Passage and Fine Scale Movements of Paddlefish and Smallmouth Buffalo near Claiborne Lock and Dam

Abstract

Dams often impede spawning migrations of fishes, concentrating adults in their tailwaters. Little is known about behavior of migrating fishes as they approach dams, including where fish are located in the tailrace, their vectors of approach, and their residence time in the tailrace. During two spring migration periods (2018 & 2019) I quantified approach paths and locations of two migratory fishes (Paddlefish Polyodon spathula, Smallmouth Buffalo Ictiobus bubalus) at the lowermost lock-and-dam on the Alabama River to determine fish approach patterns, staging locations, and residence times. I implanted acoustic/radio transmitters in 330 fish (165 of each species) of which 181 (89 Paddlefish; 92 Smallmouth Buffalo) also received a coded electromyogram (CEMG) transmitter to measure muscle activity, and used an array of 17 passive receivers to generate two dimensional locations, movement patterns (including dam passage), residence times, and mean coded electromyogram scores. Of the tagged individuals, 39 paddlefish and 23 Smallmouth Buffalo were triangulated in the array. Sixty-three Paddlefish and 53 Smallmouth Buffalo passed upstream over the spillway (none moved upstream through the navigational locks). Fish locations combined with a U.S. Army Corps of Engineers Engineer Research and Development Center flow model showed that fish used low flow velocity microhabitats within the tailrace while staging. Individuals that passed the dam via the crested spillway when it was inundated had significantly longer residence times than those that did not pass, suggesting that residence time may influence passage success.