UK Wildlife Blog

This colourful fish has a deep body which is laterally compressed and grows to about 22cm long. Despite its small size they are popular with anglers (Sea grant, 2002) due to there ‘strong fight’ when caught.
I usually inhabits smaller, cool, clear, shallow well vegetated lakes and slow flowing rivers. Here it feeds on plankton, invertebrates and fish fry (including its own species). It breeds between May and October, when the male digs a pit and the female lays 600-4000 eggs (Lever, 1977), with these nests often occurring in colonies (Cihar, 1994). The may will then aggressively guard them until they hatch and the fry leave.
It was first brought to the UK as an ornamental fish about 100 years ago (The Argus, 2005). From what I can gather from the literature the Pumpkinseed fish (Lepomis gibbosus ) has been introduced to Europe by 3 possible means:

1)Introduced by aquarists (Cihar, 1994), to ornamental ponds and then escaping or released from aquariums when they grew to large and/or ponds due to there habit of eating and fighting with each other and other species of fish
2)Accidentally introduced as fry among other more economically important fish (Cihar, 1994)
3)Purposeful attempts to naturalized a population in the UK (Lever, C., 1977)

Lever (1977) reports that the Pumpkinseed was imported to continental Europe between 1887 (to France) and 1917, where it is now established from France eastward across to western Russia.
The Pumpkinseed was established and breeding in 4 separate waters according to Lever (1977). During the 1st World war there are reports from Groombridge in Sussex and a colony being established in Fife. There are also reports in the 50s, 60, and 70s from Bridgewater, Somerset and Crawley, Sussex and Leytonstone Essex in 1974.
The Environment Agency is researching the possible threat to native species from this fish (The Argus, 2005). They report its presence to be mainly in East and west Sussex, with reports from London and Cambridgeshire too. The worry is there habit of eating fish eggs and fry, which could have a damaging effect on native species. In fact the selling and purchasing this species without a license in now illegal in the UK.
Lever (1977) commented on the relatively unsuccessful colonisation of the UK by this fish, when compared to the invasion of Europe, citing “adverse climatic conditions” as the probable cause. But with global warming Lever’s “adverse climatic conditions” could disappear and the Pumpkinseed could spread, possibly at the expense of native species (The Argus, 2005)




References

Cihar, J., 1994, Freshwater Fish , Harvey bookshops Ltd., pg174-175

Lever, C., 1977, The Naturalized Animals of the British Isles , Hutchinson of London, pg 484-486

Miller, P., 1997, Collins Pocket Guide: Fish of Britain and Europe, Harper Collins, pg.182

Sea grant, 2002, http://www.seagrant.wisc.edu/greatlakesfish/fpumpkinseed.html

The Argus, 2005, http://archive.theargus.co.uk/2005/2/3/105721.html



For more on the Non native fauna in the UK see here: Alien species