9334 - Laserfiche WebLink

Home Browse Search

Reviews in Fisheries Science, 1(3). 22'x-237 (1993) The Application of X-Radiography in Feeding and Growth Studies with Fish: A Summary of Experiments Conducted on Arctic Charr Malcolm Jobling, J:orgen S. Christiansen, Even H. J~ergensen, and Arne M. Arnesen Norwegian College of Fishery Science, University of Tromso 9037 Tromso, Norway ABSTRACT: The X-radiographic method first described by Talbot and Higgins (1983) can, with suitable modifications and in combination with other simple techniques, have a wide range of applications in feeding and growth studies with fish. The method can be used for the accurate determination of feed intake, something that is required for the construction of feed tables for farmed fish. The method also may be used in studies designed for the investigation of feeding behavior and modes of feeding. The most useful application may, however, be related to the study of feed-growth relationships because the method enables the monitoring of feeding and growth performances of individual fish within groups. The application of the method to the study of feed-growth relationships is described using the effects of different levels of sustained exercise on these relationships as an example. The data show that exposure of fish to moderate water currents for prolonged periods leads to both higher rates of weight gain and improved feed conversion when compared to fish reared in standing water. KEY WORDS: Feeding behavior, daIly rations, diel rhythms, feed acquisition, growth. 1, iNTRODUCT/ON Several workers have used X-radiography either in qualitative studies of digestive phyyiology, or for the measurement of gastric emptying and intestinal transit times in fish (reviewed by Fange and Grove, 1979; Talbot, 1985). Talbot and Higgins (1983) described a refinement of previous methods in which a particulate, rather than a dispersed X-ray dense marker, was incorporated into the feed. The method allows several aspects of digestive physiology to be studied in more detail than was previously possible (Grove, 1986; dos Santos and Jobling, 1991), and also permits quantitative estimation of the quantity of material within the gastrointestinal tract to be made. The method was successfully used in the study of gastric evacuation rates in Atlantic salmon (Salmo salary (Talbot and Higgins, 1983; Talbot, 1985), but preferential retention of the marker created problems in using the method for similar studies with both Arctic charr (Salvelinus alpinus) (J~rgensen and Jobling, 1988) and Atlantic cod (Galas morhua) (dos Santos and Jobling, 1991). 1064-1262 /93/$.50 ©1993 by CRC Press 223