Silvertip Sharks

Photo provided by Bing Images

The Maldives are a heaven for shark lovers like myself. During Mermaid Week Maldives with Mermaid Kat, one of the many species of shark we were lucky enough to encounter was the silvertip shark, Carcharhinus albimarginatus.

Their name comes from the Latin for white “albi” and enclosed with border “marginatus” which is a reference to the white margins on their fins. All of their fins have white tips bordering them, and their pectoral fins are long and sickle-like with pointed tips. Their first dorsal fin is large and triangular, with a ridge between their first and second dorsal fins. They have a subtle white band along their sides, and their coloration is blue-grey above and white below. They have a long broad snout and large round eyes and are part of the requiem shark family. The grey reef shark is the closest relative to silvertip sharks.

Silvertip sharks are found in the Indian and Pacific oceans, from Baja California to the Red Sea to South Africa. They can be found on all levels of the water column and like continental and insular shelves from 30-800 meters (98-2625 feet). Juveniles prefer coastal shallows and lagoons whereas adults like deeper water. They are usually found alone or in pairs, though adult females will hang out in groups. They are territorial and aggressive towards each other but are found in mixed species aggregations with grey reef sharks.

Larger silvertip sharks are more sluggish and will use benthic prey. A typical meal for a silvertip shark would consist of bony fish, such as grouper or tuna, but they will occasionally snack on eagle rays, smaller sharks, or octopus.

Silvertip sharks are attracted to artificial low-frequency sounds, which lead them to ships. They are inquisitive and bold, which can make people believe they are potentially dangerous. They have been known to inspect, circle, and pursue divers. As of 2008, there have been 4 provoked attacks by silvertip sharks, none fatal.

When pursued by divers, silvertip sharks will enact a “stereotypical threat display”, giving a warning that they are prepared to attack if necessary. When giving this display, the shark will retreat to a distance of 15 meters (49 feet), where it will then turn and charge toward the threat. When it is about two of its body lengths away, it will stop, turn on its broadside, drop its pectoral fins and lower its rear, gape its jaw, and shake to emphasize its fins. If the threat continues towards the shark, it will rapidly close the distance while slashing with its upper teeth.

The International Union for Conservation of Nature lists silvertip sharks as Vulnerable. They are often caught in commercial and artisanal fisheries. The export market sells their skin, cartilage, fins, meat, jaws, and teeth. Pelagic fisheries often fin them at sea. Due to their slow reproductive rate - 1-11 pups born in a liter after a 1 year gestation period - they are susceptible to overfishing. Do not support this industry - write to your legislation to ban the shark fin trade and do not eat shark fin soup. Find out which countries have laws against shark fin trades at https://awionline.org/content/international-shark-finning-bans-and-policies