls and diver survey methods in Yaquina Bay, Oregon, and in bays of Kodiak Island, Alaska. In Yaquina Bay the camera sled with a tickler chain (to induce flatfish movement) yielded density estimates for juvenile flatfish (English sole, Pleuronectes vetulus) that were equivalent to those of the divers, but greater than with a 1 m beam trawl or the camera sled without a tickler chain. Crab ( Cancer magister) density estimates were similar between the divers and the camera sled (with or without the tickler chain), but were underestimated with the beam trawl. In Kodiak, densities of juvenile flatfish (northern rock sole, Lepidopsetta polyxystra) were similar between the camera sled with a tickler chain, divers, and a 2 m beam trawl. Density estimates from the camera sled were obtainable for flatfish as small as 20 mm. Habitat features, such as empty bivalve shells, were underestimated with the beam trawl compared with the divers and the camera sled. These results demonstrate the effectiveness of an inexpensive, simple to operate, towed camera sled in surveying abundance and habitat associations of juvenile flatfishes, crabs, and other taxa.