Effect of temperature and ration on growth and ž / condition of king scallop Pecten maximus spat

Ž . Ž . Hatchery-reared king scallop Pecten maximus L. spat 5–14 mm shell height were held in mesh-based Perspex cylinders suspended in 2.5 l beakers of seawater. This seawater was Ž . Ž maintained at eight temperatures 58C–238C inclusive , and various rations 0.012–0.492 g Ž . y1 Ž . y1. organic weight of algae g live weight of spat week of a diet consisting of a mixture of Ž . PaÕloÕa lutheri Droop Green and Chaetoceros ceratosporum Ostenfeld were fed. Size of the animals was estimated weekly by computer analysis of video images taken of the scallops in the cylinders while in seawater. The relationship between temperature and food ration was evaluated. As temperature increased, the scallops consumed a bigger ration, and the highest ration that they consumed efficiently determined their maximum growth rate. This ration, and the corresponding growth rate, both increased with temperature. At the end of each 3–4 week experiment, the Ž . condition ratio of dry meat weight to dry shell weight of the spat was estimated. Condition was greatest between 108C–178C and least below 8.08C. Condition decreased with lower rations at all temperatures above 108C. Comparison of results with preliminary observations made at commercial scallop cultivation sites suggest that temperature rather than food is the factor most often limiting for growth in the sea. Crown Copyright q 2000 Published by Elsevier Science B.V.