A thorough visual survey of the watercourse and its surrounding 100-meter buffer (where access permits) will be conducted. Field signs indicative of otter presence, including live or dead otters, holts, dens, couches, tracks, trails, and spraint, will be recorded.

To complement visual observations, trail cameras may be deployed to capture otter activity on record.

Otter surveys can be conducted throughout the year, although they are often integrated with water vole surveys, which have more restricted seasonal windows.

Otter surveys should be avoided during and immediately following periods of heavy rain and high water levels, as these conditions can wash away key evidence of otter presence.