Brown Bullhead Catfish
Habitat: Slow flowing freshwater streams and rivers as well as low energy lakes with maximum depth of 40m
Description: Ameiurus nebulosus, the brown bullhead is a species of catfish native to North America and introduced to a number of other countries around the world as a game fish.The brown bullhead (A. nebulosus) is frequently confused with black bullhead Ameiurus melas (southern Canada, USA and parts of Mexico), yellow bullhead Ameiurus natalis (southern Canada, parts of USA), snail bullhead Ameiurus brunneus (southern USA), spotted bullhead Ameiurus serracanthus (southern USA) and flat bullhead Ameiurus platycephalus (southern USA). A. nebulosus is immediately distinguishable from spotted bullhead by the lack of obvious darkened blotches running the length of the body, whereas a strongly depressed head distinguishes the flat bullhead. Differences between brown, black and yellow bullhead are more conspicuous and concern the morphology of anal rays and pectoral spines. While the yellow bullhead’s anal fin overlaps anterior rays of its caudal fin, both brown bullhead and black bullhead have anal fins that do not reach anterior rays of the caudal fin. Yellow bullhead have relatively smooth pectoral spines; black bullhead possess barbs that point towards head when fins are closed against the body; whereas, the barbs of brown bullhead point towards the caudal fin when closed (Scott and Crossman, 1973; Fuller et al., 1999).
It is a hardy species that can tolerate a wide range of environmental conditions, including water pollution, allowing it to successfully establish outside of its native range. It can be highly adaptable to different environments and is a habitat generalist. It tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc. and is pioneering in disturbed areas. It is capable of securing and ingesting a wide range of food and is very fast growing with a high reproductive potential.
Origin and Distribution: Native to North America but is now present in parts of Europe, Russia, China and New Zealand
Impacts: The impacts associated with this species are currently unclear but similar to all non-native species there is concern for this species to spread parasites and fish disease. There are also some reports of potential impacts on trout and eel fisheries and reports of impacts on crayfish which is of particular concern to the endangered White Clawed Crayfish.
In areas where it is invasive, it has been known to alter habitats and trophic levels in water bodies and damage ecosystem services, reducing native biodiversity.
How could it get here? Highly likely to be transported internationally deliberately for angling purposes. Considered a valued game fish in some areas.
Is it found in Ireland? Status in either Ireland or Northern Ireland is unconfirmed.
You can check at National Biodiversity Data Centre species maps for Ireland - http://maps.biodiversityireland.ie/
or at CEDaR Invasive Species maps at - www2.habitas.org.uk/records/maps