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TThe giant bar is up to its name – the bulky fish can extend up to almost 9 feet long and weigh more than 500 pounds. He also has a fairly massive fan club: the beloved bone fish enchants divers along the coasts of California and Mexico, who like to photograph it. Now the researchers have exploited the celebrity status of the giant bar for science.
The researchers counted the first direct estimate of the population of beloved species, thanks to more than 1,600 photographs – a “Facebook of fish” – compared to recreational divers and fishermen between 2015 and 2022. This work also adds to recent evidence that the population of the Big Fish increases, a welcome sign after decades of conservation efforts: the giant sea was listed more critical within two years. Decreased in the present case in the 1930s, and the state prohibited fishing at the giant bar in 1982.
The giant bar has distinctive places which can serve as “digital imprints”, allowing algorithms to identify individual fish from Paparazzi photos of the Pacific – a method previously used to study other sea creatures, including whale sharks and sand tigers. It has been shown that this technique identifies individual fish with precision up to 95%, explains the author of the study Andrew Pettit, a marine biologist who conducted research as a master’s degree at the University of California in Santa Barbara.
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After the scientists criticized the data, they determined that some 1,221 individual adult giant circulated from southern California between 2015 and 2022, as indicated in the journal Marine ecology progress series. Previous estimates were based on fisheries data, which report accidental sockets of the species and genetic analyzes.
“The population estimate is responsible and in fact good news because genetic evidence had recently suggested a number of half of this,” said Larry Allen, a marine biologist and emeritus professor at California State University, Northridge, who consulted research but did not participate directly in the study. “The number one question for many of us studying the giant bar in the past two decades has been:” How many are there now? ” “In 2015, Allen’s newspaper suggested that less than 500 giant bars lived off the southern Pacific coast of California and northern Mexico.
Large fish like the giant bar are particularly vulnerable to forces such as climate change and overfishing because they develop relatively slowly and reach sexual maturity late in life. This means that there are many more opportunities for fish to die before mating and having babies. However, this species also plays a crucial role at the top of the food chain: they are apex predators of fish and invertebrates in the forests of Varech and rocky reefs. They keep prey in check and act as “cultures”, preventing a single species from becoming too abundant and disturbing the balance of the ecosystem. The fish also hosts tiny parasitic crustaceans, which then become dinner for Señorita fish, a type of Wrasse that acts as a “cleaner” fish for the giant bar.
The giant bar has distinctive places that can be used as “fingerprints”.
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The recent photographic analysis provided data not only on the number of populations of giant bass, but also in the relative isolation of this particular population. In the waters off the southern coasts of California, less than 5% of people spotted on several occasions were documented by traveling long distances. This is aligned with genetic analysis studies: scientists have observed low genetic diversity among the giant bars along the southern coast of California, which could make it more difficult for these fish to adapt to a changing marine environment.
The photo analysis method is a win-win: it is less invasive than marking of fish and engages in the giant community that loves sea bars, explains the author of the study Molly Morse, marine scientist at the University of California in Santa Barbara.
“These are such a charismatic species – people spend a ton of money to dive and have the opportunity to meet one,” explains Pettit. “We realized that people publish all these giant bar photos, so that we can simply collect this data and analyze them.”
But relying on diving and fisherman photos, only painted part of the image, says Ramírez-Valdez. This biased the data on fish that live in these private waters during the summer months and in geographic spots that divers tend to frequent, he said.
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To obtain a more precise statement of the population, Morse says that she and her colleagues plan to follow giant bars off the California coast with labels that send real -time data to a satellite system. Researchers also hope to engage with scientists and divers in Mexico. In 2021, Ramírez-Valdez and his colleagues suggested that the majority of the species really lives off the Pacific coast in Mexico, and that conservation efforts neglected the populations just above the border-where they seem to flourish.
Anyway, it seems that this famous fish could still have a great future.
Lead photo by Douglas Klug
