![]() "This very large stock of fish that we have just discovered, that holds 95 per cent of all the fish biomass in the world, is untouched by fishers," he says. He says the survey also showed the oceans were healthier than previously thought. "The food web … in the central gyres of the ocean … it's a lot more efficient than we thought." "The largest fish stock in the ocean is not in the coastal areas … but actually in the central gyres of the oceans. "They are not desert at all, they are very vibrant ecosystems that support a very high biomass. "We actually called them oceanic deserts," he says. Prof Duarte says research into the five ocean gyres, where vast amounts of flotsam collect, turned up surprising results. The sheer amount of biomass means they may respire about 10 per cent of primary production in deep waters. The findings have significant implications. "So instead of different nets what we used were acoustics … sonar and echo sounders." "Because the fish are very skilled at avoiding nets, every previous attempt to quantify them in terms of biomass that fishing nets have delivered are very low estimates. "They are able to detect nets from at least five metres and avoid them," he says. They have large eyes to see in the dim light, and also enhanced pressure-sensitivity. He says most mesopelagic species tend to feed near the surface at night, and move to deeper layers in the daytime to avoid birds. Prof Duarte led a seven-month circumnavigation of the globe in the Spanish research vessel Hesperides, with a team of scientists collecting echo-soundings of mesopelagic fish. "Because the stock is much larger it means this layer must play a more significant role in the functioning of the ocean and affecting the flow of carbon and oxygen in the ocean," he says. UWA Professor Carlos Duarte says mesopelagic fish – fish that live between 1m below the surface – must therefore constitute 95 per cent of the world's fish biomass.
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