Madagascar may be a secret base for “living fossil” fish
Madagascar may be the secret base of the coelacanth, a “living fossil” fish thought to be extinct until it was captured by fishermen in 1938.
Its incredible first specimen was received from the South African coast, but the same species of coelacanth – Latimeria Carmune – Since then, I have left Tanzania, the Comoros (a group of islands off the east coast of Africa) and Madagascar. Currently, a re-examination of bycatch or incidental catch in Madagascar’s fishery could capture at least 34 confirmed specimens and raise many specimens that have not caught the attention of biologists and conservationists. It was revealed that the sex is high. The overall population remains a mystery, but the authors of the new study suspect that Madagascar is an important habitat for coelacanths and may even be the home of their ancestors.
The coelacanth has a history of 420 million years, a coastline of 88 million years, and is older than Madagascar, which has been around 40 million years in its current location. However, they are best known in the Comoros only around 15 million years ago. Researchers suspect that the fish have lived in Madagascar for a long time and were colonized in the Comoros later in history.
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“We know that Madagascar has a vast coastline and a canyon along it,” South African ichthyologist Mike Bruton told Live Science. “And we know that coelacanths like to live in canyons that are about 150 to 500 meters deep. [500 to 1,600 feet].. “
Madagascar is much older than the Comoros, which has the highest recorded coelacanth catch. Given that the fossil history of the coelacanth dates back 420 million years, Bruton and his colleagues believe that Madagascar may have been the homeland of the coelacanth longer than the Comoros.
“It’s a long story that makes the coelacanth fascinating.Annotated Old Fourlegs: An Updated History of the Coelacanth“(University Press of Florida, 2018). These fish evolved 180 million years ago. dinosaur It first appeared, moved continents, and survived even when asteroids wiped out much of life on Earth, including the following “sea monsters”. Mosasaurus.. First known from fossilsThe coelacanth was believed to be extinct until December 1938, when a trawler caught the coelacanth with a gillnet near South Africa. Australian museumThe crew were totally intrigued by the odd-looking large fish and notified the Museum in East London, South Africa. The scientist brought the specimen to the attention of South African ichthyologist JLB Smith. Smith confirmed that the creature was a coelacanth and gave it a scientific name. (Another species, Latimeria Manado Ensis, Discovered near Indonesia in 1998.)
According to Bruton, information on coelacanths in Madagascar’s waters is still scattered and disorganized. Never before has an island-based coelacanth expert. Given the promising habitats around the coast, researchers have started collecting reports on coelacanth catches. They found that the number of reports increased over time, possibly due to the growing popularity of large mesh gillnets used to catch sharks in the shark fin market. These gillnets, called jalifanets, are left on the high seas and are sometimes fed by small fish. Fish hunt at night and the nets are probably not detected by the coelacanth until it is too late, mainly using electrical reception, the detection of small electrical fields created by prey in the water. The network does not generate an electric field. To make matters worse for coelacanths, unlike trawls, which must be used on relatively smooth seabeds, nets can be placed in rocky canyons they prefer.
Of the 34 catches recorded with enough detail to confirm the coelacanth, the fish weighed between 66 and 198 pounds. (30-90 kilograms). The lengths ranged from about 4 to 6 feet (121 to 190 centimeters) or more.
Protect the coelacanth
The catches took place over 1000 km on the west coast of Madagascar, from the southernmost point of the island to the northwest coast. The largest cluster was captured in the Onirahi Canyon off the southwest coast of the island. This level of bycatch can be dangerous for the survival of coelacanths. According to Bruton, the species is endangered and exhibits many characteristics that make fish endangered.
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Coelacanths could also live off the east coast of Madagascar, researchers said on March 29. South African Science JournalAccording to Bruton, fishing activity is light in the east, so surveys using a remote-controlled vehicle will help find ancient fish on this side of the island. According to Bruton, the African Coelacanth Ecosystem Program, a project of the South African Institute for Aquatic Biodiversity, has submersibles capable of carrying out these studies, but the planned expeditions involving Madagascar are COVID-19. It was postponed because of. PandemicHe and his colleagues want the expedition to be postponed.
“Only then can we know the full spectrum of the population, their state of health and recommend measures to ensure their survival,” said Bruton. ..
For now, researchers recommend that Madagascar set up a coelacanth sanctuary in the Onilahy valley and add an invoice. L. chalumnae On the list of protected species in the country. Fishing for Jarifanets should be banned in areas rich in coelacanths, they wrote in the South African Scientific Journal. Fish tissues are poor to eat as they contain a variety of smelly oils and wastes called urea (the main component of urine), but they can also be eaten in Madagascar.
According to Bruton, being able to brief the crew of a fishing boat on nature maintenance could help advance coelacanth research. Fishermen may be advised to break up dead coelacanths caught to preserve tissue for genetic analysis. Gene sequencing could help determine if there is coelacanth reproduction between Madagascar and other populations in the western Indian Ocean, Bruton said.
“This will be valuable information that we don’t know at this point,” he said.
Originally published in Live Science.