Abalone have been a highly valued product for centuries, wherever cool ocean waters and kelp beds are found. Fisheries throughout the world were historically based on collecting by hand in shallow waters, or free diving further off shore. With the advent of scuba equipment in the middle of the last century, harvest pressure on wild abalone populations increased significantly and many fisheries collapsed or were closed in attempts to conserve these mollusks. In the U.S., a tightly-restricted sport fishery for abalone continues in California, and farming currently occurs in both California and Hawaii.
Although abalone farming is said to have begun in Japan and China around 1960, abalone culture was first attempted in the U.S. at Stanford's Hopkins Marine Station at Pacific Grove, California in 1940. Initial efforts focused on spawning adult red abalone, a species native to the state’s waters, and studying their larval stages. California's commercial abalone industry began near Morro Bay in the mid-1960s, as an extension of continuing research and development (R&D) activities. For over 20 years commercial R&D efforts continued, with additional research being conducted by the California Department of Fish and Game and the University of California. By the late 1980s the first commercial abalone farms were in transition from R&D to true commercial viability.
For the next several decades the number of abalone farming operations increased, but by the early 2000’s the trend had been reversed. California abalone growers have cultured nearly all of the state’s native species at one time or another. However, because of its high value and adaptability to culture conditions the Red abalone has historically been the principal species grown in California. Pink and Green abalone are also of interest to growers in southern California because they can be grown at relatively higher water temperatures, but there is currently no commercial production of either of these species in the state.
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.
The 2018 USDA Census of Aquaculture reported only four abalone farms in the U.S. Three were in California and one in Hawaii. Sales of food size abalone totaled 1,882,000 animals valued at $6,432,000. The total number of farms and total sales were both down considerably from the 2013 Census values of 10 and $8,529,000. With an estimated live weight of 339,000 lb., the average value per animal was $19 in 2018.
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.
Regulatory issues can also impact marketing activities. Permits will be typically be required to culture and sell abalone, to pump seawater (in some locations), to discharge water from production systems, and to handle, pack or process harvested product. Historically, abalone growers have sold to wholesalers, restaurants or directly to consumers (including online sales). Direct sales generally generate higher prices, but they often require some sort of processing or packing facility and all the associated regulatory considerations. If abalone are processed prior to being sold, producers can also access markets for abalone shells to be used for jewelry and other decorative purposes.
Emerging trends in ocean acidification and seawater warming may complicate successful culture of red abalone in the coming years, at least in areas where they traditionally thrived. On-going research may help solve some of these potential problems, however, since recent findings suggest red abalone from more northerly regions in California may be better adapted to cope with these environmental changes.
Although commercial fisheries for abalone have been closed in the U.S. for many years, some illegal harvests continue. Additionally, imports of abalone products have increased dramatically in recent years according to fishery statistics from the National Oceanic and Atmospheric Administration. This trend reflects a large increase in supplies from Asian countries, possibly fueled by the adoption of artificial diets in abalone culture throughout the region.
Prepared by C. Greg Lutz, Louisiana State University Agricultural Center