Managing and Monitoring Bottom Cage Placement in Deep Water Oyster Culture

View the project final report

Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture

Oyster farms are moving from shallow water (<2 feet depth) to deeper water (>20 feet depth) as local nearshore areas become limiting. Regional conditions dictate that oyster farms in deeper water must be managed on the bottom using compartmented cages to hold stocked oyster bags. However, the technology to properly manage those cages is lacking, primarily in placing cages on the bottom with the proper cage orientation (sitting upright on supporting runners) and in a distribution pattern that optimizes space use on the farm. In order to achieve these management conditions, Blue Stream Aquaculture (BSA) proposes to evaluate strategically placed buoyancy on the cage to ensure an upright deployment on the bottom following release and free-fall from the surface. Using a side/top-scan fish finder, commonly available to recreational fishermen, coupled with detection software, BSA will develop a means to “visualize” cages on the bottom in three-dimensions, allowing the farmer to assess the cage orientation and distribution of cages on the farm site. With this knowledge, the farmer can optimize space use and ensure the best possible production for the site. Results from these studies will be distributed using a written bulletin addressing cage buoyancy and a short video produced to demonstrate the observation of cages on the bottom with sonar. All outreach materials will be available through an established website in conjunction with the Technical Adviser for the project as well as incorporated into current classes for new farmers offered via two outreach organizations.

This project seeks to improve upon deploying deep water oyster cages by assisting in the placement and by developing a means to visualize the cage distribution on the bottom. To achieve this goal, we propose the following objectives:

1. Develop a means to ensure that cages released from the surface will land on the bottom in an orientation to ensure optimal growth of the seed within. By testing two different means to maintain cage orientation as it falls, we will evaluate the efficacy of promoting an upright landing and will monitor the cost in terms of both time and expense to apply the deployment techniques. The success of the enhanced cage release, in terms of proper cage orientation, will be compared to a control of an unencumbered release of the cage from the surface.
2. Develop a method to visualize the orientation and placement of cages on the bottom using commercially available “fish finder” technology. With the application of side-scan sonar, the farmer will observe a three-dimensional representation of the array of cages on the bottom with fine enough resolution to monitor both overall placement relative to other cages and the orientation of the cage as it lands.