Is there a negative decadal trend in abundance of the weedy seadragon ( <i>Phyllopteryx taeniolatus</i> )? Comment on survey data summarised in Edgar <i>et al</i> . (2023)

ABSTRACT Decadal changes in abundance of marine organisms along the Australian coastline were reported in a recent Nature paper by Edgar et al. (2023). We reexamine the data used in that paper, and show that the conclusion of a 59% decline in weedy seadragons (Phyllopteryx taeniolatus) cannot be justified based on these data. The data are too sparse, especially for the final survey years of 2020 and 2021, and it is this sparsity in combination with particular modelling choices made by Edgar et al. (2023) that drives their results. While not specifically considered here, it is likely that these issues also affect the results on other rare or cryptic species reported in Edgar et al. (2023).