Estimation of nektonic insect populations

SUMMARY 1. A water column sampler is described for obtaining absolute population estimates of nektonic insects in shallow waters.
2. Relative population estimates were obtained for Corixidae (Hemip-tera) and Buenoa (Hemiptera: Notonectidae) using a standardized sweep net procedure and compared to absolute estimates from column samples. These two types of estimates were highly correlated among lakes.
3. Simultaneous prediction and tolerance intervals for predictions from linear regressions indicated that reliable absolute population estimates generally cannot be expected from relative estimates