The San Diego Unified Port District (Applicant) proposes to expand upon previous baseline health assessments of juvenile shellfish by performing baseline testing of the health and quality of adult oysters, mussels, and seaweed at one location offshore Imperial Beach using shellfish baskets and conducting concurrent water quality monitoring at this location (the shellfish and seaweed health testing and water quality testing are collectively referred to as the “Project”). During the spring of 2023, the Project is anticipated to occur over the course of one month and would include: (1) species harvesting and depuration; (2) the installation of a buoy system (see Figure 1), which would include four shellfish baskets containing shellfish and seaweed species; and (3) sampling of the shellfish and seaweed. Due to its nature and limited scope, construction of the Project would generate a minor amount of vehicle trips and would require limited use of equipment. Therefore, impacts related to air quality, greenhouse gas emissions, and transportation and traffic are not anticipated to occur. Furthermore, the Applicant would be responsible for compliance with all laws and regulations associated with the activities on or in connection with the above-described premises, and in all uses thereof, including those regulating stormwater and hazardous materials.?
The purpose of the Project is to better understand the relationship between microbial contaminants, water quality, and the presence of certain shellfish and seaweed species. The results of the Project would provide data on microbial contaminants and water quality, which could inform the potential for future shellfish and seaweed aquaculture siting, as well as the use of shellfish and/or seaweed for potential restoration activities and bioremediation projects. The Project would study two species of shellfish and one species of seaweed: adult Pacific oysters (Crassostrea gigas) and adult Bay mussels (Mytilus galloprovincialis/M. trossulus) and green algae (Ulva lactuca). As described below, all shellfish and seaweed used in the Project would be harvested from existing shellfish and seaweed populations in San Diego Bay (Bay).?
Shellfish and seaweed would be harvested by hand from existing piling or riprap structures within the Bay. Then the harvested organisms would undergo depuration at the Coastal and Marine Institute Laboratory at San Diego State University to eliminate the sampling bias associated with the existing Bay water quality conditions. This depuration would occur seven days before deployment. After harvesting and depuration, the shellfish and seaweed species would be placed into four (4) shellfish baskets for deployment.
Following depuration, the buoy system (see Figure 1) would be installed at the Project location. This would include:
• One 600-pound 2 foot by 2 foot by 2-foot concrete block and up to three additional concrete weights in five-gallon buckets that are up to 100 pounds each and would be placed on the seafloor
• One 5/8” nylon line approximately 45 feet in length, which would connect the concrete block to a surface buoy
• One 5/8” nylon line approximately 15 feet in length (tether line), which would be connected to an additional surface buoy and connected to the longer nylon line with a 3/8” shackle
• Four shellfish baskets, approximately 25 inches by 10 inches by 6 inches in size, which would be secured to the tether nylon line via secure clips on the baskets, and
• Potentially one additional submerged standard rubber marine-grade buoy, to ensure the baskets remain at a depth compatible with sampling, if necessary.
In total, the buoy system would have an approximate total radius of up to 30 feet and a bottom radius of three to four feet distributed between the concrete block and additional weights.
A maximum of two people would be required to deploy (and later remove) the buoy system at the project location, which would be sited approximately 3,100 feet Northwest of the Imperial Beach Pier (32.586 N, -117.142 W). Please see Figure 1 for a diagram of the buoy system.? The four baskets would be filled with the shellfish and/or seaweed species as follows:
• One basket would contain approximately 100 adult Pacific oysters
• One basket would contain approximately 100 adult Bay mussels
• One basket would contain approximately 100 adult Pacific oysters and 3 pounds of green algae
• One basket would contain approximately 100 adult Bay mussels and 3 pounds of green algae.
The buoy system would be deployed over a 14-day period. Shellfish tissue, seaweed samples, and water samples would be taken on day zero, 7, and 14 of the deployment. The deployment period would allow adequate time for the shellfish to filter water and accumulate any microbial contaminants present in the surrounding waters. Taking multiple samples would be necessary because it would allow the Applicant to assess how water quality, shellfish tissues, and seaweed samples change over time with the presence of shellfish and seaweed during the deployment period.?The Applicant would send the collected samples to both the University of North Carolina at Chapel Hill and the Applied Industrial Microbiology Lab in Vista, CA, for analysis.
On day 14, or the final day of deployment, all equipment, including any remaining shellfish and algae, would be removed from the water. Removal of the buoy system from the Project location would require approximately one day to complete. The Project location would be accessed by small boat for basket installation, sampling, and removal.?
The Applicant would be responsible for compliance with all laws and regulations associated with the activities on or in connection with the above-described premises, and in all uses thereof, including those regulating stormwater and hazardous materials, as well as acquiring necessary permits from relevant resource agencies, such as the California Coastal Commission, Army Corps of Engineers, and Regional Water Quality Control Board, including the necessary real estate or access agreements, or coastal development permitting for the proposed project sites that are not within the District’s permitting or coastal jurisdiction.?
Figure 1 Diagram of buoy system.?