Using local knowledge to understand and manage ecosystem-related decline in fisheries productivity A case study of seagrass decline in Corner Inlet, Victoria Dr John Ford, A/Prof Robert Day and A/Prof Kate Barclay 2016 FRDC Project No 2013-021 Final June 2016 © 2016 Fisheries Research and Development Corporation. All rights reserved. Using local knowledge to understand and manage ecosystem-related decline in fisheries productivity FRDC Project 2013-021 2016 Ownership of Intellectual property rights Unless otherwise noted, copyright (and any other intellectual property rights, if any) in this publication is owned by the Fisheries Research and Development Corporation and the University of Melbourne. This publication (and any information sourced from it) should be attributed to [Ford, J.R., Barclay K., and Day R.W. 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It is a statutory authority within the portfolio of the federal Minister for Agriculture, Fisheries and Forestry, jointly funded by the Australian Government and the fishing industry. Researcher Contact Details FRDC Contact Details Name: Dr John Ford Address: 25 Geils Court Address: School of Biosciences Deakin ACT 2600 Melbourne University VIC 3010 Phone: 02 6285 0400 Phone: 0423 227 090 Fax: 02 6285 0499 Fax: Email: [email protected] Email: [email protected] Web: www.frdc.com.au In submitting this report, the researcher has agreed to FRDC publishing this material in its edited form. FRDC Final Report June 2016 23 rd May 2016 Dr John Ford Marine Research Fellow School of Biosciences Rm G31, Biosciences 4 Building The University of Melbourne VIC 3875 Dear John, Re: A case study of seagrass decline in Corner Inlet Thank-you for providing the West Gippsland Catchment Management Authority with a draft final copy of the “Using local knowledge to understand and manage ecosystem-related decline in fisheries production- A case study of seagrass decline in Corner Inlet’ report . The WGCMA has valued the opportunity to be involved with this research over the past 3 years, as it has assisted in addressing a number of key knowledge gaps, whilst developing and strengthening our partnership with the commercial fishing industry, as well the University of Melbourne and the Fisheries Research Development Corporation. Corner Inlet supports outstanding environmental values that have been recognised through its listing as a wetland of international importance under the Ramsar Convention. The size and diversity of habitats across Corner Inlet (e.g. seagrass, mud and sand flats, mangroves, saltmarsh, and permanent shallow marine water) support many aquatic and semi-aquatic plant and animal populations. In particular, the seagrass ecosystem is a driver of marine ecology and has a critical role in carbon sequestration, providing habitat and food for fauna including fish and migratory and resident wader birds. As such, seagrass plays a critical role in the viability of the Corner Inlet commercial fishery. With national parks, waterways, farmland and coast, the land surrounding Corner Inlet is also a place of natural beauty, productivity and internationally recognised environmental values. However, as identified in the Corner Inlet Water Quality Improvement Plan (WGCMA, 2013), poor water quality in Corner Inlet (as a result nutrient and sediment run-off from the catchment) threatens the condition and extent of seagrass meadows. The WGCMA, in partnership with the local community, landholders, industry and government agencies (national, state and local) are committed to improving the quality of water entering the Corner Inlet Ramsar site in order to protect its unique and significant values. The WQIP provides a long-term, on-ground works program to achieve measurable reductions in the level of nutrient and sediment entering Corner Inlet form the surrounding catchment. The outcomes of FDRC funded project will support the implementation of the WQIP through: • Provision of a robust, cost effective and easily repeatable method for mapping the extent of seagrass across Corner Inlet. Previous attempts to understand the historical extent of seagrass decline have been hampered by the use of different mapping methods and interpretations. The work undertaken by this project has assisted greatly in understanding historical fluctuations in seagrass through the use of local knowledge from Corner inlet fisherman. Further, the project has created a 2013 seagrass extent map that combines modern GIS techniques with the knowledge of the fishermen. The technique developed by the project is repeatable, and provides an opportunity for mapping seagrass across the 30- year life of the WQIP to assess if the on-ground catchment works having an impact on seagrass. • Having established a clear link between catchment nutrients/sediment, algal blooms and seagrass decline. Prior to this project, there was limited documentation on the type and extent of algal blooms in Corner Inlet. The project has identified two types of blooms, one which appears to be fuelled by nutrients coming from the natural breakdown of seagrass and has been occurring for many decades, and the other fuelled by nutrients originating in the catchment and which is increasing in impact over the past decade. This information is important in informing the on-going nutrient/sediment reduction work in the catchment and the associated monitoring requirements. • Water quality monitoring of streams draining to Corner Inlet undertaken through the project has confirmed the findings of the WQIP- that high nutrient and sediment loads are entering the Inlet from the north and NW, and the western tributaries have high concentrations of nutrients. This information will support the WGCMA and partners in targeting limited financial resources to undertake on-ground nutrient/sediment reduction works in these priority sub-catchments. • As stated previously, strong partnerships are the key to achieving change in Corner Inlet. The work over the past 3 years through the project has fostered a strong partnership with the local commercial fishing industry, and we look forward to continuing this into the future. Further, the information generated through the project (e.g. seagrass map, water quality information and interested generated through field days and presentations) will assist the WGCMA to strengthen the community engagement programs ran in Corner Inlet. We look forward to seeing the final report and hope to continue working with the FRDC and University of Melbourne staff into the future. Yours sincerely Martin Fuller Chief Executive Officer West Gippsland CMA Contents Contents .................................................................................................................................... 3 Acknowledgments .................................................................................................................... 7 Abbreviations ........................................................................................................................... 8 Executive Summary ................................................................................................................. 9 Introduction ............................................................................................................................ 13 Objectives................................................................................................................................ 21 Method .................................................................................................................................... 22 Seagrass mapping .............................................................................................................. 22 Local knowledge ............................................................................................................... 25 Algal blooms ....................................................................................................................