The excessive removal of Large Woody Debris (LWD) has been identified as a primary cause for the decline of many large-bodied Australian native fish species. Our project, which is based in the Murray River in South Eastern Australia, is creating substantially more physical habitat for native fish in a degraded reach of river by re-introducing large amounts of LWD (up to 4000 by the end of the program). By creating this habitat, the size of the native fish population in this reach is expected to increase thereby improving the conservation status of the native species present.

To ensure that these outcomes are being met a comprehensive monitoring and evaluation program has been implemented. This program aimed to determine if any change in fish population structure is a result of: (1). increased survival of adults in the reach; (2) increased immigration of adults and juveniles from nearby refuges; and (3) decreased emigration form the reach. Previous programs have shown that native fish will use re-introduced snags, however there have been few studies undertaken which show that this use is directly related to an increase in population size.

Our presentation will discuss the final results of this seven year intervention experiment. In particular, we present a multiple lines of evidence approach to define fish population change in response to the management intervention.