On Wednesday, Costa Rica passed a law banning the practice
of shark finning in its coastal waters. Finning occurs when fishermen catch
sharks, remove their fins, and then discard the remainder overboard.
Oftentimes, the sharks are alive during this process, and are left to die in
the ocean. Catching sharks for food is still legal under this law.
Shark finning is illegal in the waters of many nations,
including the United States and the European Union. The main motivation for the
practice is mostly due to the popularity of shark fin soup in Asian markets,
especially in China. Much of a shark's body is not valuable relative to the
fins, and it is much easier to transport many fins rather than fewer dead
sharks, leading to finning as a method to conserve transport space and maximize
profits.
Fishermen who practice finning tend to focus on pelagic sharks
such as Shortfin Mako and Blue sharks, which act as top predators in their
ecosystems. In addition to the normal increases in fishing due to superior
technology and greater numbers of workers, shark finning in particular
magnifies the effect of overfishing by allowing the harvest of many more sharks
than if they were taken whole. Combined with the long development times of most
shark species, such practices can be devastating to adult shark populations.
There is not only danger for the species threatened by the
practice. As top predators, their depleted numbers have the potential to cause
trophic cascades, affecting the entire food web below them. A simple example of
a predator regulating an ecosystem can be seen in the relation between kelp
forests and urchin barrens: Sea Otters act as a major predator of urchins. When
sea otter populations decline, urchin populations increase due to decreased
predation. Urchins feed upon kelp, by severing the kelp at its holdfast. This
increase in urchin population causes a decrease in kelp density, to the point
that some areas are barren of kelp entirely. Piscovorous sharks could easily
regulate the pelagic system in a similar manner.
See the full article at:
http://www.reuters.com/article/2012/10/11/uk-costarica-sharks-ban-idUSLNE89A00820121011
- Colin Fujii
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