Fish volitional and non-volitional swimming performance for fishway design: an evidence-based review

Abstract Integration of fish swimming performance data is critical for defining flow in fishways. However, current design approaches often rely on limited data that did not account for natural variation in locomotory capacity. To guide application of swimming performance data, we reviewed relevant literature from 1990 to 2023 and identified patterns relevant for developing fishways. Among the 167 relevant publications, non-volitional tests like exercises in swim tunnels were employed more frequently (84%) than volitional assessments, but their estimates were more conservative, indicating that test methods influence quantification of fish swimming performance. Higher swim speed and shorter fatigue time from volitional endurance data of cypriniform fishes suggested that volitional tests could identify fish tendency to employ higher swim speeds to negotiate passage quickly, rather than maintaining energetically sustainable gaits throughout passage as is typically assumed when designing fishways. This highlights volitional method’s potential for estimating a realistic, unrestricted prolonged or sprint swimming abilities for predicting extended passages employing multiple swim gaits and rapid negotiation of short, difficult passages. Contrastingly, consistent significant effects of temperature and body length on aerobic performance were identified primarily through analyses of non-volitional sustainable speeds. While more volitional assessments are needed, especially for under-studied species, this indicated that non-volitional assessments remain useful for providing insights on relative swimming performances as influenced by bioecological variation relevant to fishway passage. We propose recommendations for diversifying assessments and improving realism through integration of biological and environmental variation for holistic understanding of fish locomotion for better fishway design.