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Ninety-five per cent of world's fish hide in mesopelagic zone

Ninety-five per cent of world's fish hide in mesopelagic zone

March 5, 2014 - An international team of marine biologists has found mesopelagic fish in the earth's oceans constitute 10 to 30 times more biomass than previously thought.

UWA Professor Carlos Duarte says mesopelagic fish – fish that live between 100 and 1000m below the surface – must therefore constitute 95 per cent of the world's fish biomass.

"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.

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.

He says most mesopelagic species tend to feed near the surface at night, and move to deeper layers in the daytime to avoid birds.

They have large eyes to see in the dim light, and also enhanced pressure-sensitivity.

"They are able to detect nets from at least five metres and avoid them," he says.

"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.

"So instead of different nets what we used were acoustics … sonar and echo sounders."

The findings have significant implications.

Sources and more information:

Fish in the Twilight Cast Light on Ocean Ecosystem

By Guest , March 4, 2014 Fish in the Twilight Cast New Light on Ocean Ecosystem Lantern Fish (Photo: Joan Costa CSIC) New research, published this week in Nature Communications ( Irigoien et al. 2014 ), shows that the fish biomass in the global ocean has been largely underestimated, by at least 10 times and most likely 30 times.

Scientists find deep sea fish make up 95% of all fish biomass in the world

comments Scientists have vastly underestimated the number of fish in the sea - and say the majority of them have never been fished. Australian researchers found that mesopelagic fish, which live between 100 and 1000m below the surface, constitute 95 per cent of the world's fish biomass and are untouched by fishing.

OPINION: Fish in the twilight cast new light on ocean ecosystem

( via phys.org )


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