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Posts Tagged ‘carp’

A Ghost Fish Returns

Posted in Uncategorized, tagged , , , , , , on January 24, 2025| Leave a Comment »

Photo: Wonders of the Mekong.
Recent sightings of the “Mekong ghost” fish in Cambodia offer hope for a creature once presumed extinct.

Today’s report on the reappearance of a giant fish in the Mekong River near Cambodia is a little piece of good news in an era when governments are shrugging off saving the planet and leaving it all to those of us who care.

I first saw the good news at Yale Environment 360: “Recent sightings of the ‘Mekong ghost’ fish in Cambodia offer hope for a creature once presumed extinct. The giant salmon carp, so named because it resembles a large salmon, had not been documented by science since 2005. But scientists have now confirmed that three fish caught between 2020 and 2023 in the Mekong and Sesan rivers are members of this elusive species.

“Giant salmon carp can measure up to 4 feet long and weigh more than 60 pounds, making them a type of ‘megafish.’ The carp are in good company in the Mekong basin, which is home to some of the largest freshwater fish on the planet, including the giant catfish and giant freshwater stingray. Such creatures have been victims of excessive fishing, pollution, and the construction of massive dams.

“In the new study, published in Biological Conservation, scientists call for scanning river waters for giant salmon carp DNA and for working with local fishers to track its potential whereabouts — first steps, they say, toward protecting the imperiled species.” More at Yale e360, here.

At the Mekong Fish Network website, I found additional detail: “Dr. Zeb Hogan, who leads USAID’s ‘Wonders of the Mekong’ project, says, ‘Giant fish are flagship species that symbolize the ecological integrity of the Mekong River. The disappearance of these animals is a warning that we need to take urgent action to improve the ecosystem health of this remarkable river.’

“Several Mekong megafish species are now endangered and both the number and size of fish caught have declined. The biggest include the Mekong freshwater stingray (Urogymnus polylepis), which can have a wingspan of up to 4.3 m [14 feet], Pangasianodon gigas (Trey Reach), Catlocarpio siamensis (Trey Kolriang), and Pangasius sanitwongsei (Trey Popruy), which can grow up to about 3 meters [10 feet] in length … and Aaptosyax grypus (Trey Pasanak), Probarbus jullieni (Trey Trasak) and Wallago attu (Trey stourk), which can grow up to 20 kilograms [44 pounds]. All of these are listed by the IUCN as Critically Endangered, and current and future threats may put these species at risk of population extirpation or extinction.

“Based on a recent study by Wonders of the Mekong on traditional ecological knowledge about large and endangered fish, megafishes in the northern Cambodian Mekong Basin in Kratie and Stung Treng are very rare, decreasing in population abundance, at high risk of extinction, and decreasing in body size. Also, the population of three giant species of Mekong River fishes (C. siamensis, W. micropogon, and P.jullieni) previously thought to be in serious decline can still be found, although, their body sizes are significantly decreasing.

“Unfortunately, the Mekong Giant Catfish, P. gigas, considered critically endangered by IUCN, is still rare in this stretch of the Mekong. The presence of giant and endangered species in Mekong River deep pools demonstrates the importance of these habitats in fish conservation and provides a starting point for the preservation of these species. The decline of Mekong megafish in northern Cambodia can be attributed to a variety of causes such as threats from multiple anthropogenic pressures. These threatened fishes are all rapidly declining and could ultimately face extinction. The impact of these threats could be minimized by proper management and an effective conservation plan, such as the sustainable management of fishing.

“In light of this, since 2017, approximately 100,000 larvae of endangered fish such as Mekong giant catfish (Pangasianodon gigas), giant barb (Catlocarpio siamensis), striped catfish (Pangasianodon hypophthalmus) and other species have been confiscated from illegal fishing operations or collected during research activities. These juvenile fishes are kept in a rearing facility before being released back into the river at a larger size. During rearing in ponds at Cambodia’s Freshwater Aquaculture Research and Development Center (FARDC), Mrs. Hoy Sreynov, an official of the Department of Aquaculture Development of the Fisheries Administration, does monthly monitoring to observe fish growth, feeding, and lifespan. Running this catch, raising and release program requires an understanding of conservation importance and a strong network to promote effective conservation management.”

