Project number: 2017-010
Project Status:
Budget expenditure: $92,121.00
Principal Investigator: Miriana Sporcic
Organisation: CSIRO Oceans and Atmosphere Hobart
Project start/end date: 30 Jun 2017 - 29 Sep 2018


It is over 10 years since the original model design, which was conditioned on Commonwealth logbook data over 2001 – 2005, was introduced and much has changed in the SESSF over this period, such as marked changes to the fishing fleet resulting from government buy-outs during 2006 and potential climate change on fisheries and fish distribution, particularly in south-east Australia. This approach may now be outdated by potential changes to the relative abundance of different SESSF species and changes in species behaviour. In an effort to find efficiencies in the sampling design, it is timely to re-examine underlying model assumptions (e.g., depth preference, day-night preference, and species range limits). This will provide updated model-based CVs using more recent Commonwealth logbook data, and should provide more reliable fishery independent abundance indices for selected SESSF species.

The FIS was originally intended to support management of SESSF species, providing an abundance series that is free of the influence of fisher behaviour, market forces, closed areas, management regulations and changes in gear used. Given the investment by the fishing industry and Government in the five completed surveys over the last 10 years, it is appropriate to consider how FIS abundance indices can be used as an input to manage the SESSF. To date, these indices have been incorporated in Tier 1 stock assessments for only three species, where it does not appear to be influential. It is not clear how these estimates could be used for non-Tier 1 species.


1. re-examine some of the underlying assumptions of the survey
2. update data that conditions the model and find efficiencies in sampling design
3. use a data simulation exercise to examine the utility of the estimates given the process and sampling errors that have been observed.

Final report

ISBN: 978-1-925994-01-8
Authors: Miriana Sporcic Jemery Day and David Peel
Final Report • 2019-09-01 • 5.53 MB


The model-based Fishery Independent Survey (FIS) for the Southern and Eastern Scalefish and Shark Fishery (SESSF) was developed in the lead up to the first survey in 2008 and is unique in a fisheries context in that it differs from a random stratified design, thereby allowing considerable flexibility in sampling station location and survey implementation for this complex multispecies fishery. However, the model required refinement to condition it on more recent and more relevant data from 2008 onwards and to account for considerable changes that occurred in the fishery following the structural adjustment. This project addressed these refinements
Implications for relevant stakeholders
Implications 1: Station re-examination
The framework developed could assist with any future refinements to the FIS design. The set of candidate stations is dependent on the species chosen, so a different set of key species would produce a different set of candidate stations for relocation.
Implications 2: 2018 reconditioned model (FIS2)
Software was updated. The reconditioning analyses led to a reduction in the CVs, increasing the utility and confidence in the FIS2 results.
Implications 3: Data simulation using 2018 reconditioned model estimates
Large variation was observed in possible trends from simulations using the calculated CVs for the five survey abundance estimates. Simulation analyses suggest that process error should be explicitly considered, as sampling error alone could not produce such variable results.
Implications 4: Reconditioned model accounting for within-year variation (FIS3)
Differences in seasonal patterns between years were accounted for which led to a further reduction in both abundance CVs and inter-survey variability, hence increasing the utility of the FIS3 results.
Implications 5: Stock assessment scenario exploration
Due to the relative length of the FIS abundance series compared to other data sources, the FIS series is likely to be too short to adequately assess the impact on stock assessment results in most scenarios explored.

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