Featured Research

from universities, journals, and other organizations

Scientists discover the largest assembly of whale sharks ever recorded

Date:
May 30, 2011
Source:
Smithsonian
Summary:
Whale sharks are often thought to be solitary behemoths that live and feed in the open ocean. However, scientists have now found that this is not necessarily the case, finding that whale sharks can be gregarious and amass in the hundreds to feed in coastal waters.

This is an aerial photograph of whale sharks feeding at the Afuera aggregation in August 2009.
Credit: Oscar Reyes

Whale sharks (Rhincodon typus) are often thought to be solitary behemoths that live and feed in the open ocean. Scientists at the Smithsonian Institution and colleagues, however, have found that this is not necessarily the case, finding that whale sharks can be gregarious and amass in the hundreds to feed in coastal waters.

Related Articles


Aggregations, or schools, of whale sharks have been witnessed in the past, ranging from several individual sharks to a few dozen. However this new research, which involved both surface and aerial surveys, has revealed an enormous aggregation of whale sharks -- the largest ever reported -- with up to 420 individuals off the coast of the Yucatán Peninsula in Mexico. What brings them together is food.

"Whale sharks are the largest species of fish in the world, yet they mostly feed on the smallest organisms in the ocean, such as zooplankton," said Mike Maslanka, biologist at the Smithsonian Conservation Biology Institute and head of the Department of Nutrition Sciences. "Our research revealed that in this case, the hundreds of whale sharks had gathered to feed on dense patches of fish eggs."

While whale sharks may seem conspicuous as the heaviest and longest of all fishes, growing more than 40 feet long, there is still much that is unknown about them. They have a very widespread distribution, occurring in all tropical and sub-tropical regions of the ocean around the world. Understanding this filter-feeder's diet is especially important since food sources determine much of the whale shark's movement and location.

During the dozens of surface trips that team members made to the aggregation, called the "Afuera" aggregation, they used fine nets to collect food samples inside and immediately outside the school of feeding whale sharks. Scientists then used DNA barcoding analysis to examine the collected fish eggs and determine the species. They found that the eggs were from little tunny (Euthynnus alletteratus), a member of the mackerel family.

"Having DNA barcoding is an incredibly valuable resource for this research," said Lee Weigt, head of the Laboratories of Analytical Biology at the Smithsonian's National Museum of Natural History. "It not only allowed us to know what exactly this huge aggregation of whale sharks were feeding on, not readily done from only physical observations of eggs, but it also revealed a previously unknown spawning ground for little tunny."

The team of scientists also examined a nearby, less dense aggregation of whale sharks, known as the Cabo Catoche aggregation, off the northern tip of the Yucatán Peninsula. They found that the prey of this group mostly consisted of copepods (small crustaceans) and shrimp. Increased sightings at Afuera coincided with decreased sightings at Cabo Catoche, and both groups had the same sex ratio, implying that the same animals were involved in both aggregations.

"With two significant whale shark aggregation areas and at the very least one active spawning ground for little tunny, the northeastern Yucatán marine region is a critical habitat that deserves more concerted conservation effort," said Maslanka.

The whale shark is listed as "vulnerable" with the International Union for Conservation of Nature and Natural Resources. Populations appear to have been depleted by harpoon fisheries in Southeast Asia and perhaps incidental capture in other fisheries.

The scientists' findings were published in the scientific journal PLoS ONE, April 2011. In addition to the Smithsonian Institution, team members were from the Comisión Nacional de Áreas Naturales Protegidas in Cancún, Mexico, the Center for Shark Research in Sarasota, Fl., project DOMINO and the Georgia Aquarium, Inc. in Atlanta, Ga.


Story Source:

The above story is based on materials provided by Smithsonian. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rafael de la Parra Venegas, Robert Hueter, Jaime González Cano, John Tyminski, José Gregorio Remolina, Mike Maslanka, Andrea Ormos, Lee Weigt, Bruce Carlson, Alistair Dove. An Unprecedented Aggregation of Whale Sharks, Rhincodon typus, in Mexican Coastal Waters of the Caribbean Sea. PLoS ONE, 2011; 6 (4): e18994 DOI: 10.1371/journal.pone.0018994

Cite This Page:

Smithsonian. "Scientists discover the largest assembly of whale sharks ever recorded." ScienceDaily. ScienceDaily, 30 May 2011. <www.sciencedaily.com/releases/2011/05/110525164114.htm>.
Smithsonian. (2011, May 30). Scientists discover the largest assembly of whale sharks ever recorded. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2011/05/110525164114.htm
Smithsonian. "Scientists discover the largest assembly of whale sharks ever recorded." ScienceDaily. www.sciencedaily.com/releases/2011/05/110525164114.htm (accessed October 24, 2014).

Share This



More Plants & Animals News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) — Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) — Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) — One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) — Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins