6 results

Indicators for density and biomass of exploitable abalone – developing and applying a new approach

Project number: 2020-065
Project Status:
Current
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
Contact:
FRDC

Need

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.

Objectives

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.

Report

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

Summary

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.

Best practice and policy in abalone stock enhancement, restocking and translocation

Project number: 2019-110
Project Status:
Current
Budget expenditure: $41,802.00
Principal Investigator: Lachlan Strain
Organisation: Department of Primary Industries and Regional Development (DPIRD)
Project start/end date: 31 Dec 2019 - 29 Jun 2021
Contact:
FRDC

Need

Stock enhancement and restocking of marine species is an ever-evolving field given the development of new technology and pressures put on species by factors such as fishing, environment and disease. In Australia there have been several large-scale experimental abalone projects conducted, primarily in NSW and WA, with promising results and conclusions. However, these research projects have cost just over $1.7 million and none of the outcomes have translated into commercial-scale abalone stock enhancement, restocking or translocation. Even so, there is still considerable and continuing interest in stocking where stocks are so depleted as to render recovery without intervention impossible. The question is therefore, why do very few ideas/proposals progress to R&D projects and none have progressed to commercialisation?

This project will review abalone stocking in Australia and jurisdictions current strategic direction and management policies. Through this, potential roadblocks to the commercialisation of abalone stocking in Australia, such as government policy, scientific research, aquaculture practices, genetics and biosecurity/disease will be investigated. At present there is no formal abalone stocking programmes being conducted in Australia, even with the stock declines present in numerous fisheries. However, several major projects have been proposed and the interest in stocking as a fisheries management tool has remained high with substantial investments made. A national approach to abalone stocking will allow regulatory bodies to decide on appropriate stocking programmes and for industry to have confidence in the benefits for the fishery.

Objectives

1. Detailed review of abalone stocking in Australia and current jurisdictional policies.
3. Develop a national approach to abalone stock enhancement, restocking and translocation.

Can spatial fishery-dependent data be used to determine abalone stock status in a spatially structured fishery?

Project number: 2017-026
Project Status:
Current
Budget expenditure: $562,128.00
Principal Investigator: Craig Mundy
Organisation: University of Tasmania (UTAS)
Project start/end date: 31 Jul 2018 - 29 Sep 2020
Contact:
FRDC

Need

With the advent of the Status of Australian Fish Stocks (SAFS) process, there is now a requirement to provide a stock ‘status’ determination in addition to the annual TACC determination. The ‘status’ reflects changes in the overall biomass, the fishing mortality, or in their proxies. This has led to disagreements among researchers, managers and industry, largely due to uncertainty around how best to derive a meaningful overall stock status indicator to meet the requirements of the SAFS reporting process. These higher-level reporting processes are an important demonstration of sustainable management of Australian fisheries, but only if stock status determinations are accurate and defensible.

Australian abalone fisheries primarily use harvest control rules based around CPUE (Kg/Hr) to set TACC. However, with abalone, stable catch-rates may not indicate stable biomass and/or stable density. Catch-rates are frequently criticised because the effort needed to take a quantity of catch may be influenced by density but also by density independent factors such as conditions at the time of fishing, experience, and the ability of fishers to adjust their fishing strategy to maintain catch rates (diver behaviour driven hyper-stability). While there are many issues with the assumption that CPUE is a reliable proxy for abundance, it is assumed to be so despite the absence of robust data to validate use of CPUE in this way. In some jurisdictions CPUE is supplemented by sparse fishery-dependent size and density data. There is an urgent need to review common assumptions, methods and interpretations of CPUE as a primary indicator, and to determine whether inclusion of spatial fishery data could provide a ‘global’ indicator of stock status for abalone fisheries.

Objectives

1. Characterise the statistical properties, coherence, interpretability and assumptions of spatial and classic indicators of fishery performance
2. Develop methods for inclusion of fine-scale spatial data in CPUE standardisations
3. Identify methods for detecting hyper-stability in CPUE
4. Determine feasibility of spatial data based stock status determination in spatially structured fisheries