Commercial fishery bycatch risk for large juvenile and adult smalltooth sawfish (Pristis pectinata) in Florida waters

Abstract

Incidental catch of marine species can create ecological and economic issues, particularly for endangered species. The smalltooth sawfish (Pristis pectinata) is endemic to the Atlantic Ocean and listed as Endangered in the US Endangered Species Act. One of its major threats is bycatch mortality in commercial fisheries. Despite the protection afforded by the US Endangered Species Act, smalltooth sawfish are still captured as bycatch in commercial fisheries. Acoustic and satellite tag data collected on 59 sawfish between 2011 and 2019 were analysed to assess commercial fishery bycatch risk for large juveniles and adults off Florida. This study focused on shrimp trawl, south‐east coastal gillnet, and shark bottom longline fisheries, as these were identified in the recovery plan as having the greatest potential threats to recovery. Bycatch risk associated with the shrimp trawl fishery was significantly higher than the other fisheries, indicating that this fishery currently poses the greatest threat to recovery. Bycatch risk was concentrated in all seasons in the Gulf of Mexico adjacent to the lower Florida Keys for the shrimp trawl fishery, off Cape Canaveral in the south‐east coastal gillnet fishery, and in the Atlantic Ocean adjacent to the Florida Keys in the shark bottom longline fishery. Tagging location and sex were predictors of bycatch risk. Individuals tagged in Charlotte Harbor had the highest shrimp trawl bycatch risk. Females tagged in south Florida tended to reside in the deepest water, which is where shrimp trawl effort is highest. Therefore, females may be at more risk in these deeper waters. Results from this study indicate a year‐round closure of waters off south‐west Florida to the shrimp trawl fishery between Charlotte Harbor and the western Florida Keys would reduce sawfish bycatch, and thus mortality, which is in line with recovery plan goals.

Modeling protected species distributions and habitats to inform siting and management of pioneering ocean industries: A case study for Gulf of Mexico aquaculture

“…They were listed as endangered under the ESA in 2003. Smalltooth Sawfish location data were obtained from three point sources: 1) US Sawfish Recovery Encounter Database (Simpfendorfer and Wiley 2006; International Sawfish Encounter Database 2021), 2) Acoustic tag data (Graham et al 2021; Graham et al 2022), and 3) Satellite tag data (Carlson et al 2014) ( Figure 2B ). The US Sawfish Recovery Encounter Database provides data on sawfish observations from 1999–2017; additional data are continually added.…”

“…Since 2011, members of the Smalltooth Sawfish Recovery Team have been satellite-tagging juvenile and adult sawfish to track broad-scale movements (Carlson et al 2014; Graham et al 2021; Graham et al 2022). Maximum likelihood positioning estimates generated by Wildlife Computers GPE3 positioning software for 15 satellite-tagged sawfish were provided by Jasmin Graham (Florida State University, 2021).…”

“…juvenile and adult sawfish to track broad-scale movements(Carlson et al 2014;Graham et al 2021;Graham et al 2022). Maximum likelihood positioning estimates generated by Wildlife Computers GPE3 positioning software for 15 satellite-tagged sawfish were provided by JasminGraham (Florida State University, 2021).Smalltooth Sawfish point data derived from the three aforementioned sources were merged into a single GIS dataset and filtered to include only locations in the Gulf of Mexico EEZ.…”

Gene Expression and Evolution in the Smalltooth Sawfish,Pristis pectinata

“…Altogether, these results suggest unique physiology of ion channels and subunits in P. pectinata , and their identification could allow tailored bycatch-reduction technology. Developing this technology for trawls is a priority as shrimp trawls have been identified as still having the highest bycatch risk for sawfishes in the ‘stronghold’ nations of the U.S. and Australia 9 .…”

“…Bycatch in fisheries and habitat degradation continue to pose the greatest threats to sawfishes, including in ‘stronghold’ locations such as the United States and Australia (NMFS 2009) 9 . Fisher education and trade bans on sawfish and their parts have been used to mitigate sawfish declines 10,8 .…”