Relationship between Length of Roundtail Chub and Infection Intensity of Asian Fish Tapeworm Bothriocephalus acheilognathi

Abstract

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