Featured Research

from universities, journals, and other organizations

Whale sharks may produce many litters from one mating, paternity test shows

Date:
August 31, 2010
Source:
University of Illinois at Chicago
Summary:
Biologists analyzed genetic information from preserved whale shark embryos taken from a female caught off the coast of Taiwan 15 years ago. They found all offspring to have the same father -- an unusual reproduction characteristic for sharks.

Whale shark. UIC researcher Jennifer Schmidt, associate professor of biological sciences, studies the large fish.
Credit: Jennifer Schmidt; Copyright University of Illinois Board of Trustees

How do female whale sharks meet their perfect mates and go on to produce offspring? While little is known about the reproductive behavior of these ocean-roaming giants, a newly published analysis led by University of Illinois at Chicago biologist Jennifer Schmidt reveals new details about the mating habits of this elusive, difficult-to-study fish.

Schmidt, a UIC associate professor of biological sciences, determined paternity of 29 frozen embryos saved from a female whale shark caught off the coast of Taiwan in 1995. The embryos, studied in collaboration with Professor Shoou-Jeng Joung at the National Taiwan Ocean University, are extremely rare.

The pregnant shark carried a surprisingly large number of embryos -- 304 -- still in the uterus and representing a spectrum of age and development stages ranging from being still egg-encased to developed, near-term animals.

Schmidt and her colleagues spent several years developing DNA genetic markers to study whale sharks, initially for population genetics, but in this study the tool was used to determine paternity.

Shark reproduction is still an emerging science, but what is known suggests that most broods are sired by more than one male. That is not what Schmidt found with this particular female whale shark.

"These differently aged embryos -- itself unusual across animal species -- had the same father," Schmidt said. "We have to be very cautious in drawing conclusions from a single litter, but the data suggest female whale sharks store sperm after a single mating event, and subsequently fertilize their own eggs as they are produced."

If the finding can be supported from analysis of other whale shark litters, Schmidt said, "it would suggest that there is no whale shark breeding ground where large numbers of animals meet to mate, but rather that mating occurs as an isolated event."

Follow-up studies may be serendipity. International protocols protect whale sharks from capture, few are housed in aquariums, and those that are are usually less than 25 years old and not yet sexually mature. Scientists typically study whale sharks at seasonal feeding grounds, but those animals are usually juveniles not mature enough to breed. Rarely are adult females observed in the wild.

"Protections for whale sharks have increased in many parts of the world, yet shark numbers seem to be declining, and the average size is getting smaller," said Mark Meekan, principal research scientist with the Australian Institute of Marine Sciences.

"This is a classic sign of overfishing, where larger, more valuable animals are selectively removed," he said. "Targeted fishing of breeding-age animals in a late-maturing species can be devastating for its survival."

The findings are reported in the journal Endangered Species Research, published online Aug. 4. Other authors include Meekan; Joung and Chien-Chi Chen of the National Taiwan Ocean University; Saad I. Sheikh, formerly of UIC; and Bradley Norman of ECOCEAN Inc.

The work was funded by a grant from Project Aware.


Story Source:

The above story is based on materials provided by University of Illinois at Chicago. Note: Materials may be edited for content and length.


Journal Reference:

  1. Schmidt et al. Paternity analysis in a litter of whale shark embryos. Endangered Species Research, 2010; 12 (2): 117 DOI: 10.3354/esr00300

Cite This Page:

University of Illinois at Chicago. "Whale sharks may produce many litters from one mating, paternity test shows." ScienceDaily. ScienceDaily, 31 August 2010. <www.sciencedaily.com/releases/2010/08/100824184754.htm>.
University of Illinois at Chicago. (2010, August 31). Whale sharks may produce many litters from one mating, paternity test shows. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2010/08/100824184754.htm
University of Illinois at Chicago. "Whale sharks may produce many litters from one mating, paternity test shows." ScienceDaily. www.sciencedaily.com/releases/2010/08/100824184754.htm (accessed April 18, 2014).

Share This



More Plants & Animals News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Vermont Goat Meat Gives Refugees Taste of Home

Vermont Goat Meat Gives Refugees Taste of Home

AP (Apr. 18, 2014) Dairy farmers and ethnic groups in Vermont are both benefiting from a unique collaborative effort that's feeding a growing need for fresh and affordable goat meat. (April 18) Video provided by AP
Powered by NewsLook.com
The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Flamingo Frenzy Ahead of Zoo Construction

Flamingo Frenzy Ahead of Zoo Construction

AP (Apr. 17, 2014) With plenty of honking, flapping, and fluttering, more than three dozen Caribbean flamingos at Zoo Miami were rounded up today as the iconic exhibit was closed for renovations. (April 17) Video provided by AP
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
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:
from the past week

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