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Elongated rostra evolved in diverse animal groups as adaptations for feeding, defense, sensory perception, and reproduction. Sawfish rostra have tooth-like dermal denticles, referred to as rostral teeth, along their lateral margins. Embryos have a sheath, or covering, for the calcified rostral teeth during gestation, and it persists until after parturition. Little is known about the morphology and composition of the sheath. During 18 years of tagging juvenile smalltooth sawfish (Pristis pectinata), sheaths were documented for 36 neonates with stretch total lengths of 581-812 mm, and samples were collected from 6 specimens for laboratory evaluation. The multilayered, skin-like sheath, which cannot be easily removed manually, has a vascularized inner layer of connective tissue composed primarily of fibrous proteins (e.g., collagen, reticulin, and keratin) surrounded by an outer layer of columnar and spherical epithelial cells overlying a basement membrane. The columnar cells contain condensed chromatin and differentiate into the outermost spherical cells that contain carbohydrates. After birth, the sheath is shed evenly over 4 d, through sloughing and apoptosis, fully exposing the rostral teeth. The sheath is an ephemeral embryonic organ that protects the female and the embryos from injury during gestation and birth. [ABSTRACT FROM AUTHOR]

Sawfishes (Pristidae) are large, highly threatened rays named for their tooth‐studded rostrum, which is used for prey sensing and capture. Of all five species, the smalltooth sawfish, Pristis pectinata, has experienced the greatest decline in range, currently found in only ~20% of its historic range. To better understand the genetic underpinnings of these taxonomically and morphologically unique animals, we collected transcriptomic data from several tissue types, mapped them to the recently completed reference genome, and contrasted the patterns observed with comparable data from other elasmobranchs. Evidence of positive selection was detected in 79 genes in P. pectinata, several of which are involved in growth factor/receptor tyrosine kinase signaling and body symmetry and may be related to the unique morphology of sawfishes. Changes in these genes may impact cellular responses to environmental conditions such as temperature, dissolved oxygen, and salinity. Data acquired also allow for examination of the molecular components of P. pectinata electrosensory systems, which are highly developed in sawfishes and have likely been influential in their evolutionary success. [ABSTRACT FROM AUTHOR]

Although conservation efforts have reduced threats, the endangered smalltooth sawfish, Pristis pectinata , is still at risk from anthropogenic effects such as entanglement in recreational and commercial fishing gear. From 2017 to 2021, data from field research and the public in Florida documented 176 individuals that were entangled, injured, or killed by debris or human interactions. While entanglements in fishing gear (e.g., trawls, fishing tackle) remain the most frequent threat, interactions with household items have increased. Since 2017, 30 sawfish were reported with encircling debris (e.g., monofilament loops, rubber bands, ball bungee cords) around anterior parts of their bodies. Ball bungee cords have emerged as a problem, likely related to the popularity of their use in securing boat lift canopy covers. Collectively, encircling items have interfered with eye, spiracle, gill, and mouth function. Continued outreach is a priority to address these pollutants, their sources (e.g., manufacturers), and their effects on recovery. A dead juvenile smalltooth sawfish reported through the U.S. Sawfish Recovery Hotline was found with a ball bungee cord damaging the gills and cutting into the anteriormost gill arch. [Display omitted] • Marine debris is an ongoing problem affecting smalltooth sawfish recovery. • Negative anthropogenic effects were two times greater than previous work. • Ball bungee cords are a novel pollutant affecting this species. • Encircling pollutants interfere with eye, spiracle, gill, and mouth function. • Outreach is a priority to address these pollutants and their sources. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Formerly common in tropical and subtropical waters of the Atlantic Ocean, the Critically Endangered smalltooth sawfish, Pristis pectinata, underwent severe declines over the past century, restricting population(s) to south and south‐west Florida in the US, and Bahamian waters.Anecdotal evidence (e.g. encounter reports from the public) suggests that P. pectinata have recently been observed in historically occupied US waters; however, no directed surveys have been conducted to verify their extent of occupancy.Here, environmental DNA (eDNA) surveys were used to investigate the occurrence of P. pectinata in three formerly occupied estuaries in US waters. Water samples were collected in the summer from the Indian River Lagoon and Tampa Bay, Florida, in 2018 and 2019, and from Mississippi Sound, Mississippi, in 2018, and screened for target DNA using a highly sensitive Droplet Digital™ polymerase chain reaction assay.Target DNA was detected at four sites in the Indian River Lagoon in 2018 and at one site in 2019 (average concentration: 0.086 copies μl−1; SE = 0.004), but was not detected in either year in Tampa Bay. Target DNA was also detected at three sites near Deer Island in Mississippi Sound in 2018 (average concentration: 0.090 copies μl−1; SE = 0.005). These surveys provide additional lines of evidence that P. pectinata is re‐occurring within two historically occupied estuaries in US waters.More comprehensive eDNA surveys in historically occupied regions, combined with clearly defined post‐survey management actions, can direct additional research and outreach initiatives in emerging priority areas, fostering recovery of this Critically Endangered species. [ABSTRACT FROM AUTHOR]

