Sandbar Whaler - The Mighty Fin
Sandbar Whaler sharks are the most abundant species of shark in the western Atlantic Ocean. In Australia, it can be found from southern Western Australia, along the north coast and extending south as far as Coffs Harbour in New South Wales.
This shark prefers temperate to tropical waters and will undergo a seasonal migration driven by temperate and ocean currents, travelling distances up to 2,700 kilometres.
Sandbar Whaler sharks live in coastal waters, favouring water up to 280 metres deep, but occasionally venturing as down to depths of up to 1,800 metres. Only occasionally can its large dorsal fin be seen protruding from the water’s surface, as the Sandbar Whaler shark prefers to remain near the bottom.
They also venture into river mouths, bays and harbours but avoids the sandy beaches of surf zones and coral reefs. As Sandbar Whalers avoid areas of prominent human activity, they are not seen as dangerous to people.
Sandbar Whaler sharks are characterised by their heavily set bodies, short rounded snouts and distinctive tall, triangular dorsal fin – which can constitute for up to 18% of its entireweight.The large fin increases stability when cruising the sea bottom in coastal areas. Sandbar Whalers are one of the biggest coastal sharks in the world and can grow up to 2.4 metres long.
Like many sharks and rays, the Sandbar Whaler shark uses the effective camouflage technique of countershading. The dorsal side or top of the Sandbar Whaler is bluish-grey to a brownish-bronze and when viewed from above it blends in with the dark sea floor. At the same time its ventral or under side is a pale colour that blends in with the light background of the ocean’s surface. This gives the Sandbar Whaler the handy ability to appear ‘invisible’ to its predators and prey.
Like most other sharks, Sandbar Whaler sharks display a bit of tough love when courting. The male sharks bite the female to let them know they are interested and it is not uncommon to see female sharks with scarring. After a gestation period of around 12 months, Sandbar Whaler sharks give birth to live young in litters of up to 10 pups.
Considering the rough courtship it is not surprising that female sharks only breed every two years, taking a rest year after pupping. Litters usually comprise of an equal male to female ratio. The pups live in nursery areas that are shallow coastal sites, separate from the adult population. After several years they will leave these nurseries to join breeding stock as sub-adults or adults.
Sandbar Whaler sharks actively hunt during the night, continuously patrolling for small bottom-dwelling fish, rays, molluscs and crustaceans. Its common delicacies include various bony fishes, eels, skates, rays, octopus, squid, shrimp and crabs.
It is believed that Sandbar Whalers have a very successful feeding strategy and receive a more regular supply of food than many other types of sharks. This is due to the high percentage of Sandbar Whalers found with partially-full stomachs, as well as their relatively large liver, which contains a high percentage of oil and vitamins.
Natural predators of the Sandbar Whaler shark include the Tiger shark, Bull shark and occasionally the Great White shark. However, their primary predator is man.
Practices Reducing Populations?
While Sandbar Whaler sharks are not seen as harmful to humans, we are certainly a threat to them. Commercial hunting and subsequent over-fishing has the potential to dramatically reduce population numbers. Their flesh is consumed by humans, the thick skins are prized for leather, vitamin-rich oil is extracted from the liver, and the fins are sold to Asian markets for use in shark fin soup.
These sharks are also naturally vulnerable to threats due to their low reproductive rate and slow maturation, which can take up to 16 years.