How marine predators find food hot spots in open ocean 'deserts'

Published:19 Sep.2022 Source:ScienceDaily

A new study finds that marine predators, such as tunas, billfishes and sharks, aggregate in anticyclonic, clockwise-rotating ocean eddies (mobile, coherent bodies of water). As these anticyclonic eddies move throughout the open ocean, the study suggests that the predators are also moving with them, foraging on the high deep-ocean biomass contained within.We discovered that anticyclonic eddies -- rotating clockwise in the Northern Hemisphere -- were associated with increased pelagic predator catch compared with eddies rotating counter-clockwise and regions outside eddies. Increased predator abundance in these eddies is probably driven by predator selection for habitats hosting better feeding opportunities.

This discovery suggests a fundamental relationship between predator foraging opportunities and the underlying physics of the ocean. It findings highlight the connection between the surface and deep ocean, which must be considered in impact assessments of future deep-sea industries. As deep-sea prey fisheries continue to expand, there comes the need for more information on deep-sea ecology, particularly how much deep-prey biomass can be harvested by fisheries without negatively affecting dependent predators or the ocean's ability to store carbon and regulate the climate. A better understanding of the ecosystem services provided by the deep ocean via eddies, particularly with respect to predator fisheries, will help inform responsible use of deep-ocean resources.