عربي English Türkçe اردو فارسى
Logo
Latest News
Varieties

Freshwater Fish Can Do Math, New Study Suggests

A researcher from University of California, Davis catches hatchery salmon from a tank to measure their size, as part of a joint project between ecologists and rice farmers trying to reclaim the great flood plains of the Sacramento River for salmon habitat, in Robbins, California, US, February 4, 2022. REUTERS/Carlos Barria
A researcher from University of California, Davis catches hatchery salmon from a tank to measure their size, as part of a joint project between ecologists and rice farmers trying to reclaim the great flood plains of the Sacramento River for salmon habitat, in Robbins, California, US, February 4, 2022. REUTERS/Carlos Barria
TT
20
TT

Freshwater Fish Can Do Math, New Study Suggests

A researcher from University of California, Davis catches hatchery salmon from a tank to measure their size, as part of a joint project between ecologists and rice farmers trying to reclaim the great flood plains of the Sacramento River for salmon habitat, in Robbins, California, US, February 4, 2022. REUTERS/Carlos Barria
A researcher from University of California, Davis catches hatchery salmon from a tank to measure their size, as part of a joint project between ecologists and rice farmers trying to reclaim the great flood plains of the Sacramento River for salmon habitat, in Robbins, California, US, February 4, 2022. REUTERS/Carlos Barria

Some primates, bees, birds, and now freshwater fish: the circle of animals with mathematical skills is widening. A recent study has found that some types of fish have mathematical abilities such as addition.

It’s scientifically proven that all vertebrates, and even some invertebrates have the ability to measure quantities- a vital function creatures need when searching for food, avoiding predators, moving in group, and mating.

But scientists are now investigating how these creatures can quantify: is it a simple estimate based of the object’s size, or they are actually able of doing accurate math? Former studies showed that some monkeys, parrots, pigeons, spiders, and bees are capable of processing numerical information, and even performing simple mathematical functions.

A recent study at the University of Bonn’s Institute of Zoology revealed that some types of fish such as cichlids, stingrays, and zebra mbuna have some math skills. The findings were published in the journal Scientific Reports.

Eight fish of each type underwent hundreds of tests in large tanks specially designed to monitor their performance. In the tanks, the fish were trained to associate the blue color with addition (+1), and the yellow color with subtraction (-1).

Then, the scientists spread cards featuring blue and yellow shapes, and made the fish choose from two sliding doors each featuring a card with different number of shapes; one of the two doors has the correct answer.

For instance, when a fish sees a card with three blue shapes, it is supposed to swim towards the door with the card featuring four blue shapes as blue refers to addition. On the contrary, if the fish sees a card featuring four yellow shapes, it should head towards the door with the card featuring three yellow shapes, one shape lesser than the original card, as yellow refers to subtraction.

When the fish passed through the correct door, it was rewarded with its favorite food. The study showed that six of the mbuna fish and four stingrays successfully linked blue to (+1), and yellow to (-1).

According to researchers, the mbuna fish needed more time to select the door, and mbunas and stingrays remembered addition more easily than subtraction.

The researchers said their work unveils new cognitive abilities that could help mbunas and stingrays recognize other fishes from the same species based on their appearance, by counting the lines or spots on their bodies.

Most Viewed

 
Varieties

Ethiopia's Vast Lake Being Pumped Dry

Lake Dembel's depth has halved since 1990 due to over-pumping. Marco Simoncelli / AFP
Lake Dembel's depth has halved since 1990 due to over-pumping. Marco Simoncelli / AFP
TT
20
TT

Ethiopia's Vast Lake Being Pumped Dry

Lake Dembel's depth has halved since 1990 due to over-pumping. Marco Simoncelli / AFP
Lake Dembel's depth has halved since 1990 due to over-pumping. Marco Simoncelli / AFP

There is a constant hum around Ethiopia's enormous Lake Dembel -- the sound of its water steadily being sucked out by pumps.

The pumps irrigate farms all around the lake, which is four times the size of Manhattan, and are vital for hundreds of thousands of people, AFP said.

Ethiopia has already lost at least one large lake -- Haramaya, in the east of the country -- to over-pumping.

Now it risks losing another.

Lake Dembel's depth has halved since 1990 from four meters to two (13 feet to over six), according to Wetlands International, an NGO.

"If things continue like this, the lake could disappear," said its project manager Desalegn Regassa.

Pumping by farmers and industry is not the lake's only problem. Heavy pesticide use is also killing its fish, locals and the NGO say.

Belachew Derib has been fishing the lake since the 1980s but says stocks are disappearing.

"I built my house thanks to the income from fishing and support my three children through this work," Belachew, 60, told AFP as he rowed his small boat out to pull up his nets.

"Previously, we could catch 20 to 30 fish a day. Nowadays, young fishermen are lucky to catch two or three," he said.

Just a few dozen meters (yards) from the shore, AFP found Habib Bobasso, 35, liberally covering his small onion plot with pesticides from a pump strapped to his back.

"There are many worms that can damage the plants... we could lose the entire harvest," he said as he sprayed, with just a shawl to cover his face.

He knows the pesticides are harmful but sees no alternative.

"The fertilizers and pesticides we use degrade the soil. We spend too much money on fertilizers and chemicals for a low yield," he said.

Degradation

Water management is essential for Ethiopia, a land-locked giant in east Africa with a rapidly growing population already estimated at more than 130 million and often hit by droughts.

But a lack of funds and government oversight has allowed bad practices to continue for decades.

A recent report by the Stockholm International Water Institute blamed Ethiopia's "lackluster policy frameworks" for "the demise of Lake Haramaya, the shrinking of Lake Abijata (and) the pollution of Awash River and Ziway and Hawassa Lakes."

Lately, the government has shown signs it is taking the problem seriously.

It passed a law earlier this year imposing a fee to extract water from Lake Dembel, which lies around 120 kilometers (75 miles) south of the capital Addis Ababa.

A local official, Andualem Gezahegne, told AFP he hoped this would curtail the pumps.

It cannot come too soon -- Wetlands International said there were some 6,000 pumps installed around the lake last year, running 24 hours a day, and "maybe more today".

AFP witnessed two huge tanker trucks filling up for a nearby highway project during a recent visit.

Keeping fishing under control is another challenge, said Andualem.

"Unfortunately, the peak fishing activity coincides with the fish spawning periods, from January to May," he said.

On the surface, the lake is still full of life -- from hippos to marabou storks.

But as the fishermen head out at dawn, the steady hum of the pumps strikes an ominous note for the future.