Invasive Alien Species in Northern Ireland

Abramis brama, Common bream

Abramis brama (Linnaeus, 1758)
 
Introduction
Since, unlike Great Britain, Ireland had no freshwater connection to the rest of Europe at the end of the last ice age all purely freshwater fish (that is, fish that cannot live in sea water) including those of the Cyprinid family (common bream, rudd, roach, common carp, gudgeon, tench, dace and minnow), and others such as perch and pike, have been artificially introduced to Ireland. The common bream has been present for several centuries in Ireland. It is an important species for ‘coarse’ angling.
 
Description
The common bream is a very deep–bodied freshwater fish with noticeable side–to–side compression and a relatively small head. The back of the fish is dark brown or grey in colour and the sides are silver, often with a bronze hue in older fish. The fins are black. Common bream can grow to about 80cm in length and 9kg mass. It is a long–lived species with fish of over 20 years having been recorded. Common bream interbreeds readily with both roach and rudd producing fertile hybrids, and in some waters hybrids are more numerous than the parental species. Hybrids can be difficult to identify without detailed morphological or genetic analysis.
 
Country of origin
The common bream is native to south–eastern England, Europe and western Asia.
 
Current distribution
The common bream is found throughout most of England, Wales and southern Scotland as well as Europe and western Asia.
 
Location in Ireland
Bream is found throughout slow–flowing sections of the Foyle and Erne and Neagh systems, as well as many smaller water systems, in Northern Ireland. It occurs throughout the Republic of Ireland with the exception of the south-west.
 
Life cycle
Spawning takes place in May and June in shallow weedy areas. Females produce large numbers (up to 300,000 per kg) of small (c.1.5mm) eggs, which are adhesive and stick to water weeds. The young hatch in about 10 days and after the yolk sac is absorbed they feed on plant and animal plankton. Older fish feed largely on insect larvae, snails, crustacean, and other bottom–living invertebrates, for which their extrusible mouth is well adapted. The species prefers enriched weedy lakes, slow–flowing rivers and canals with muddy bottoms and can withstand very low oxygen levels.
 
Wildlife and habitat impacts
As common bream does not achieve the high numbers typical of roach it appears to have limited effect on other freshwater species although inevitably, given its feeding habits, there must be some direct and indirect competition. Its feeding habit of stirring up the bottom mud can result in increased turbidity and release of nutrients when large numbers of fish are present. This can result in decreased submerged plant growth and a decrease in bottom–dwelling invertebrates. Transfer of bream can result in the transfer of diseases and parasites, which can have adverse effects on native fish species.
 
Human impacts
Angling for common bream is popular and it is an important economic resource for angling tourism and recreation.
 
Key vectors
Most spread is due to deliberate introductions to establish angling stocks.
 
What you can do as an individual
Do not move common bream to waters where they do not occur.
 
Advice to specific groups relevant to this species
Common bream should not be introduced into waters where they do not already occur.
 
Management measures
Once introduced, it is effectively impossible to eliminate common bream from larger waters.
 
Management groups
Environment and Heritage Service Northern Ireland
Department of Culture Arts and Leisure Northern Ireland
Fisheries Conservancy Board
Loughs Agency
Central and Regional Fisheries Boards, Republic of Ireland
 
Further information
Links
http://www.cfb.ie/fishing_in_ireland/coarse/bream.htm
http://www.efishbusiness.co.uk/news/040816.pdf
 
Literature
Kennedy, M. and Fitzmaurice, P. (1968). The biology of the bream Abramis bramain Irish waters. Proceedings of the Royal Irish Academy 67B: 95-161.
Rowley, H., Graham, D.A., Campbell, S., Way, K., Stone, D.M., Curran, W.L. and Bryson, D.G. (2001). Isolation and characterisation of rhabdovirus from wild common bream Abramis brama, roach Rutilus rutilus, farmed brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss in Northern Ireland. Diseases of Aquatic Organisms 48: 7-15.
Maitland, P.S. (2004). Keys to the freshwater fish of Britain and Ireland, with notes on their distribution and ecologyFreshwater Biological Association Scientific Publication No. 62. (available from the FBA Publications Department – www.fba.org.uk/fbapub.html).
 
Text written by:
Prof. Andy Ferguson