More at Mekong Fish Network. You may also be interested in my previous post about the Mekong’s revival, here.

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The Musicality of Other Species

Posted in Uncategorized, tagged , , , , on June 6, 2019| 7 Comments »

Photo: American Kennel Club
Most species respond to music, just not in the same way humans do.

Now that you have absorbed yesterday’s post on the responsiveness of cheese to music, it should come as no surprise that mammals, birds, and fish also have an affinity for music.

University of Amsterdam professor of music cognition Henkjan Honing writes at Nautilus, “We are all born with a predisposition for music, a predisposition that develops spontaneously and is refined by listening to music. Nearly everyone possesses the musical skills essential to experiencing and appreciating music. … Is musicality something uniquely human? Or do we share musicality with other animals. …

“By the beginning of the 20th century, Ivan Pavlov had discovered that dogs could remember a single tone and associate it with food. Wolves and rats also recognize members of their own species by the perfect pitch of their call and can also differentiate tones. The same applies to starlings and rhesus macaques. …

“Zebra finches turn out to focus mostly on the musical aspects of [sequences, as opposed to the order]. This does not mean they are insensitive to the order … but it is mainly the differences in pitch (intonation), duration, and dynamic accents [that] they use to differentiate the sequences. …

“Humans may share a form of musical listening with zebra finches, a form of listening in which attention is paid to the musical aspects of sound (musical prosody), not to the syntax and semantics that humans heed so closely in speech. … The research on starlings and zebra finches reveals that songbirds use the entire sound spectrum to gather information. They appear to have a capacity for listening ‘relatively,’ that is, on the basis of the contours of the timbre, intonation, and dynamic range of the sound. …

“What we know for sure is that humans, songbirds, pigeons, rats, and some fish (such as goldfish and carp) can easily distinguish between different melodies. It remains highly questionable, though, whether [animals] do so in the same way as humans do, that is, by listening to the structural features of the music.

“A North American study using koi carp — a fish species that, like goldfish, hears better than most other fish — offers an unusual example. Carp are often called ‘hearing specialists’ because of their good hearing. The sensitivity of a carp’s hearing can be compared to the way sounds might be heard over a telephone line: Though quality may be lacking in the higher and lower ranges, the carp will hear most of the sounds very clearly.

“Three koi — Beauty, Oro, and Pepi — were housed in an aquarium at Harvard University’s Rowland Institute, where they had already participated in a variety of other listening experiments. … In the discrimination experiment, the koi were exposed to compositions by Johann Sebastian Bach and the blues singer John Lee Hooker to see whether they could differentiate between the two. In the categorization experiment, the koi were tested to see if they could classify a composition as belonging to either the blues or the classical genre. In the latter experiment, they were alternately exposed to recordings of different blues singers and classical composers ranging from Vivaldi to Schubert.

“The surprising outcome was that all three koi were able to distinguish not only between compositions by John Lee Hooker and Bach, but also between the blues and classical genres in general. The fish appeared to be able to generalize, to correctly classify a new, as yet unheard piece of music based on a previously learned distinction. …

“Rock doves, too, [pigeons] can distinguish between compositions by Bach and Stravinsky. And, like carp, rock doves can also generalize what they have learned from only two pieces of music to other, unfamiliar pieces of music. They can even distinguish between compositions by contemporaries of Bach and Stravinsky. …

“These species can do all of this with no significant listening experience. … This, in itself, is an exceptional trait. Most likely it is a successful tactic to generate food. Yet it still offers no insight into the ‘perception, if not the enjoyment,’ of music. That may be one aspect of musicality that belongs to humans alone.”

More at Nautilus, here. And while we are on the subject of critters’ artistic sensibilities, be sure to read the children’s book This is a Poem that Heals Fish. Hat tip: The inestimable Brainpickings.

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