Distribution and abundance of the Patagonian lamprey (Geotria macrostoma) in the largest unfragmented river of southern Patagonia, Argentina

QUIROGA, PAMELA; BAKER, CINDY F.; BAIGÚN, CLAUDIO; STEWART, MICHAEL; LANCELOTTI, JULIO L.; RIVA ROSSI, CARLA

ENVIRONMENTAL BIOLOGY OF FISHES

SPRINGER

Lugar: Berlin; Año: 2023

0378-1909

The distribution, relative abundance,and rearing habitat of larvae of the Patagonian lam-prey (Geotria macrostoma) were investigated in theSanta Cruz River basin, Patagonia, Argentina, usingelectrofishing and bile acid (petromyzonol sulfate)concentration. Both techniques revealed that larvaeare widely distributed along the basin, aggregated athabitats of fine substrates and slow waters. Both, den-sity and pheromone concentrations were consistent indetecting the presence of larvae and for gauging theirabundance. Throughout the basin, length distributionof larvae ranged from 10 to 122 mm; larvae of the smaller length classes were present at both, upper sec-tions and at the lower course of the main stem river,suggesting that these sites contained 0 + recruits fromthe previous spawning season. Currently construc-tion of two hydroelectric dams in the main courseof the Santa Cruz River will interrupt the migratorycorridor of adult lamprey in search of their spawn-ing grounds and will flood critical habitats for larvaerearing. The information generated in this study maybe used as guidance for developing sampling surveysfor the purpose of monitoring changes in populationstrends for Patagonian lamprey in this river and otherPatagonian drainages altered by human activities.