DeepVision in-trawl imaging: Sampling the water column in four dimensions

摘要

An in-trawl stereo camera system (DeepVision) collected continuous, overlapping, images of organisms ranging from krill and jellyfish to large teleost fishes, including saithe (Pollachius virens) and Atlantic cod (Gad us morhua) infected with parasitic copepods. The four-dimensional position (latitude, longitude, depth, time) of individuals was recorded as they passed the camera, providing a level of within-haul spatial resolution not available with standard trawl sampling. Most species were patchily distributed, both vertically and horizontally, and occasionally individuals were observed at significant vertical and horizontal separation from conspecifics. Acoustically visible layers extending off the continental rise at 250 m depth and greater were verified as primarily blue whiting (Micromesistius poutassou), but also included a small proportion of evenly distributed golden redfish (Sebastes marinus) and greater Argentines (Argentina silus). Small, but statistically significant, differences in length by depth were observed for blue whiting within a single haul. These results demonstrate the technology can greatly increase the amount and detail of information collected with little additional sampling effort