A new report released today by the Lenfest Ocean Program in Washington DC has revealed that as many as 96% of Mediterranean sharks are gone as the result of intense overfishing.

Evidence for severe declines in large predatory fishes is increasing around the world. Because of its long history of intense fishing, the Mediterranean Sea offers a unique perspective on fish population declines over historical timescales. We used a diverse set of records dating back to the early 19th and mid 20th century to reconstruct long-term population trends of large predatory sharks in the northwestern Mediterranean Sea. …Hammerhead (Sphyrna spp.), blue (Prionace glauca), mackerel (Isurus oxyrinchus and Lamna nasus), and thresher sharks (Alopias vulpinus) declined between 96 and 99.99% relative to their former abundance. According to World Conservation Union (IUCN) criteria, these species would be considered critically endangered.

The most frightening part of this whole situation is the shocking rarity of mature females - sharks have very low fecundity and small litters, meaning that they take a long time to mature, a relatively long period of time between each mating season, and have fewer babies. These factors decrease the speed at which a  population can recover and put shark populations in drastic danger of going extinct. I’ve written before about the dangers that face Hammerhead sharks - it’s sad to see a study that confirms that the grand majority of them are already gone in the Mediterranean.

This is not an isolated problem - it’s notoriously difficult to study wild oceanic populations, but the Mediterranean has provided a microcosm to study these species. The Mediterranean has been a specifically pressurized place for fish populations because of the number of nations competing for the fish stock. Many of the countries that border the Mediterranean sea have long-standing traditions regarding fishing and the use of the oceans as a resource. However, as their populations experienced rapid growth and industrial fishing fleets took to the seas, this proximity rapidly became a problem.

It’s especially hard to regulate fish populations that are being pursued by more than one nation, and especially when stocks are declining. When a large nation like the US or Australia decides to regulate a fish population, they can do that - when the western Chinook salmon populations imploded earlier this year, the government was able to cancel the fishing season without fear that Mexico or Canada would ride in and take the fish while American fishermen were being forced to let the population heal.

In a situation like this, when the population begins to decline, fishermen tend to just fish harder, taking more and more fish before their neighbors do. Their regulatory bodies struggle to come to agreements on responsible catch and how to divvy up the fish between the nations in question. International bodies have often struggled as well to get nations to come to terms over problems like this in which their fishermen share an area or migratory fish populations pass through more than one country’s waters.

I hope that this will motivate the IUCN to reconsider these sharks status next year and that something can be done to save these animals.

Do you think this news will help change peoples’ minds about the importance of saving shark species?

 

Technorati Tags: sharks, shark week, conservation, environment, discovery channel

Technorati Tags: sharks, shark week, conservation, environment, discovery channel