Development and efficacy of an electrified benthic trawl for sampling large-river fish assemblages

Sampling small benthic and lithophilic fish species in large rivers and lakes presents challenges not adequately addressed by conventional survey methods such as boat electrofishing and gill netting. The development of the Missouri trawl has helped to address these issues; however, our observations by scuba diving when using the Missouri trawl have revealed avoidance of the trawl by benthic fishes, especially in rocky substrates. Therefore, we equipped a Missouri trawl with a cathode-anode electrical array to facilitate capture by attracting and immobilizing fish. In 40 paired comparisons with a standard Missouri trawl in the upper Ohio River drainage of Pennsylvania, this electrified PSU trawl captured significantly more fish and species as well as more large fish. The PSU trawl also captured more species and more fish across habitats and rivers within the drainage. The PSU trawl is therefore a useful new device for sampling large-river benthic fish communities.