Opportunistic Use of a Towed Stereo Video System

As part of a larger ongoing Atka mackerel mark-recapture study in the Central and Western Aleutian Islands, we deployed a stereo camera system to identify fish species and habitats in areas utilized by the endangered western Steller sea lion. Our camera was developed at the NOAA Alaska Fisheries Science Center using low cost GoPro cameras towed from a vessel-mounted winch. We were able to opportunistically sample locations near trawl hauls from a passively drifting fishing vessel. While this did not allow for a formal survey design, it did provide a platform to develop and test the camera system in the field; in addition, it provided preliminary data to develop analysis techniques in a remote area where dedicated research effort is often prohibitively costly. We analyzed video transects for benthic habitat characteristics as well as fish species composition and size frequency distribution. In addition, we described observed patterns of camera avoidance by Atka mackerel.  Our towed camera system has the potential to be applied in more rigorous surveys of Atka mackerel habitat, but more work to understand camera avoidance is needed.  We suggest that pre-existing platforms, when available, can be a relatively affordable tool in gear and methods development.