Data from the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, and sister networks, were used to evaluate fish movements in the Florida Keys—an extensive reef fish ecosystem just north of Cuba connecting the Atlantic Ocean and Gulf of Mexico. We analysed ~2 million detections for 23 species, ranging from reef fish such as Nassau grouper (Epinephelus striatus, Serranidae) to migratory apex predators such as white sharks (Carcharodon carcharias, Lamnidae). To facilitate comparisons across species, we used an eco‐evolutionary movement strategy framework that identified measurable movement traits and their proximate and ultimate drivers. Detectability was species‐specific and quantified with a detection potential index. Life stages detected in the study area varied by species and residency varied with life stage. Four annual movement types were identified as follows: high site‐fidelity residents, range residents, seasonal migrants and general migrants. The endangered smalltooth sawfish (Pristis pectinata, Pristidae), a seasonal migrant, exhibited the greatest within‐ecosystem connectivity. Site attachment, stopover and deep‐water migration behaviours differed between individuals, species and annual movement types. All apex predators were migratory. General migrants were significantly larger than fish in the other movement types, a life‐history and movement trait combination that is common but not exclusive, as many small pelagics also migrate. Most teleosts exhibited movements associated with spawning. As concerns grow over habitat and biodiversity loss, multispecies movescapes, such as presented here, are expected to play an increasingly important role in informing ecosystem‐based and non‐extractive fisheries management strategies. [ABSTRACT FROM AUTHOR]

We report 24 new records of the Brazilian cownose ray Rhinoptera brasiliensis outside its accepted geographic range. Sequencing of a 442‐base pair portion of the mitochondrial NADH dehydrogenase subunit 2 gene for 282 Rhinoptera samples revealed eight records off the east coast of the USA and 16 from the eastern Gulf of Mexico. Both sexes of all life stages were documented in all seasons over multiple years in the Indian River and Lake Worth lagoons, Florida, indicating that their range extends further in the western North Atlantic than previously described. [ABSTRACT FROM AUTHOR]

Understanding how endangered species use nursery habitats is vital for recovery planning. Research on the smalltooth sawfish (Pristis pectinata) has shown that areas of estuarine nurseries, called hotspots, are used consistently. The objectives of our study were 1) to determine whether 10 young-of-theyear smalltooth sawfish in an artificial, non-main-stem portion (i.e., a seawall canal system) of a hotspot were descended from one or different mothers and 2) to document long-term habitat use by these individuals. At least 4 mothers contributed to the group, which comprised siblings, half-siblings, and unrelated individuals. Young sawfish exhibited site fidelity to their capture location, spending 61% of their time there. Continuous residency lasted as long as 86 days, but these fish made small-scale diel (<1 river km) movements between the capture location (day) and the nearby main-riverstem portion of the hotspot (night). Larger-scale (5-7 river km) downriver and upriver relocations between the capture location and the river mouth, including 2 other known natural hotspots, occurred after a tropical storm. This research shows that 1) young-of-the-year from different mothers can have high site fidelity at specific locations within a nursery hotspot and 2) these hotspots can be important for young-of-the-year even when there is a drastic change in freshwater inflow. [ABSTRACT FROM AUTHOR]

