Fish in River Kennet change their diet following pollution incident

The full ramifications of the changes will not be known for some time, the annual general meeting of the Action for the River Kennet (ARK) conservation group heard.
The meeting took place in the Hungerford Corn Exchange on Thursday, November 7, and one of the main items on the agenda was the pesticide pollution update.
More than 60 ARK members heard that the pollution incident continued to cause major environmental changes.
The pollution was first discovered on July 1 by ARK volunteer riverfly monitors.
Subsequent investigations by the Environment Agency (EA) revealed the culprit was a lethal insecticide identified as chlorpyrifos.
As little as a few teaspoonsful are thought to have entered the watercourse from a water treatment works in Marlborough, Wiltshire, leading to a 15km stretch of water down to Hungerford being affected.
The River Kennet is a Site of Special Scientific Interest (SSSI) and one of England’s finest chalkstreams. The incident is one of the largest ever and wiped out insect life – a major source of food for fish and other wildlife – in around a third of the river.
The source of the contamination was never found.
The meeting heard that brown trout and other fish in the river appear ill-equipped for winter following the disastrous chemical spill.
ARK director Charlotte Hitchmough said the entire base of the food chain has been removed, causing fish to alter their diets.
She added: “They are partly eating more terrestrial invertebrates, smaller fish and even small crayfish.
Delegates heard that, while large fish appear to coping at the moment, smaller fish stocks have been greatly reduced.
This, in turn, could have a knock-on effect as there are fewer small fish for the large fish to eat.
ARK chairman Geoffrey Findlay said: “The rapid response and follow-up actions of all concerned were a good example of voluntary sector and public partners working together.”