Addressing Key Challenges in Green Sea Urchin Aquaculture

Commodities

• Animals: shellfish, other

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.