Shark overfishing endangers reefs, study finds

2013-09-19 13:01
Shark.

Shark. (Patrik Stollarz, AFP)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

Sydney - Scientists studying remote reefs off Australia said on Thursday sharks played a fundamental role in coral health, with overfishing of the marine predators increasing reef vulnerability to global warming and disasters.

A research team, led by Mark Meekan from the Australian Institute of Marine Sciences, studied the impact of sharks at the Rowley Shoals and Scott Reefs some 300km off Australia's north-west coast over a period of 10 years.

"Where shark numbers are reduced we see a fundamental change in the structure of food chains on reefs," said Meekan.

"We see increasing numbers of mid-level predators such as snappers, and a reduction in the numbers of herbivores such as parrot fishes.

"The parrot fishes are very important because they eat the algae that would otherwise overwhelm young corals on reefs recovering from natural disturbances."

Global warming

The study compared the impacts of cyclones and bleaching events on the marine-protected Rowley Shoals, where fishing is banned, with the neighbouring Scott Reefs, where Indonesian fishermen are permitted to hunt sharks.

It found less coral and more algae on the fished reefs after a major disturbance, which Meekan said was a significant result as the pressures of global warming increased.

"With many of the changes from a warming climate already locked in, there may be little we can do to prevent increased frequency of disturbances on coral reefs in the near future," he said.

"However, this is not the case with the loss of reef sharks."

Meekan said the findings showed declining global reef shark populations due to overfishing was of "great concern" because it would leave the coral structures more vulnerable to bleaching events from warmer, more acidic oceans, and large cyclones.

But even small no-fishing zones in reef areas could provide valuable feeding sites for sharks, maintaining a delicate ecosystem balance ensuring algae-eating species could thrive, he added.

According to the team their study, published in the latest edition of peer-reviewed scientific journal Plos One, had offered a "unique opportunity" to isolate and examine the impacts of sharks on an entire reef ecosystem's health in a way not attempted before.
Read more on:    marine life

Join the conversation!

24.com encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
0 comments
Comments have been closed for this article.

Inside News24

 
/News

Book flights

Compare, Book, Fly

Traffic Alerts
There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.




Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.