Fish use of Tasmanian coastal saltmarsh wetlands

 

Application for Scientific Permit – Available for Public Comment

​Public comment on the folowing application for a Scientific Research (Fauna) Permit is open until 13 July 2020

Applicant: University of Tasmania

Species/Taxon: Sampling targets fish using saltmarsh flats. Species likely sampled include Atherinosoma microstoma, Smallmouth hardyhead,  Kestratherina esox, Pikehead hardyhead, Leptatherina presbyteroides, Silver fish, Nesogobius maccullochi, Girdled goby, Pseudogobius sp., Eastern bluespot goby, Aldrichetta forsteri, Yellow-eye mullet, Rhombosolea tapirina, Greenback flounder, Pseudaphritis urvillii, Congolli, Gymnapistes marmoratus, Soldierfish, Arripis truttaceus, Western Australian salmon, and Galaxias maculatus, Common galaxias. Other taxa present but not targeted for sampling include gastropods and crustaceans.

Location: Proposed south-eastern Tasmania sampling locations (subject to access permissions being granted): 1) Dorans Road saltmarsh, Lauderdale/Sandford, Clarence City Council and PWS reserve (Ralphs Bay Conservation Area); 2) Pitt Water saltmarsh, private land, 3) Marion Bay saltmarsh, south of causeway, Crown land; and 4) Little Boomer saltmarsh, Boomer Bay, Crown land. Proposed north-west sampling location: Duck Bay saltmarsh, PWS reserve (Duck Bay Conservation Area).

Title of research: Fish use of Tasmanian coastal saltmarsh wetlands

Aim of project: This research aims to investigate the contribution of coastal saltmarsh to fish habitat in Tasmania, and the implications of this contribution for conservation management and fisheries.

Justification: Coastal saltmarsh wetlands are increasingly recognised as providing fish nursery habitat and as an important part of broader seascape food webs. There is a need to extend our understanding of fish use of saltmarshes in areas, such as Tasmania, where such studies could potentially positively affect community perceptions and enable policy changes favouring saltmarsh conservation. Little is known about the role of saltmarsh as fish habitat in Tasmania. The first study conducted on fish use of Tasmanian coastal saltmarshes (Prahalad et al. 2019) documented 11 species at a mean density of > 72 fish per 100 m2. This was the highest number yet reported in Australia and indicates that Tasmanian saltmarshes may provide higher value habitat for fish in comparison to elsewhere in Australia, possibly due to the comparatively more frequent and prolonged flooding, and because the lack of adjacent mangroves makes saltmarshes a more important structural component of Tasmanian coastal seascape. This research will benefit our understanding of Tasmanian coastal ecology, with important implications for conservation and restoration policy and management.

The proposed sampling will be carried out on coastal saltmarsh flats. About 50% of saltmarshes in Tasmania are in reserved land and hence sampling in these areas is essential to provide a full picture of fish use of saltmarshes.

We note that all sampling will happen in regularly flooded areas, which are unsuitable for bird nesting. Where these areas are likely to be used for bird foraging, given the small proportion of the total marsh area used for sampling, there will be nearby suitable habitats for the birds to occupy. Given the focus of this research is to increase the conservation profile of saltmarsh, this has future benefits to birds which share the habitat with fish.

Maximum likely numbers of individuals involved: We would expect 50-75 fish per 100m2. Sampling effort will include 5x5m pop nets set up to 264 times.

Activities undertaken and methods: Buoyant pop nets will be used to sample fish. Pop nets are 5x5m, 1m high, with 2mm mesh size walls.

Fate of animals: Surveyed fish will be identified, counted, measured and released into seawater outside the sampling net. A few representative samples (<200) will be terminally anaesthetised, preserved and taken for verifying our field identification and for high resolution photography. Fish will be subject to a terminal anaesthetisation technique using a lethal dose of 170mg/L AQUI-S®. It will be ensured that the anaesthetised fish are dead by watching for any movement for 20 minutes. Once confirmed dead, fish will be preserved in-situ using 95% ethanol.

Likely impact on species involved (including any by-catch): Impacts to fish will include brief removal from the water for identification and measurement. A few representative samples will be terminally anaesthetised. The taking of these individuals is not expected to have an impact on the total populations of the species. With the exception of some gastropods and crustaceans, sampling is not expected to have any by-catch. Impacts on gastropods and crustaceans are expected to be minimal. A small number of crabs may be relocated to the outside of the sampling nets during sampling. Care will be taken to restrict movement through the back marsh to the flooded flats in order to avoid disturbing birds. We have also, in our project design, avoided selecting marshes that are regularly used by resident and migratory shorebirds (e.g. Orielton Lagoon).

 

Contact

Scientific Research Permits
Natural Values Conservation Branch
134 Macquarie Street
Hobart TAS 7000
Email: Scientific.Permits@dpipwe.tas.gov.au

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