Quantifying post-release survival of skate bycatch in the Heard Island and McDonald Islands Patagonian Toothfish longline fishery

  • Research Theme
    Fisheries & Aquaculture
  • Cross-disciplinary Theme(s)
    Ocean-Antarctic Governance
  • Funded By

    Australian Fisheries Management Authority, Fisheries Research  and Development Corporation

  • Principal Investigator

    Colette Appert (PhD candidate)

  • Contributor(s)

    Supervisors: Dr Jaime Cleeland (IMAS, Australian Antarctic Division), Associate Professor Sean Tracey (IMAS).

    Onshore support: Dr Alyssa Marshell (IMAS),

    Collaborator: Clara Peron (Museum of Paris)

  • Project Summary

    Skates (Rajidae) represent the greatest biomass of incidental bycatch caught in the Patagonian toothfish (Dissostichus eleginoides) longline fishery operating within Australian waters around Heard Island and MacDonald Islands (HIMI) in the Southern Ocean.

    Due to their life history characteristics of slow growth and late maturation, their populations are particularly vulnerable to fishing mortality which can lead to overall and localised population declines.

    As bycatch-managed species, sustainable bycatch limits are informed by a stock assessment (using the Generalised Yield Model) which models long-term population viability. Such models can be sensitive to the input parameters of assumed total fishing mortality.

    Currently, in the HIMI fisheries, only retained skates are counted towards fishery removals, but the overall fisheries-induced mortality may be substantially higher due to the high number of skates released after capture and the unknown, but potentially low, post-release survival.

    Post-release survival becomes increasingly important as the scale of discarding increases, with a high proportion of skate bycatch in the HIMI longline fishery being released it is imperative that post-release survival is quantified to get an accurate estimate of total fishing mortality.

    This PhD project has three core objectives to support the sustainable management of skate bycatch in the HIMI region:

    1. Quantify post-release survival rates for longline caught skates using satellite pop-up tags.

    2. Develop indirect methods to predict post-release survival using blood chemistry and fishing parameters.

    3. Characterize post-release behaviour to understand the effects of capture related to physiological stress using accelerometry data.

    Interested in this project?

Authorised by the Executive Director, Institute for Marine and Antarctic Studies
15 March, 2023