No detection of Batrachochytrium salamandrivorans after non-native salamander putative pet release in Massachusetts, USA

The disease caused by the amphibian chytrid fungus Batrachochytrium salamandrivorans (Bsal) has caused mass mortality of salamanders across Europe (Stegen et al. 2017; amphibians are not known to be susceptible to the disease (Martel et al. 2014). Bsal puts North American amphibian biodiversity at risk (Martel et al. 2014; Gray et al. 2015) despite imports of potentially infected amphibians (USFWS 2016; WAPTR 2018; Grear et al. 2021). Recently, the U.S. has announced the finalization of the 2016 interim rule to the Lacey Act (USFWS 2016) to restrict imports of all species of salamanders from 20 genera to the list of injurious amphibians and has added 16 genera to the injurious amphibian list in a new interim rule in response to updated research on salamander susceptibility to Bsal infection (USFWS 2025). A large-scale survey across the USA failed to detect Bsal in over 10,000 individuals (Waddle et al. 2020), and ongoing efforts by North American colleges and universities are similarly conducting Bsal surveillance without more recent detection (e.g., Hyman and Hill 2024). Concerned amphibian and disease specialists nevertheless are preparing for a Bsal invasion into North America (Grant et al. 2017; Olson et al.2024). Despite the initial survey results, the risk of Bsal incursion into North America remains due to broad host susceptibility of North American amphibian species (Gray et al. 2023). The major driver of Bsal introduction risk in the U.S. is expected to be captive amphibian release (Cunningham et al. 2015; Grear et al. 2021). Bsal primarily affects salamanders but anuran species can also be vectors (e.g., Towe et al. 2021; Monzon et al. 2022; Gray et al. 2023; Olson et al. 2024), increasing the risk of a released amphibian carrying Bsal into the natural environment (Grear et al. 2021). An early survey of pet salamanders in the United States did not detect Bsal (Klocke et al. 2017), but even one animal released with Bsal could have a major effect on local amphibians. Early detection and rapid response can improve host outcomes (Bletz et al. 2024; Gray et al. 2018), but the lack of timely knowledge about unwanted release of non-native pets to natural systems causes inevitable delay. Herein, we describe our experience responding to a report of a released non-native amphibian species, common in the pet trade (Gerson 2012; Maximo et al. 2021). We suggest improvements to early detection and rapid response efforts for amphibians and amphibian disease