THE PARASITISM OF FISH FROM LAKE-CONSTANCE - A COMPARISON OF PRESENT AND EARLIER DATA

Commercial fish (perch, roach, bream, dace, and burbot) were caught be low Langenargen in 1988-1990. Their infestation with cestodes and dige nean trematodes was studied. The results were compared with earlier da ta. The infestation of perch with Diplostomum spathaceum and Ichthyoco tylurus variegatus noted in 1988-1990 had increased as compared with t hat observed in 1974-1976. The infestation of perch with Triaenophorus nodulosus seen in 1990 had increased as opposed to that noted in 1988 . The infestation of bream with D. spathaceum and of perch and roach w ith Tylodelphys clavata observed in 1988-1990 had remained the same as that seen in 1974-1976. The infestation of perch with D. spathaceum n oted in 1988-1990 had decreased as opposed to that reported for 1974-1 976. The infestation of bream, dace, and burbot with T. clavata noted in 1988-1990 had decreased as compared with that observed in 1974-1976 . The infestation of perch with T. nodulosus seen in 1988/1989 had dec reased as opposed to that noted in 1974-1976. All three cyprinids stud ied as well as the burbot had been less intensively infested in 1988-1 990 than in 1974-1976. Only perch had been more intensively infested i n 1988-1990 than in 1974-1976, especially with D. spathaceum and I. va riegatus.