- Department of Aquaculture, Swedish University of Agricultural Sciences
This thesis deals with feeding ecology of percids, with special focus on pikeperch. An increased knowledge of how prey (or feed) characteristics and environmental factors affect different stages of young-of-the-year pikeperch will increase the understanding of important regulatory processes, both in natural ecosystems and in aquacultures. The results show that there is a critical period at onset of feeding when the larvae are dependent on high prey densities. This period is short, most critical is the first 5 days of exogenous feeding, and after 25 days at 20° C, the critical resource level is two orders of magnitude lower than at onset of feeding. Turbidity and light (time of day) had neither any major effect on functional response and consumption nor growth on juvenile pikeperch. This was in contrast to perch that was negatively affected by both increased turbidity and low light. The species related differences were believed to be a combination of visual physiology and foraging behaviour. In an aquaculture system relying on natural feed during the larval stages followed by habituating (weaning) juveniles to formulated feed, the properties of the feed is an important factor. Fish fed an appropriate formulated diet accepted the diet readily within 9 days with maintained high growth rate. Conclusively, the results suggest two factors that might contribute to explain distribution patterns and variation in year-class- strength of pikeperch. The first is the need for high resource levels at onset of feeding, and the second is the foraging efficiency that is unaffected by differences in turbidity and light conditions. Regarding further development of aquaculture of pikeperch, the underlying experiments reveal that the studied characteristics relevant for aquaculture (growth, feed conversion factor, performance in elevated turbidity and weaning success), indicate that pikeperch is an interesting candidate for aquaculture.
Sander lucioperca; Perch; Perea fluviatilis; zooplankton; prey abundance; Neomysis integer
Acta Universitatis Agriculturae Sueciae. Silvestria
2002, number: 255
Publisher: Department of Aquaculture, Swedish University of Agricultural Sciences
Fish and Aquacultural Science