Sharks dive by the moon

2013-04-16 14:09

(Patrik Stollarz, AFP)

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

kalahari.com

Sydney – The moon and water temperature affect the diving behaviour of sharks, researchers reported on Tuesday, in a discovery that could help prevent fishermen from catching the marine predators inadvertently.

A team from the University of Western Australia's Oceans Institute and the government-run Australian Institute of Marine Science spent nearly three years monitoring grey reef sharks off Palau in the Pacific.

They tagged 39 sharks, common on coral reefs throughout the Indo-Pacific region, and used acoustic telemetry to follow them, finding they stayed in deep water on full moon nights but rose to the shallows with the new moon.

Similar patterns have previously been recorded in species such as swordfish, yellowfin and big eye tuna, suggesting the reef shark behaviour was related to feeding.

The study also said it may be an anti-predator response where reef sharks seek to avoid increased light nearer the surface that may aid the hunting abilities of larger sharks.

"We also found that the diving behaviour of grey reef sharks was related to water temperature," said lead researcher Gabriel Vianna.

The sharks, mostly adult females, dived to an average depth of 35m in winter when deeper water was colder and 60m in spring when temperatures warmed up.

In summer, when the warmer layer of surface water expanded, the sharks tended to move in a broader range of depths.

The authors said that because sharks were cold-blooded, they may prefer warmer waters to conserve energy.

Findings

The research, published in the science journal Plos One, also found that the time of day could affect how deeply sharks dive.

"We were surprised to see sharks going progressively deeper during the morning and the exact inverse pattern in the afternoon, gradually rising towards the surface," Vianna said.

"This matches how light changes on the reef during the day. To our knowledge, this is the first time such patterns have been observed in detail for reef sharks."

Vianna said the research had conservation implications with their diving behaviour potentially helping prevent sharks being inadvertently caught by fisherman at different times of the day.

"In places such as Palau, which relies heavily on marine tourism and where sharks are a major tourist attraction, the fishing of a few dozen sharks from popular dive sites could have a very negative impact on the national economy," she said.

- SAPA

Read more on:    australia  |  marine life
NEXT ON NEWS24X

Read News24’s Comments Policy

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
Add your comment
Comment 0 characters remaining
 

Inside News24

 
 

Zuma: Pray for peaceful polls

President Jacob Zuma has asked members of the Universal Church of the Kingdom of God to pray for peaceful elections on 7 May.

 
 

Latest elections multimedia

Why Jack Parow wants you to vote on 7 May
The ad the SABC doesn't want to air
Elections 2014 in one cartoon
This year's election posters
 
Traffic
Lottery
 
  • Saturday Cape Town - 07:32 AM
    Road name: N2 Inbound
    ACCIDENT after Jan Smuts Drive
  • Saturday Constantia - 07:19 AM
    Road name: Rhodes Drive Both Ways
    ROAD CLOSED between Constantia Nek and Canterbury Road until 1300
 
More traffic reports...
 

Jobs in Cape Town [change area]

Property [change area]

Travel - Look, Book, Go!

Escape winter, head to Mauritius

Escape winter by spending 7 nights in Mauritius' tropical bliss from R13 215 per person sharing. Includes return flights, airport transfers and accommodation. Book now!

Kalahari.com - shop online today

Get many eggs in one basket!

Gaming bundles: 2 Super Hits games for R99, 3 Disney games for R99 and more + exclusive accessory bundles only available on kalahari.com. While stocks last. Shop now!

25% off bestselling books!

The Real Meal Revolution by Tim Noakes, Jeffrey Archer’s Be Careful What You Wish for, Man’s Search for Meaning by Victor E. Frank and many more titles. Shop now!

Up to 25% off electronics

Buy top electronics and save up to 25%. Such as kalahari.com’s 1# selling product the gobii eReader, Patriot X Porter flash drive, Asus Nexus 7” 3G tablet, Samsung Galaxy SIII, Lenovo G580 Notebook and many more. Shop now!

DStv HD PVR Decoder now R949

The DStv HD PVR Decoder has further revolutionised the television experience with lifelike viewing, sharper images, more vibrant colours and precision picture quality. Now R949, save R550. Offer valid while stocks last. Shop now!

Up to 30% off appliances & homeware

Save up to 30% on appliances and homeware this Easter! Offer valid while stocks last. Shop now.

OLX Free Classifieds [change area]

Samsung Galaxy s4

Mobile, Cell Phones in South Africa, Western Cape, Cape Town. Date October 24

Best bargain in big bay

Real Estate, Houses - Apartments for Sale in South Africa, Western Cape, Cape Town. Date October 25

VW Golf 6, 1.6 Trendline (Excellent condition)

Vehicles, Cars in South Africa, Western Cape, Cape Town. Date October 25

Samsung Galaxy Note 16GB

GALAXY Note combines the market's largest HD Super AMOLED display,...

From R3899.00

I'm shopping for:

Horoscopes
Aquarius
Aquarius

Self-indulgence may be strong today. You may want to enjoy yourself to the fullest and share it with those that make you feel...read more

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.