Why understanding Eastern King Prawn habitat is important

Diagram of an Eastern King Prawn

The eastern king prawn (EKP) fishery is one of the most valuable fisheries in NSW. Despite the significance of EKP fisheries in NSW, little is known of their ecology during the estuarine juvenile stages in NSW or about how habitat change has affected productivity.

This research project has been developed because there is a need to understand the critical habitat factors that affect prawn recruitment in NSW estuaries, and nursery habitats that support the eastern king prawn (EKP) fishery. This is necessary to improve the understanding of the impact of habitat change amongst both commercial fishers and coastal land managers, with a view to targeting restoration and rehabilitation activities to maximise fishery benefits.

A research study in the USA has shown that a hectare of restored wetland habitat can contribute up to 60,000 prawns to the post-juvenile population. Based on this figure, it is estimated that similar habitat rehabilitation could increase the EKP fishery yield in NSW by about 425 kg per year for each hectare of rehabilitated habitat. The eastern king prawn (Melicertus plebejus) is endemic to the coastal regions of eastern Australia between central/northern Queensland and eastern Victoria. Its life-cycle is relatively well known – spawning predominantly occurs in deeper waters off northern NSW to Swains Reef in Queensland, and pelagic larvae develop as they drift south in the east Australian current. Post larval prawns recruit into the lower reaches of estuaries and leave the estuaries as late-juveniles. Prawns further develop in coastal habitats before reaching maturity and commencing a northward migration back to the northern spawning areas.

The estuaries of northern NSW are considered to be some of the most important recruitment areas for EKP. Despite the lack of quantitative research on the early estuarine stages of EKP in NSW, fishers have provided many anecdotal reports of the extensive use of estuarine swamps by young EKP prior to wetland degradation. Also, anecdotal information suggests adverse effects of freshwater inundation and lowering of salinities in estuarine nurseries on the growth and abundance of prawns.

Quantitative knowledge on the use of estuarine nurseries by EKP is essential to accurately value coastal wetland habitats, and assess the benefits of rehabilitation. This project will investigate these relationships.

mangrove and seagrass habitat

Project funding

This project is supported by funding from the Fisheries Research and Development Corporation (FRDC) on behalf of the Australian Government, with significant in-kind support from Fisheries NSW. Additional funding support for the project is being provided by the former Hunter-Central Rivers Catchment Management Authority (CMA) and the Northern Rivers CMA, now Local Land Services, as well as Hunter Water, the Newcastle Ports Corporation, and Origin Energy. The project is supported by the NSW Professional Fisherman's Association, the Newcastle Commercial Fishermen's Co-operative and Oceanwatch.

What the project involves

The project will run until July 2016 and has the following objectives.

  1. Determine to what extent young EKP are using natural, degraded or rehabilitated habitat in estuaries, and the contribution of these habitats to the fishery
  2. Determine the hydrographic conditions which provide for maximum growth and survival of EKP within nursery habitats
  3. Determine the extent of key EKP habitat lost and remaining in a number of key estuaries between the Tweed and the Hawkesbury
  4. Outline the potential improvements to the EKP fishery that could be achieved through targeted wetland rehabilitation and freshwater flow management
  5. Extend information on EKP habitat requirements to commercial fishers, landowners and other catchment stakeholders and incorporate recommendations into fisheries or water management.

Investigations for Objectives 1 and 2 will be undertaken collaboratively with Newcastle University by a dedicated PhD project. Phase 1 of the project will focus on piloting some methods that might be used to sample juvenile EKPs and mapping out what is known of the habitat conditions in which EKP thrive. In addition, we will be using this first part of the project to look at historical references and talk with current and former commercial fishers in this fishery to get a picture of just how productive it once was.

Project staff

Role

Name(s)

Contact details

Project Manager and Principal Investigator

Dr Matt Taylor (Fisheries NSW)

02 4916 3937
0407 375 309

Researcher (estuarine habitats)

Dr Craig Boys (Fisheries NSW)

 

Researcher (estuarine food webs)

Prof. Brian Fry (Griffith University)

 

Researcher (marine ecology; supervisor of PhD project)


Spatial analyst (estuarine habitat mapping)

Assoc. Prof Natalie Moltschaniwskyj
(Uni of Newcastle)

Mr Greg West (Fisheries NSW)

 

Habitat rehabilitation

Mr Craig Copeland (Fisheries NSW)

02 6626 1353
0419 185 538

Modelling

Dr James Smith (University of NSW)

 

Stakeholder engagement and communication

Mrs Charlotte Jenkins (Fisheries NSW)

02 6620 9319
0407 154 320

Commercial fisheries management and liaison

Darren Hale (Fisheries NSW)

02 6645 0503

Project updates

Project updates are available below.

Research results

Research data will be published in a variety of ways, including plain English summaries. Journal articles and conference presentations will also be used to inform people about the research. Results will be made available here.

Learning from commercial fishers

Members of the project team will be visiting co-ops whose members are EKP fishers to talk with these fishers about what they know about EKP habitat and if and how these habitats have changed. In addition, we want to know more about communicating effectively with EKP fishers so will be both talking with them about where and how they access information and doing a short survey. The results of the discussions and survey will help us provide more relevant information more appropriately. Information about engagement activities and survey results are available here.

Useful links

This section provides links to project partners, funders and sponsors. Also included are links to other organisations working on sustaining EKP fishery productivity through habitat rehabilitation. Visit the Useful links page.