Abalone

Abalone Culture in British Columbia
Market demand and price for abalone has been so high that most capture fisheries around the world are in serious decline and many countries, including Canada, have imposed either severe harvest restrictions or an outright ban on capture of wild stock. Australia remains the only country in the world with a significant abalone fishery. There is, therefore, a significant effort underway worldwide to establish aquaculture industries. South Africa is now the world’s biggest producer of cultured abalone, followed by Taiwan, Chile, Iceland and Mexico. The United States, mainly California, and Australia, also produce cultured abalone. Canada has not yet produced any cultured abalone for market. Japan and China are the largest consumer nations of abalone and in both countries abalone aquaculture and enhancement have been the focus of a great deal of research and development work. In British Columbia there has been a long term interest in moving forward to develop abalone aquaculture. A pioneering effort was undertaken near Sooke on southern Vancouver Island in the late 1980’s. A small facility was constructed and some success at spawning and juvenile rearing was achieved. More recently there has been a renewed effort at developing hatchery and culture techniques in BC. Since 1999, a small number of fledgling enterprises have been launched. All of these projects are restricted by regulations regarding access to broodstock animals and none have yet produced marketable abalone.

Market and Products
Abalone is a luxury product. Market and price are sensitive to economic performance. However, the inability of supply to exceed demand has resulted in generally high prices for abalone products. The Asian markets of Japan and Hong Kong are the largest and most significant destination for abalone and abalone products. In Japan, the highest quality live abalone (Ezo Awabi) are sold for sashimi or sushi and command a high price. Only certain species, including H. kamtschatkana, qualify for this market. Product quality must meet high and exacting standards for this market.Canned abalone is also valuable and finds a market primarily in China / Hong Kong and Taiwan. There is a small live market in North America and Europe, but most of the abalone in these markets is sold as fresh or frozen fillets.

Species
The species of abalone common to the british Columbia coast is the Pinto or Northern Abalone, Haliotis kamtschatkana.

All commercially valuable species worldwide belong to the genus Haliotis. Abalone are gastropods with a single shell. In their natural habitat, abalone prefer rocky substrate where they can protect themselves from predators by attaching firmly to the rock. The main predators of the abalone are the sea otters, (Enhydra lutis) and various sea stars. Pinto abalone have the typical series of perforations, or foramina, in the shell. Water can flow in through these holes and and wastes carried out through them. Abalone are nocturnal, moving and feeding mainly at night. Younger animals feed on corraline algae and they will shift their diet to various species of macroalgae. They will usually trap fragments of kelp under the shell and graze on them under its protection. This characteristic and the manner in which they feed present a significant challenge to successful containment rearing of abalone. Availability of the appropriate species in sufficient quanitites, or the development of adequate and cost-effective feeds, will be a primary condition for the development of an aquaculture industry for abalone.

H. kamtschatkana is biologically very similar to the Japanese ezo abalone H. discus hannai. It is likely that much of the research and developmnent that has been carried out on the latter will be transferrable to the former.

Planning for Production
Rearing abalone from seed to market size can take three or more years. The development of culture techniques for H. kamtschatkana will have to overcome a significant biological barrier: the slow rate of growth of this species. For the live market the target size is 9cm (3.5 inches) shell length and approximately 100g live weight, including the shell. For other products, the abalone can be somewhat smaller starting at about 75g live whole weight.

The production cycle consists of a hatchery phase(spawning and larval stages), juvenile phase and growout phase. Where abalone are already cultured, they are usually reared in land-based tank systems necessitating high capital investment in sea water pumping systems and infrastructure. Feed, usually kelp, must also be supplied to abalone stock in such production systems. Suspended systems in sea water have also been investigated and attempted with some degree of success. Various types of containment have been implemented including plastic barrels as well as mesh pouches. Rigid plastic mesh cages suspended from rafts have also been used successfully in California. However, feeding the stock is still a requirement for these systems and an efficient means of accessing the containers to insert feed is necessary.

The requirement for regular feeding and maintainance of the abalone stock will likely lead most abalone farms to adopt tanks or raceways as the primary culture system. The Malcolm Island operation, for example, is developing a land-based tank and raceway system modelled on techniques used in South Australia. Kelp, usually species of Macrocystis, Laminaria or Nereocystis will be harvested from the local area and fed to the abalone. However, due to the limited availability of kelp, there has been an increasing effort to produce a cost-effective manufactured feed.

Steps of Production: Hatchery and Seed
Selecting broodstock is the first step to hatchery production of seed. In abalone the sexes are separate and can be distinguished by the color of the gonad. Males will normally have white, cream, or yellowish gonads while the female gonad is typically dark green, but may be brown, gray or violet. Mature females will produce anywhere from several hundred thousand to a few million eggs. Males produce many millions of sperm. Conditioning of broodstock and induction of spawning are basic hatchery strategies for seed production. In British Columbia abalone broodstock must be selected from wild stocks in the region. The Malcolm Island Shellfish Co-op, for example, require about 100 animals taken from local populations to form the broodstock core of future seed production. Regulatory barriers have made access to broodstock a major problem for abalone culture in BC.

