Basking Sharks Gather Off Irish Coast Prompting Warning to Swimmers

Basking sharks (Cetorhinus maximus) up to 30-feet long have been sighted congregating near Achill Island, Ireland, as conservationists urge beachgoers to keep their distance.

According to the Irish Independent, there could be as many as nine sharks filmed in the area, with one thought to be around 30 feet (9 meters) long. Seán Molloy, a local who shot footage at Keem Bay using a drone last week, told the paper sightings of basking sharks—categorized as endangered by the IUCN Red List—have increased in recent years.

"Former shark fisherman, Brian McNeil, estimates that these sharks are above average size with one particularly large one, well over 30 feet or nine meters," Molloy told the Irish Independent.

Large numbers of basking sharks have been reported along the west coast of Ireland since the last week of April, The Irish Basking Shark Project (IBSP) reports. Researchers with the project advise beachgoers to extend the process of social distancing to the shark: "While this is certainly exciting, the Irish Basking Shark Project asks those encountering basking sharks at sea to please respect their space and maintain social distancing."

The basking shark is frequently found swimming near the surface of the water with its mouth wide open to scoop up zooplankton. The shark can filter 2,000 tons of seawater every hour and at lengths of up to 40-feet and weights of more than 5 tons, it is the second largest species of fish in the world—only out-sized by the whale shark (Rhincodon typus).

The species is found in temperate waters around the world, from the coasts of Canada, Norway and Japan in the northern hemisphere to New Zealand and Chile in the southern hemisphere. Basking sharks can be seen in Irish waters throughout the year but are particularly noticeable in spring. According to IBSP, it is an important feeding period, while gatherings like those spotted in recent weeks are believed to be part of the species' courtship rituals.

However, 2020 seems to have seen a particularly strong showing—an event experts attribute to a combination of sunshine and calm seas. In light of the sightings, researchers at IBSP have encouraged locals to keep their distance, suggesting beachgoers enjoy their presence by watching from the shore and urging swimmers not to get to close. The sharks themselves are not thought to pose much of a threat to humans but scientists with the IBSP are concerned that approaches could disturb the animals and lead to "unknown consequences" for the endangered species.

"While there is no law against swimming with these sharks, as they are not protected in Irish waters, we would ask swimmers, boaters and kayackers to respect social distancing so as not to disrupt the sharks' natural behaviour," said Simon Berrow, who is a founding member of the Irish Basking Shark Project and has been studying basking sharks in Irish waters since 2008.

"For basking sharks, the recommended social distancing is 4 meters, not the 2 meters as required by our species," he added, in a statement published by IBSP.

Basking shark
Stock image of a basking shark, taken off the west coast of Scotland. Conservatonists are urging beachgoers to keep their distance from basking sharks as they gather off the Irish coast. Rebecca-Belleni-Photography/iStock