DPIRD scientists are learning more about the growth and survival of juvenile rock lobsters through shallow water surveys in Western Australia.
The new research, funded through the Western Rock Lobster Council’s partnership agreement with the Fisheries Research and Development Corporation, is focussed on forecasting recruitment of western rock lobsters, which is crucial for assessing the stock in the West Coast Rock Lobster Managed Fishery.
Puerulus monitoring in WA was world-leading when it was first undertaken in the late 1960s. Annual monitoring has enabled prediction of the abundance of legal-sized lobsters three to four years in advance. This also helps pro-active management in the fishery.
The puerulus start settling on inshore reefs in May and this continues through until April next year, with peak settlement expected between August and December.
Puerulus settlement counts for the northern and southern sectors of the fishery in 2025/26 were the best in decades. However, recent shifts in the correlation between puerulus settlements and the number of undersized lobsters has underscored the urgent need for a standardised sampling regime for juvenile lobster recruitment in the fishery.
This has led to the establishment of the independent shallow water survey (ISS), which helps to provide a standardised sampling regime that replaces CPUE (Catch Per Unit of Effort) of undersized lobsters from commercial monitoring in shallow waters.
This new ISS is capable of collecting a better measure of the size, composition and abundance of juvenile lobsters throughout the fishery than the monitoring of commercial catches alone can provide.
The collection team now has the ability to review its data in near real time, which provides a secondary check of its accuracy and allows post-survey analysis to be conducted within hours of a survey finishing.
DPIRD Principal Research Scientist Simon de Lestang said the use of in-pot cameras (called POTBots) would continue to help us in building a better understanding of the links between habitat and juvenile lobster survival.
“The shallow water surveys provide a more accurate measure of pre-recruit abundance than commercial monitoring data can and is more appropriate for informing quota decisions and managing stock sustainability,” Dr de Lestang said.
“Continuing the time series for the surveys is critical to capturing broader environmental variability, understanding puerulus to index relationships and how habitats influence this.
“Incorporating environmental drivers such as temperature and habitat quality into future analyses will further strengthen recruitment forecasts.”
