scientists go in search of elusive river shark

by:Marslite     2019-10-05
For decades, a shark has crossed the rivers of Asia and the South Pacific, sometimes taking a large chunk from unsuspecting swimmers or people who wash their clothes.
But few people have actually seen this endangered predator.
Now, an international research team is doing more research on the shark family, known as sugar phis.
Using DNA sequencing, researchers concluded this week in a study published in the Proceedings of the National Academy of Sciences that three different species are actually just one, the porpoise.
The range of this shark is considered to be from the rivers of India-hence its name --
All the way to Malaysia.
In another paper published earlier this month on PLOS One, many of the same researchers also rediscovered two sharks --
Garricki and G. glyphis -
In the rivers of Papua New Guinea, this is the first time since 1970 generations.
They used DNA sequencing again to determine that they were the same species found in northern Australia.
Related: research has found that there are more sharks swimming in East Coast waters than ever before. A professor at Charleston College and South Carolina Medical University
The authors of the two papers told Fox News. com.
\"They are typical, typical sharks, like gray reefs or cattle sharks.
\"They look a bit like them, but they have small eyes and very wide fins,\" he said . \".
\"These are the conditions for living in very turbid water.
If you look at where these things live, visibility is about an inch.
It\'s muddy water.
\"It was discovered as early as 1839, and Naylor said that little was known about this group of sharks simply because very few live sharks were caught.
This helps them to have a great reputation as one of the top predators in the river system.
\"Many people have never seen these animals,\" Naylor said . \" He pointed out that many animals are identified from various body parts that appear on the market or in museums.
\"They have this mysterious reputation.
It is believed that they-at least one species-the shark of the Ganga-occasionally bite the swimmers in the Ganga.
But no one has ever seen them.
Some kind of monster caught you, it was a mysterious and terrible thing, but no one knew what it was.
\"The fact that little is known contributes to a lot of misinformation about sharks-beyond its threatening reputation.
Before Naylor and his colleagues began investigating sharks, it was believed that there were three sharks in Southeast Asia-the Ganga species, as well as the white phis from Malaysia and the white phis from Myanmar.
But due to recent DNA work, all three species are the same.
In the western province of Papua New Guinea, William White of the Australian Federal Scientific and Industrial Research Organization began to study shark and ray fisheries.
As part of four
In one year\'s project, he worked with local fishermen in a place called Daru and found two river sharks, also known as Australia\'s home.
Related: The rare \"sofa shark\" shocked scientists. \"they found a big G.
A local fisherman for sale.
He also has different fins that look like garricki, a North River Shark, \"said Naylor.
\"Will makes sense to get some sample of the organization to see if it is the same as the sample we got from northern Australia.
We sequenced them.
The shark\'s discovery is good news, Naylor said.
\"It gives you hope, but you\'re not sure if they \'ve been there all the time, we just found them because of increased fishing pressure, or we found them because they\'re making a comeback, he said.
\"It\'s hard to say.
White agrees, but acknowledges that these findings suggest that little is known about things that live in rivers in remote mountainous areas like Papua New Guinea.
\"In the context of river sharks, more work needs to be done to determine whether processes such as mining can affect pollution and habitat degradation,\" White said, the senior curator of the Australian national fish collection told Fox News. com, via email.
\"At this stage, we have little baseline data for some species (such as sharks) to measure the impact of threats such as mining.
However, this needs to be a major consideration when discussing management decisions that need to be made in the future.
In comparison with many other parts of the world, Baoxin may still have relatively good river shark populations.
Along with white, Nayler said the findings help answer some questions about sharks and help protect them, because we know that the range of sharks in the Ganga is much wider, it is likely to include salt and fresh water.
Related: professional surfers fight sharks in incredible encounters \"if you have a lot of different species, each should happen in a different habitat, then you have to be very careful to protect these species, \"said Naylor.
\"If you find that, in fact, this is a species that is distributed in a wider area, then there is not much pressure to protect each of them when these different populations are the same.
It also tells us that the same species can adapt to different environments.
It can live in Pakistan.
It can live in Borneo or Myanmar.
But he and White admit that the elusive shark still has a lot to learn about, including how they sail in the muddy river and \"make a living there, how many young people they have and the mechanisms they use to transition from salt to fresh water and back.
With recent discoveries in Papua New Guinea, this raises the question of whether more sharks will be found.
\"The DNA sequence data obtained from jaws collected from Bangladesh is significantly different from any data described so far.
But we don\'t have a sample, \"he said.
\"It\'s completely different from any other one.
So there\'s a species we don\'t know.
Editor\'s note: to clarify information on shark DNA sequence data, the story has been updated from earlier versions.
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...