A novel approach to spatially assessing instream woody habitat densities across large areas.

Fish habitat restoration efforts frequently involve the reintroduction of instream woody habitat (IWH) in areas where large scale removal has taken place over time. Identifying areas of low IWH density for reintroduction requires a 'current state' spatial representation of the IWH densities that is traditionally a labour intensive and costly exercise. We present a meso-macro scale assessment procedure that incorporates a rapid on-ground field survey method with a novel analytical approach to map IWH densities. In situ IWH locations with categorical values for size and complexity were obtained along the lower Ovens River in South Eastern Australia. Despite relatively high densities of IWH and limited access, 120 km of river was able to be investigated. A bound kernel density estimate (BKDE) analysis was performed using the IWH point locations, weighted by an average volume inferred from the point size and complexity values. A fine scale map is obtained providing a continuous representation of IWH densities (m(3) m(-2)) indicating a high degree of IWH density variability along the river. The relative high resolution map is produced for habitat restoration managers to assess river sections generally less than 1 km long for IWH reintroduction.