Rays’ and Sharks’ Futures Look Dark

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Caribbean Reef Shark off the coast of South Caicos, photo taken by Charlie Gaines.

 

According to a study done by Nicholas K Dulvy and his colleagues at Simon Fraser University in Canada, many species of Sharks and Rays face a risk of extinction due to a rapid expansion in human activities.  Currently, one-quarter of rays and sharks species (class Chondrichthyes) are threatened according to the IUCN Red List criteria due to targeted and incidental overfishing.

Chondrichthyans make up one of the oldest and most ecologically diverse lineages dating back at least 420 million years ago.  This group now plays extremely important functional roles in the top-down control of coastal and oceanic ecosystem structure and function.  Due to teleost species being less accessible because of depletion, fishing pressure on Chondrichthyans has increased drastically.  These species are targeted for their fins, one of the most valuable seafood commodities in the world.  It is estimated that the fins of between 26 and 73 million individuals are traded each year, putting stress on the population sizes.  Protecting these species is very important because the loss of apex predators cascades through the marine ecosystems, which could cause problems for other predatory species.

Some of the hot spots for threatened shark and ray species include the Indo-Pacific, Red sea, and the Mediterranean Sea.  Dulvy claims that chondrichthyans have slipped through the jurisdictional cracks of national and international management authorities.  He also states, “Rather than accept that many chondrichthyans will inevitably be driven to economic, ecological, or biological extinction, we warn that dramatic changes in the enforcement and implementation of the conservation and management of threatened chondrichthyans are urgently needed to ensure a healthy future for these iconic fishes and the ecosystems they support.”

For more information you can access the journal article here.

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Journal Reference

1. N. K. Dulvy, S. L. Fowler, J. A. Musick, R. D. Cavanagh, P. M. Kyne, L. R. Harrison, J. K. Carlson, L. N. Davidson, S. V. Fordham, M. P. Francis, C. M. Pollock, C. A. Simpfendorfer, G. H. Burgess, K. E. Carpenter, L. J. Compagno, D. A. Ebert, C. Gibson, M. R. Heupel, S. R. Livingstone, J. C. Sanciangco, J. D. Stevens, S. Valenti, W. T. White. Extinction risk and conservation of the world’s sharks and rays. eLife, 2014; 3 (0): e00590 DOI: 10.7554/eLife.00590

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