The world’s oceans are increasingly over-crowded with sardines, researchers say.
In the last 100 years, the number of small fish – such as pilchards, herrings, anchovies, sprats and sardines – has more than doubled, according to a study.
The rise is caused by a major decline in big ‘predator fish’ such as sharks, tuna and cod due to over-fishing.
Without the natural hunters to keep numbers under control, the population of smaller, plankton-feeding fish has boomed.
School of sardines: In the last 100 years, the number of small fish has more than doubled, according to a study
The scientists who made the discovery say the growing number of small ‘forage fish’ could have serious consequences further down the food chain – and may increase the risk of algae blooms, where populations of simple algae get out of control and choke the oceans.
There are growing concerns among scientists about the impacts of overfishing.
While there are signs that some fish – such as North Atlantic cod – are recovering from years of industrial fishing, some species – such as the giant bluefin tuna praised by Japanese chefs and served in fashionable London restaurants – are now just few years away from extinction.