Transactions of the American Fisheries Society 132:791–808, 2003 q Copyright by the American Fisheries Society 2003 Development of a Multimetric Index for Assessing the Biological Condition of the Ohio River

Abstract.—The use of fish communities to assess environmental quality is common for streams, but a standard methodology for large rivers is as yet largely undeveloped. We developed an index to assess the condition of fish assemblages along 1,580 km of the Ohio River. Representative samples of fish assemblages were collected from 709 Ohio River reaches, including 318 ‘‘least-impacted’ ’ sites, from 1991 to 2001 by means of standardized nighttime boat-electrofishing tech-niques. We evaluated 55 candidate metrics based on attributes of fish assemblage structure an