Red Sea Urchin is a recreational and commercial hand-collected species along the coast of south-eastern Australia. The species likely has long life spans, comparatively narrow environmental tolerances, and despite having planktonic larvae and ample habitat may have limited recruitment in southern NSW due to the cold intolerance of the larvae (Byrne et al., 2022). With climate warming and more favourable thermal conditions for larvae and adults, Red Urchins may increase along the NSW south coast. Unfortunately, the demography, potential recruitment and connectivity of the species is not known.

The Red Sea Urchin resource has been supported by a SUTS closure network since 1994, but there is no long-term knowledge on how this affects populations or what protection it offers for the stock . Limited reproductive information means we are unable to estimate a suitable size at first capture for the species, and current fisheries management provisions may not sustainably maximise productivity . In addition, the impacts of ocean warming on Red Sea Urchin distributions remain unknown. The SUTS closures have recently been opened to harvesting of Centrostephanus rodgersii, thereby also affording an important opportunity to investigate potential ecological interactions between these two species.

The biological and ecological data gaps related to the Red Sea Urchin fishery must be addressed to support sustainable management of this resource over the long term, and ensure that the fishery remains productive, commercially profitable, and capable of supporting cultural and recreational fishing needs. This project will address biological and ecological knowledge gaps to support management of the Red Sea Urchin Fishery by:

• Characterising the Red Sea Urchin demography across SE Australia, including associated spatial variation such as that inside and outside SUTS closures ;
• Estimating reproductive parameters (size, age, roe quantity and quality) for Red Sea Urchin in SE Australia, including associated spatial variation such as that inside and outside SUTS closures;
• Quantifying ecological relationships between Red Sea Urchins (density, size) and environmental conditions (depth, substrate, relief, temperature) and with respect to co-distributed Long Spined Sea Urchin
• Predicting the impacts of ocean warming on Red Sea Urchin populations with comparative data for the Long Spined Sea Urchin; and
• Modelling larval dispersal potential of the Red Sea Urchin, particularly for larvae originating from within SUTS closures, to determine if they act as sources for adjacent fished areas .