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Why Sharks are Vital to our Ecosystem

Why are Sharks vital to our Marine Ecosystems?

Without sharks there would be nothing. They are the most essential keystone species to many aquatic ecosystems. Whilst people think that sharks are “dangerous” and “scary” they only attack on average sixteen people per year, with only one in two years leading to be fatal.

If we compare this to the number of sharks humans kill per year, the number is between 63 and 257 million tonnes, that is roughly 11,417 sharks per hour. With this mass extermination of sharks we are going to lose our vital oceans.

Separate the good from the bad

Sharks are the apex predators of the oceans, they have many roles which maintain a balanced ecosystem. They are able to prey on slower, diseased, infected and older fish within schools. This means that infected fish with diseases are not able to transmit the pathogens to other members of the schools, thus improving the fishes health and maintain schools numbers, removal other ill fish will also mean less transmission in future generations. Sharks will also remove older and slower fish.

Older fish could have dominance over the school, once removed they create room for new younger dominant fish which can have better chance of healthy offspring production. They also allow for the removal of other predators below them on the food chains which is essential to the survival of certain habitats. This means that primary and secondary consumer numbers are kept at a level where producers are able to sustain a balanced ecosystem.

Sharks are also saving vulnerable habitats

Tiger sharks found in Hawaii are a prime example of how sharks not only balance the ecosystem, but are also saving vulnerable habitat. There has been studies proving that tiger sharks are essential to the survival of the sea grass beds found here. This is because when there are a lack of sharks the local turtles are able to feed on the beds of sea grass, one single turtle can eat up to 2 kilograms of seagrass per day.

Did you know that one square meter of seagrass provides 10 liter of oxygen?

The tiger sharks will hunt on the turtles, the older and ill turtles will not be able to sense the sharks and as a result they are reduced in numbers. However, when there are healthy turtles they can move around the sharks. The reason why these grass beds are essential is because they provide large quantities of the earths oxygen, one square meter of seagrass provides 10 litres of oxygen per day through photosynthesis. Seagrass also absorbs 11 percent of the earths carbon dioxide but only occupies 1% of the oceans floor.

What would happen without sharks?

Without sharks there will depletion in fish stock levels, this is fish such as snapper and other commonly eaten species. Not only will there be a depletion in fish stock levels there will also be a decrease in vital aquatic habitats such as the sea grass beds which are essential to not only aquatic organisms survival but as well as terrestrial life.

Why I joined the Gili Shark Conservation Project

This is the reason why I have joined the Gili shark conservation team, to help to protect and create a safe no fishing zone for the local sharks to the Gili islands, it is especially essential in Indonesia as it is the number one shark fishing continent world-wide. If we can turn the Gili’s in to a marine protected zone for sharks and other marine life it will eliminate shark fishing and hopefully begin to be the first of many areas to see the importance of sharks, and how they are essential the environment.

During my time here I have been collecting vital information on the marine life through roving survey dives and BRUV’s to estimate and compare the data collected to see the number of sharks in more protected areas compared to those where there is no protection, in efforts to prove that this area is also a shark nursery and a special area for the sharks to reproduce.

Author: Henry Gould

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