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.
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| 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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