Shark deaths pack oceans with small fish
The oceans are becoming over-crowded with sardines due to the decline of big predators.
London: The oceans are increasingly becoming over-crowded with sardines thanks to the huge decline of big predators like sharks, as also tuna and cod due to overfishing, scientists say.
Over the 100 years since Victorian times, the number of small fish, including sardines, has more than doubled, according to a study.
University of British Columbia scientists in Canada, who made the discovery, say the growing number of small `forage fish` could have serious consequences further down the food chain.
They may increase the risk of algae blooms, where populations of simple algae get out of control and choke the oceans, the Daily Mail reports.
The new study, carried out by a team of international scientists, is the first world-wide analysis of the impact of commercial fishing since Victorian times, according to a British Columbia statement.
Using data on fishing going back to 1880, the researchers took more than 200 local snapshots of marine life from around the world and used computer models to estimate numbers.
Lead researcher Villy Christensen, of the University of British Columbia, said: "Overfishing has absolutely had a `when cats are away, the mice will play` effect on our oceans.
"By removing the large, predatory species from the ocean, small forage fish have been left to thrive.
He added: "If you take out the lions, then the number of antelope go up - and that`s what`s been happening in the oceans."