Study Confirming The Obvious About Sharks

Ars Technica does a good job of summarizing a study on declining shark populations. However I think the study is too tentative in identifying causes and effects. Simply put sharks are disappearing because of overfishing (for shark fins, once those are removed from the shark, it is thrown back in the sea to drown). The numbers being fished every year are up for debate, the office number is 38 million, realistically that number is probably closer to 70 million, and I have seen estimates of 100 million (probably for effect.) Over the past 20 years there has been a 50% decline in the global shark population. Even if fishing were to stop now, it would take a long time (a human generation or more) for stocks to get back up to ‘normal’ levels (say the numbers we had 20 years ago) because sharks take a long time to reach sexual maturity.

The effects of this reduction in the top predator are already being felt. For example there has been an increase on the stingray population which creates pressure on the mollusk population, and a large increase in the number of Humboldt Squid in the sea of Cortez. And for all intents and purposes, the Mako shark population on the east coast of the US is now non-existent.

Unfortunately the trends are clear, if this de-population goes on, sharks will be reduced to very small numbers in my lifetime, and the best chance to see one will be either the aquarium or in pictures.

 

Good-bye Shark Week? Large sharks in decline due to fishing:

Sharks have been honed into efficient predators by over 400 million years of evolution, but that didn’t prepare them for commercial-scale fishing. Sharks, skates, and rays are fantastically abundant in unexploited parts of the ocean, but a new review shows that even light fishing—both targeted at sharks and other species—can send populations into a tailspin. Large, top-predator shark species appear to suffer the most, and their dwindling numbers are drastically affecting many marine ecosystems.

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