Reemergence of the endangered smalltooth sawfish (Pristis pectinata) in a historical nursery in southeast Florida

The endangered smalltooth sawfish (Pristis pectinata) has been protected under the U.S. Endangered Species Act since 2003. Once common throughout the Indian River Lagoon, in Florida, the species was extirpated from this estuarine system by the 1970s because of bycatch mortality. Hotline reports of small juveniles in this estuarine system were rare until 2015, when an increase in reports began and peaked between 2020 and 2023, prompting research to assess habitat use. Seven small juveniles were acoustically tagged and monitored for 1–2 years. Individuals spent up to 87% of the days on which they were detected in a 0.4-km2 area of the South Fork of the Saint Lucie River, a major tributary to the Indian River Lagoon. In the South Fork, juveniles were most frequently detected in the following water conditions: temperatures of 24°C–29°C, salinities of 15–30, dissolved oxygen levels of 5–7 mg/L, and freshwater inflows of 50–150 m³/s. These findings indicate that the Indian River Lagoon is a nursery again. Identifying high-use areas within the broader nursery, such as the upper Saint Lucie River, is an important step toward safeguarding key habitats, and such habitat protection is essential for promoting reestablishment of this species into historical parts of its range.