Biological and Economic Optimization of Shell Size and Timing for Sea Scallop (Placopecten magellanicus) Ear-hanging in the Northeast U.S.

View the project final report

Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture
• Education and Training: decision support system
• Farm Business Management: agricultural finance

The Atlantic Sea Scallop, Placopecten magellanicus, supports the 4th most valuable fishery in the U.S ($541 million USD ex-vessel value in 2018). However, the U.S. annually imports an almost equal amount of scallops. Maine scallops consistently fetch prices at the high end of the range. The national trade imbalance and price premium for Maine scallops represent a significant market opportunity for an aquacultured product landed daily and available year round. However, slow scallop growth and high mortality generate substantial capital and labor costs, a product of low density net culture. Ear-hanging, suspending scallops vertically in the water column, increases growth rates and eliminates the costly need to manage nets. Yet, there is a distinct data gap in the U.S. regarding the parameters that minimize expenses. We propose taking a nested effects (ear-hanging date and size grade) approach to optimizing this system. We plan to conduct ear-hanging trials in April, May, and June. On each date, scallops will be graded into three size classes. Over the following 5 months (June - October), we will measure scallop growth and survival. We will also track total costs. The data from this project will allow growers to make informed decisions regarding best husbandry practices. Increasing production of farmed Maine scallops through improved ear-hanging techniques has the potential to improve productivity, reduce costs, and increase net farm income; improve water quality; enhance employment in farm communities; and improve quality of life for farmers, their employees, and the farming community.

This project seeks to explore two primary objectives: 1) what is the optimal scallop size range and the timing of drilling that maximizes scallop growth and minimizes mortality on ear-hanging lines, and 2) how do the scallop grader and the parameters deduced from objective 1 impact cost of ear-hanging production? Under objective 1, we will determine the effects of initial size and the timing of deployment on scallop growth and mortality. Under objective 2, we will quantify the impact of size grading, timing, and the subsequent scallop growth and mortality on cost of production. We plan to collect labor, operating, and capital costs over the course of the ear-hanging period (April - June) in addition to scallop growth and mortality information. These data will help growers and researchers identify production bottlenecks, better manage inventory, plan seasonal ear-hanging tasks, weigh the benefits of the practice against next best alternatives (net culture), and identify future research needs. There is a general consensus that ear-hanging improves growth. However, we contextualize the growth benefits with respect to cost of production.