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Lionfish invade Brazil

Time:2022-11-29 16:25:15 source:ucutxmastrees.com author:Fish Read:591次
Lionfish invade Brazil

Lionfish (often called lionfish) is an invasive species native to the Indo-Pacific region that has established its "base" in the Caribbean Sea, parts of the Western Atlantic Ocean, and off the coast of Brazil. They have a voracious appetite and have no major native predators (other than humans). PHOTO: HUMBERTO RAMIREZ, GETTY IMAGES TEXT: REBECCA DZOMBAK Lionfish are one of the most harmful invasive species in the oceans today. Now, they have traveled south to Brazil to continue their destructive expansion. Lionfish have been migrating south for many years. They were first caught in the Gulf of Mexico in 1985, possibly escaping from the aquarium trade, and then rapidly expanding to the east coast of the United States and the Caribbean. They reached the coastline of South America around 2010. But the species' "expansion journey south" has stalled near Venezuela and Trinidad and Tobago. For 10 years, freshwater and confluent currents flowing from the Amazon into the Atlantic have acted as a geographic barrier, preventing fish from continuing their journey south. But around 2020, when few scientists were paying attention to it due to the Covid-19 pandemic, the lionfish began to slip through the barrier and swim south. Now, dozens of lionfish have been spotted along Brazil's 150-mile coastline, according to a new study in Frontiers in Marine Science. Between March and May of this year, the waters were clear enough to track the fish, and researchers and fishermen recorded 72 closely related fish. Such high densities suggest that they likely established new, successful populations -- a dangerous and irreversible trajectory for invasive species. "Since March 2022, lionfish have covered 700 kilometers of coastline," said marine ecologist Marcelo Soares, lead author of the new study. He also reported that the number now exceeds 300. "Without urgent action, we expect lionfish to invade the remaining 6,000 kilometers of Brazilian coast within two years." For many scientists, the question is not whether these fish will continue to migrate south, but when. "We know that once they cross the Amazon barrier, they spread like fire," says Osmar Luiz, an aquatic ecologist at Charles Darwin University in Australia. He was not involved in the study. The most destructive invasive fish, the lionfish, is native to the Indo-Pacific region and is incredibly destructive. Wherever they swim, they wreak havoc on local ecosystems, eat native species and disrupt food chains, making them "notorious" and considered one of the most destructive invasive fish. In addition to spreading south to Brazil, lionfish have established populations in the Mediterranean through the Indian Ocean and the Suez Canal. Louis said he wouldn't be surprised if they "hitchhiked" the ocean currents from the Brazilian coast and made it to West Africa soon. Adding to their devastating impact, lionfish lay thousands of eggs every two to four days. Their backs are covered with stingers, and they are incredibly adaptable to different environments and foods. Millions of larvae are carried over great distances by ocean currents, sometimes even in hurricanes. Worst of all, they have few natural predators in an invasive environment, and the threat they pose is often not fully appreciated. "They have a lot of traits of a 'successful invader' in them," said Nicola Smith, a marine ecologist at the University of British Columbia who was not involved in the new study. "They're on the Atlantic coast, and now in Brazil, I'm not at all. Surprised." "The lionfish is a voracious predator," Soares said, and an invasion of lionfish could threaten vulnerable species to extinction. Unlike other hunters who turn to large numbers of prey when a species is hunted, lionfish will relentlessly chase the last of a prey species until they disappear. Due to this hunting habit, endemic species -- creatures found only in one area -- are particularly vulnerable to lionfish. Brazil is full of endemic species. Lionfish in Brazil Soares and his colleagues used descriptions from researchers, fishermen and social media posts to document an increase in lionfish populations off the coast of Brazil. More than half of the 72 lionfish found in the three-month survey were found near man-made structures such as artificial reefs, which locals use to fish. "This raises concerns about what impact lionfish will have on fisheries," Soares said. "There is a considerable amount of artisanal fishing off the Brazilian coast, which is critical for food security in areas with high levels of social inequality." Populations of two important commercial fish species, snapper and grouper, are likely to decline; in the Bahamas, for example, lionfish aggressively kill grouper, leading to a decline in grouper fishing. (Groupers are finally starting to recover at the moment.) Underwater "hunters" shooting and piercing fish are a common method of managing invasive species, achieved through spear-gun fishing. But in the survey, lionfish lurked in murky, sediment-clogged water, which made spear-gun fishing more difficult. A recent paper found that at least 29 species of fish endemic to Brazilian waters are particularly vulnerable to lionfish, such as the scaly-finned rock bass (Haemulon squamipinna), a small yellow striped fish that is critical to coastal subsistence fisheries Very important. Rocky archipelagos like Fernando de Noronha, hundreds of miles offshore, are home to numerous species that have some of the smallest geographic footprints in the world — some as small as a few square meters, says Louis. "We know very little about all marine biodiversity, especially rare and enigmatic species," Soares said. "If lionfish have the same densities in these habitats as they achieve in the Caribbean, local rare and enigmatic species may decrease.” Now that lionfish have established populations in Brazilian waters, the next step, inevitably, is that they will spread farther. "Once [lionfish] are 'inhabited' in an area, you can fish as much as you want," Smith said. "But you can't control that because they're going to reproduce." The challenge of taming lionfish is For other fish, removing their individuals from an area results in lower population densities. But lionfish don't, Smith said. "As long as you kill lionfish quickly, they can resettle immediately," Smith said. Because lionfish tend to migrate to areas with fewer lionfish, "the more lionfish you kill, the more lionfish there will be. The lionfish come up from the depths and replace the part of the population you kill." Smith says human methods for controlling lionfish populations include fishing competitions, which can quickly remove many lionfish over a large area, and specially designed lionfish traps, although about half of the lionfish escaped. Chefs are also pushing to turn lionfish into a popular seafood option. But it's not easy to turn this stinger-topped invasive fish into a local delicacy. Lionfish are often considered unsafe. Also, hunting them with a spear is more time-consuming because their spines are dangerous and their fillets, while delicious, are small. According to Smith, it's still worth making lionfish for dinner. "I've eaten a lot of lionfish. It tastes good and tastes like grouper," Smith said. While attempts to eradicate them entirely may be futile, efforts to reduce their numbers at least help limit damage to native species. An important next step is to track the lionfish's movements and try to stop them from establishing new populations, Louis said. Monitoring offshore waters that are not frequented by fishermen and tourists, including remote archipelagos, is important. For Brazil's native species, the battle is about survival. "The best we can hope for is to prevent lionfish from causing the extinction of any native species," Louis said.

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