U.S.Male largemouth sharks, about 3.7 m long, and the larger one, about 4.6 m long, of unknown sex, swam together, presumably in courtship or foraging.
A pair of largemouth sharks, the smaller of which is a male, swim near a fishing boat. video: Andrew Chang/David Stabile
Despite being one of the largest fish in the ocean, the greatmouth shark (Oceanic Gap) is so mysterious that scientists know very little about its past and biology, IFL Science Reported on March 27. The animals have only been seen 273 times since 1976, and no one saw two largemouth sharks swimming together until last year.
On September 11, 2022, off the coast of San Diego, California, USA, anglers spotted two largemouth sharks. They recorded their short videos and passed the footage to scientists via social networks. A team of experts conducted video analysis and conducted interviews with those on board.Their research is published in the journal Fish Environmental Biology.
The pair swam to a distance of about 45-60 meters from the fishing boat. The larger one is about 4.6 meters long and appears to be surrounding the smaller one which is 3.7 meters long. The smaller one, identified as the male, continued to swim deeper as the boat approached. The older (sex unknown) then swims to another depth for the boat.
The pair of sharks do not eat during this time. The larger one moved around the boat a few times, while the male stayed in the deep water most of the time, only once slowly surfacing, near the side of the boat.
Smaller male sharks swim below the larger sharks. image: Fish Environmental Biology
The team came up with two main theories as to why the pair of largemouth sharks were swimming together. First, they go out to eat. Little is known about the animal’s diet, but they are thought to be filter feeders, feeding mainly on krill, squid and other molluscs. Although the photographer did not see them feeding, it is possible that the presence of fishing boats disturbed them. The people on the boat also reported that there are many moonfish and molluscs around. Moonfish and largemouth sharks are often seen together, and both feed on soft creatures.
The second theory is that the pair of largemouth sharks are courting. The team believes that the stalking behavior of male sharks is similar to the courtship behavior of other sharks. In other shark species, they say, mating opportunities may arise when foraging congregate. No mating attempts occurred during the shark-boat encounters, but the researchers note that encounters with mating sharks, especially filter-feeding sharks, are extremely rare.
Based on the video and previous insights, the team concluded that the two sharks were likely engaging in pre-mating behavior. As social media, awareness and maritime traffic develop, similar reports are likely to become more common and provide more details about the sharks’ lives, they added. Mysterious big mouth.
Qiu Tao (Theo IFL Science)
