Growth and food intake models in Octopus vulgaris Cuvier (1797): influence of body weight, temperature, sex and diet F. AGUADO GIMÉNEZ* and B. GARCÍA GARCÍA IMIDA – Acuicultura, Consejeria de Agricultura, Agua y Medio Ambiente de la Region de Murcia, Las Salinas 7, Puerto de San Pedro del Pinatar, P.O. Box n o 65, San Pedro del Pinatar, 30740, Murcia, Spain; *Author for correspondence (e-mail: felipe.aguado@carm.es; phone: 00 34 968 184518; fax: 00 34 968 184518) Received 11 December 2001; accepted in revised form 6 October 2002 Key words: Cephalopods, Food intake model, Growth model, Growth, Octopus vulgaris Abstract. Multiple regression analysis was used to develop mathematical models applicable to the growth and food intake of Octopus vulgaris. The variables considered were: body weight (Bw: 175– 3,500 g), temperature (T: 13–28 °C), sex (S: male = 0, female = 1) and diet (D: bogue fish = 0, crabs = 1). Growth and food intake may be succesfully expressed by means of the following equations: Ln (AGR + 14) = -2.0135 + 0.0895 Ln Bw + 0.5087 T - 0.0142 T 2 + 0.2997 D (R 2 = 71.79; ANOVA p < 0.0001) and Ln (AFR) = - 5.6577 + 0.5137 Ln Bw + 0.5266 T - 0.0132 T 2 + 1.1135 D (R 2 = 78.71; ANOVA p < 0.0001), where AGR: absolute growth rate, AFR: absolute feeding rate, Bw: body weight, T: tem- perature and D: diet. In our experimental conditions, sex did not affect growth or food intake. The op- timum temperature for growth (17.5 °C) and food intake (20 °C) was independent of body weight. Growth and food intake were higher with the crab diet. Nevertheless, food efficiency was better for animals fed on fish (bogue). Maximum food efficiency was reached at 16.5 °C for both diets. When the temperature was above 23 °C, weight losses and mortality were recorded; the temperature at which this occurred depending on body weight and diet, so that smaller and bogue-fed individuals were more sen- sitive to increasing temperatures. O. vulgaris growth may provide optimum economic performance from 16 to 21 °C. This range is too narrow, considering the wide natural range (12–29 °C) in some Mediter- ranean areas. Therefore, O. vulgaris growth will be limited by seasonality of temperature or must be carried out with other systems (e.g. recirculation in closed systems with temperature control) for it to be economically viable. Abbreviations: Adj R 2 – adjusted determination coefficient, AFR – absolute feeding rate, AGR – ab- solute growth rate, Bw – body weight, D – diet, FE – feeding efficiency, IF – ingested food, R – cor- relation coefficient, S – sex, s.d. – standard deviation, s.e. – standard error, S.E.E. – standard error of estimation, SFR – specific feeding rate, SGR – specific growth rate, t – time in days, T – temperature, Wa – average weight, Wf – final weight, Wi – initial weight Introduction Cephalopod growth is rapid regardless of diet composition (Forsythe and Van Heu- kelem 1987). In general, cephalopods prey on a variety of species, mainly crusta- ceans and molluscs, and to a lesser extent on other invertebrates or fish (Nigmatu- Aquaculture International 10: 361–377, 2002. © 2003 Kluwer Academic Publishers. Printed in the Netherlands.