Brown trout Salmo trutta Linnaeus, 1758,
is a priority species for conservation and management
efforts in many European countries. In its native range,
interactions with non-native fishes often adversely
affect somatic growth rates and population abundances.
Consequences of introduced North American
pumpkinseed Lepomis gibbosus (Linnaeus, 1758) for
native S. trutta were examined in stream stretches with
and without L. gibbosus. Data for somatic growth rates
and trophic niche breadth (using stable isotope L. gibbosus for S. trutta in the study stream were
minimal, with S. trutta populations responding more
to natural mechanisms regulating their populations
than to the presence of this non-native fish species.