Black Carp: Biological Synopsis and Risk Assessment of an Introduced Fish

Chapter 13: Control of Mollusks: Use of Black Carp and Alternatives

doi: https://doi.org/10.47886/9781888569681.ch13

Humans have long been concerned with control of mollusks, particularly snails, because of their critical role in maintaining the life cycles of many disease-causing parasites that affect livestock as well as humans (e.g., schistosomiasis). Although use of different molluscivorous fishes to reduce mollusk populations has been widely discussed, in reality, very few well-documented field trials have been conducted (Hora 1953; Slootweg et al. 1994; Petr 2000). Over the years, a number of investigators have suggested that black carp Mylopharyngodon piceus could be used as a biological agent to control snail populations in ponds where snails might compete for food with herbivorous fishes (Bardach et al. 1972:81) or where snail populations serve as an intermediate host of dangerous human parasites (Hickling 1971; Ling 1977). In a discussion of Chinese pond systems and aquaculture, Lin (1955:117) stated that black carp will devour most of the snails and mussels occurring in a pond. Hickling (1968, 1971) suggested stocking of snail-eating fish to help combat snail infestation of ponds and to control “snail fever.” Hickling was particularly positive toward black carp, basing much of his thinking on Liu (1955), who described the traditional Chinese practice of collecting mollusks from adjacent paddy fields and rivers and subsequently adding these to fish ponds as food for captive black carp. Hickling included translations of portions of Liu’s paper, including all or parts of certain tables. In one pond, according to Liu, 134,650 kg of snails and bivalves (mostly Viviparus, Corbicula, and Anodonta) were fed to 700 (or more) black carp in a pond 6,065 m² (i.e., 0.6 ha) over the course of 8 months, resulting in a net total growth of 2,122 kg by the black carp (a conversion of 63–1). Hickling (1971), extrapolating from Liu’s data, calculated that each black carp devoured more than 227 kg during the entire period (actually, depending on how the author incorporated the few black carp mortalities into the equation, the true figure may be somewhat less). It should be noted that the pond described by Liu also contained common carp Cyprinus carpio (and other fishes), some of which probably had been feeding on the mollusks as well. According to a more recent report (FAO 1983:50), principles of Chinese polyculture recommend adding 75–100 black carp per hectare of pond to control snails.