Addressing Key Challenges in Green Sea Urchin Aquaculture

View the project report

Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture
• Education and Training: on-farm/ranch research
• Pest Management: biological control

The green sea urchin (GSU) fishery is in decline and to sustain the industry, the emerging sector of aquaculture needs to address challenges preventing its expansion. One is to optimize production methods, information needed by growers, and another is a lack of awareness of this species as an option for aquaculture. GSUs have also shown potential to be integrated with shellfish and graze upon and reduce labor intensive biofouling species and consequently help increase shellfish growth. Pilot trials in commercially used lantern net cages with an Atlantic sea scallop grower have shown that GSUs and scallops integrate well with modest reductions in biofouling, and this study takes the next steps towards optimizing methods to achieve more dramatically beneficial results. The objectives are to: 1) Optimize GSU stocking density and size classes integrated with scallops by trialing higher than previously tested GSU stocking densities (6 and 8 GSUs per lantern tier) and size classes (medium (35-43 mm) and large (44-52 mm); 2) Determine whether GSUs can be reared on the outside of aquaculture gear to reduce external net biofouling by using an external mesh enclosure; and 3) Using strong outreach, increase and disseminate technical knowledge on rearing GSUs with shellfish to increase awareness of and grower confidence in the uptake of this industry, measurable through numbers of people reached and requests and uptake of GSU seed from the region’s only operational GSU hatchery who also partners in this project.

This project aims to sustain the northeastern green sea urchin (GSU; Strongylocentrotus droebachiensis) industry which mainly operates out of the state of Maine by addressing challenges preventing the expansion of the emerging sector of aquaculture. The objectives are to:

1. Determine the ideal stocking density and size classes of GSUs to be integrated with shellfish such as sea scallops inside lantern nets to maximize growth of both animals and reduce biofouling on scallops and net interior.

To address this, the project will conduct farm trials to optimize GSU stocking density and size classes integrated with scallops by trialing higher than previously tested GSU stocking densities (6 and 8 GSUs per lantern tier) and size classes (medium (35-43 mm) and large (44-52 mm) and measuring species survival, growth and amount of biofouling on gear and shellfish.

2. Determine whether GSUs can be reared on the outside of gear to reduce external net biofouling. 

To address this, the project will conduct a proof of concept farm trial by maintaining GSUs onto the external net gear surface to graze upon and reduce biofouling, retained on the net by using an overlaying mesh enclosure often used as predator mesh enclosures in industry. This will translate from previous successful work for GSUs enclosed onto mussel (Mytilus sp.) longlines (Sterling et al., 2016) using similar effective stocking densities (6 and 9 GSUs per net) and GSU sizes (42 mm) which showed positive species growth and reduction in biofouling. Responses to be measured will include species survival, growth and amount of biofouling on gear and shellfish.

3. Increase of and uptake in GSU aquaculture using strong outreach and transferring technical knowledge on rearing green sea urchins with shellfish to increase grower confidence.

Using a strong technology transfer and outreach plan, this project will increase awareness of GSU aquaculture through stakeholder attended events, broad targeted communications to regional extension networks including underserved and underrepresented communities, tribal and minority-owned small business owners. Technical transfer of production methods will be adopted immediately by a grower and to the GSU aquaculture network. Responses to be measured will include the number of requests and uptake of GSU seed from the region’s only operational GSU hatchery who also partners in this project.