Marine biologists on an expedition to find the world's largest mako shark encountered a massive female specimen off the California coast that may have exceeded the species' elusive 13-foot size record. The Shark Week mission, featured in the Discovery Channel episode 'Biggest Mako on Earth,' was prompted by tourist reports of a 15-foot mako shark seen near Cabo San Lucas, Mexico.
Researchers Tristan Guttridge and his team explored waters off Mexico and California in an effort to determine if such exceptionally large makos could exist. Their breakthrough occurred late in the expedition when a large female mako appeared near their vessel and tore into a piece of tuna. Although an exact measurement was not possible, the shark appeared to be longer than another mako that measured over 12 feet, leading expert Kendyl Berna to suggest it "very possibly broke the 13-foot ceiling."
The investigation began near Cabo San Lucas, where a group of tourists reported seeing a shark estimated at 15 feet long, significantly larger than the largest reliably photographed makos.
Clara Calatayud, who witnessed the sighting, guided Guttridge back to the area. Guttridge noted that the witnesses had experience with these sharks and described the animal as "definitely a massive animal." Typically, adult makos reach about nine feet, with females growing up to 12 feet. However, anecdotal accounts of makos exceeding 13 feet have circulated for decades, though few have been substantiated with photographic evidence.
Mako sharks migrate annually between Mexico and California. The researchers aimed to lure a potential giant close enough for reliable measurements. After attracting several blue sharks with bait, a seven-foot mako appeared, causing the blue sharks to retreat. However, this was not the giant specimen they sought.
The team relocated their search to the cooler waters near Catalina Island, California. Their hopes were also fueled by a 1952 photograph of fishermen with a shark they claimed was 19 feet long, though its species and exact size could not be confirmed.
A key part of the research involved understanding the feeding habits of makos to determine if they could consume enough to reach such immense sizes. Sharks of this species burn energy rapidly and require substantial food. The team conducted a feeding test with 500 pounds of tuna to assess their feeding capacity. A nine-foot male mako, within the average range, consumed about 10 percent of its body weight, suggesting that makos are capable of consuming enough to potentially grow to 15 feet or larger.
Using chum suspended at various depths, the researchers attracted several makos. A large female eventually appeared but seemed deterred by a steel cage. The team then deployed a transparent Plexiglas "ghost cage," which had been compromised by a great white shark in a previous expedition. Guttridge entered this cage and observed makos, including a large female that drove others away and consumed a 100-pound tuna slab.
Two makos measured just over 11 and 12 feet. As the team prepared to depart, a final, enormous female mako appeared and seized tuna being trailed by the boat. While Guttridge could not obtain a precise measurement, the encounter left the possibility of even larger makos remaining a tantalizing mystery.