Workshop on post settlement processes affecting the southern rock lobster (Jasus edwardsii) in southern Australia
University of Tasmania (UTAS)
1. To identify the current 'status of knowledge' in post-settlement spiny lobster research, including technological advances, which will be useful in study post-settlement process in southern rock lobster.
2. To bring together key industry, government and research partners to discuss a collaborative research plan aimed at investigating post settlement processes in southern rock lobster.
3. To foster international links in this field of research.
Research into the southern rock lobster in Australia has concentrated on the catching sector (primarily commercial) with limited research being undertaken on the post-settlement and juvenile stages. To maximise the outputs of investigating these stages, while at the same time minimising costs, a comprehensive understanding of the latest developments in the field is necessary. It was considered that this was best served by holding a workshop to review existing research, facilitate discussion amongst those involved in the area of research, and plan future research in relation to southern rock lobster.
Key issues for the workshop were considered to be: (1) the relevance of juvenile research to catch prediction; (2) growth information for stock assessment modelling; (3) impact and management of puerulus extraction for aquaculture; and (4) contribution to broader management in relation to conservation of egg production vs perceptions of stability of recruitment due to density dependent mortality.
Participants at the workshop reviewed the current status of knowledge in post-settlement rock lobster research, including methods used to research these cryptic stages. Participants included key industry, government and research partners and their discussions resulted in a collaborative research plan aimed at investigating post-settlement processes. Key areas were documenting macro-habitat requirements, growth rates, mortality estimates of juveniles and puerulus, identifying predators and competitors. The over-riding goal was considered to be the identification of
"Bottlenecks" are phases during development where a factor affecting abundance decouples the link between the abundance of a size class for that proceeding it. For instance, shelter limitation for a particular size class is a bottleneck as this would result in reduced inter-annual variation in the abundance of larger animals. The research proposed from this workshop would evaluate bottlenecks by identifying the stages and factors during juvenile development where density dependent mortality influences abundance. These factors reduce the signal between puerulus abundance indices to fishery recruitment and are important in understanding the effect of puerulus removal or habitat changes.
International participation at the workshop (from NZ, Japan & USA) was helpful in fostering links in this field of research.
Keywords: Southern rock lobster, resource sustainability, recruitment, aquaculture, mortality, density dependence.