WWW.WA S .ORG • WORLD AQUACULTURE • MARCH 2022 41 ( C O N T I N U E D O N P A G E 4 2 ) Each ALS line consisted of two 15-cm × 4.9-mmarine-treated wood pilings driven approximately 3 m into the sediment, and eleven 7.6-cm × 4.3-m Schedule 80 PVC posts spaced at 3-m intervals, driven approximately 1.8 m into the sediment. Wood pilings were driven using the bucket of an excavator and PVC posts were driven in using a pneumatic post-driver. A 6-mm diameter cable in an 11-mm diameter outer sleeve was stretched from one piling to the other and supported by riser clips attached at various heights on the PVC posts between the pilings. Baskets were suspended from the cable between the riser posts, with each section capable of supporting three baskets. With this arrangement, baskets were capable of being placed at different heights within the water column, or completely out of the water, by raising or lowering the cable onto riser clips at different heights on the PVC riser posts. Let the Oyster Farming Begin Broodstock oysters were collected fromMatagorda Bay in March 2020 and sent to Dr. Scott Rikard at the Auburn University Shellfish Laboratory, Dauphin, Alabama for conditioning and spawning. Oysters were spawned in May 2020, producing the seed that would be stocked at the oyster farm. In July 2020, after the farm installation was completed, approximately 160,000 seed oysters were received and stocked into floating cages and the ALS system (Fig. 5). Seed to be ultimately grown in floating cages were initially The research oyster farm has a single line of 29 OysterGro® LowPro™floating cages,1 capable of holding approximately 14,500 market-sized oysters (Fig. 2). These smaller, two-slot cages were selected because they were light-weight and easier to handle and because there would often be only one person flipping and handling the cages. Cages were installed parallel to the prevailing winds to minimize drag and stress on the line from wind and waves. Installation of the floating cage system was undertaken according to OysterGro® recommendations. Installation of the ALS was more challenging and required a contractor with a barge, excavator and pneumatic pile-driver. This grow-out system required installation of pilings and riser posts, which is usually done by either water-jetting or pile-driving. Related to the type of sediment at the farm site, ALS pilings and risers were installed via a portable pile-driver to an appropriate depth to avoid shifting (Fig. 3). Pile-driving also reduced installation time of the ALS by avoiding need for settlement. The oyster farm was designed to contain six 33-m ALS lines, each capable of holding thirty 15-L SEAPA® baskets2 for a total capacity of 180 baskets capable of holding approximately 14,400 market-sized oysters (Fig. 4). Lines were installed perpendicular to the prevailing wind and wave direction to allow better tumbling and to help maintain even distribution of oysters within baskets. Installation of the ALS system was undertaken according to SEAPA® recommendations. FIGURE 3. Installation of the adjustable longline system (ALS) at the HRI oyster farm using a pneumatic post driver (Photo: Ellis L. Chapman Jr.). FIGURE 4. Raising a line of SEAPA® baskets on the adjustable longline system (ALS) at the HRI oyster farm (Photo: Ellis L. Chapman Jr.).
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