UV avoidance of coregonid larvae

Although several authors have shown that UV radiation can cause damage to fish larvae, the UV avoidance behaviour of larvae has received little attention. Larval coregonids are vulnerable to the recently enhanced UV levels because immediately after hatching in spring they show a distinct positive phototaxis. The behavior of three size groups of vendace (Coregonus albula (L.)) and whitefish (Coregonus lavaretus (L.) s.l.) larvae were studied under enhanced UV-B irradiation in the laboratory. In addition, field data from four coregonid lakes in Finland were analysed. Coregonid larvae avoided UV radiation both in the laboratory and field. The smallest vendace larvae were the most sensitive to changes in UV irradiation in the laboratory experiments. In the field, the avoidance behaviour was more pronounced in lakes with low dissolved organic carbon (DOC) concentrations than in a lake with a high DOC concentration.