One invasive fish can suppress another—and leave a native remnant in the middle
WHAT THE EVIDENCE SAYS
A river survey recorded 2,546 fish representing 17 species, seven of them introduced. Sharptooth catfish frequency was negatively associated with fish diversity, while invasive black bass showed the opposite broad association; flow barriers, high catfish abundance and turbidity appeared to suppress visually hunting bass enough for endangered Berg-Breede whitefish to persist at very low frequency.
WHY IT MATTERS / OUR READ
In invaded systems, management can face interacting pressures rather than one clean native-versus-invasive axis. Removing one stressor can change the effect of another, which makes food-web and barrier context relevant to control decisions.
CAVEATS / UNCERTAINTY
The whitefish remnant is persistence, not recovery. The evidence is observational and site-specific, and antagonism among invasive fishes is not an argument to retain invasive species or barriers; intervention effects would need direct testing.
SOURCE
Biological Invasions
View original evidence ↗
In South Africa’s Breede River, flow barriers, turbidity and abundant sharptooth catfish appear to damp black-bass predation enough for an endangered whitefish to persist at extremely low frequency.
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