Deep‑sea cows and sleeper sharks
Scientists dropped a cow carcass 5,344 feet into the ocean as bait and recorded rare sleeper sharks showing up at the site, a detail that circulated on social channels today. The short social report about the deep‑sea bait experiment and resulting shark sightings was shared with hundreds of interactions (x.com).
Deep-sea biologists lowered a dead cow 1,629 meters, or 5,344 feet, into the South China Sea and filmed eight Pacific sleeper sharks feeding on it. (pmc.ncbi.nlm.nih.gov) The carcass was placed on the seafloor off the southeast coast of Hainan Island with a metal frame and cameras, and the paper was published in *Animals* on July 25, 2024. The team said it was the first reported record of Pacific sleeper sharks in the South China Sea. (pmc.ncbi.nlm.nih.gov) A whale fall is what ocean scientists call a dead whale that sinks and becomes a concentrated food source on the deep seafloor. The cow was used as a stand-in for that kind of carcass so researchers could watch which scavengers arrived and how they fed. (oceanservice.noaa.gov) (pmc.ncbi.nlm.nih.gov) The video let the researchers distinguish eight individual sharks by visible markings and estimate their lengths at 1.9 to 5.1 meters. The footage also showed the sharks tearing at the carcass and taking turns in what the authors called queue-feeding behavior. (pmc.ncbi.nlm.nih.gov) Pacific sleeper sharks are difficult to study because they live in deep, dark water and are rarely seen alive in the wild. The International Union for Conservation of Nature lists the species as Near Threatened and describes its usual range as the North Pacific, from Taiwan northward into Arctic waters and across to Baja California. (fisheries.noaa.gov) (iucnredlist.org) That is why the Hainan footage drew attention again this week on social platforms: it paired an odd bait experiment with evidence that the species’ known range extends into the northern South China Sea. The study authors said the observation points to a southwestward expansion of the shark’s documented distribution. (pmc.ncbi.nlm.nih.gov) The paper stops short of proving why the sharks were there, but it notes that deep-sea habitat shifts can occur under climate change and other human pressures. It also suggests large carcasses may be an undercounted food source for big predators in the South China Sea’s deep waters. (pmc.ncbi.nlm.nih.gov) So the cow was not a stunt on its own terms. It was bait for a whale-fall experiment, and it ended up producing one of the clearest records yet of elusive sleeper sharks feeding nearly a mile below the surface. (oceanservice.noaa.gov) (pmc.ncbi.nlm.nih.gov)
