Anthony Townsend from New South Wales Department of Primary Industries sent in this recently released report on adaptive environmental water use for fish and fish habitats in New South Wales.
The document outlines the current status of adaptive environmental water holdings in NSW for each major valley and the associated consideration in planning and decision making given to fish and fish habitats. Fisheries NSW is represented on all of the environmental water advisory groups within NSW, however the development of flow-related actions to support native fish abundance and diversity varies considerably across the Basin. The acknowledgment of the specific flow-related needs of native fish and associated habitats within environmental water planning is a major step forward for the conservation of our inland fisheries resources.
As the frameworks surrounding the planning and delivery of environmental water continue to mature, a number of important issues relevant to native fish warrant further consideration.
Utilising environmental water in conjunction with unregulated events.
The input of carbon and nutrients from unregulated events creates significant increases in riverine metabolism and productivity. Many of these responses may not be replicated through the delivery of regulated environmental water alone. The development of environmental watering plans that seek to maximise the benefit from unregulated events will assist in the conservation of native fish populations.
Aligning life-history requirements of native fish to the delivery of environmental water
Increased flow does not always benefit native fish. The sustained higher discharges in many regulated valleys during Spring/Summer may in fact hinder the recruitment of native fish in many circumstances. Identifying specific features of the hydrograph that support the life history requirements of individual species and guilds of fish (groups of species with similar life history) and delivering water accordingly will lead to improved outcomes for native fish.
Increasing our understanding of habitat/flow interactions
Habitat availability within rivers is a function of flow. With a finite amount of water available to the environment, understanding the relationship between flow and critical habitat features such as large woody debris, benches and anabranch systems will allow managers to maximise the benefits of environmental water delivery.
Developing long-term objectives to support a full range of species
No single flow regime will provide benefits to all native fish species. To periodically meet the requirements of all species within a population, inter-annual variation of priorities and delivery strategies is essential. Consideration must be given to the recruitment strategies, life expectancy and resilience of current populations to develop watering plans that have a timeframe of ten or more years. Like all long-term planning, the annual objectives will have to respond to antecedent conditions, however a strategic understanding of the native fish outcomes being sought over longer time periods is essential.
You can access the full report by following this link Fish and Flows Environmental Water June 2014