Growth and the energy budget of juveniles of the abalone Haliotis tuberculata (L.)

Abstract

The spawning season of the most commercially important European abalone {Haliotistuberculata) was evaluated during the summers of 1996,1997 and 1999. The results of the present study show that the best time to start with semi-artificial spawning is from mid July using cultured abalone from the open sea in Guernsey, Channel Isles. Until 1996 Tetraselmis sueccica was the main source of food for juvenile H.tuberculata during their rearing stage (one to twelve weeks old) on glass plates. Nevertheless, this study showed that T. sueccica, as a sole food, is not sufficient for successful development and growth of early juvenile abalone. However, marine diatoms such as Skeletonema costatum, Navicula ramosissima and Cylindrotheca closterium were easily ingested and assimilated depending on the size of the animal and conditions of culture. This thesis studied the effect of different diets (mix of fresh seaweed, fishmeal and anabalone commercial) and temperatures (15, 18 and 22C) on growth and energy budget of juvenile abalone H. tuberculata over a 210 day period. Energy budget was obtained by Ingestion (I), Egestion (E), Somatic growth (Pg), Reproductive investment (Pr), Excretion (U) and Pedal mucus production (M). All these parameters were assessed for grouped and individual organisms. Animals fed on formulated diets (energetically rich) and cultured at 18 and 22C were shown to give better growth rates than the natural diet and preferentially allocated energy to gonad development. Thus, the combination of diet and temperature were factors that contributed to enhance growth rates and gonad development. The abalone commercial diet (CO) used in this study produced shell deformation in 89% of the population after four months of feeding juvenile abalone. The information of these studies have important implications when considering the nutritional requirements of cultured abalone when fed on formulated diets, which need to contain not only the energy, but also the necessary micronutients which are required to produce good growth rates and also healthy animals.

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