Frequency distributions of fish parasites in the perch Perca fluviatilis L. from Lake Constance

Abstract

Seventy perch (Perca fluviatilis) caught in Lake Constance at Langenargen in May 1990 were examined for parasites. The frequency distributions of the eyefluke Diplostomum spathaceum (Rudolphi, 1819), and the tapeworms Proteocephalus percae (Müller, 1780) and Triaenophorus nodulosus (Pallas, 1781) fitted closely to a negative binomial. Only a few fish were highly parasitized. These fishes are devoured by the final hosts: gulls (Diplostomum spathaceum) or the pike (Triaenophorus nodulosus). The fish population was influenced negligibly and the parasite population stayed at a moderate level. During the spawning period female perch were infested with Proteocephalus percae more than the males. This may be because the females had a higher food consumption and became more infected by copepods (intermediate hosts). In contrast, Diplostomum spathaceum, Ichthyocotylurus variegatus, Triaenophorus nodulosus, and Tylodelphys clavata did not occur in different numbers in female and male perches. The frequency distribution of Ichthyocotylurus variegatus (Creplin, 1825) and Tylodelphys clavata (Nordmann, 1832) did not conform to a negative binomial.

Compound processes as models for clumped parasite data

“…The observed prevalences are computed for the age classes (0, 1], (1,2], (2,3], (3,4], (4,5], 5+, where 5+ summarizes all sheep older than 5 years. For the age classes 1 − 4, the majority of the observed ages coincide with the end points of the interval.…”

“…The data typically exhibit two well-known features, a substantial proportion of zeros and skewed positive counts [1,2,3], meaning that some hosts harbor many parasites while most have just a few. To analyze such aggregated parasite data, the fitting of the negative binomial distribution is a common method, as in [4] to model the abundance of the fluke Diplostomum spathaceum in fish, in [5] for European red mite on apple leaves, in [6] for the tapeworms Echinococcus granulosus and multilocularis in dogs, in [7] for the nematode Trichinella spiralis in rabbits and in [8] for the larval stage of the mites Allothrombium pulvinum Ewing in lice. However, these models do not take into account the age of the hosts, which is known to influence the parasite pattern [9,10,11].…”

Prevalence and intensity of parasitic helminths of thicklip grey mulletChelon labrosus in hosts in Beymelek Lagoon Lake in Antalya, Turkey,according to season, host size, age, and sex of the host

“…In this study, the overall prevalence of L. angustus and N. agilis was higher in male than in female and juvenile fish, whereas S. obesum showed a higher prevalence in female than male and juvenile fish. Balling and Pfeiffer (1997) reported higher Proteocephalus percae infection in female perch than in males during the spawning period. They also explained that this might be the result of the higher food consumption of females; thus, females are more likely to become infected by copepods.…”

Seasonal differences in infestation of the perch Perca fluviatilis L. from Lake Constance with digenean trematodes

“…The dierences observed in infestation with B. luciopercae and I. variegatus were examined with the H-test. The other methods were identical to those applied earlier (Balling and Pfeier 1997).…”

“…The question as to whether perch migrate should be examined according to the infestation of a number of dierent and geographically well-separated populations. Since an investigation of the infestation of ®sh from dierent locations at various seasons was missing, we began to study this question (Balling and Pfeier 1997). In perch caught at six dierent sites it was found that various species of digenean trematodes did not behave uniformly during the year; whereas some species showed clear seasonal dierences, others did not.…”