Growth and survival of the Japanese abalone Haliotis discus hannai were studied over a six-month period at the Center for Abalone Production, Universidad Católica del Norte, Coquimbo, Chile. Cultures were carried out in lantern and basket nets suspended in seawater tanks having a constant flow of fresh seawater from La Herradura Bay. A total of 900 juveniles were observed, starting with individuals having an average length of 20 mm. The abalone juveniles were fed with two species of macroalgae, half of which was Gracilaria chilensis, and the other was half Ulva sp (mass basis), fed ad libitum. Artificial pelletized food was fed as a supplement, at a rate of 2% of the body mass of the abalones daily. Water quality in the cultures was monitored twice daily, included water temperature, pH, dissolved oxygen, and water flow rate. The average survival of the abalones at the termination of the experimental period was 96.2% in the lantern nets, and 94.6% in the culture baskets, although these differences were not statistically significant (P > 0.05; nested ANOVA). The highest mean specific growth rates were obtained in the lantern net systems with rates of 0.34% per day in length and 1.02% per day in weight; comparative values for the basket systems were 0.31% per day and 0.86% per day. Higher growth rates for weight and length of the shell were obtained in the lantern systems than in the basket culture systems. An analysis of covariance of values for growth in weight and length of the abalones showed significant differences between results from the lantern and basket systems (P < 0.05). Based on the results of the study, the lantern systems should be considered as an interesting alternative for the culture of Haliotis discus hannai both in land-based cultures, and at sea, because they have a larger carrying capacity for abalones compared with the baskets in the culture tanks and only occupy one third of the water column space. The lantern nets not only provided the best growth, but were also more economical, and easier to handle than the baskets.
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Vol. 26 • No. 3