Why are smaller, less interconnected bull trout populations genetically less resilient?
They are less resilient to disease, environmental fluctuations, or random mortality events.
The inherent fragility of the bull trout is amplified by its current fragmented distribution pattern, where remaining populations exist as small, disconnected groups. From a genetic stability perspective, small, isolated populations inherently lack the robustness of large, contiguous populations. They cannot effectively buffer against adverse events. For instance, if one isolated stream segment experiences a catastrophic die-off—caused by a sudden pollution spill or an extreme, short-term heatwave—that entire sub-population may be completely wiped out. Because migration corridors are frequently blocked, there is no nearby, healthy recovery population available to naturally repopulate the devastated area, making the protection of every single tributary absolutely critical for species survival.
