In the last ten years, overgrowths of purple sea urchins along the coast of California have led to “urchin barrens” where urchins have devoured the kelp and turned the kelp forest into a degraded habitat akin to a clear-cut forest on land. Because urchins can live for a long time with little to no food, their presence also prevents the regrowth of kelp forests. One approach to address this issue is to harvest the urchins and feed them in aquaculture tanks on land until their roe can be harvested for sushi. This could provide both high-value seafood while at the same time restore the many ecological benefits of healthy kelp forests. Called “urchin ranching,” this technique has proven successful in Norway, Japan, and Canada, but is not yet in practice in the US.
This project aims to develop techniques to turn a destructive pest into a valuable seafood product. The researchers will conduct experiments to determine the feasibility and specific aquaculture methods needed to implement a new aquaculture industry for the purple urchin in California. Specifically, they plan to determine the amount and timing of artificial feed that urchins need over a nine-week time period to develop marketable roe, and the optimal stocking density for urchins in a land-based recirculating aquaculture facility.
A typical barren urchin at the start of a 9-wk feeding experiment; miniscule gonads are thin orange streaks lining the aboral surface of the inner test.
A typical urchin after 9 wk of feeding ad libitum on Urchinomics feed; plump orange gonads (roe, uni) have developed to a marketable size.
The project also includes stakeholder engagement and education components, including an urchin ranching exhibit to be shared at schools and public seafood and science events in central and southern California.
