A mark-recapture method for ecological studies of schistosomiasis vector snail populations

Mark-recapture methods have been used only sporadically in studies of the population biology of the snail vectors of schistosomiasis, yet mark-recapture has potential advantages for obtaining estimates of absolute abundance and recruitment and loss rates for snail populations in the field. A case study is described that uses Bailey's triple catch design to estimate these parameters for Bulinus globosus and Biomphalaria pfeifferi in a small river in Zimbabwe. The assumptions inherent in the design and tests of these assumptions are described. The parameter estimates obtained are biologically plausible, suggesting significant recruitment into the population at the time of the study and a life expectancy for B. globosus of about three weeks. The major drawback is the lack of precision of these estimates. Means of improving precision are discussed, and mark-recapture is evaluated as a research tool for the study of vector snail population biology.