LAUSR

Researchers have used laboratory experiments to examine how fish might be affected by anthropogenic alterations and conclude how best to adjust fish passage and culvert remediation designs in response. A common way to document swimming performance for this purpose is measuring fish critical swimming speed (Ucrit ). However, the Ucrit protocol as defined by Brett (1964) may be inappropriate for studying swimming performance and how it relates to upstream migration in benthic fish, as they may not actively swim throughout the entire Ucrit test. An alternative method to estimate swimming performance is sprint swimming speed (Usprint ), which is suggested to be a measure of the burst speed of fish rather than maximum sustained swimming speed. We conducted comparative swimming performance experiments to evaluate whether Usprint can be used to compare swimming performance of benthic species to pelagic, actively swimming species. We measured individual swimming speeds of īnanga (Galaxias maculatus), an actively swimming pelagic species, and banded kōkopu (Galaxias fasciatus), a fish that exhibits benthic station-holding behaviour, using both the Usprint and Ucrit test. Experiments revealed no significant statistical difference between swimming speeds estimated using the Ucrit versus Usprint test protocols for both G. maculatus and G. fasciatus. Our result suggests fish swimming speeds obtained using these two methods are comparable for the species in this study. By using Usprint for benthic associated fish and Ucrit for pelagic fish, we may be able to compare a broader range of species' swimming abilities for use in a fish passage context.