Ongoing collapse of coral reef shark populations

Dec 04, 2006

Investigators have revealed that coral reef shark populations are in the midst of rapid decline, and that "no-take zones" -- reefs where fishing is prohibited -- do protect sharks, but only when compliance with no-take regulations is high. The findings, reported by William Robbins and colleagues at James Cook University and its ARC Centre of Excellence for Coral Reef Studies, appear in the December 5th issue of Current Biology.

Reef sharks are so-called apex predators on tropical coral reefs and are therefore of significant potential importance to the functioning of coral reef ecosystems. The reproductive biology of reef sharks makes them particularly vulnerable to fishing, but until now, there have been no studies of the response of these sharks to fishing pressure.

The new work focused on Australia’s Great Barrier Reef, which is widely considered to be one of the world’s least degraded, and best managed, reef systems. For balancing conservation with sustainable use, the Great Barrier Reef is regulated through an extensive series of management zones in which different areas are open to different levels of fishing. In their study, the researchers determined the status of two species of reef shark—the whitetip and grey reef sharks—by employing a unique combination of fisheries-independent abundance estimates and measurements of the survival and reproduction of individual sharks.

Their findings show that reef shark abundance on reefs open to fishing are about ten times lower than on unfished reefs. Moreover, high reef shark abundance was only apparent on the most strictly enforced of the no-take zones, suggesting that even moderate levels of poaching can derail attempts to protect shark populations. These observations, coupled with population modeling showing ongoing, rapid declines in population size in fished areas, lead the authors to conclude that reef sharks are approaching “ecological extinction”—that is, becoming so rare that they can no longer perform their natural role in the functioning of coral reef ecosystems.

Source: Cell Press

Explore further: Montana oil spill estimate lowered to 30,000 gallons

add to favorites email to friend print save as pdf

Related Stories

The latest fashion: Graphene edges can be tailor-made

11 hours ago

Theoretical physicists at Rice University are living on the edge as they study the astounding properties of graphene. In a new study, they figure out how researchers can fracture graphene nanoribbons to get ...

Infrared imaging technique operates at high temperatures

11 hours ago

From aerial surveillance to cancer detection, mid-wavelength infrared (MWIR) radiation has a wide range of applications. And as the uses for high-sensitivity, high-resolution imaging continue to expand, MWIR sources are becoming ...

Recommended for you

Carbon accumulation by Southeastern forests may slow

2 hours ago

Carbon accumulation levels in the Southeastern U.S. may be slowing due to forest dynamics and land use changes, according to findings of U.S. Forest Service researchers published in the journal Scientific Reports, Friday ...

Study of new perspective on water management

2 hours ago

Water management should focus more on how robust different areas are in terms of coping with floods and drought. A robust system means that we can deal better with extreme events. High river discharges and long periods of ...

Montana oil spill estimate lowered to 30,000 gallons

19 hours ago

Authorities have lowered their estimate of how much oil spilled from a broken pipeline beneath the Yellowstone River in eastern Montana, briefly contaminating the water supply of a city downstream.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.