Larval transport and recruitment processes of southern rock lobster

Project number: 2002-007

Project Status:

Completed

Budget expenditure: $333,640.00

Principal Investigator: Barry Bruce

Organisation: CSIRO Oceans and Atmosphere Hobart

Project start/end date: 29 Jun 2002 - 30 Jan 2008

Contact:

FRDC

Need

This project arises from the need within the SRL fishery to address a series of regional and fishery-wide questions including:

What areas contribute to successful recruitment within regions of the fishery?

Will increasing the spawning biomass in regions, where it is currently very low, be likely to increase recruitment to the fishery globally, only in certain restricted areas or not at all?

To what extent are management zones linked via larval transport from both west to east and east to west?

What drives puerulus settlement across the range of the fishery and how can regional and interannual differences in settlement be utilised to assess the health of the stock, and assist in the future with the prediction of catch rates?

These needs have been identified by managers, industry and research providers in South Australia, Victoria and Tasmania. In Tasmania, the Crustacean Research Advisory Group gave this issue their highest priority ranking due to its importance in targeting the current management objective aimed at rebuilding egg production.

Addressing these questions will help to ensure the sustainability of the fishery, assess the merits of alternative management strategies for improving recruitment (and hence yield) and provide the basis for possible future predictions of catch rates based on puerulus and or ocean monitoring.

Objectives

1. To examine the relationship between spawning region and settlement success across the range of the SRL fishery - identify where successfully settling puerulus come from

2. To model the effects on settlement, throughout the range of the fishery, of changing spawning output in various areas of the fishery – provide information on whether increasing spawning stock biomass in some areas will help to increase recruitment and, hence, yield

3. To identify major physical processes contributing to differences in settlement between years and between regions – help understand whether variations in puerulus settlement result from management changes or environmental effects

4. To identify mechanisms for incorporating findings of the project into on-going assessments of recruitment indices and stock status – how best to develop the model outputs into a form that managers, researchers and industry can use on an on-going basis