Researchers recently found out that the mesopelagic fish's biomass is 10 times more than what they previously thought.
The Malaspina Expedition, led by Carlos Duarte from the University of Australia Oceans Institute, travelled 32,000 miles to look closer into the life beneath the ocean waves. The team took readings between 40 degrees north and 40 degrees south, and a depth measurement of 200 to 1,000 meters.
Mesopelagic fish are those who thrive in the twilight zone of the ocean, which is between 650 and 350 feet under the surface of the waters. Mesopelagic fish accounts for the biggest number of vertebrates in the biosphere and their biomass was estimated to measure up to one billion tons before Duarte performed his research. Examples of mesopelagic fish include lantern fish and cyclothonids.
The researchers found out that mesopelagic fish can avoid nets used for trawling.Trawling has been the predominant method in counting the population of the fish andthis ability may have been the reason why previous population estimates for the mesopelagic fish have been too low.
"Malaspina has provided us the unique opportunity to assess the stock of mesopelagic fish in the ocean. Until now we only had the data provided by trawling. It has recently been discovered that these fishes are able to detect the nets and run, which turns trawling into a biased tool when it comes to count its biomass." Duarte said in a press release.
The study also discovered that during the night, mesopelagic fish stay in the upper layers of the water to feed themselves and when the day comes, they'll swim deeper into the ocean to avoid their predators. This practice allows the fish to transport carbon in the form of their feces, half a mile under the surface waters, a distance which is farther than what scientists have previously believed.
The role of the fish in the carbon cycle for ocean ecosystems is an important one, for they will help maintaining the balance between predators and planktons. The fish is also responsible for consuming huge amounts of oxygen in the deeper layers of the water.
The study was published in the Feb. 7 issue of Nature Communications.
