Project number: 2020-065
Project Status:
Budget expenditure: $147,900.00
Principal Investigator: Keith Sainsbury
Organisation: Western Abalone Divers Association (WADA)
Project start/end date: 30 Nov 2020 - 30 May 2022


Most jurisdictions have developed and used various combinations of indicators in stock assessment and TAC setting of their abalone fishery. Applications often use a time series of commercial catch rate or FIS density to detect trends and identify reference points of stock status. The use of fishery dependent indicators from logbooks and GPS loggers have been criticized for their potential to be biased and insensitive (‘hyper-stable’) because of commercial selection of all observations that are made. As a consequence, Fishery Independent Surveys (FIS) have also been used in stock assessment, with varying coverage in all state’s abalone fisheries. However, FIS have also been criticized for their large cost and considerable uncertainty about how representative and useful the data is for intensely spatially-structured abalone fisheries (e.g. spatial mismatch of the FIS and the stock). FIS reviews in several states found variable relationships between FIS estimates and other indicators of the fishery.

Alternatively, both GPS loggers and FIS have considerable complementary strengths. GPS logger information has strengths of extensive fine-scale detail about catch (e.g. allowing spatial standardisation, that represents one of the main challenges to fishery dependent data) with good coverage of the fishery, while FIS have strengths of repeatable and local scale detail that is independent of the fishery.

The project will review data available from GPS loggers, catch records and FIS in WZ Victoria, with possible extension to other fisheries depending on data access and funding. Methods to calculate density and biomass from different sources of data will be consolidated and applied at different spatial scales, and the precision and statistical coherence of estimates compared. These comparisons will enable the development of criteria to improve design of FIS, logger programs and related observations, and recommendations and guidance on the use of indicators of legal density and biomass in fishery harvest strategies.


1. Use the Victorian Western Zone (and other fisheries data, where available) as a test-bed to develop and evaluate a new approach to calculating density and biomass indicators of exploitable abalone.
2. Consolidate methods to calculate indicators of local exploitable density from reported catch, GPS logger and fixed site survey observations.
3. Assess the consistency, accuracy and reliability of these new indicators, and their likely performance for management decisions
4. Develop and apply new methods to (i) calibrate logger-derived local density from overlap of local observations of loggers and surveys, (ii) use logger observations to estimate the area fished and to which the calibrated local density estimates could be extrapolated to apply, and (iii) combine the density and area estimates to give an index of exploitable biomass in the fished area.
5. Provide criteria for the design of surveys, logger programs and related observations (e.g. the spatial scale of catch reporting) to give calibrated logger density and biomass indicators.
6. Provide recommendations and guidance on the use of indicators of exploitable density and biomass in fishery harvest strategies.
7. Provide training to develop capacity to understand and implement the approach with logger data.


Authors: Keith Sainsbury Duncan Worthington and Bill Venables
Report • 2023-05-10 • 2.69 MB
2020-065 interim progress report.pdf


The objectives of this project are to use the Victorian Western Zone (WZ) abalone fishery to develop and evaluate a new approach to calculating abalone density and biomass indicators from the combination of three information sources. The three information sources are:
   i.   Logbook reported catch and effort,
   ii.  Global Positioning System (GPS) logger records plus depth and catch from fishers, and
   iii. Fishery Independent Survey (FIS) observations collected by the government Victoria Fisheries Authority (VFA) and surveys done by the Western Abalone Divers Association (WADA).
This document provides a update on project progress to date, which has been mostly on reconciling the input data and replicating the analyses that were done historically to recommend a Total Allowable Commercial Catch (TACC) for the fishery.

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