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Ingvar writes on aqua- and mariculture
Abalone in Iceland
Abalone has come to Iceland to
Red Abalone is already domiciled in the country
and has now been joined by Ezo Awabi
Abalone - in Japanese: Awabi - are marine snails. They belong to the phylum Mollusca, which includes clams, scallops, sea slugs, octopuses and squids. Abalone join other snails, whelks and sea slugs in the class Gastropoda, which have one shell - also known as univalves - as opposed to clams with two shells, known as bivalves. Abalone belong to the family Haliotidae and make up the genus Haliotis. Worldwide, more than one hundred species of abalone have been identified, of which about ten are being harvested or grown for commercial purposes.
Abalone breed through broadcast spawning. In culture, spawning is controlled by the water temperature - and by light. The egg hatches as a microscopic freeliving larva, which drifts with the currents for about a week. It then settles to the bottom, sheds the swimming hairs and begins to develop the adult shell form. If a suitable habitat is located, it will grow to juvenile- and adulthood. At six months of age, the spat begins to consume kelp and becomes a juvenile (diagram above).
Abalone are nocturnal - active at night. In nature, they contend with a variety of predators throughout their lives. Eggs and larvae are consumed by filter feeding animals. Juveniles are preyed upon by crabs, lobsters, predatory snails, starfish, octopuses and fish. Adults are removed by large fish, seals, sea otters and the most effective of all predators - man.
Weaned-on-kelp juveniles - WoK's - feed on brown algae and continue to do so throughout their adulthood. In culture, they consume 3 to 5% of their own weight per day and convert the food at a rate of 1:10 to 1:20. Abalone grow to market sizes of 80 to 100 mm shell lengths and 80 to 150 gram live weights in some two-and-a-half to four years from the date of spawning.
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On the Reykjanes Peninsula (map below), in the very south-west of Iceland, geological strata are of spectacular volcanic characteristics, offering a variety of possibilities for the management of the combined harnessing of water supply and geothermal energy. These quite unique conditions - believed by many to be unsurpassed world wide - come in handy in the cold-temperate climate of the country. A cross-sectional view of the Water-Energy Reservoir (diagram above, select diagram for a full size view) explains how two water wells, supplying fresh water and seawater repectively, and a geothermal deepwell are drilled within the same general area at ground level.
The drilling technology is similar to that employed in the oil industry. It permits an experienced driller to obtain any specific water temperature and quality he desires. Pollution levels in Iceland are quite low to begin with - whether on land, in the air or in the surrounding sea. Seeping through the volcanic strata, all water, both fresh and salty, attains a superb pureness. The high permeability facilitates generous flow rates. At the production level, hot geothermal fluids - water, brine or steam - are passed through heat exchangers, thus permitting the desired temperatures and quality of water for the culture to be maintained.
In late 1988, three separate lots of Red Abalone juveniles (Haliotis rufuscens ), of shell lengths ranging between 20 and 45 mm, were brought to Iceland from a grow-out facility in California, USA. The purpose of the excercise was to test the species' ability to thrive in an intensive mari-environment created through geothermally heated seawater from drilled wells (diagram in the box above) and gauge its growth expectations if fed the locally available diet.
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The tank-to-tank transit time of twenty-five hours was composed of the packing process and several hours on the road in California, two commercial flights of five hours' duration each, transfers at two airports (Los Angeles and New York) and, finally, clearance through customs in Iceland including a half hour's travel by road to the experimental marifarm of the Marine Research Institute (MRI) at Grindavik in the southwest of Iceland (map above).
Mortality in the two first transfers was high. In the last one, however, a 100% survival was attained. Hence, it could be insisted that the techniques of moving live abalone over extended distances and periods of time had been mastered. The comparatively high initial mortality may, in its own way, have been a natural selection of strong individuals, resulting in a surviving stock of strong and healthy Red Abalone animals ('survival of the fittest'). The present appearance of the stock, in which a number of individuals display shell lengths of 125-150 mm (5" to 6") and live weights of 450-500 gr (16 to 18 oz), certainly supports this theory (pictures below).
Monitoring of shell lengths, weights and the consumption of kelp indicate that growth rates and feed conversion ratios are comparable to those experienced in culture elsewhere in the world. Temperatures in the quarantine were maintained around 15 degC, considered optimum. The animals were fed Laminaria digitata , which occurs in abundance around Iceland. Supplementing the brown algae diet with Palmaria palmata (dulse) and Alaria esculenta at a rate of 10 to 20% was found to increase growth rates, improve the colour of the shell and be conducive to good health and general wellbeing among the animals.
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