Serving the estuary (with lemon)
Grassy Bar Oyster Co. (GBOC): Morro Bay National Estuary
* Fields A-OG-B-C. Tumbled. Bottom-grown. Stone-grown. Transfer. Miyagi. Triploid. Seed. Plant. Flip. Sort. Harvest. “That’s amore!”
* Not so much related to oyster farming as it is related to shoving the boat over eelgrass beds with a long wooden pole. Must be said in imitation of Dean Martin while thinking of Venetian gondolas.
Here's a peek into what has been going through this intern’s mind after two weeks of working on the farm at Grassy Bar Oyster Co. in Morro Bay, California. I had only ever seen the farm from a distance as I passed by on a boat or kayak, as a little building on the estuary that didn’t have much fuss to it. On day 1, I quickly learned the severity of my underestimation regarding the size and complexity of both the business and the spread of tasks required to keep things going smoothly from farm to table.
Grassy Bar Oyster Co. (GBOC) distinguishes itself by its harnessing of the Morro Bay National Estuary to grow their Pacific oysters and Manila clams. This form of aquaculture is categorized as an intensive open system, which is recognized for its high degree of involvement throughout the cultivation process and the open circulation of resources from the adjacent natural environment. There are three areas that may pique one’s interest when it comes to managing a profitable business operation while keeping the best interest of the ecosystem in mind: (1) what does open-system cultivation entail, (2) how do farm practices support the company and the ecosystem, and (3) what comes next for GBOC?
The past two weeks have best illuminated some answers to the first question. When I first learned about GBOC and how they form part of the estuary ecosystem, I considered two potential management options: (a) a high degree of involvement regarding resource inputs and minimal intervention during growth, or (b) a low degree of involvement regarding resource inputs and intense intervention during growth. In fact, it is the latter. The farm crew is constantly working to manage the various types and life stages of their Pacific oysters while they grow in the fields, but do not add or remove any nutrients from the estuary.
Thus, the resources provided to the oysters are all naturally-occurring from the estuary cycling processes. This situation both benefits and challenges the farm; though there is no need to intensively acquire and monitor inputs that could impact the natural estuary ecosystem, anything that could pose detriment to the estuary may be conferred to the oysters as well. While there is opportunity to temporarily relocate oysters to tanks on land in order to limit contamination, this is a complicated and time-consuming endeavor that must be undertaken a week in advance of the disturbance.
It is often easy to determine whether oysters are responding positively or negatively to the estuary conditions - they “tell” you. Their form of communication with us is often best witnessed while flipping the oyster bags. This task is preferably conducted monthly on the bottom-grown oyster bags to limit buildup of anoxic mud on their surfaces and reduce the likelihood of oysters growing on each other in “doubles”. When the bags are flipped, the clattering of oyster shells will either be dull - like tumbling rocks - or hollow - like wooden wind chimes. The former sound indicates a bag with mostly live oysters, while the latter indicates a bag with mostly dead oysters.
The survivorship of oysters is variable throughout the year, but the general pattern is that they grow fastest during the summer, when the abundance of their phytoplankton food source is greatest. The head crewman at GBOC farm, Robert Moon, explained that both the consumer demand and farm supply of oysters fluctuate on an annual basis, and the company often has to quickly adapt to constraints as they balance on a narrow profit margin.Given this situation, much effort is directed towards reducing expenses at the farm while maintaining production. This idea leads us to topic 2, which considers the farm operations with regard to their costs and benefits for the company and the ecosystem.
Beginning at the business end, I note that the supplies used at the oyster farm are often acquired at low-cost and able to be used for multiple years. For example, the three types of bags (bottom, clip, and tumble) are reused as oysters pass through life stages and are harvested. Further, twist ties are used and reused for sealing oyster bags that are filled with harvestable oysters. Moving on to a middling resource - ones that are frequently used and discarded - at the farm are hog-rings, which are used to seal oyster bags that will be placed back into a field for growing. These, however, are minimally impactful to the environment if they are lost when broken, as they rust away in the brackish waters of the estuary.
The material with the greatest potential for damage in the estuary are the plastic tape tags used to identify the types and size classes of oysters. In fairness, these tags are applied only as frequently as is necessary to ensure organization across the farm. Still, GBOC is open to productive experimentation, and is considering use of metal tags to reduce plastic waste and potential marine debris.
Photo of Lexi Cango Ruiz with GBOC Friends
Pollution is the primary concern for farm hands at GBOC when interfering with the environment, and it seems that it is for good reason. When I started at GBOC, I worried that the oyster farming could be damaging to the estuarine ecosystem. Within the first few hours of work, as we dumped the oyster bags’ contents onto the table, I saw the myriad of wildlife hosted in these miniature systems. There were oysters (as one would hope from an oyster farm), but also a wide variety of other marine invertebrates, seaweeds, fish, and more. Outside of the bags, I frequently saw shorebirds along the fields, likely reaping the benefits of the centralized habitat structures. Bat rays, leopard sharks, sea otters, and harbor seals are likewise among the visitors to the farm.
Given my existing knowledge on the subject, the prevalence and abundance of organisms at various trophic levels suggest that there cannot be too much harm done to this ecosystem from oyster farming. Additionally, though these oysters are not native to the California Coast, they have no invasive potential, as they are unable to produce viable spawn in this climate. This works out well to prevent undue impact to the ecosystem, but leads to additional costs and effort for the farmers.
This is where a merger with Holdfast Aquaculture and its future opportunities come into play. Holdfast was primarily a research-and-development company for oysters, mussels, clams, and seaweeds. In joining with GBOC, there is now a direct line from hatchery to nursery to farm that can be used to the benefit of both entities. With Holdfast’s taxa of interest all in residence at GBOC, research opportunities abound to broaden horizons for business growth, promote learning in oyster biology, and open doors to increase efficiency in production of high-quality aquaculture products. One direction that Holdfast Aquaculture CEO, Dr. Diane Kim, highlighted was to identify areas where leveraging technologies could accelerate processes and complement the essential “human touch” in GBOC operations. Though large-scale changes are years away, the forward-thinkers at GBOC and Holdfast Aquaculture have the knowledge and drive required to sustainably manage an oyster farm and educate aquaculture enthusiasts.
Through my work at GBOC as a first-time aquaculturist, I have gained a more profound understanding of the motivations, practices, processes, and outcomes of oyster farming in an intensive open system. This experience has also fostered appreciation for the nuances in supporting a business that directly relies on its encompassing natural landscape. After completing my internship with Minorities in Aquaculture, I look forward to continuing my work at GBOC, and carrying this knowledge and sentiment into my future in advocacy for sustainability in aquaculture.
meet THE AUTHOR
Lexi Cango Ruiz
B.s. from California Polytechnic State University & 2025 MIA Summer intern
