Hundreds of fish and eels were found dead in one of London’s busiest canals after the heatwave.
Environment Agency teams were called at the weekend after the marine life was spotted on the surface of the Grand Union Canal. About 400 fish were removed from a basin of water near to Kensal Green that included pike, tench, perch and roach.
Tests are being carried out by the Canal & River Trust to find the cause. An Environment Agency spokesman said: “We currently believe the causes were natural following the hot weather, however, at the moment we can’t rule out pollution in the canal.”
Extra oxygen was pumped into the water after the removal operation. Waterways can heat up in summer causing a reduction in oxygen levels.
The canal is also experiencing high levels of duckweed, that can also threaten marine life by depleting sunlight hitting the water and further reducing oxygen levels.
Duckweeds are ladybird-sized flowering aquatic plants that float on the surface of slow-moving water, blanketing it in a green crust. Nearly 800 tons of the suffocating weed have been scooped from London’s waterways by the trust since April as temperatures have risen. Joe Coggins, spokesman for the trust, said: “Our teams working out on the water will continue to monitor for any signs of fish distress and will continue to remove duckweed.
“We look after over 100 miles of canals in London and ask people living and working on the water to get in touch if they are concerned about fish.
“The cooler weather and rain will definitely help improve conditions for wildlife on the water, and helps to disperse duckweed.”
