Scarring of Whitefish (Coregonus lavaretus) by European River Lamprey (Lampetra fluviatilis) in Loch Lomond, Scotland

Whitefish are abundant in Loch Lomond and have been attacked by lampreys for over 100 yr. In all samples (totalling about 1000 whitefish) taken from different parts of the loch between 1951 and 1979 the incidence of lamprey scarring was high (from 26 to 50%), many times that of any of the other 14 species of fish in the loch. Multiple scarring was common. Small whitefish (less than 25 cm) were rarely scarred, whereas larger ones (more than 25 cm) frequently had been attacked. Scars occurred all the year round, but fresh wounds only in the summer — especially July and August. Almost all the scars occurred along the backs of the fish between the head and adipose fin, and above the lateral line. There is little evidence that these attacks affected the growth or condition of the whitefish concerned. Lampreys do not appear to attack fish in freshwater in other parts of Great Britain, but parasitism has been recorded in a few lakes in Finland and Russia.