I
Ian Cloke
Guest
The Environment Agency has successfully culled more than 100,000 top mouth topmouth gudgeon from a pond in Surrey.
The fish, which are one of the most threatening invasive species in the country, were culled at Juniper Pond, Shalford, on behalf of Guildford Borough Council.
Despite being only 3-4 centimetres long, topmouth gudgeon are particularly threatening to native fish in Britain, and are number seven on the Environment Agency?s list of most wanted invasive species.
As well as eating the eggs of other fish, topmouths, which were introduced to the wild in Britain in the 1960s from their native Asia, breed at four-times the rate of native fish and carry a parasite, similar to, or possibly the same as, a disease called "rosette agent" which is found in some US fish stocks.
Topmouth Gudgeon also eat vast quantities of plant life and invertebrates, which upsets the natural balance of a pond, lake or river. As a result, algal blooms can occur turning the water into a green soup. Had they been left to thrive in the pond, it was feared that they would have seriously affected the ecology of the pond.
The pond is also in the River Wey floodplain and it was feared that a larger flooding event could have washed them into local rivers, where they would have spread to the Thames and threatened a much wider fish population.
The operation involved the use of a fish-orientated pesticide, Rotanone, which killed all the fish in the pond, including several hundred native species such as tench and carp. The fish were then removed from the pond by fisheries officers using nets.
John Sutton, fisheries and biodiversity team leader, who led the operation, said: "It is very sad for us to have to kill native fish along with the topmouth gudgeon, but we have to protect the long term future of our native species.
"Topmouth gudgeon are extremely difficult to get rid of by other means. Using nets to catch them, or transferring other fish out of the pond before the culling takes place is too risky as topmouth fry, which can be the size of an eyelash, can be hidden away in the mouths and gills of other fish and get accidentally transferred to other waters.
continues.......
The fish, which are one of the most threatening invasive species in the country, were culled at Juniper Pond, Shalford, on behalf of Guildford Borough Council.
Despite being only 3-4 centimetres long, topmouth gudgeon are particularly threatening to native fish in Britain, and are number seven on the Environment Agency?s list of most wanted invasive species.
As well as eating the eggs of other fish, topmouths, which were introduced to the wild in Britain in the 1960s from their native Asia, breed at four-times the rate of native fish and carry a parasite, similar to, or possibly the same as, a disease called "rosette agent" which is found in some US fish stocks.
Topmouth Gudgeon also eat vast quantities of plant life and invertebrates, which upsets the natural balance of a pond, lake or river. As a result, algal blooms can occur turning the water into a green soup. Had they been left to thrive in the pond, it was feared that they would have seriously affected the ecology of the pond.
The pond is also in the River Wey floodplain and it was feared that a larger flooding event could have washed them into local rivers, where they would have spread to the Thames and threatened a much wider fish population.
The operation involved the use of a fish-orientated pesticide, Rotanone, which killed all the fish in the pond, including several hundred native species such as tench and carp. The fish were then removed from the pond by fisheries officers using nets.
John Sutton, fisheries and biodiversity team leader, who led the operation, said: "It is very sad for us to have to kill native fish along with the topmouth gudgeon, but we have to protect the long term future of our native species.
"Topmouth gudgeon are extremely difficult to get rid of by other means. Using nets to catch them, or transferring other fish out of the pond before the culling takes place is too risky as topmouth fry, which can be the size of an eyelash, can be hidden away in the mouths and gills of other fish and get accidentally transferred to other waters.
continues.......