Navigation Links
Scientists discover the largest assembly of whale sharks ever recorded
Date:5/25/2011

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.

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 sharksthe largest ever reportedwith up to 420 individuals off the coast of the Yucatn 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 Yucatn 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 Yucatn 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.


'/>"/>

Contact: John Gibbons
gibbonsjp@si.edu
202-633-5187
Smithsonian
Source:Eurekalert  

Related biology news :

1. Jefferson scientists deliver toxic genes to effectively kill pancreatic cancer cells
2. Scientists identify novel inhibitor of human microRNA
3. Argonne scientists peer into heart of compound that may detect chemical, biological weapons
4. MU scientists go green with gold, distribute environmentally friendly nanoparticles
5. Scientists identify gene that may contribute to improved rice yield
6. Scientists discover why a mothers high-fat diet contributes to obesity in her children
7. MU scientists see how HIV matures into an infection
8. Earth scientists keep an eye on Texas
9. Thinking it through: Scientists call for policy to guide biofuels industry toward sustainability
10. Scientists identify a molecule that coordinates the movement of cells
11. Scientists Find new migratory patterns for Mediterranean and Western Atlantic bluefin tuna
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Scientists discover the largest assembly of whale sharks ever recorded
(Date:2/4/2016)... Feb. 4, 2016 The field of ... of the most popular hubs of the biotechnology ... other huge studies of human microbiota, have garnered ... years, the microbiome space has literally exploded in ... This report focuses on biomedical aspects of ...
(Date:2/3/2016)... Feb. 3, 2016 Vigilant Solutions announces today ... in Missouri solved two recent ... (LPR) data from Vigilant Solutions. Brian Wenberg ... which the victim was walking out of a convenience store and witnessed an ... to his vehicle, striking his vehicle and leaving the ...
(Date:2/2/2016)... , Feb. 2, 2016 This BCC ... bioinformatic market by reviewing the recent advances in ... that drive the field forward. Includes forecast through ... Identify the challenges and opportunities that exist in ... software solution developers, as well as IT and ...
Breaking Biology News(10 mins):
(Date:2/11/2016)... 11, 2016   BioInformant announces the February ... Research Products, Opportunities, Tools, and Technologies – Market Size, ... The first and ... cell industry, BioInformant has more than a decade of ... market, by stem cell type. This powerful 175 page ...
(Date:2/11/2016)... ... February 11, 2016 , ... ... a new agreement with Bankok,Thailand-based Global Stem Cells Network (GSCN) to distribute exosome ... Latin American countries, including Mexico, Costa Rica, Dominican Republic, Colombia, Argentina, Nicaragua, Panama, ...
(Date:2/10/2016)... MONTREAL , Febr. 10, 2016 /PRNewswire/ - BioAmber Inc. ... is pleased to announce that Mitsui & Co. Ltd., ... bio-based succinic acid plant, is investing an additional CDN$25 ... equity, increasing its stake from 30% to 40%.  Mitsui ... of bio-succinic acid produced in Sarnia ...
(Date:2/10/2016)... Feb. 10, 2016  The Maryland House of Delegates ... announced that University of Maryland School of Medicine Dean ... University of Maryland Medical System President and CEO ... Medallion," the highest honor given to the public by ... Dean Reece and Mr. Chrencik for their ...
Breaking Biology Technology: