Predator-guided sampling reveals biotic structure in the bathypelagic

We targeted habitat used differentially by deep-diving, air-breathing predators to empirically sample their prey’s distributions off southern California. Fine-scale measurements of the spatial variability of potential prey animals from the surface to 1200 m were obtained using conventional fisheries echosounders aboard a surface ship and uniquely integrated into a deep-diving autonomous vehicle. Significant spatial variability in the size, composition, total biomass, and spatial organization of biota was evident over all spatial scales examined and was consistent with the general distribution patterns of foraging Cuvier’s beaked whales (Ziphius cavirostris) observed in separate studies. Striking differences were found in prey characteristics between regions at depth, however, did not reflect differences observed in surface layers. These differences in deep pelagic structure horizontally and relative to surface structure, absent clear physical differences, change our long-held views of t...