Area Occupied Justification:
Still widely distributed in the Sacramento-San Joaquin watershed and Russian River
Pop Size Justification:
Not known but large populations seem to exist.
Intervention Dependence Score:
Intervention Dependence Justification:
Monitoring is needed to establish current status but known stressors (e.g. unnatural flow regimes, alien species predation) should be mitigated.
Hardhead are sensitive to habitat alterations associated with flow, turbidity and temperature.
Genetic Risk Justification:
Many populations are small and isolated.
Climate Change Justification:
Hardhead may be vulnerable in inland waters due to changes in flow and sediment regimes associated with climate change.
A number of major threats can change status quickly
Information on life history, habitat preferences and environmental tolerances were available. However, information on current status (e.g. population index, abundance estimates) was not.