Ocean eddies help marine predators find food

A new study published in the journal Nature describes how marine predators utilize anticyclonic (clockwise-rotating) ocean eddies to obtain food. The research suggests that marine predators follow anticyclonic eddies as they move throughout the open ocean – in pursuit of the biomass they contain. 

Study lead author Dr. Martin Arostegui is a postdoctoral scholar at the Woods Hole Oceanographic Institution and the University of Washington Applied Physics Laboratory.

“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,” explained Dr. Arostegui. “Increased predator abundance in these eddies is probably driven by predator selection for habitats hosting better feeding opportunities.”

The study’s data consisted of over 20 years of commercial fishery information and satellite data from the North Pacific Subtropical Gyre. This nutrient-poor region sustains marine predators that are important to the Pacific Island nations.

The scientists studied marine predators in various latitudes and depths, including an ecologically diverse sample of warm and cold-blooded fishes. The team concluded that the anticyclonic eddies have an expansive effect on the food chain, from top to bottom. 

“The idea that these eddies contain more food means they’re serving as mobile hotspots in the ocean desert that predators encounter, target and stay in to feed,” said Dr. Arostegui.

The study also highlights the interconnectedness between the surface and deep ocean, which is essential to consider when contemplating deep sea fishery management. Knowing more about deep sea prey fisheries and the ecosystem benefits of deep ocean eddies will help managers make more informed decisions.

“The ocean benefits predators, which then benefit humans as a food source,” said Dr. Arostegui. “Harvesting the food that our food eats, is something we need to understand in order to ensure the methods are sustainable for both the prey and the predators that rely on them. That is critical to ensuring both ocean health and human wellbeing as we continue to rely on these animals for food.”

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By Erin Moody , Earth.com Staff Writer