The Process of Shellfish Aquaculture
Shellfish aquaculture, also known as shellfish farming, is the cultivation of shellfish such as oysters, clams, mussels, and scallops. The process begins by producing larvae in hatcheries, then moving them to nurseries, and finally transferring them to grow-outsites that may be directly on the sea
bed or suspended in the water using rafts or longlines[1]. The many positive aspects to shellfish aquaculture include the benefits to the natural ecosystem, the benefits to the local economies, and the remarkable sustainability of the overall process with respect to the environment.
Environmental Benefits of Shellfish Aquaculture
Unlike other types of aquaculture, cultured shellfish aquaculture has been one of the few industries that have a proven positive effect on the health of the ecosystem in which they exist. The Audubon Society, the Monterey Bay Aquarium’s Seafood Watch, and Ecofish Research, all ecological leaders using an evidence-based approach, agree that shellfish aquaculture contributes to environmental health [2]. Shellfish feed at the bottom of the food chain by filtering plankton and organic particles from the water. These critical ecological functions prevent a process called eutriphication by removing excess nutrients such as nitrogen and phosphorus.
The Problem of Eutrophication
Eutriphication happens as a result of excess nutrients in the water and can lead to several harmful effects on the aquatic ecosystem which relies on a balance between all organisms. Excess nutrients in the water allow for a rapid overgrowth or excess of algae, or algal blooms. Algal blooms can make water appear dirty as they produce toxins that are harmful to aquatic life which in turn, leads to multiple harmful effects for humans. Not only is aquatic life disrupted when algal blooms produce toxins; dying algae is decomposed by bacteria that deplete oxygen from the water, leading to an environment that is uninhabitable for aquatic life [3]. This loss of biodiversity and water quality degradation has devastating consequences for both human recreational use and economic activities.
Integrated Multi-Trophic Aquaculture (IMTA)
In a move towards further increasing the positive effects of shellfish cultivation on the biodiversity and health of the environment, an approach called Integrated Multi-Trophic Aquaculture (IMTA) can be incorporated into the process. This approach combines the farming of shellfish with farming other species such as fish or seaweed to create an environment with symbiotic relationships where nutrients from the organisms are created and shared amongst themselves. Some shellfish farming projects can also have multiple uses including providing habitats for other organisms, stabilizing the seabed and preventing erosion, or the balancing of natural populations – all alongside farming practices [4]. For these reasons, shellfish aquaculture is known to play a vital role in ecosystem health.
Economic Benefits of Shellfish Aquaculture
The positive effects of shellfish aquaculture on local economies cannot be understated. As the global population grows exponentially, the demand for seafood grows as well. While both seafood capture and cultivation practices have come under well-deserved scrutiny in the past decades, shellfish cultivation deserves to be viewed through an entirely different lens. Bivalve shellfish feed entirely on naturally occurring particles and therefore, nothing is added to the environment in which they grow. Their waste is returned to the environment and falls to the seabed to become food for worms or crustaceans that feed on it, which in turn, feed and increase fish populations. The operating cost of this cultivation can stay quite low while also improving the growth of other food sources for humans. Such a marine environment, particularly in rural areas, leads to an increase in tourism and employment in an otherwise economically depressed area [2].
Historical Perspective and Legislation of Shellfish Aquaculture in BC
In the mid 1900s on the West Coast, the native Olympia oyster came close to extinction due to a combination of toxic waste from pulp mills and over-harvesting. During this time, shellfish farmers introduced the Japanese oyster to the area which saved the industry from destruction. Having seen first-hand how crucial a healthy environment and a balance of biodiversity is for the area, oyster farmers have been pioneers in legislation protecting these environments on the West Coast and save their industry [2].
Shellfish Aquaculture Supplies
Farmers have several options for structures used in shellfish farming – all of which are not destructivebut rather enhance existing habitats and prevent erosion. These structures are comprised of lines, trays, rafts, and nets which can either be suspended above the seabed or provide structure and habitats for other organisms on the seabed. The structures are not moved the way fishing lines or nets are, meaning that there is no disturbance to the environment. Farming methods require the structure to only be moved during harvest time while wild harvesters will disrupt the same area many times [2].
The ‘Supertray’ Shellfish Grow-Out System: The Ideal Sustainable Oyster/Shellfish Farming Tool
The ‘Supertray’ Shellfish grow-out system is the perfect tray for oysters or other shellfish aquaculture. This sustainability gem is made from recycled injection-moulded high-density polyethylene and is 100% recyclable at the end of its useful life. An ideal oyster farming solution; it is an affordable, sustainable, and easy option for growing small or jumbo oysters, especially when water acreage is limited as it often is in our fjordic coasts. The “Supertray” is optimized for growing shellfish in deep waters using the water column. This saves space and, when deep enough, prevents fouling buildup on the tray which can limit water flow and therefore shellfish growth. In colder climates where the surface of the water can freeze, the “Supertray” can be used at depths that do not freeze, making it an ideal alternative to floating shellfish aquaculture equipment.
The openings on all sides offer maximum water flow and the high-density polyethylene ensures the highest durability in extreme weather and water conditions. These trays can be stacked on top of each other and securely strapped together to be suspended. Lids are available for each container and each unit is portable for use in a stack or as a single unit. This economical and practical design of our Supertray shellfish grow-out container is optimized for the fastest shellfish growth time and therefore the highest profits. The outer dimensions are 24” x 24” x 8.25“ (61 cm X 61 cm X 21 cm) and the inner dimensions are 22” x 22” x 7.5” (56 cm X 56 cm X 19 cm). The containers are made completely with recycled plastics, coloured in black.
Conclusion
Shellfish aquaculture is a profoundly sustainable way to feed our growing population. This industry contributes to local economies, keeps our waters clean, and promotes healthy ecology in the environments in which it exists. With the “Supertray” Shellfish Grow-Out System from Thunderbird Plastics, the sustainability of this industry is deliciously amplified.
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References
1. Stevens, Craig, et al. “The Physics of Open-Water Shellfish Aquaculture.” Aquacultural Engineering, vol. 38, no. 3, 2008, pp. 145-160. ScienceDirect, https://doi.org/10.1016/j.aquaeng.2008.01.006.
2. Shumway, Sandra E., et al. “Shellfish aquaculture–in praise of sustainable economies and environments.” World aquaculture 34.4 (2003): 8-10.
3. Shumway, Sandra E., ed. Shellfish aquaculture and the environment. John Wiley & Sons, 2011.
4. OECD/Thierry Chopin. “Integrated Multi-Trophic Aquaculture.” Advancing the Aquaculture Agenda: Workshop Proceedings, OECD Publishing, 2010, Paris. OECD Publishing, https://doi.org/10.1787/9789264088726-15-en.