Table 1 Intensity of Gyrodactylus salaris Malmberg, 1957 infection on Salmo salar L. from the River Dee, Wales and from the Laerdalselva, Norway (control group), from Salmo trutta L. from the River Tyne, England and from Thymallus thymallus (L.) from the River Nidd, England

1

87.0 ± 8.2 (28–215)

79.6 ± 6.6 (46–108)

59.7 ± 3.5 (32–107)

59.8 ± 4.3 (28–146)

5

157.4 ± 11.2 (76–314)

183.4 ± 17.0 (114–291)

90.1 ± 8.5 (39–280)

93.4 ± 7.5 (37–251)

12

343.6 ± 21.3 (151–615)

349.1 ± 35.8 (184–544)^a

145.9 ± 13.4 (55–305)

182.5 ± 8.4 (94–310)

19

581.6 ± 28.6 (200–923)

560.4 ± 35.3 (385–679)

74.0 ± 7.2 (20–191)

252.6 ± 11.7 (144–385)

26

1043.5 ± 54.1 (511–1812)

1003.1 ± 73.2 (714–1284)

52.0 ± 5.6 (9–137)

206.7 ± 14.8 (77–436)

33

1741.5 ± 93.1 (810–2890)

1459.7 ± 111.5 (1114–2165)

37.3 ± 5.5 (4–138)

151.1 ± 13.3 (34–293)^d

40

-

-

20.7 ± 4.4 (1–133)

66.1 ± 7.8 (5–158)

49

-

-

13.1 ± 2.8 (0–84)

29.7 ± 4.9 (0–115)

63

-

-

11.8 ± 2.4 (0–63)

16.9 ± 2.7 (0–48)

77

-

-

14.5 ± 3.0 (0–70)^b

8.5 ± 1.9 (0–38)^e

100

-

-

10.6 ± 1.8 (0–39)^c

2.1 ± 0.8 (0–21)^f

110

-

-

0.9 ± 0.3 (0–6)

0.3 ± 0.2 (0–5)