A viable abalone operation may require over one hundred broodstock animals. Since most of the animals can only be conditioned to spawn once per year and the survival rate of larvae very low, a continuous cycle of spawning requires a large pool of breeding adults. The adult animals are conditioned to spawn by one or a combination of the following methods: ultra-violet filtration of water, addition of hydrogen peroxide to the water, and gradual raising of water temperature followed by a sudden temperature drop. Males and females are spawned in separate containers, eggs are washed and sperm added. Fertilization is verified by observing egg cell cleavage. After 48 hours, the trocophore larvae emerge and 24 hours later develop into the veliger larval stage. The duration of the larval cycle is temperature dependent and may last up to two weeks. During this stage the larvae do not feed, although there is evidence that they may uptake amino acids and other dissolved organic matter directly from seawater. Special tanks are used to hold the larvae during this phase.

Under natural conditions, the abalone larvae seem to prefer initial settlement on corraline red algae before migrating to other surfaces. Researchers believe it is a specific amino acid which probably induces settlement. Mucus trails on such surfaces from mature abalone may also play a role in larval settlement. In the hatchery larvae are induced to settle with the use of an amino acid called GABA (gamma-aminobutyric acid) which is the compound produced naturally by the coralline algae. The larvae settle and metamorphose on flat or wavy PVC plates in tanks. The plates have been innoculated with a thin film of bacteria and benthic algae such as diatoms on which the juvenile animals can feed. Culturing the abalone through settlement and first feeding is a critical hatchery challenge.

Juvenile Rearing
The plates with the juvenile abalone are transferred to tanks where water flow and aeration ensure adequate replenishment of the algal film on the plates. The plates are inserted vertically in racks built into the tanks. This results in a large surface area for the juveniles on which they can move about and feed.

Abalone are normally nocturnal animals. They move and feed at night and seek out sheltered darkened areas during daylight hours. In a culture system, growers want to maximize the feeding opportunities for the animals and thus tanks are normally kept in darkened conditions with tank covers or by building structures to contain the tanks under controlled light conditions.

Maintaining stock at the appropriate densities is critical so that there is adequate feed on the plates for all the animals grazing on them. In one scenario at Malcolm Island, juvenile animals were set at 10 per plate with each juvenile rearing tank containing 120 plates. The tanks are connected in series of 5 tanks per series with inflow water at the rate of 30-50 Litres per minute entering the top tank. Each tank is equiped with an aeration grid at the bottom to facilitate removal of waste material from the tanks.

Feeding on the plates is continued until the juveniles measure 5-10mm in length. Depending on water temperature and feed system, juveniles will take about 10-12 months to reach this size. The point at which the young abalone are ready for transfer to the grow-out system is determined by the size of their mouth parts which enables them to begin feeding on macro-algae or feed pellets. In most culture systems the juvenile abalone will be placed in raceways or tanks containing a variety of surface area enhancements to provide more space and feeding surface. Adequate water flow in the tanks or raceways is essential.

Grow-out
Once juveniles are able to consume kelp or feed pellets they are moved to grow-out raceways. Normally the animals measure approximately 1 centimetre (shell length) at this stage. The juveniles are carefully scraped off of the plates and placed in the raceways. At the Malcolm Island operation, a new experimental shallow bi-directional raceway is being tested.

This type of raceway requires only minimal water depth (e.g. 2 cm), reducing water usage and enabling access to the stock for feeding and observation. In addition to the water sweep to remove wastes, the raceway must also be periodically emptied and brushed clean. The availability of low-cost effective feeds will be a key factor in successful abalone rearing operations. Commercially produced feeds have been devised in Australia and are available for purchase. However, with such high costs, work is underway to develop abalone diets locally. Abalone do feed naturally on kelp, so it may be used as a complement to prepared feeds. Kelp is added to some of the prepared feeds more as an attractant than a nutriotional requirement. The objective is to keep feed costs below 20% of the total cost of production.

Grow-out period will depend on temperature and diet. With enhanced temperature regime, the Malcolm Island operation has observed growth rates as high as 3mm per month. The average growth rate is around 2mm per month but there is a wide range of variation in growth rates. This may be due to genetic factors or strictly a result of competition between individuals. It may be neccessary to cull a portion of the most under-performing animals.

The Northern abalone are subject to a naturally occuring disease in which a pathogen infects mainly juvenile animals. The infection of the head and foot is caused by a parasite called Labyrinthuloides haliotidis. The larger the animal the more resistant they are such that animals 25mm in length did not get the disease even when the foot was innoculated by the pathogen. This disease wiped out the juvenile stock of the first cultured abalone operation in BC in 1986. Measures will need to be instituted to control this disease (Bower 1996). Close observation of stock will alert the grower to potential problems. A good test of the health of an abalone is to flip it on its shell and observe how long it takes to plant its foot and right itself.

Printed sources to consult about abalone:

  • Viana, Maria Teresa. 2002. “Abalone aquaculture; an overview”. World Aquaculture. Vol. 33, No. 1, March 2002, pp.34-39.

Web sites to consult:

  • Fisheries and Oceans Canada:Species and Habitat of Shellfish.
  • Fisheries and Oceans Canada:Diseases and Parasites of Shellfish

Thanks to Pelle Argerup (Malcolm Island Shellfish Co-op), Guy White (Bamfield Huu-ay-aht Abalone Project), and Island Scallops Ltd. for information and photos.