Abstract:
The black bullhead Ameiurus melas was introduced to
Europe from North America in the early 20th Century and
invasive populations are now present in many European
countries (Novomesk a et al., 2013). Their invasion is assisted
by their traits of high reproductive output, parental care,
omnivory, aggressive behaviour and tolerance to environmental
parameters (e.g. Leunda et al., 2008; Novomesk a
et al., 2013). In the UK, however, they are not invasive, with
only a single, persistent wild population believed to be present
(Britton et al., 2010). The lag phase – the time period
between the introduction of a species and an invasion developing
– can be considerable for non-native fishes. For many
species, its cessation requires a change in environmental conditions
and/or the provision of a new dispersal opportunity
(Fausch, 2007).
The aim of this study was to assess the reproductive ecology
and diet of A. melas in UK conditions through assessment
of this persistent population. As there was only one
population available, the plasticity of their traits in UK conditions
could not be assessed; however, the study results are
compared with their populations elsewhere. An assessment is
then made to identify whether these aspects of their ecology
are inhibiting their invasion of UK freshwaters. Note that
Novomesk a et al. (2013) recently concluded that morphological
plasticity was not a factor affecting their invasive ability
and so is not considered here.
