Determining Optimal Seed-clam Size for Littleneck/Oyster Polyculture

View the project final report

Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture
• Crop Production: intercropping
• Energy: solar energy

This project will test four seed-clam sizes for growth, retention, and mortality over the 2020 farming season as part of a subtidal polyculture with oysters. It will address the need for larger seed established in prior research of this intensive farming technique, which provides farmers with additional crops, resilience to disease and changes in the market, and reduces spatial pressures on both wildlife and human users. Because large seed is unavailable in this part of the northeast, a small-scale downweller will be constructed to produce the large seed tested in this project. A "minimum viable" seed size (based on growth and mortality) and an "optimum" seed size (that takes into account prices of large seed in other regions) will be determined at the end of the growing season. Results will be shared through social media, press, and industry specific list-serves. As a part of outreach, two thirds of seed reared in this experiment will be reserved for other farmers hoping to try the technique (in return for freely shared data).

This project aims to find a “minimum-viable” and “optimal” seed-clam size that can be grown in a polyculture with oysters on subtidal farms in the method described in SARE projects FNE17-877 and FNE18-901, using inexpensive conventional aquaculture equipment (mesh shellfish bags). Success of treatments will be gauged by growth (% change in shell length) and survivorship (mechanical loss and mortality). This information will inform hatcheries and nurseries of the marketable seed size for this polyculture system. Availability of larger seed would remove barriers to entry for farmers by eliminating the specialized nursery-phase of clam production, allowing them to diversify their crops and expand their farms without increasing their overall footprint.

The goal of the downweller-assisted portion of this experiment is to produce the large seed that enables the main tests described above. It is included because large seed is not available in this part of the northeast.