The misunderstood predators of our oceans

august-37When one thinks of sharks; the picture that comes to mind is of a fearsome fish that can kill and eat people. The common misconception that these fish are stone cold killers have, thanks to many Hollywood movies such as Jaws, created an inaccurate image of these ocean wanderers. Despite the reputation, these fish are in more danger from humans; who exploit them for their fins, which is considered a delicacy in East Asian cuisine.

Sri Lanka is home to a few shark species, some found throughout the year, and some occasional visitors to our shores.

One of the most unique differences between sharks and other fish is that their bone structure is made of cartilage, with the exception of the jaws. Sharks also have five to six gill slits on the sides of its head and pectoral fins that are not fused to the head.

august-18Having a keen sense of smell, sharks have the ability to detect one part per million of blood in seawater. Traditionally, sharks are described as a solitary hunters scouring the ocean for food, but this is applicable only to a few species. There are certain shark species that have more interactive social lives, with some sharks gathering in large numbers.

Most sharks are carnivores but few species like the Whale shark, Basking sharks and Mega-mouth sharks are specialized to feed on plankton.

Sri Lanka has recorded 60 species of sharks. The Bull Shark found in our waters and is one of the species that have a reputation for attacking humans. This species can live in saltwater and fresh water, often seen up rivers. There are few photographs and sightings of this shark seen swimming in the Menik River in Yala National Park. The largest species of fish – the Whale Shark – can reach lengths of over 40 feet, and as mentioned is a peaceful plankton feeder. One of the most common sharks found in our waters is the White Tipped Reef Shark. It’s a small animal not exceeding 5 feet, and easily recognisable with its slender body and short, broad snout. The Black Tipped Reef Shark as its name suggests has a black colouration on the tip of its fin. Found commonly around coral reefs in the Indian Ocean, these sharks prefer shallow inshore waters. The Silky Shark is one of the most regularly found species in our oceans, they are often found on the edge of the continental shelf. Having a slender and streamlined body, they typically grow to around 8 feet in length. One of the most unusual species of shark is the Hammerhead.

This is a grouping of shark which encapsulate several species. They are so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a “hammer” shape.

One of the primary threats to sharks globally is due to demand for the fins of the animal, which some people use as an ingredient for soup in East Asia. Sri Lanka is ranked as one of the top 20 countries that kill and exploit sharks for this trade. About 70% of the catch consists of Silky Shark, followed by Thresher Shark and Hammerhead Sharks.

august-59The Thresher Shark is a protected species and yet they continue to get caught and very little monitoring or regulation is carried out. There are dozens of fishing boats particularly targeting sharks for fins, which have a big export market. The long-line fishing method – that has several hooks attached to a line – is being widely used for shark fishing.

What most people fail to understand is the importance of sharks to the ocean ecosystem. Generally healthy shark populations signify healthy marine life. It is imperative that relevant protection steps are taken in order to sustain these oceanic predators in our waters.