Colin Simpfendorfer on overfishing deep sea sharks

Colin Simpfendorfer: We know little about sharks in general, and these are the sharks that live a long way down in the ocean.

EarthSky spoke to Colin Simpfendorfer of Australia’s James Cook University about deep sea sharks, which he said are increasingly threatened by overfishing.

Colin Simpfendorfer: It’s an area we don’t get to very much, and so we don’t encounter them very often. And so there’s been limited opportunities to actually look at these animals and so there’s been limited biological work on them.

He said there are nearly 600 species of sharks inhabiting the deep ocean. As shallower waters become overfished, fisheries are turning towards deep ocean sharks.

Colin Simpfendorfer: There’s pressure on the fisheries to keep catches coming in, so they move deeper and deeper, exploiting new resources and unregulated resources.

Simpfendorfer said the overfishing of these sharks may lead to an imbalance in the deep sea ecosystem.

Colin Simpfendorfer: If you take larger sharks out of ecosystems, their predatory influence flows down through the ecosystem, and you see quite large changes in the abundance of other groups that you may not have expected.

Plus the sharks themselves aren’t yet known or understood very well.

Colin Simpfendorfer: There are an amazing diversity of sharks in the deep sea. And if we’re not careful, very quickly, they can be depleted and extinct, before we even really know fully what’s down there.

The sharks could get caught in fishing nets, and as by-catch their bodies are discarded. They are slow to grow and reproduce, which makes it difficult for them to recover their populations.

Colin Simpfendorfer: Research is slowly getting into the deep sea but fisheries are moving more rapidly.

Our thanks to:
Colin Simpfendorfer
James Cook University
Queensland, Australia

August 3, 2008

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