Size selectivity is an important aspect of southern rock lobster stock assessment models and has been estimated for different fleets, pot types, and areas. However, several mechanisms for changes to size selectivity have created particular concern due to their potential to influence management decisions. This project aims to understand the impact of changes in size selectivity on ongoing stock assessment modelling/harvest strategies to ensure robust assessments and avoid future management bias. It will do this by:

• determining lobster density and size structure impacts on selectivity;
• developing a method for adjusting for lobster density / size structure changes and for quantifying the impacts of high grading on selectivity changes on an ongoing basis; and

• gaining an understanding of intra-seasonal size selectivity changes.

  These data will be used to upgrade the rock lobster stock assessment model to include selectivity changes.