Fish Migrate to Safer Grounds to Avoid Predators

Fish opt for migration as a strategy to avoid the threat of being eaten by predators, according to press reports.

Study researchers noticed that the roach fish, the commonest fish in the U.K. waters, migrate from lakes into the surrounding streams or wetlands in order to protect themselves from predators.

The study was conducted by researchers at the Lund University in collaboration with Danish researchers.

Prior to this, other studies have shown how animals migrate in search of food, and other drastic environmental factors which have made them migrate.  But only a few have showed that migration is a strategy to avoid predators. It is very challenging to determine and calculate the risk of an animal being eaten.

"Our findings are therefore quite unique," Ben Chapman, a researcher from the Department of Biology at Lund University, said in a press statement.

In the presence of a large number of cormorants hunting in the lake, the roach fish safely migrate to streams and wetlands. Predators are the reason for the seasonal migration in animals.

In this study, the researchers individually marked thousands of fish with a small chip that was similar to a barcode. They moved the resting place of cormorants and scanned the ground for the chips in the birds' excrement.

With this technique, they managed to get a huge quantity of data relating to fish that were eaten. They observed that the larger roach served as a prey to the cormorants.

The study is published in the scientific journal Biology Letters and will be featured in Nature.