Are populations of the weedy seadragon Phyllopteryx taeniolatatus declining? Response to critique of Schlögl and Booth (2025)

Schlögl and Booth (2025) critique our analysis of population trends in reef species around the Australian continent (Edgar et al., 2023). They stress that species-specific decline figures should not be overstated in the scientific literature, as doing so risks undermining public trust in conservation science. Their concerns focus on declining populations of the weedy seadragon (Phyllopteryx taeniolatus) over the decade to 2021, arguing that our dataset is sparse, dominated by zeros, and subject to large year-to-year variability. We here show that their critique misinterprets Red List Guidelines and mischaracterises our data. Moreover, IUCN validated the magnitude of our P. taeniolatus population trend a year later by listing the species as Vulnerable (i.e. >30% decline). While we agree that rare and cryptic species, such as seadragons, can best be numerically characterized by targeted single-species surveys, our analysis was designed to be sufficiently broad to encompass sharks to macroalgae. We also emphasize that this one species contributed negligibly to our studies’ overall aims, results and conclusions for >1000 species. We conclude that failing to highlight evidence-based species declines arising from continent-scale surveys, despite high local variability, can itself undermine confidence in conservation science and increase extinction risk.