Unlike most other popular molluscs, including Scallops, Oysters and Mussels which are bivalves with two shells hinged together, Abalone has just one shell. Called gastropods or univalves, such single-shelled creatures are often of less culinary interest than their two-shelled cousins, but the 100 or so species of Abalone found around the world are a notable exception.
Abalone have been a highly valued product for centuries, wherever cool ocean waters and kelp beds are found.
Abalone farming began in the late 1950s and early 1960s in Japan and China, when it became necessary due to high demand and overfishing. In recent years, growth of the abalone industry has been made possible by a number of innovations in low- cost seed production and highly efficient sea-based cage culture systems.Broodstock are induced to spawn using either ultraviolet irradiated seawater or a solution of hydrogen peroxide. Both methods stimulate mature female abalone to release eggs and males to release sperm. Fertilized eggs are hatched and reared through the free-swimming larval stages in flow-through water systems equipped with screens to prevent escape.
Abalone hatcheries typically use filtered and UV-treated seawater at a temperature of about 15°C (59°F). Upon settling, abalone veligers shed their cilia and develop the familiar shell and body form, including the characteristic abalone foot.
Juvenile abalone are subsequently reared in flow-through tank systems with filtered and sterilized seawater. Control of temperature, water quality, and feed availability are critical to attain acceptable survival rates. At this stage of development the animals are fed benthic diatoms that are seeded into the tanks prior to stocking. The diatoms form a thin surface film on multiple vertical PVC plastic sheets. The young abalone are continuous grazers, so maintaining a constant supply of these diatoms in sufficient quantities is critical.
As the young abalone grow, they begin to consume a type of algae known as dulse. Most farms culture their own supplies of dulse, which serves as an important dietary transition between the diatom films and the final grow-out diet of kelp. Dry formulated feeds are common in the industry in many parts of the world, and many producers have found artificial diets particularly useful for abalone between 3 and 6 months of age. However, artificial diets are not used in the U.S. industry.
By the time they reach 6 months of age, abalone are transferred into larger tanks of cages with sheets of corrugated PVC for advanced grow-out. At this age, abalone are typically weaned from their earlier diets to a diet of kelp, a natural food of many species of abalone.
At this size the abalone’s mouth parts are sufficiently developed to graze on the thicker, tougher fronds of the kelp, and kelp will be their primary food for the rest of the production cycle.
Successful grow-out systems have included near-shore submerged and screened concrete pipe culverts, fifty-five gallon plastic barrels, and off-shore cage culture. Nowadays, growers primarily use cage culture and land-based, flow-through tank systems.
Land-based grow-out production systems usually consist of large reinforced concrete or fiberglass tanks that are plumbed for flow-through seawater and continuous aeration using forced air.
Tanks must have secondary back-up systems for pumped seawater and forced air to provide the necessary oxygenated water essential to abalone survival in the event of a power outage or equipment failure. Energy expenditures to operate the seawater pumping and aeration systems are a major cost for land-based systems.
Land-based systems are usually operated in greenhouses or similar structures. Greenhouses are typically covered with shade cloth, often to the point of significantly reduced light levels. Anecdotal evidence suggests that dark conditions result in faster growth.
Many abalone cages are built by abalone growers, but commercially constructed cages are also available. Cages are often constructed from PVC frames covered with heavy gage plastic mesh. Additional surface area is provided by securing plastic or fiberglass plates in the cages, in a similar configuration as would be found in onshore tanks. Additional economic considerations in cage production include costs for boat, motor, fuel and hydraulic or manual wenches to lift cages for feeding, maintenance, and harvest.
In both cages and flow-through tanks, it takes 3 to 4 years for abalone to grow to a commercial market size of about 7.6 to 8.9 cm (3 to 3 ½ inches). This is the most capital intensive and time-consuming portion of abalone aquaculture, and labor and feed costs are a major consideration for both types of culture systems. Kelp for abalone is typically harvested from offshore kelp beds, and regulated under permits issued by local authorities.
An abalone farm may have the option to harvest kelp using its own vessel and operators or to purchase kelp from a licensed kelp-harvesting company. In either case, kelp must be sustainably harvested, because farm operations depend on a reliable, steady supply. Farm capacity and productivity will be limited by kelp abundance and availability, so identifying kelp supplies and costs is an important component of any abalone operation’s business plan.
Abalone farming is a capital intensive business. Initial costs include water supply systems, pumps (both for the primary seawater supply and various circulation pumps), an emergency generator, culture tanks, greenhouses or comparable structures, hatchery installations, seaweed (dulse) cultivation facilities, supplemental plumbing, electrical installation, packing facilities, office and restroom facilities, and boats and vehicles associated with kelp harvests and general business operations.
Operating expenses are also significant, including energy costs for continuous pumping and aeration, labor (management, abalone husbandry, harvesting kelp, security, office staff, etc.) feedstuffs (primarily kelp), and other miscellaneous expense categories. Grow-out and marketing schedules will be impacted by cash flow considerations. Abalone take a particularly long time to reach marketable size (3 to 4 years), so a business must have sufficient cash reserves to cover all expenses until the first harvests (and sales) are realized.
Abalone, prized for its delicate flavor and unique texture, has been a culinary delicacy for centuries. Harvesting this precious mollusk is an art that requires a deep understanding of its natural habitat, meticulous techniques, and a commitment to sustainable practices.
Abalone, often found clinging to rocky surfaces in coastal waters, has long been harvested from the wild. However, the increasing demand for this sought-after delicacy and concerns over the depletion of wild populations have led to the emergence of sustainable aquaculture practices. Today, both wild harvest and aquaculture contribute to the availability of abalone in the market, each with its unique challenges and benefits.
Traditional abalone harvest involves skilled divers venturing into the depths of the ocean to collect the mollusks. Equipped with handheld tools, they carefully pry the abalone off the rocks without damaging their delicate shells. This method requires experience, precision, and a deep respect for the marine environment. It is a testament to the connection between humans and the sea, passed down through generations.
One of the key challenges in abalone aquaculture is replicating the natural diet of wild abalone. In the wild, abalone feed on a variety of seaweeds and algae, which contribute to their unique flavor profile. Aquaculture farms strive to provide a similar diet, carefully selecting and cultivating seaweed species that mimic the natural food sources of abalone. This attention to detail ensures that farmed abalone maintains the distinctive taste that connoisseurs appreciate.
Once harvested, abalone undergoes careful processing to preserve its freshness and quality. The shells are meticulously cleaned, and the meat is skillfully removed, ready to be enjoyed in various culinary creations. Abalone is renowned for its versatility, often prepared as sashimi, grilled, sautéed, or incorporated into exquisite seafood dishes.
In conclusion, the art of abalone harvest represents a delicate balance between tradition and sustainability. Whether harvested from the wild or cultivated through aquaculture, the process demands a deep respect for nature and a commitment to responsible practices. By embracing sustainable harvesting methods, both wild and farmed abalone can continue to grace our tables for generations to come. So, the next time you savor the exquisite flavors of abalone, remember the intricate journey it undertakes, from the depths of the ocean to your plate, and the dedication of those who ensure its sustainable harvest.