Larval fish drift in a large river with a comparison of sampling methods
Susquehanna River, larvae, carp, sucker, night, efficiency, mesh
Journal or Book Title
Transactions of the American Fisheries Society
Larval fish drift in the rocky-bottomed Susquehanna River (northeastern Pennsylvania)was investigated during 1974-1975. At least 18 species of drifting larvae were collected by netsmounted on a stationary boat or by pumping. Maximum densities of 15.4 and 27.1 larvae/10 m3were found in June 1974 and 1975, respectively. Quillback, (56%), minnows (25%), and carp,(14% of the total) were the most abundant larvae caught in 1974 by pumping. The few larvae thatdrifted during the day were mostly near the bottom. large numbers of quillback, white suckershorthead redhorse and tessellated darter larvae drifted near the river surface at night. Drift wasmaximum at about 2400 h. Overall, the day/night drift ratio was 1/3.8. Boat-mounted nets and thepump sampler had equal sampling efficiencies. Condition of larvae in pump samples was relatedto net material, mesh size , net shape, and pumping duration. Larvae in best condition were in 5-min samples pumped into slender nets (mouth/length ratio 1/10) made of fine-meshedmonofilament nylon.