Spotting a basking shark off the coast of California is a rare thing after their notable absence for the last 30 years, but a spate of sightings by local fishers and sightseers has experts hoping this may be a sign of a comeback.
Basking sharks, the world’s second largest fish, are often mistaken for great white sharks because of their similar dorsal fins.
However, while the animals, which can measure up to 30 feet in length and weigh over 10,000 pounds, are larger than the feared predators, they are entirely harmless to humans. Similar to the world’s largest fish – the whale shark – and the world’s largest animal – the blue whale – basking sharks are filter feeders that swim slowly across the water with their mouths wide open to capture unsuspecting krill and plankton.
The fish, which get their name due to their tendency to feed at the Ocean’s surface, were once found in large numbers in the temperate waters of both the Pacific and Atlantic oceans.
However, by the 1960s, the shark had almost vanished from ecosystems on the California coast due to excessive and unregulated fishing for its large fins, meat, and liver, which was coveted for its oil.
By 2009, the once abundant animals were listed as a vulnerable species on the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species.
While researchers from the US-based National Oceanic and Atmospheric Administration (NOAA) managed to gain some insights from four tagged specimens between 2010 and 2011, they have been unable to tag any more since.
Fortunately, this past April, Ryan Freedman and his team from the Channel Islands National Marine Sanctuary off of California’s Pacific Coast, managed to deploy satellite tags on two basking sharks in a single day. The researchers, who plan to tag four more sharks if the opportunity arises, hope observing the fish will provide them with more information about the elusive animals.
Though researchers are not sure of the cause of the sharks’ resurgence in California waters, many speculate the warming oceans and an increase in plankton, brought on by nutrient-rich rainwater runoff, may be a factor.