WRL puerulus settlement has been unexpectedly low over the past two settlement periods, with the most recent settlement period (2008/09) being the lowest on record. This extremely weak settlement has occurred despite environmental conditions being favourable for an above average settlement (i.e. a strong Leeuwin Current, warm sea temperatures and la Nina like conditions).
The recent poor settlements could be attributed to a number of possible scenarios, including, reduced egg production from depleted brood stock or a shift/change in oceanic conditions possibly due to climate change. Understanding what scenario(s) are responsible will be crucial for the effective conservation and management of the WRL stock, and ultimately the longevity of the fishery. Anecdotal evidence suggests that colonisation of the puerulus collectors by a number of other species commonly found during processing of these collectors have also been extremely low in recent times. Beginning to examine of the marine flora and fauna communities colonising the puerulus collectors over a range of 1200 km during this time of extremely low settlement (i.e. prior to the end of the settlement season in April 2009) and determining how these communities vary in relation to the varied environmental conditions experienced, will provide valuable information as to what may be influencing puerulus settlement. If settlement of other marine flora and fauna show a related response to that of the WRL pueruli, it could indicate environmental change may be responsible for the decreased settlement. This data will complement other research, such as the oceanographic modelling application (JM010) submitted by DoF and is crucial to the effective management of the WRL fishery. Furthermore, this spatial analysis conducted on a monthly scale has the potential to further identify possible indicator species of localised environmental conditions that could continue to be monitored as part of the standard WRL puerulus monitoring program.