Use of stereo camera systems for assessment of rockfish abundance in untrawlable areas and for recording pollock behavior during midwater trawls

• Main Authors: Williams, Kresimir, Rooper, Christopher N., Towler, Rick
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2010
• Subjects: Biology; Ecology; Fisheries; Bering Sea; Alaska
• Online Access: http://hdl.handle.net/1834/25399

We describe the application of two types of stereo camerasystems in fisheries research, including the design, calibration, analysis techniques, and precision of the dataobtained with these systems. The first is a stereo video system deployed by using a quick-responding winch with alive feed to provide species- and size- composition data adequate to produce acoustically based biomass estimatesof rockfish. This system was tested on the eastern Bering Sea slope where rockfish were measured. Rockfish sizes were similar to those sampled with a bottom trawl and the relative error in multiple measurements of the same rockfish in multiple still-frame images was small. Measurement errors of up to 5.5% were found on a calibration target of known size. The second system consisted of a pair of still-image digital cameras mountedinside a midwater trawl. Processing of the stereo images allowed fish length, fish orientation in relation to the camera platform, and relative distance of the fish to the trawl netting to be determined. The video system was useful for surveying fish in Alaska, but it could also be usedbroadly in other situations where it is difficult to obtain species-composition or size-composition information.Likewise, the still-image system could be used for fisheries research to obtain data on size, position, andorientation of fish.