Sprinting behavior of free-ranging fish has long been thought to exceed that of captive fish. Here we present data from wild-caught brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta), volitionally entering and sprinting against high-velocity flows in an open-channel flume. Performance of the two species was nearly identical, with the species attaining absolute speeds > 25 body lengths·s−1. These speeds far exceed previously published observations for any salmonid species and contribute to the mounting evidence that commonly accepted estimates of swimming performance are low. Brook trout demonstrated two distinct modes in the relationship between swim speed and fatigue time, similar to the shift from prolonged to sprint mode described by other authors, but in this case occurring at speeds > 19 body lengths·s−1. This is the first demonstration of multiple modes of sprint swimming at such high swim speeds. Neither species optimized for distance maximization, however, indicating that physiological limits alone are poor predictors of swimming performance. By combining distributions of volitional swim speeds with endurance, we were able to account for >80% of the variation in distance traversed by both species.

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-Passage performance of brown trout (Salmo trutta), Iberian barbel (Luciobarbus bocagei), and northern straight-mouth nase (Pseudochondrostoma duriense) was investigated in a vertical slot fishway in the Porma River (Duero River basin, Spain) using PIT telemetry. We analysed the effects of different fishway discharges on motivation and passage success. Both cyprinid species ascended the fishway easily, performing better than the trout despite their theoretically weaker swimming performance. Fishway discharge affected fish motivation although it did not clearly influence passage success. Observed results can guide design and operation criteria of vertical slot fishways for native Iberian fish. Key-words:Iberian fish / vertical slot fishway / fish passage / motivation / transit time Résumé -Aptitude au passage de la truite, Salmo trutta, et de deux cyprinidés ibériques, le barbeau ibérique, Luciobarbus bocagei, et le nase à bouche droite, Pseudochondrostoma duriense dans une passe à poissons à fentes verticales. La performance de passage de la truite (Salmo trutta), du barbeau ibérique (Luciobarbus bocagei), et du nase à bouche droite (Pseudochondrostoma duriense) a été étudiée dans une passe à fentes verticales dans la rivière Porma (bassin de la rivière Douro, Espagne) en utilisant la technologie PIT. Nous avons analysé les effets de différents débits dans la passe à poissons sur la motivation et la réussite de passage. Les deux espèces de cyprinidés montaient la passe facilement, étaient plus performantes que les truites, malgré leur performance de nage théoriquement plus faible. Le débit dans la passe affectait la motivation des poissons bien qu'il n'ait pas influencé clairement le succès de passage. Les résultats observés peuvent guider dans les critères de conception de passes à fentes verticales pour les poissons indigènes.

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