Figure 3.

Catch rate of wetland fish species exposed to ambient and deterrent CO₂ treatments at the Royal Botanical Gardens fishway. (A) Raw catch rates of fishes caught in a total abundance than > 1 individual. Each point displays the catch rate of an individual trial, with the boxplots indicating the 25th percentile, median and 75th percentile. (B) Estimated marginal mean catch abundance ±95% confidence interval of each species and treatment. The marginal means were estimated from the general linear model reported in the results using the R package ‘emmeans’. The predicted catch abundances of each species were allowed to independently vary across time within the general linear model, so the marginal means presented here were predicted for the median date of the study, 13 June 2019. The catch abundance of each species in each trial was also standardized across trap exposure time; therefore, the catch abundances were predicted for the median trap exposure time of 12.6 hours. Species are indicated between the panels, with the total catch per species indicated in brackets. An estimated marginal mean was also predicted for the aggregation of all low abundance species (150 per species). Catch rates between each treatment were compared for each species in a pairwise post hoc Tukey–Kramer test. Ambient and deterrent catch rates significantly differed for common carp, brown bullhead and the aggregation of all low abundance species. Large confidence intervals can be observed for the low abundance species during the deterrent treatment.