A beacon of hope: distribution and current status of the largetooth sawfish in Costa Rica

Abstract

The Critically Endangered largetooth sawfish Pristis pristis is one of the most threatened elasmobranch species and is currently thought to be locally extinct in at least 27 countries. Although largetooth sawfish information in Central America is scarce, recent records show that this species is still present in Costa Rica, yet its distribution and current status remain unclear. This study investigated the spatial and temporal distribution of the largetooth sawfish in Costa Rica and identified local threats affecting the populations. We conducted 275 structured interviews in coastal and riverine communities across the country, which resulted in 134 confirmed records in the Pacific, 1 in the Caribbean and 51 in the northern region. Historical and recent records suggest the largetooth sawfish has undergone significant reductions in abundance and distribution from coastal and riverine areas, mainly due to interaction with fishing gear such as gill nets and hook and line. Most sawfish captured by gill nets were reported in the Central Pacific region, whereas hook and line records were more common in the northern region and the South Pacific. Although largetooth sawfish populations in Costa Rica have followed the global decline trend, we found 2 main hotspots where recent sightings and captures appear to be more common, suggesting there is still hope for the species to recover in Costa Rica and possibly in the region. Moreover, Costa Rica recently became the 17 th country to ratify national legal protection for sawfishes, which may strengthen conservation efforts to protect populations locally and in the Central American region.

Identifying priority areas for research and conservation of the largetooth sawfishPristis pristisin Colombia and Panama

“…Interviewees stated that once sawfish were caught, the meat was consumed and the rostrum was cut off and kept mainly for decorative purposes or later sold to buyers looking for their teeth. In Panama, some fishers reported that the teeth were fashioned into artificial spurs used in cockfighting, as documented from Perú (Cogorno Ventura 2001), something that has been observed by the authors on online sales sites and corroborated in other studies in Latin America (McDavitt 2014, Valerio-Vargas & Espinoza 2019. In Colombia, some fishers mentioned that the meat was used for consumption, but most pointed out that the rostrum was the most valuable sawfish body part because of its decorative value.…”

Monitoring elasmobranch assemblages in a data-poor country from the Eastern Tropical Pacific using baited remote underwater video stations

“…Elasmobranch studies in Costa Rica using fishery-independent methods have also reported similar species richness and composition compared to our study, at least at local scales (Table 4, Table S2). For example 39 , used data collected by divers over 21 years to investigate elasmobranch population trends at Cocos Island, whereas 38 analyzed video footage from submarine surveys between 2006 and 2012 to examine elasmobranch assemblages in deep waters. All the species recorded by 39 were also detected in our study (Table S2).…”

“…All the species recorded by 39 were also detected in our study (Table S2). However, due to the capability of the submarine to survey deeper waters (up to 330 m) 38 , reported four elasmobranch species that were not detected by our BRUVS (Table S2). Our study also reported more elasmobranch species at Caño Island than traditional underwater visual surveys 48 , which are often biased by divers' experience and limited by time, depth and weather conditions 15 .…”

“…Anthropogenic impacts such as habitat loss and degradation represent additional threats in coastal areas, which are generally exposed to multiple chronic stressors 56,65 , and therefore, may be important drivers of elasmobranch population declines 4,38 . Efforts towards monitoring key coastal habitats for elasmobranchs are needed, as some of these may also function as critical habitats (e.g.…”

“…For example 34 , showed that elasmobranch assemblages from Isla del Coco are negatively associated with the El Niño Southern Oscillation (ENSO) event, whereas 35 found that depth was one of the main drivers shaping demersal elasmobranch distribution along the continental shelf of the Pacific of Costa Rica. For a few threatened elasmobranchs such as the scalloped hammerhead shark and the largetooth sawfish Pristis pristis , there has been recent efforts to understand what factors shape their distribution and abundance patterns 36 – 38 . However, major information gaps remain for most species, particularly those demersal and reef-associated that are found along the continental shelf.…”