Why Sharks? (Part 3 of 3)


Now, after my recent posts I feel I need to persuade (some of..) you somewhat. There is a reason people make such a fuss about sharks, because they serve an important role in the ecosystem, and actually, in all of our lives. Let me at least try to explain :)

Sharks are known as ‘keystone species’ because if they are removed, this can cause an ecosystem collapse with very damaging consequences. This applies to all species. Many predatory sharks sit at the top of the food chain, effectively managing ecosystems by helping to maintain the population numbers of species they feed on, in particular secondary predators, such as tuna. This is because unlike sharks, they have the potential to repopulate quickly. In the absence of shark predation, there are more animals that need food, and prey species populations decline quickly. In effect, these secondary predators then starve, leaving the ocean relatively empty.

Filter feeding sharks such as the basking shark, feed on small organisms called plankton. These can be either animal (zooplankton) or plant (phytoplankton). Swimming with their mouths agape, they filter small organisms from the water through their gills.  Detrivores such as the cookie cutter shark feed exclusively on dead matter and waste that sinks to the ocean floor, and play a vital role in recycling nutrients so nothing is wasted. For more information about their roles, please visit our ‘Roles in Ecosystems’ Shark File. Again, all animals fill a certain niche within an ecosystem, but as keystone species within the most vital ecosystem on this planet, it must be said, we NEED sharks.

Copyright Rob Allen Photography: A whale shark, one of the filter feeding sharks, also a good choice for eco-tourism dives (keep reading!)

Now if you think about it we might rely on the same fish that live in the sharks environment, and so we rely on them to maintain populations, that is if we haven’t already over-exploited them ourselves already. Particularly in coastal communities, if the fish disappear, fishermen lose their jobs, people begin to starve, recreational divers don’t want to pay to go see an empty ocean, tour companies then lose out etc., you get the picture..

And tourism is an important factor worth highlighting. It is believed that because of what has been dubbed ‘eco tourism’, so for example snorkeling with whale sharks or cage diving with great whites (as long as it actually aims to benefit the conservation efforts for the species in question, which sadly, it often doesn't), sharks can be worth more alive than dead! This incentive could potentially be used to turn the whole shark finning industry around, if done properly.

Back to our dependence on the ocean.. You may not realize especially if you live inland, that you rely on the ocean so much, but even if you eat farmed animals they are mainly fed on fish. Ice cream is made with a type of seaweed and probably most of the toiletries you use in everyday life have ingredients derived from the ocean. We are more dependent on it than we can probably ever imagine.. And sharks are essential to the oceans health. Sorry to have to go all hippie-fied, but we are still part of the ‘web of life’ and our actions can quite easily tear large, unnecessary holes in it.

The sad fact is we are currently a sharks worst enemy, but they NEED us too. On a brighter note it is possible for us to turn the tables and become their best friends! If we concentrate on what we could gain from having sharks around; without causing them harm, ruining the oceans and inevitably putting our own livelihoods at risk; then we could save them. For the benefit of us all! 

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