Stock Assessment

The western stock snapper resource is a shared resource harvested by recreational fishers, mostly in Victorian waters, and commercial fishers from both State (i.e. Victoria and SA) and Commonwealth management jurisdictions. Increased growth in catches by all sectors/jurisdictions over the last decade has been met with increasing concerns over fishery and resource sustainability, and security of access. These concerns, along with uncertainty of future resource availability due to fluctuating recruitment, have raised the importance of developing a harvest management system that involves all sectors and jurisdictions, and developing resource sharing and governance arrangements to facilitate implementation of harvest management recommendations.

While a new stock assessment approach is being developed by FV to provide a more objective quantitative assessment of stock status, this project is needed to ensure that stock assessment outcomes can be translated into appropriate recommendations for changes in fishing mortality/catches that can be applied across the different fishing sectors and management jurisdictions (i.e. a multi-sector/jurisdiction harvest strategy). Importantly, while commercial catch is monitored by established reporting systems, and managed to a certain extent by licence regulations/limits, there is a clear need to develop cost effective methods for ongoing monitoring of catch and effort by the ‘open access’ recreational sector. Furthermore, modelling tools are required to allow managers to compare the response of sector catches to different regulatory approaches, particularly for the recreational sector. Reliable catch estimation and effective management of recreational catches are essential to achieving both biological sustainability and any fishery sharing objectives. Development of a harvest strategy and methods for long-term monitoring of recreational sector catches are essential to underpin development of a multi-sector/jurisdiction resource sharing framework, governance and harvest management framework to foster long-term stakeholder security and sustainability of the fishery.

Objectives

1. To provide managers and stakeholders with a robust and transparent approach to harvest management decisions that provides for both biological sustainability and certainty of access

2. To provide managers with cost effective options for ongoing monitoring of recreational catch and a tool to assist in deciding among different regulatory approaches for managing catches by the recreational sector

3. To develop a multi-sector, multi-jurisdiction sharing and governance framework, and an associated implementation plan for the western stock snapper fishery.

Final report

ISBN: 978-1-76090-126-4

Author: Paul Hamer

Final Report • 2019-05-28 • 12.57 MB

2013-201-DLD.pdf

Summary

This report involves the ‘Western Victorian Snapper (Chrysophrys auratus) Stock’ (WVSS) which supports arguably the most important marine fin-fish fishery for Victoria. While the majority of the harvest is by Victorian fisheries, this stock is a straddling stock shared with South Australia. This report describes a largely scientific project conducted by the Victorian Fisheries Authority (VFA) in collaboration with fisheries modelling scientists from MEZO Research. The project was initiated in 2013 to address concerns about uncertainty of management risks associated with increased fishing pressure across sectors and jurisdictions, and the inability to track recreational harvest trends and adequately incorporate recreational fishing pressure into stock assessment and management.

The project developed approaches using remote internet protocol (IP) cameras at boat ramps to monitor recreational boat fishing effort in the main Victorian fishing areas of Port Phillip Bay and Western Port Bay, and to integrate the fishing effort data with recreational survey (boat ramp creel survey) data on Snapper catch rates and length compositions to create a ‘harvest index’ to track Snapper harvest trends over time. The boat ramp camera trial explored two monitoring approaches; time lapse image capture, where an image of the ramp is recorded every two minutes and sub-sampling routines are applied to estimate total effort, and an ‘activity sensor’ approach, where images are recorded only when certain types of activity are detected (i.e. boat/vehicle movement) within a specified activity area.

A new ‘Management Strategy Evaluation (MSE)’ modelling tool, ‘SnapMSE’, utilising the free population modelling framework, ‘Stock Synthesis’, was created to evaluate management risks and trade-offs associated with different levels of fishing mortality in relation to specified objectives. The analytical tools developed utilised ‘R’, an open source software environment for statistical computing and graphics that is commonly used by scientist worldwide, and have been created so they are accessible to fisheries scientist with moderate experience using R. The MOU agreement between the VFA and PIRSA was developed via numerous phone meetings and a drafting workshop. An operational framework was developed for guiding implementation of the MOU.

