Gulf of San Miguel and Tuira River is an important reproductive area for one ray species. Darién Province is considered an important nursery area for Largetooth Sawfish (Kyne et al. 2014) and has been identified as a bright spot for this Critically Endangered species in the Eastern Pacific (López-Angarita et al. 2021). There are several contemporary records (since the year 2000) of Largetooth Sawfish in the Gulf of San Miguel and Tuira River with one of the largest clustering of records in Panama (n = 10 records from six sites; López-Angarita et al. 2021). Largetooth Sawfish regularly occur in the area, with contemporary records from the years 2005, 2009, 2013, 2015, and 2022 (López-Angarita et al. 2021; Instagram 2022).

Records from 2005–2015 mostly originate from interviews with local fishers who were able to provide location-specific details of where sawfish were caught. Largetooth Sawfish is the only sawfish species occurring in the Eastern Pacific, is distinctive from other shark and ray species, and is recognisable based on its elongated, tooth-studded rostrum. In addition to these interview results, one record is from a rostrum collected from the Tuira River in 2015 (López-Angarita et al. 2021). The rostra length was 45 cm (López-Angarita et al. 2021) and using published rostra to total length (TL) relationships (Whitty et al. 2014), this individual would have ranged 167–214 cm TL and hence been a juvenile given these sizes are below known size-at-maturity (see Kyne et al. 2021).

The most recent record is a small individual captured and released on 06 August 2022 in the Tuira River, Chepigana (Instagram 2022). From the video footage of the release, this individual was estimated to be ~80 cm TL. This falls within the published size-at-birth for the species: 76 cm TL (Lake Nicaragua, Western Atlantic; Astorqui 1967); 73–80 cm TL (Lake Nicaragua, Western Atlantic; Thorson 1976; and 72–90 cm TL (Australia, Indo-West Pacific; Peverell 2009).

While the limited number of captures indicates low densities of the species, the 2022 capture of a neonate/young-of-the-year sized individual provides evidence that the species is still breeding in the area with the Gulf of San Miguel and Tuira River functioning as a nursery area.

Outside of the Eastern Pacific, it has been documented that Largetooth Sawfish spend the first 4–5 years in freshwater environments before moving to estuarine and coastal marine waters (except for the unique but depleted Lake Nicaragua population where individuals may have spent their whole life-cycle in freshwater; Thorson 1976, 1982; Thorburn et al. 2007). Apart from Lake Nicaragua, pupping is generally thought to occur around estuaries and river mouths (Kyne et al. 2021).

Despite the lack of further detail on the size classes of most contemporary Largetooth Sawfish records in the area (i.e., if these were neonates, juveniles, or adults), several factors infer that the Gulf of San Miguel and Tuira River is a reproductive area for the species: (1) one of the largest clustering of contemporary records anywhere in Panama; (2) known life-cycle; (3) known habitat preferences with extensive areas of core mangrove and riverine habitat in the area; (4) documentation of contemporary records across multiple years; and (5) the recent 2022 capture of a neonate/young-of-the-year.

Largetooth Sawfish are locally extinct from much of the Eastern Pacific (Kyne et al. 2013; López-Angarita et al. 2021; Yan et al. 2021), therefore the temporal and spatial scale of contemporary records in the Gulf of San Miguel and Tuira River is regionally, if not globally, significant.