Fish migrate to safer environments

Mar 01, 2013
Antennas that detect pittagged fish migrating between lake and stream. Credit: Jes Dolby

Research now reveals that fish can migrate to avoid the threat of being eaten. A new study from Lund University in Sweden shows that roach fish leave lakes and move into surrounding streams or wetlands, where they are safer from predators.

Every year, millions of animals migrate worldwide. In most cases, this is due to a shortage of food or other . However, few research studies have focused on migration as a strategy to avoid predators. It is not easy to measure and quantify the risk of an animal being eaten.

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

In collaboration with Danish colleagues, the researchers at Lund University have published the results of their study. These show that fish, in this case roach, flee from a lake to surrounding streams and when there are a large number of cormorants hunting in the lake. Ben Chapman and his colleagues note that their findings are among the first evidence that the threat of predators can be a reason for seasonal migration in animals.

The researchers used an inventive method to track the fate of individual roach. They individually marked thousands of fish with a little chip resembling a , and then went to the cormorants' resting places and scanned the earth for chips in the birds' excrement – i.e. the remains of the fish that have passed through the birds' digestive systems. In this way, the researchers have been able to obtain large quantities of data on which fish were eaten. It emerged that it was mostly larger roach that fell victim to the cormorants. 

The has been carried out in the Danish lakes of Viborg and Loldrup on Jutland. In the next fieldwork season, the researchers plan to expand their work to include Krankesjön lake in southern Sweden and to investigate whether fish can change their in response to increasing numbers of .

The study has been published in the scientific journal Biology Letters rsbl.royalsocietypublishing.or… 121178.full.pdf+html and will also be featured in Nature.

Explore further: Sea star disease strikes peninsula marine centers

More information: Skov, C. et al. Migration confers survival benefits against avian predators for partially migratory freshwater fish, Biol. Lett. 2013, 9, 2012 1178, 27 February 2013.

Related Stories

Dead midges reveal living conditions of fish

Apr 04, 2011

Microscopic remains of dead Phantom midge larvae (Chaoborus spp.) may explain a few hundred years of history of the living conditions of fish, acidification and fish death in Swedish lakes. Researchers at the ...

Lakes react differently to warmer climate, study finds

Oct 04, 2012

A future warmer climate will produce different effects in different lakes. Researchers from Lund University in Sweden have now been able to explain that the effects of climate change depend on what organisms are dominant ...

Great Lakes fish feed on invading shrimp

Nov 22, 2011

Hemimysis anomala, or more commonly the bloody red shrimp after its bright red spots—may become a new food source for fish, allaying concerns about how it will impact native fish populations.

Recommended for you

Seeds keep vital much longer when stored without oxygen

13 hours ago

If seed breeding companies, gene banks and the Svalbard Global Seed Vault on Spitsbergen should store plant seeds under oxygen-poor conditions, it would be possible to store them for much longer while still ...

Native species may be hindering fox control efforts

13 hours ago

Native species interfering with ground distributed baits used to control red foxes in south west Western Australia may mean the baits are not available to the target species, a Murdoch University study has ...

Giant anteaters kill two hunters in Brazil

Jul 26, 2014

Giant anteaters in Brazil have killed two hunters in separate incidents, raising concerns about the animals' loss of habitat and the growing risk of dangerous encounters with people, researchers said.

User comments : 0