Spatial arrangement and physical characteristics of structural woody habitat in a lowland river in south-eastern Australia

1. The importance of structural woody habitat (SWH) as instream fish habitat in eastern Australia has been well documented. In response, many native fish restoration programmes are returning SWH to rivers where it had previously been removed. However, there is little information to direct the placement of this SWH within a river landscape. 2. Low-level, high-resolution aerial photographs were used to investigate the spatial pattern of SWH in the Murray River between Lake Mulwala and Tocumwal. It was found that SWH occurred in aggregations that were closely associated with eroding banks on meanders. 3. The physical characteristics of the SWH in these aggregations varied (basal diameter range 0.44-2.45m, length range 1-44 m); however, small- to medium-sized trees (basal diameter range 0.7-1.4m, length range 5-20m) were most common. 4. The association between eroding banks and SWH suggests that bank erosion may be an important determinant in the formation of SWH aggregations.