Summary

The NSW Department of Primary Industries (DPI) is committed to ensuring that there is no overall loss of the ecologically important seagrass habitat in NSW. In situations where the development of public infrastructure is considered necessary in NSW and the destruction of seagrass habitat cannot be avoided or reduced, developers may be required to offset any direct and indirect loss of seagrass meadows. This can occur through the use of various restoration techniques to create new areas of seagrass habitat. As part of a policy under the Fisheries Management Act 1994, NSW DPI requires that such offsetting replace two times the area of seagrass habitat that was lost.

The aim of this report is to assess the efficacy of using seagrass restoration techniques as an offset measure to ensure no net loss of seagrass habitat in NSW. Attempts at restoring seagrass habitat around the world completed up to the late 1990s showed large variations in success and were only successful in replacing small areas of habitat. This assessment considers improvements to the technology and overall success of seagrass restoration since the late 1990s. Such improvements are documented in this report through a review of the seagrass restoration work conducted in Australia and overseas since the late 1990s.

It was found that seagrass restoration methods cannot currently be used with confidence to create new areas of seagrass habitat in NSW, especially large areas of habitat. Some reasons for this are:

• there is very little information on the growth, and factors that influence the growth, of seagrasses in NSW, such information would greatly assist in the development of successful methods for seagrass restoration; 
• success cannot be guaranteed with the use of any current seagrass restoration method;
• large-scale seagrass habitat restoration is yet to be achieved with the use of any current seagrass restoration method on any seagrass species;
• many seagrass restoration methods are still at a developmental stage; and
• most seagrass restoration attempts conducted in NSW have failed.

To increase the confidence of using seagrass restoration methods as an offset measure for seagrass habitat loss in NSW, an adaptive co-ordinated scientific approach is recommended. This should aim to develop successful methods that are suited to local environmental conditions and seagrass species in NSW. Recommendations for the research to achieve these aims are made in this report.

Considering that restoration techniques cannot be relied upon to create areas of seagrass habitat, the most effective and least costly way of ensuring no net loss of seagrass habitat in NSW is to protect existing seagrass beds from further loss and destruction.