Project Science Plan: Supporting Management of Listed and Rare Species


Science Description:

Reliable and cost-effective assessment and monitoring tools are urgently required for the conservation and management of data-poor, low abundance, rarely-encountered, threatened species in Australia, including euryhaline and estuarine elasmobranchs (sharks and batoids) of northern Australia. Management of globally-significant populations of priority species, particularly sawfishes (Pristis species) and river sharks (Glyphis species), is currently compromised by an acute lack of data and knowledge, including in the river and estuarine waters of the Northern Territory (NT). Essential baseline data and an understanding of distribution, abundance, biology, patterns of connectivity, critical habitat requirements and population genetic structure are needed. While Pristis and Glyphis species are protected under the Commonwealth Environment Protection and Biodiversity Conservation(EPBC) Act as well as State/Territory legislation and fisheries regulations, current reporting from fisheries is inadequate to quantitatively determine population status. Subsequently, this limits the assessment of the effectiveness of current management initiatives (such as retention bans, fishing effort reduction, gear regulations, seasonal closures, spatial closures etc.).

Population monitoring methods, population modelling and integrated assessment strategies are urgently needed to estimate population status, undertake population assessments, and predict population trajectories, as well as to assess management effectiveness. Research tools encompassing field surveys, tagging and acoustic telemetry, and novel genetic techniques can be integrated in order to meet these needs, resulting in the assessment of the status of rare and threatened species more effectively and at a radically reduced cost. Integrated assessment strategies developed for euryhaline and estuarine elasmobranchs are potentially transferable to other data-poor, low abundance, rarely-encountered and/or threatened marine and aquatic species across a variety of taxa (fishes, reptiles, mammals).

Objectives:

This project will improve the understanding and management of data-poor, low abundance, rarely-encountered, threatened euryhaline and estuarine elasmobranch species, through the development of innovative population monitoring and integrated assessment strategies. Threatened sawfishes and river sharks of northern Australia will represent the test case, with an initial focus on Largetooth (Freshwater) Sawfish Pristis pristis and Speartooth Shark Glyphis glyphis in 2-3 selected river/estuary locations in the NT. The key project objectives are to:

(1) Develop integrated assessment strategies in order to assess the population status of data‐poor, low abundance, rarely-encountered, threatened species. This will include the development of quantitative tools to assess the status of populations and measure the effectiveness of current management measures in northern Australia (e.g. quantitatively assess the effectiveness of management initiatives or proposed aquarium collections against EPBC and IUCN criteria).

(2) Develop a novel and innovative population monitoring method (using a combination of acoustic telemetry and close‐kin genetics) for quantitatively assessing the population status of data‐poor, low abundance, rarely-encountered, threatened species. Population estimates will be based on juvenile sampling, close‐kin genetics and mortality estimates derived from acoustic telemetry. Largetooth Sawfish in the NT will be the test case for this methodology as this species is data-poor, adults are rarely-encountered (but juveniles are accessible), and significant, albeit unquantified declines have occurred (note that Speartooth Shark Glyphis glyphis may also be used as a test case if a lower than expected sample size is obtained for Largetooth Sawfish).

(3) Improve understanding of habitat utilisation and requirements, short and long‐term movement patterns, connectivity (i.e. freshwater-estuarine-marine exchange) and spatial dynamics of Largetooth Sawfish (and other priority euryhaline and estuarine elasmobranchs), through designing and implementing an intensive acoustic tagging program in selected river systems. Largetooth Sawfish (and other priority species) will be tagged with acoustic tags, enabling collection of data on short-term (days to months) habitat utilisation within rivers and estuaries, and long-term (years) movement and migration from rivers.

(4) Gather baseline data on the distribution, temporal (seasonal) occurrence, abundance, and life history of sawfishes and other priority euryhaline and estuarine elasmobranchs in the NT through field surveys.

(5) Provide better information to inform management and to increase public awareness and understanding of the status of threatened sawfishes and other priority euryhaline and estuarine elasmobranchs in the NT, and the threats facing their populations. The project will encourage improved public reporting, advance public education and develop industry and Indigenous participation and collaborative partnerships in the monitoring and management of threatened sawfishes and other priority elasmobranchs in the NT.

Scientific Methods:

  • Close-kin genetics
  • Long-term telemetry
  • Short-term telemetry
  • Fishery-independent surveys

Outputs & Outcomes:

  • A framework (integrated assessment strategy) to design practical and cost-effective monitoring, assessment and management of data-poor, low abundance, rarely-encountered, threatened species.
  • An assessment of the application of close-kin genetics combined with acoustic telemetry as a population monitoring method for data-poor, low abundance, rarely-encountered species (using Largetooth Sawfish as a model species).
  • Quantitative estimates of population size for Largetooth Sawfish (and possibly other priority species) which will act as a baseline level to assess the population status and effectiveness of recovery plans and current management measures.
  • Improved ecological understanding in terms of habitat utilisation and requirements, short and long-term movements, connectivity and spatial dynamics of Largetooth Sawfish and other euryhaline and estuarine elasmobranchs of northern Australia.
  • Improved understanding of the temporal (seasonal) occurrence, species richness and abundance of euryhaline and estuarine elasmobranchs of northern Australia.
  • Recommendations for the management of Largetooth Sawfish (and other priority species) in northern Australia.
  • Increased public awareness of data-poor, low abundance, rarely-encountered threatened species (particularly euryhaline and estuarine elasmobranchs) in northern Australia.

Key Scientific Advances:

  • Critical evaluation of the application of close-kin genetics as a method for the estimation of population size in data-poor, low abundance, rarely-encountered species.
  • Population estimates for Largetooth Sawfish (and possibly Speartooth Shark) in northern Australia.
  • Natural mortality estimates for Largetooth Sawfish (and possibly Speartooth Shark).
  • Short and long-term movement and habitat utilisation patterns for Largetooth Sawfish (and possibly other priority species).
  • Species richness, relative abundance and temporal (seasonal) dynamics of euryhaline and estuarine elasmobranchs within key NT river/estuary systems.


Key Contacts:

Peter Kyne (Project Leader)
Charles Darwin University
peter.kyne@cdu.edu.au

Richard Pillans (Project Leadership Team)
CSIRO Marine and Atmospheric Research
Richard.Pillans@csiro.au

Thor Saunders (Project Leadership Team)
NT Fisheries
Thor.Saunders@nt.gov.au