Thursday, October 11, 2012

Costa Rica Bans Shark Finning

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.

- Colin Fujii

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