King AJ, Ramsey D, Baumgartner L, Humphries P, Jones M, Koehn J, Lyon L, Mallen-Cooper M, Meredith S, Vilizzi L, Ye Q and Zampatti B (2009) Environmental requirements for managing successful fish recruitment in the Murray River Valley - Review of existing knowledge. Arthur Rylah Institute for Environmental Research Technical Report Series No. 197. Department of Sustainability & Environment, Heidelberg, Victoria, Australia. 209 pp. ISSN 1835 3835 (online).

Summary

Understanding the environmental factors that influence the early life history of fishes is important for fisheries management and providing environmental flows. Currently however, there is little information readily available for scientists to provide specific recommendations. In order to develop flow and habitat recommendations to assist water managers in the Murray Valley, this study aimed to review all existing reports and datasets on fish spawning and recruitment along the Murray River.

A total of 101 publications, from 77 projects, were identified as relevant. From these, a total of 187 flow statements, and 147 spawning and nursery habitats statements were identified. Of the projects reviewed, there were relatively few projects specifically designed to determine the influence of flow, or other environmental factors, on spawning and recruitment of native fish. Most projects were conducted for less than five years, and therefore their ability to assess patterns or relationships over extended times periods was limited. Few of the statements identified from the projects were rated as having ‘high’ or ‘medium’ scientific confidence. The overall low levels of scientific confidence resulted from several factors including:

• The length of the project or range of flow conditions experienced was limited;
• Most studies were not designed to address flow related questions;
• Relatively low numbers of individual fish were collected.

This synthesis of existing knowledge suggests that the current flow management for fish are likely to have uncertain outcomes at present. We consider that the challenge for scientists and managers is to develop a structured framework of monitoring and evaluation that results in increased understanding about the potential benefits of flow delivery. This study is an important step in understanding existing knowledge. Further, it has provided a sound basis for the development of a framework for the improved delivery of environmental flows in the Murray River.

NOTE: The report will be available for download from the Department of Sustainability & Environment web site at the following link:
http://www.dse.vic.gov.au/DSE/nrenari.nsf/LinkView/089F22002F
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