(ORDO NEWS) — Marine predatory fish in the nutrient-poor North Pacific congregate in anticyclonic currents, where most of the primary biomass is concentrated.
These new insights into the relationship between ocean physics and ecosystems will help shape more effective marine conservation strategies.
Scientists from the Woods Hole Oceanographic Institute and the University of Washington (USA) have shown that marine predators gather in anticyclonic ocean currents, directed clockwise in the Northern Hemisphere.
Researchers believe that predators move along with these warm currents to forage for food from the deep-sea biomass they contain.
The scientists analyzed data that commercial fishing companies had been collecting for 20 years, as well as satellite images of the North Pacific Current, one of the largest oceanic ecosystems, which is also poor in nutrients. The authors assessed how the species and number of predators differ in latitude and depth of the ocean.
It turned out that predatory fish that live in the water column, such as tuna, marlin and sharks, are much more common in warm anticyclonic currents than in cold cyclonic ones.
This is because such currents provide the fish with the best feeding opportunities. They contain more phytoplankton, with larger cells, hence their primary productivity is higher compared to cyclonic currents.
Although the effect of this difference on the productivity of intermediate trophic levels between phytoplankton and predators is unknown, it is very likely that it contributes.
Thus, anticyclonic currents act as a kind of mobile “hot spots” where predatory fish accumulate. This discovery points to a fundamental connection between marine ecosystems and ocean physics.
Scientists have long studied the behavior of marine predators by tagging individuals and modeling their movements, but the effect of currents on their behavior, especially in nutrient-deficient areas, has not been studied before.
The study will allow the development of more effective strategies for the conservation of marine fauna, as well as the promotion of effective fisheries management.
The fishing industry continues to expand every year, so there is a need for more information about the ecology of deep seas.
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