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

Mar 03, 2014 by Geoff Vivian
Most mesopelagic species tend to feed near the surface at night, and move to deeper layers in the daytime to avoid birds. Pictured:The mesopelagic ‘ocean sunfish’ (Mola mola). Credit: Chris Zielecki

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 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 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.

The sheer amount of biomass means they may respire about 10 per cent of primary production in deep waters.

Prof Duarte says research into the five ocean gyres, where vast amounts of flotsam collect, turned up surprising results.

"We actually called them oceanic deserts," he says.

"They are not desert at all, they are very vibrant ecosystems that support a very high .

"The largest fish stock in the ocean is not in the coastal areas … but actually in the central gyres of the oceans.

"The food web … in the central gyres of the ocean … it's a lot more efficient than we thought."

He says the survey also showed the oceans were healthier than previously thought.

"This very large stock of fish that we have just discovered, that holds 95 per cent of all the in the world, is untouched by fishers," he says.

"They can't harvest them with nets.

"In the 21st Century we have still a pristine stock of fish which happens to be 95 per cent of all the in oceans.

"And that also changes our views on ocean health."

Explore further: Fish biomass in the ocean is ten times higher than estimated

More information: "Large mesopelagic fishes biomass and trophic efficiency in the open ocean." Irigoien X, et al. Nat Commun. 2014 Feb 10;5:3271. DOI: 10.1038/ncomms4271.

add to favorites email to friend print save as pdf

Related Stories

Ocean health in 'downward spiral'

Oct 04, 2013

The health of the ocean is spiralling downwards far more rapidly than previously thought, according to a new review of marine science.

Ocean acidification leaving fish in the dark

Jan 30, 2014

Increasing carbon dioxide in the world's oceans could hamper fishes' eyesight, slowing their reaction times and leaving them vulnerable to predators or unable to hunt, new research has shown.

Recommended for you

Study finds tropical fish moving into temperate waters

Dec 19, 2014

Tropical herbivorous fish are beginning to expand their range into temperate waters – likely as a result of climate change – and a new international study documents the dramatic impact of the intrusion ...

User comments : 12

Adjust slider to filter visible comments by rank

Display comments: newest first

Squirrel
5 / 5 (1) Mar 03, 2014
The article in the above link is not paywalled but open access.
_ilbud
2.3 / 5 (3) Mar 03, 2014
Lets go get 'em
StillWind
1.4 / 5 (10) Mar 03, 2014
Another slap in the face of the environmentalist wackos who have been screaming that the oceans are over fished.
KBK
2 / 5 (5) Mar 03, 2014
95% untouched, yes....except for this recent radiation issue...........

Which may eventually be shown to have wreaked extreme havoc.

Then we have the thorny issue of oxygenation of those depths. What happens when the upper layer is being messed with -as it is now?
Howhot
2 / 5 (4) Mar 04, 2014
Lets go get 'em

Drill baby! Drill!

Uh wait, wrong story.

verkle
not rated yet Mar 04, 2014
According to my dictionary the mesopelagic region is from 180 to 900 meters under sea level. When did it change to 100-1000 meters?

I wonder if these fish are edible and delicious?

dedereu
1 / 5 (2) Mar 04, 2014
Looking to the spanish financing, clearly I suspect pure spanish fishing lobbying !!
When there will be no more fishes catched, they will say : "the fish are perfectly skilled at avoiding nets ..... they are able to detect nets from at least five hundert metres and avoid them..... they have large eyes to see the nets in the dim light...."
Incredible efficient lobbying on the journal Nature !!
It is lobbying as efficient as for, tabacoo, asbestos, and for genetically modified food asking for tests on more than 10 mouses (50 necessary), but never asking for tests on more than 3 months, i.e. on several lifes of mouses, because the origin of illness and cancers are nearly impossible to prove over more than 3 months. Humans are better guinea pigs than mouses.
Modernmystic
3.4 / 5 (5) Mar 04, 2014
Looking to the spanish financing, clearly I suspect pure spanish fishing lobbying !!
When there will be no more fishes catched, they will say : "the fish are perfectly skilled at avoiding nets ..... they are able to detect nets from at least five hundert metres and avoid them..... they have large eyes to see the nets in the dim light...."
Incredible efficient lobbying on the journal Nature !!
It is lobbying as efficient as for, tabacoo, asbestos, and for genetically modified food asking for tests on more than 10 mouses (50 necessary), but never asking for tests on more than 3 months, i.e. on several lifes of mouses, because the origin of illness and cancers are nearly impossible to prove over more than 3 months. Humans are better guinea pigs than mouses.


So when a piece of science doesn't fit your worldview you cry foul? It's eviiil lobbyists eh? I hear this all the time from AWG deniers except it's eviiiil bureaucrats....
dedereu
not rated yet Mar 04, 2014
Yes, not eviiiil, who pays or gives the money is essential for the results often !!
When you loose your position and financing, if your results are too disturbing, very often you distort or not investigate.
Mesopelagic fish are small fishes typically 6cm, never harvested with nets and it is remarquable that this is not written in the title, allowing, by confusion, for too fast readers, to think that there is 10 times more bigger fishes than it is actually said or fished, lobbying to supress restrictions on fishing !!
These results are based on models of scatering of ultra-sounds waves by theses small fishes, and a lot of modeling, but never direct counting billions of theses small fishes, because theses skilled fishes escape fishing nets !!.
Theses small fishes are ten times more skilled to escape than the big fishes, overfished and disappearing.
Even if true, this implies ten time more transport of organic carbon to the ocean floors and quite faster shale gas and oil formation.
El_Nose
not rated yet Mar 08, 2014
wait wait wait ...

There is just cause to continue restricting fisheries from over fishing the coastal zones. Just because we MAY have found another source of fish does not mean we were wrong to protect the fish that are easiest to catch.

Furthermore its going to take time to figure out how to catch these fish that were just found to exist... we have been fishing for a few millennia and just in the last few months determined we missed these fish even though we have been looking at this layer specifically for the last century.

Even if we figure out a better way to catch these fish, you will need to establish new markets for them... people are fimiliar with whiting and salmon and amberjack and talapia, but restaurants may not be willing to buy loosejaws, daggertooth, and lancefish if customers don;t recognize them and there is no demand.
Returners
not rated yet Mar 08, 2014
people are fimiliar with whiting and salmon and amberjack and talapia, but restaurants may not be willing to buy loosejaws, daggertooth, and lancefish if customers don;t recognize them and there is no demand.


Super Markets would just do taste testing, like they used to do in the 80's, and restaurants can offer them initially as appetizers or minor component in combination seafood platters.

Humans eat just about anything that doesn't kill us first, so I see no reason the "new" fishes wouldn't become popular dishes.
kienhoa68
not rated yet Mar 10, 2014
Now no fish is safe. I'm certain we'll find a way to harvest any fish we can find. We may have to depend on rapidly reproducing small species that will spend less time exposed to pollution.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.