Relationship between length of roundtail chub and infection intensity of Asian fish tapeworm Bothriocephalus acheilognathi

Nonnative parasites have been blamed for the decline of native fish species in the American Southwest. The Asian fish tapeworm Bothriocephalus acheilo gnathi has parasitized many native fish species, but little is known of its effects on native cyprinid fish hosts. I found a strong negative correlati on (Spearman's rank correlation, r(s) = -0.846; P < 0.001) between total le ngth of roundtail chub Gila robusta and number of Asian fish tapeworms. A s ignificant. but weaker negative correlation existed between weight of fish and number of tapeworms (r(s) = -0.687; P < 0.001). In addition, infected f ish were significantly shorter(P = 0.0241) than uninfected fish. Infection by Asian fish tapeworm may slow growth, increase susceptibility to infestat ion, and increase predation on roundtail chub and possibly other native cyp rinids.