Understanding recruitment collapse of juvenile abalone in the Eastern Zone Abalone fishery – development of pre-recruitment monitoring, simulation of recruitment variation and predicting the impact of climate variation
University of Tasmania (UTAS)
Large fluctuations between years in fishable biomass of abalone are thought to be driven by inter-annual variation in recruitment to the fishery. Over the last decade the changes in recruitment from year to year appear to have been especially extreme which suggests that this may be caused by climate change. Eastern Tasmania is one of the fastest warming parts of Australia as a result of greater extension of the EAC. This possible link between climate change and abalone recruitment can't be investigated in detail at present because of the lack of data / time series on abalone recruitment. This project will establish collection of that data to provide future capability. When recruitment to the fishery fails, the fishery is reliant on existing older year-classes already in the fishery, leading to a rapid decrease in fishable biomass. The capacity to measure inter-annual variation in sub-legal year-class strength would provide valuable prior warning of decline. Data obtained from a pre-recruit monitoring program will provide fishery-independent data to inform TAC setting. Fishery independent pre-recruit abundance data is a valuable input to the Management Strategy evaluation (MSE) Harvest Strategy and Control Rule system being developed in Tasmania. Application of assessment and MSE (Management Strategy Evaluation) models are both limited due to the absence of data on early year class abundance patterns, and will be improved by access to pre-recruit data.
1. Optimise collector module design for quantifying abundance of juvenile abalone across a range of habitat types
2. Determine links between juvenile abundance observed on modules and abalone in surrounding habitat
3. Estimate expected juvenile abundance on collectors in a ‘normal’ recruitment year using published natural mortality data and known abundance.