Jun 13

Whitetip Reef Shark

FAMILY: Carcharhinidae

SCIENTIFIC NAME: Triaenodon obesus

COMMON NAMES: Whitetip Reef Shark, Blunthead Shark, Light-tip Shark, Reef Whitetip, Whitetip Shark

TYPE: Fish

IUCN Red List Status: Vulnerable (assessed 2020)

SIZE:

These reef sharks can grow to a max length of 7 feet, however adults rarely grow over 5.25 feet (1.6m). Males of this species reach maturity around 3.4 feet (1.05 m) and females reach maturity at 3.4-3.57 feet (1.05-1.09 m); maturation can take anywhere from five to nine years.

DID YOU KNOW:

In Hawaii, some families regarded this shark as ‘aumakua’, a guardian spirit. They would feed rather than hunt whitetip reef sharks

AVERAGE LIFE SPAN:

These sharks can live to about 25 years of age but other studies suggest most individuals live around 16 years.

Whitetip reef sharks are viviparous and give birth to litters of 1-5 pups after a gestation period of about 12 months. Shark pup size at birth is 1.5-2ft (52–60 cm

DISTRIBUTION:

As their name suggests, this species prefers rocky caves within coral reefs and are often found resting by the bottom by day and hunting by night. Their range includes: Indo-Pacific, Central Pacific and Eastern Pacific as well as off Central America.

Typically they are nocturnal sharks that live in shallow waters around reef habitats at depths of 26.25-131.23 feet (8-40 m) but have been reported at depths reaching 1,083 feet (330 m).

Whitetip reef sharks exhibit site fidelity by returning to the same caves and coral reefs. These sharks may occupy the same home range for months to years without conflict with other surrounding sharks!

DIET:

These sharks are nocturnal hunters who prey on: octopuses, spiny lobsters, crabs, eels, various species of bony & reef fishes.

Whitetip reef sharks are perfectly adapted for reef life. Tough skin and a flexible, cartilaginous skeletons allow them to wiggle into crevices within reef rock hunting prey that other animals cannot reach. Divers have even heard them scraping against coral, but again, their tough skin and protective eye ridges protect them from injury.

DID YOU KNOW:

The common name comes from the distinct white tips on the first dorsal and upper caudal fins

Some may confuse the whitetip reef shark for the silvertip shark (C. albimarginatus) however:

Silvertips are a heavier species with large first dorsal, smaller second dorsal and caudal fins lined in white rather than tipped like the whitetip.

CONSERVATION:

These sharks are rarely aggressive towards humans, the reported attacks have been unprovoked and non-fatal (ISAF). As sharks become an increasing component of ecotourism, many species like the whitetip reef sharks (although nocturnal) will swim to the surface during the day at the sound of the boat engine in anticipation of food. These situations put divers and the sharks in danger - be aware and do research before diving with an operation that may illegally or otherwise dangerously baiting for sharks and putting all involved in increased risk of getting injured. Never feed or harass wildlife!

Whitetip Reef Sharks are caught (most as incidental catches in reef fisheries targeting teleost fishes) in industrial and small-scale longline, gillnet, trawl and handline fisheries that occur in the waters around coral reefs. Once caught, these sharks are retained for their meat, fins, teeth, skin and liver. Meat from whitetip reef shark is sold fresh, frozen, salted and also dried for human consumption at local markets throughout the world. As with consuming other tropical fish species, there is a risk of ciguatera poisoning with shark meat.

Unfortunately, this species' reliance on coral reefs make it susceptible to declines in reef habitat quality. Climate change is continuously resulting in large-scale coral bleaching events causing worldwide reef degradation. In fact, "almost all warm-water reefs are projecting significant losses of area and local extinctions, even if global warming is limited to 1.5ºC" (IPCC Report, 2019).

The ongoing over-harvesting and exploitation of biological resources continues to threaten both human and shark populations globally. Additionally, destructive fishing practices, like. dynamite fishing, contributes to declining water quality and the decline of vital coral reef biodiversity & stability.

Like so many other shark species, the Whitetip Reef Shark gives birth to small litters and takes longer to reaches sexual maturity meaning they are slow to rebound from a population decreases.

Although no conservation efforts are currently in place, whitetips' site fidelity and locality could open up the possibility of protection within the establishment of Marine Reserves/protected areas (MPAs) worldwide.