With its gaping mouth, sinister movements and chilling appearance, the basking shark (Cetorhinus maximus) seems, at first sight, to be the stuff of nightmares. However, this is a superficial facade. In fact, the basking shark is simply a peaceful feeder of zooplankton and poses no threat to humans. They are the second-largest extant species of fish – after the whale shark – reaching up to 8 metres in length.
The basking shark has a vast distribution, found across all of the world’s oceans, although they prefer cooler waters further north and south of the equator. They also migrate during the summer and winter months, travelling thousands of kilometres to reach the richest supplies of zooplankton that the sea has to offer. Basking sharks are usually solitary creatures but may come together in the summer months to exploit the abundance of zooplankton.
Now it’s time to discuss the most striking feature of the basking shark – its cavernous and unearthly mouth. Their mouth opens up to 1 metre wide and remains open while they swim through the water. As they swim, plankton passively flows through the shark’s mouth. Their gill rakers filter the plankton from the water, they will then close their mouth to pump water out through their gills. This method of feeding has proved immensely effective for the basking shark; they can filter through around 1,500-2,000 cubic meters of water per hour.
Despite their large size and distribution, the basking shark remains an elusive and mysterious species. There is still much more to learn about this gentle giant. One thing we do know is that basking sharks are vulnerable and have been over-exploited for decades. Its slow and placid nature have made it the perfect target for fisheries. It has been commercially hunted for its meat, oils, liver, fins and cartilage. In China, their fins are often used in shark fin soup and other parts are used in traditional Chinese medicine (even though it has been proven that they have no scientific medicinal effect). In Japan, some parts are used as an aphrodisiac, further fuelling the demand for these defenceless fish.
Thankfully, the commercial fishing of the basking shark has been banned in many countries. Steps are being taken to conserve the species and create more protected marine areas. However, the demand still persists in many countries and cultures. Until people are educated on the ecological necessity of threatened species such as the basking shark, human greed will continue to take millions of lives and thousands of species will disappear.