Effect of temperature and ration on growth and condition of king scallop (Pecten maximus) spat

Hatchery-reared king scallop (Pecten maximus L.) spat (5-14 mm shell height ) were held in mesh-based Perspex cylinders suspended in 2.5 1 beakers of s eawater. This seawater was maintained at eight temperatures (5 degrees C-23 degrees C inclusive), and various rations (0.012-0.492 g (organic weight o f algae) g(-1) (live weight of spat) week(-1)) of a diet consisting of a mi xture of Pavlova lurtheri (Droop) Green and Chaetoceros ceratosporum Ostenf eld 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 temp erature increased, the scallops consumed a bigger ration, and the highest r ation that they consumed efficiently determined their maximum growth rate. This ration, and the corresponding growth rate, both increased with tempera ture. At the end of each 3-4 week experiment, the condition (ratio of dry m eat weight to dry shell weight) of the spat was estimated. Condition was gr eatest between 10 degrees C-17 degrees C and least below 8.0 degrees C. Con dition decreased with lower rations at all temperatures above 10 degrees C. Comparison of results with preliminary observations made at commercial sca llop cultivation sites suggest that temperature rather than food is the fac tor most often limiting for growth in the sea. Crown Copyright (C) 2000 Pub lished by Elsevier Science B.V.