Novel Integrated Macroalgal and Sea Urchin Aquaculture Systems

The green sea urchin is a valuable species of edible urchin found in northern Pacific and Atlantic oceans. Sea urchins are prized for their uni, which is present inside the shell of the urchin as five gonadal lobes, unique organs that function to both produce gametes for reproduction and to store nutrients. Uni has a rich, buttery texture, and slightly sweet, mildly briny flavor, making it a prized seafood delicacy, and one of the most valuable seafood products in the world. However, wild fishery landings have declined in the US in the past few decades, decreasing nearly 99% from 14 million pounds landed in 1993 to just over half a million pounds in 2024 in Maine. The global increasing demand for high quality uni and diminishing wild resource presents an opportunity for aquaculture, especially in Maine where there is existing seaweed aquaculture and urchin fishery infrastructure to support the new crop.As macroalgal herbivores, sea urchins can be fully integrated into a seaweed aquaculture operation, utilizing farmed seaweed in all aspects of sea urchin production, from broodstock development, to hatchery and seed production, grow out, and harvest. Springtide Seaweed proposes to develop reliable hatchery systems for production of high quality native green urchin seed, determine growth rates and uni quality of farmed urchins raised on seaweeds, and develop integrated seaweed and sea urchin aquaculture farm models to produce high quality, consistent, high-value sea urchins for uni markets.The development of new integrated seaweed and sea urchin aquaculture models will support and strengthen domestic seafood production and competitiveness, increase economic prospects and employment, and cultivate the potential of our ocean's natural resources. The development of improved hatchery techniques utilizing macroalgal cultivation methods will create commercial availability of seed urchins for the wild fishery and aquaculture industries. Culture techniques could introduce new opportunities to support the urchin industry as a whole by providing options for farming, enhancement of wild caught urchins for increased quality and value, or re-seeding wild harvest populations to increase fishing success.