by Brooks Hays
Washington (UPI) Apr 20, 2017
As shark populations decline, fish face less pressure from the top of the food chain. As a result, new research shows, fish are getting fatter.
Researchers from the University of Western Australia and the Australian Institute of Marine Science studied fish behavior in Rowley Shoals and Scott Reefs. The former, a marine preserve, hosts healthy shark populations. The latter, an atoll-like reef off the northern coast of Australia, is a popular location for shark fishermen from Indonesia.
The team of scientists observed reef fish spending more time hunting and feeding in the water column near Scott Reefs, where sharks are rare. Spending time in the water column puts fish at risk of ambush, but it's also home to more energy-rich prey.
Fish living among Rowley Shoals were observed mostly hunting and feeding close to the coral reefs, where sharks are less abundant and escape routes are plentiful. Food here, however, is less calorie-dense.
Scotts Reefs fish were 28 percent heavier than those from Rowley Shoals.
"Fear is known to be an important driver of behaviour in animals," marine scientists Shanta Barley said in a news release. "When the risk of being attacked is high, prey eat less, fight less, mate less and, in general, do less. They also spend more time in shelter."
Shark populations around the globe continue to shrink. More than half of all shark and ray species are vulnerable or threatened. Yet, the ecological impacts of their losses aren't well understood.
"These changes may have important implications for coral reefs," said Jessica Meeuwig, a professor at UWA. "Fatter fish produce more offspring than skinnier fish and have better survival rates, so our results suggest that shark overfishing has the potential to transform reefs."
A number of studies have highlighted the importance of large marine predators to ecological balance and ocean health.
Researchers published their latest findings in the journal PLOS ONE.
Edmonton, Canada (SPX) Apr 20, 2017
Four hundred and thirty million years ago, long before the evolution of barracudas or sharks, a different kind of predator stalked the primordial seas. The original sea monsters were eurypterids - better known as sea scorpions. Related to both modern scorpions and horseshow crabs, sea scorpions had thin, flexible bodies. Some species also had pinching claws and could grow up to three metre ... read more
Water News - Science, Technology and Politics
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|