Data in support of: "Swimming performance of New Zealand longfin eel (Anguilla diffenbachii) elvers in an experimental flume"

In Aotearoa-New Zealand, limited research has focused on the swimming performance of native fish species, particularly across life stages and varying environmental conditions. This study focussed on quantifying the swimming capabilities of longfin eel elvers (Anguilla dieffenbachii) by 1) determining the critical swimming speed (Ucrit), 2) testing the time to fatigue across a range of water speeds (swimming endurance) and, 3) comparing the swimming capabilities of elvers as individuals and within groups. Individual trials showed Ucrit ranged from 0.13 to 0.67 m s-1 (mean Ucrit = 0.34), while group trials ranged from 0.13 to 0.37 m -1s (mean Ucrit = 0.25). After controlling for differences in water temperatures and oxygen levels, Ucrit had a clear positive relationship with elver length, while no statistical difference was observed in mean Ucrit between individuals and group swim trials. As water speeds increased, elver swimming endurance decreased, with elvers swimming up to 210 s at the lowest water speed (0.1 m s-1) and only swimming an average of 22.1 s at water speed of 1 m s-1.