Migration of freshwater fish species and passage at a dam using a novel fishway

ABSTRACT Objective Decline of migrant freshwater fishes (potamodromous species) in the United States is a critical fisheries issue due to dams blocking migratory species from completing critical life history migrations. We studied migrations of PIT-tagged individuals from 21 species in the Eel River, Indiana, and the ascent of tagged and nontagged individuals in a new type of fishway. Methods For 4 years (2018–2021), we captured and released 3,530 PIT-tagged fish from 21 species in 57 km of river downstream of a dam with the new Kynard Fishway to determine the number of migratory species and the distance that fish migrated upstream. Nontagged fish that ascended the fishway were trapped at the top of the fishway 3 d/week, identified to species, and measured for total length (TL; mm). We analyzed the monthly migration intensity in the fishway for 34 species. Results The fishway trap captured over 32,000 nontagged fish from 48 species and 10 families. The 48 species comprised 78.7% of the 61 fish species in the river, which is the most potamodromous species to use a technical fishway in the United States. The mean TL (±SD) of nontagged fish that used the fishway ranged from 44 ± 2.8 to 281 ± 10.7 mm. Passage of small fish (≤150 mm TL) was annually 81% of the total abundance of fish passed. Individuals from the 21 PIT-tagged species had three types of migration distance patterns: Individuals from 10 species moved a short distance (≤1 km), individuals from three species moved a moderate distance (4–13 km), and individuals from eight species moved 20–57 km. Conclusions Potamodromous species were the dominant fish species in the Eel River. Migration distance by individuals within a species was individually controlled. The Kynard Fishway contributes to the global effort to develop passage for multiple species, particularly small-bodied fish.