Fishway passage success for migratory rainbow smelt Osmerus mordax is not dictated by behavioural type

Recent research has demonstrated that an individual's behavioural decisions can have a profound impact on an animal's fitness. For anadromous fishes requiring access to spawning habitat above obstructions, successful passage at fishways may at least in part be a function of an individual's behavioural type. The objectives of this study were to determine whether distinct behavioural types—bold and shy—could be distinguished within a population of anadromous rainbow smelt (Osmerus mordax) and, if so, whether passage success at a nature‐like fishway varied relative to behavioural type. Field‐caught rainbow smelt were tested for individual differences in boldness (i.e., willingness to engage in risk‐taking behaviour) using the metrics of exploratory behaviour, general activity, and response to a simulated predator. After testing, 276 rainbow smelt were implanted with a passive integrated transponder tag, released below the fishway, and their movements monitored via a stationary antenna array. The results of our behavioural assays indicated the presence of a behavioural syndrome among rainbow smelt, and that behaviour was partially repeatable. In total, 41.7% of fish entering the fishway passed successfully, but contrary to our initial prediction, boldness was not a significant predictor of successful passage. Instead, increasing water temperature and decreasing river discharge were consistent predictors of successful passage and greater distances moved through the fishway. Our findings indicate that the nature‐like fishway did not select for a particular behavioural type and that individuals representing the spectrum of bold–shy behavioural types could pass.