Across Europe, sea urchins are simultaneously too abundant and too scarce: overabundance drives the expansion of barrens in some regions, while overexploitation has depleted fishery stocks in others. How do we restore balance? That is where aquaculture comes in. Two aquaculture approaches are emerging: capture-based roe-enhancement of overabundant species and hatchery-based restocking of depleted populations. However, several bottlenecks exist that limit the economic viability of both approaches.
Using the Australian purple sea urchin (Heliocidaris erythrogramma) as a model, we integrate findings from broodstock conditioning, juvenile feeding, and commercial-scale roe-enhancement to identify key drivers of production success. For closed life-cycle culture, we successfully developed effective formulated broodstock diets and identified suitable diets across the juvenile grow-out phase. For roe-enhancement, we created "gold-standard" collection and culture techniques that ensure high survival rates (>90%) and produced roe exceeding market standards in both quality and size at commercial scale.
Here, we summarise the results of three studies and discuss how these findings can inform the emerging roe-enhancement industry of the overabundant Strongylocentrotus droebachiensis in Norway, and restocking programs for Paracentrotus lividus in Southern-Europe.