Using jaw DNA and advanced technology to look at how sharks react to threats from the weather and fishing.

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Sharks have been around for 450 million years, before dinosaurs and warriors survived in the midst of mass destruction. However, their number in the oceans has decreased by a staggering 70% in the last 50 years and many people have suffered.

More than a third of all sharks and sharks are threatened with extinction, led by overfishing, loss of habitat, pollution and climate change. . In other words, with the rise of the environment, the time is running out to save the world’s sharks. As predators, sharks are important for maintaining the stability and health of marine ecosystems.

It is not surprising, however, that with all the things that move under the surface of the world’s oceans, there is much that is not known about the effects of climate change.

Hard data on shark populations is needed to understand conservation plans and maintain catch limits at high seas, many of these marine areas are out of government control.

So researchers are using new ways to improve the shark’s knowledge, using genomic technologies that can help unravel their genetic history. More information about how shark populations change over time can provide insight into environmental problems, how humans interact and how many sharks there are. conservation of genetic characteristics, explains Professor Einar Eg Nielsen, a geneticist at the Technical University of Denmark (DTU) at. Lyngby.

“You can see that in general things are working well in some ways.

“You need to know about the population in order to navigate them properly. But if you don’t have the genomic markers with the right solution, then you can’t decipher the nature of the population. . ”

Interval samples

That’s why the DiMaS program led him to lead genetic research on sharks. The idea is to increase knowledge about the recent history of sharks to help evaluate how they respond to climate change and problems related to fishing.

The company specializes in the mako shortfin mako (Isurus oxyrinchus), which is caught commercially but is also caught anonymously as it is caught in seas around the world. It is included in the IUCN Red List, which is considered the most important conservation status for the world’s species.

Researchers have collected more than 1,000 samples of limbs and skeletons over three centuries from museums, local fisheries and private collections, as well as new samples from fishing schools. After separating the lower extremities, they then selected the other half for genomic analysis.

“The problem with these animals is that they are everywhere, so it’s hard to find the best samples,” said Prof. Nielsen. “But in conjunction with other industries, we’ve been able to come up with more models that allow us to look at physical characteristics.”

Although they significantly decreased in numbers, the results of the evaluation provided a valid reason for optimism about the makos ’long -term life expectancy because the group found that it did not decrease. they have a lot of genetics in recent years.

The high levels of association between the different mako shortfin races may have helped, Drs. Romina Henriques, formerly at DTU, is the team leader of DiMaS, and is currently a geneticist at the University of Pretoria in South Africa.

“The reality of this strong relationship shows a much stronger place,” he said.

Find a relationship

But things are not easy. It is known that the level of engagement has changed over time and some historians are more isolated and therefore more vulnerable, said Drs. Henriques.

“What I’ve noticed a lot is that this relationship twists over time, so you get a number of mako shortfins that look a lot different than the others,” he said. his. “What we think is that you may be an independent person, but there is a lot of movement.”

Another factor is that with a lifespan of 30 years or more, shortfin mako are much longer. Given the increase in fishing in the second half of the century, there may not have been enough time for a declining population to reduce genetic diversity.

But without looking at what else has been seen, the rapid migration of mako shortfin sharks and the links between populations demonstrates the importance of fishing and conservation. held locally rather than in just individual locations, said Dr. Henriques.

“The way we care is not based on the land, but it has to be about the district,” he said. “It doesn’t matter if two or three countries decide ‘no more mako fishing,’ because they’re really moving away from protected areas.”

The oxygen is gone

An important part of the study is how the climate changes the marine environment of sharks through its effect on oxygen levels, leaving the animals vulnerable to fishing.

Because warm water dissolves less oxygen, studies have shown that climate change reduces levels in the ocean and leads to an increase in what is called oxygen. minimum zones (OMZs). He thought it would be possible to cut off areas of the ocean where sharks, fish and other marine animals could live in a small area.

“One hypothesis is that the sharks are directly attached to that top layer, in a small and small body of water, and this gives itself to the high fish that the fishermen make,” explains Professor David Sims. , is a marine scientist at the Marine Biological Association in Plymouth and the University of Southampton, UK.

As a result of many of these effects that are currently unknown, Prof. Ocean Deoxyfish’s project. The Sims leaders are exploring the nature of sharks and tuna. “Ultimately, what we want is to be able to predict the distribution of sharks in the deoxygenated marine environment,” he said.

That research was aided by the authors of the list of things that could be attached to shark fins. “Over the last 20 years, marine telemetry – marine biologging, as it’s called – has made real progress with the use of small electronic devices to track sharks to see where they are. “It’s about how they move, how they behave and the environment, and how they interact with the environment,” he said. said Prof. The Sims.

In the early days of Ocean Deoxyfish, the results strongly supported the researchers ’hypothesis. In a study at OMZ in the eastern Atlantic outside Africa, the team found that the habitat of blue sharks was affected. The depth of their diving is about 40% less than other places, which can increase their vulnerability to fishing.

Cycle of death

However, it is difficult to picture because sharks can benefit from increased feeding times in these restricted areas in search of prey to avoid hypoxic waters with low levels of oxygen.

“There’s an ongoing cycle of controversy going on,” said Prof. The Sims. “The sharks are seeing the right time to feed, but the fishermen are using the time to be able to catch more sharks each time.”

Ocean Deoxyfish researchers are developing simple capture sensors that record oxygen levels in addition to shark movement and standard measurements such as temperature, pressure and depth. The data will be sent directly to the satellites, avoiding the need to pick up the signals.

The new exhibitors will capture video footage of what Prof. Sims describes it as a ‘shark-eyed’ type of animal, allowing researchers to see what they do when they dive. He added that blue sharks can do diving in low-oxygen water, and he thinks it’s about feeding the squid that can absorb these waters.

“It was amazing to catch that and see what they do there,” he said. “What we think we’re going to get are these signals that are capturing the search for these deep cephalopods. [such as squid] in the oxygen-limit. ”

Finally, he hopes the projects like his will help sharks and other species that live in the ocean for a long time.

“Overfishing is reducing these populations to levels they never had before,” he said. “The link between climate change research and fisheries management needs to be at a higher level than ever before.”


Reorganize ocean parks to better care for sharks


Presented by Horizon: The EU Research & Innovation Magazine

Directions: Using jaw DNA and advanced technology to monitor the impact of sharks on future threats from climate and fishing (2022, April 5) Retrieved 5 April 2022 from https://phys.org/news/2022-04-jaw-dna-advanced -sensors-sharks.html

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