Fish in the ponds of Clissold Park in Stoke Newington will be poisoned this month in order to eradicate a non-native species.
The topmouth gudgeon eats the eggs of native fish species and competes with them for food supplies, meaning that it poses a serious threat to population numbers of native fish species — potentially wiping them out entirely. It's thought that the topmouth gudgeon was introduced to the water by an owner who no longer wanted them — similar to the purge on non-native terrapins which were removed from Clissold Park last year.
The parks's two ponds and the New River will be treated by DEFRA (the government Department for Environment, Food and Rural Affairs) with rotenone, a piscicide (fish poison) which will kill all species of fish. It is said that other animals, such as birds, will not be harmed in the process and should not be dangerous to humans or pets. Minimal damage may be caused to invertebrate species however, but they are expected to recover quickly.
This is one of 23 populations of topmouth gudgeon known to exist throughout the country. 15 have already been eradicated successfully.
Hackney Council states that the methods used "will ensure that the fish are eradicated rapidly with minimum stress". The park will remain open throughout the work, but access to areas around the waterways may be restricted for short periods of time.
What does this mean for the future of aquatic wildlife in Clissold Park? According to Hackney Council
"The treatment and removal of this invasive non-native fish will have long lasting benefits. There will be greatly reduced impacts on native aquatic ecology leading to improved or wider biodiversity value to the waterbodies."
The council plans to restock the ponds with native fish two to three months after the work takes place, by which time the rotenone in the water will have broken down.
Anyone with questions not answered in this document can attend an Environment Agency meeting this Thursday at 7pm at the new Clissold Park Tennis Pavilion. RSVP to firstname.lastname@example.org to attend.
Take a look at the other non-native species on the loose in London.