Field Testing Razor Clam Grow-Out Systems for Sustainable Aquaculture in Maine

Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture

Razor clams (Ensis directus) represent a promising but underdeveloped opportunity for aquaculture diversification in Maine. While oysters and quahogs dominate the state's shellfish sector, farmers and hatcheries have expressed strong interest in exploring commercially viable alternative species to reduce economic risk and strengthen farm resilience. This project will field test wooden boxes and recycled-plastic grow-out containers to evaluate how gear type, site characteristics, and environmental conditions influence razor clam survival and growth over two full growing seasons.

The project objectives are to: (1) construct 200 experimental grow-out units from two gear types, (2) transport approximately 100,000 juvenile razor clams from the Downeast Institute to Merrymeeting Shellfish Company for nursery holding, (3) outplant clams at densities of 500 clams/m² across 1-3 intertidal sites, (4) conduct monthly field assessments and quarterly quantitative sampling to measure survival, growth, and environmental parameters, (5) recover all units after 24 months and assess final performance, and (6) analyze data and disseminate findings to Maine's aquaculture community.

The work plan includes gear construction at Merrymeeting Shellfish Company, nursery holding with controlled algae feeding, deployment at the Darling Marine Center and additional Limited-Purpose Aquaculture sites pending lease approval, and systematic monitoring throughout two growing seasons. Data will be analyzed in R Studio to determine optimal gear types and site conditions for commercial-scale production.

Outreach will leverage partnerships with the Maine Aquaculture Innovation Center and Maine Sea Grant to reach stakeholders through grower field days, fact sheets, culture protocols, and presentations at regional aquaculture conferences.

Objective 1. Construct 200 experimental razor clam grow-out units consisting of 100 wooden boxes (1 ft × 5 ft, built from 2×8 SPF lumber) and 100 recycled-plastic units (5-gallon buckets cut to ~10 inches in height). All units will be fitted with removable mesh tops and prepared for field deployment by July of Year 1.

Objective 2. Transport approximately 100,000 juvenile razor clams (3-5 mm) from the Downeast Institute to Merrymeeting Shellfish Company and maintain them in sediment-based nursery tanks with controlled algae feeding until they reach suitable size for outplanting.

Objective 3. Deploy all 200 units at 1-3 intertidal sites (depending on lease approval) and outplant juvenile razor clams at 500 clams per m² (~230 per box; ~25 per bucket) to assess growth and survival across gear types and environmental conditions.

Objective 4. Conduct monthly field assessments during the first six months to monitor box integrity, sediment stability, mesh condition, and predator damage. Beginning at Month 3 and continuing quarterly thereafter, perform sampling of one box and one bucket per site to quantify survival, shell length, burrow depth, and condition index. Concurrently measure environmental parameters including temperature, dissolved oxygen, salinity (using borrowed YSI probe from Darling Marine Center), and pH to correlate growth outcomes with site conditions.

Objective 5. After two full growing seasons, retrieve all remaining units, recover all surviving clams, and conduct final measurements of shell length, survival rate, burrow depth, and meat-to-shell condition index to determine optimal gear type and density for commercial production.

Objective 6. Analyze all biological and environmental data using R Studio and disseminate findings to Maine's aquaculture community through field days, grower networks, written protocols, and presentations (detailed in Outreach and Impacts section).