The project demonstrated that IP cameras can be a cost-effective approach for monitoring trends in recreational boat fishing effort, and when combined with creel survey data can be used to monitor trends in targeted Snapper fishing effort, harvest from individual access points (boat ramps) and to derive a recreational ‘harvest index’ for monitoring trends in recreational Snapper harvest across the fishery. The first MSE model framework for a Victorian fin-fish fishery was successfully developed. The evaluation of alternative harvest control rules under high, average and low recruitment regimes, showed that maintaining the annual exploitation rate at around 10-15%, similar to the status quo, was likely acceptable for meeting the trial management objectives applied in this study over the long-term.

The monitoring, modelling and other analytical tools developed will improve the assessment of overfishing risk on the WVSS and the capacity of managers, policy makers and stakeholders to work together on a planned and informed approach for managing fishing mortality risks, including development of operational objectives.

Related research

All research

PROJECT NUMBER • 2023-163

PROJECT STATUS:

CURRENT

Feasibility of recreational scalefish enhancement in Tasmania

1. Determine the economic and biological feasibility of enhancement of Sand Flathead with specific focus on faster, larger growing fish.

ORGANISATION:

University of Tasmania (UTAS)

PROJECT NUMBER • 2019-129

PROJECT STATUS:

COMPLETED

Potential transition of shark gillnet boats to longline fishing in Bass Strait - ecological, cross-sectoral, and economic implications

1. Conduct a trial using automatic longlines to target gummy shark in SESSF waters in Eastern and Western Bass Strait

ORGANISATION:

Fishwell Consulting Pty Ltd

PROJECT NUMBER • 2019-085

PROJECT STATUS:

COMPLETED

National Snapper Workshop - Rebuilding our iconic Snapper stocks

1. To identify key issues and challenges for Snapper, review Snapper research, and critique jurisdictional management arrangements.

ORGANISATION:

Department of Primary Industries and Regions South Australia (PIRSA)

Options for Tier 5 approaches in the SESSF and identification of when data support for harvest strategies are inappropriate

Project number: 2013-202

Project Status:

Completed

Budget expenditure: $114,154.00

Principal Investigator: Malcolm Haddon

Organisation: CSIRO Oceans and Atmosphere Hobart

Project start/end date: 30 Jun 2013 - 29 Jul 2014

Contact:

FRDC

TAGS

Individual Transferable Quota

Need

The current Harvest Strategy Framework has no formal process for deciding whether the Tier harvest strategy applied to a stock is appropriate or not, there is thus no formal process for deciding when to use a lower Tier. Even worse, when a Tier4 assessment is deemed inappropriate in the SESSF there is no lower Tier available for use. There is thus a need to establish guidelines for identifying when a Tier method is inappropriate for a stock, and also a need to develop an array of alternative harvest strategies for use as a Tier5 when Tier4 is deemed inappropriate. As there is such a wide range of potential Tier 5 procedures, many with the same data requirements, testing is required to allow an informed decision about which are best to implement - particularly in the SESSF context.

Section 6 of the DAFF public discussion paper for the review of the Commonwealth fisheries Harvest Strategy Policy (see FRDC project 2012/225) investigates questions of uncertainty about assessment approaches, the level of data required to maintain species within a given Tier and when to switch between Tiers. The proposed project directly addresses known issues in the SESSF that relate to this question, and timing of the review allows this project to tailor analyses to specifically address review recommendations and advice.

A parallel and complementary project (FRDC 2012/202) provides a study of the trade-off among ecological and economic risks associated with harvesting, the benefits of harvesting and the costs associated with management. This is concerned with strategic considerations over all Tiers, whereas the current project looks more specifically at data requirements within SESSF Tiers, and alternative Tier procedures for data poor species in the SESSF.