1. Sawfishes are among themost threatened fish species globally,with only the smalltooth sawfish (Pristis pectinata) currently regularly observed in the westernAtlantic. TheNational Sawfish Encounter Database (NSED) documents reported encounters with sawfishes in the western Atlantic and contains 4945 reports of 8773 individual P. pectinata (1782-2011). 2. Statistical modelling (generalized linear models and generalized additive models) and kernel density analyses were used to (1) identify spatio-temporal patterns among encounter reports, including range reduction in the western Atlantic; (2) determine current distribution to identify areas and time periods where conservation and recovery efforts could be focused; and (3) identify and describe spatio-temporal distribution patterns of large juveniles and adults. 3. Pristis pectinata were found to be year-round residents of Florida but showed relatively consistent spatial and temporal trends by life stage throughout the year. Although the historical range in the western Atlantic included coastal waters from North Carolina to Brazil, the current geographic range of the species was limited to Florida from 2001 through 2011, with occasional reports in neighbouring states, the Bahamas, and Cuba. 4. Seasonally, encounters of all life stages peaked fromMarch through July and annual recruitment of juveniles was apparent during the study period. Spatial hotspots based on increased numbers of encounters of large juveniles (201-340 cm) and adults (>340 cm) were identified in southern Charlotte Harbor, the Ten Thousand Islands, Florida Bay, theAtlantic side of theFloridaKeys, and off St. Lucie in south-east Florida. The analyses presented herein provide evidence of range reduction in the western Atlantic, provide an important tool for resource managers to focus research, monitoring, and conservation efforts, and may provide a framework to model and predict habitat use of other species. [ABSTRACT FROM AUTHOR]

Elasmobranch fin tissue has been sampled and archived for decades to support genetics research. However, these collections have the potential to provide additional information on the trophic ecology of and habitat use by elasmobranch species. The use of fin tissue is especially attractive considering the threatened status of many elasmobranchs and the call for limiting mortalities. Yet, the use of fin samples for stable isotope analysis requires either that (1) storage methods do not alter tissue isotope values or (2) any alterations in isotope composition that occur during storage are predictable. In this study, paired fin tissues sampled from Smalltooth Sawfish Pristis pectinata and cownose rays Rhinoptera spp. were stored frozen and in ethanol and were subsequently analyzed for carbon (d13C) and nitrogen (d15N) isotope ratios. Fin d13C and d15N values were highly correlated between treatments for both taxa (r² = 0.80). For Smalltooth Sawfish, ethanol storage significantly increased fin d13C values by 0.5 ± 0.1% (mean ± SE) and decreased fin d15N values by 0.1 ± 0.1% relative to frozen samples; differences were similar for cownose rays (d13C: 0.2 ± 0.2%; d15N: 0.2 ± 0.1%) but were not significant. A range of approximately 3% for d13C between treatments could have effects on data interpretation, suggesting the use of regressions for ethanol correction of d13C values, although trends were comparable between frozen and ethanol-preserved samples without correction. Given the low variability in d15N values, a correction is not warranted. For endangered species such as the Smalltooth Sawfish, stable isotope analysis of ethanol-archived fin samples can provide important information regarding habitat use and trophic ecology, with potential significance for conservation and management strategies. The general uniformity in isotope ratio shifts observed for archived samples between the two taxa suggests that these findings can be generalized across elasmobranch species. [ABSTRACT FROM AUTHOR]

The smalltooth sawfish ( Pristis pectinata) is one of seven critically endangered sawfishes worldwide that little is known about beyond their presence in estuaries and rivers primarily during early life history. Movements of 24 juvenile P. pectinata (<3 years old) were monitored over more than 2 years using acoustic tags and an array of 33 acoustic receivers. The receivers were distributed in both main-stem river habitats, which are known to be used by this species, and non-main-stem habitats (i.e., natural mangrove-lined creeks, seminatural creeks, seawall-lined canals) of the highly altered, flow-managed tidal Caloosahatchee River, Florida to determine (1) the extent of non-main-stem habitat use and (2) responses to freshwater inflow-related changes by P. pectinata. Twenty P. pectinata used non-main-stem habitats, and 11 used these habitats more than 10 % of the time, which has implications for management within the federally protected nursery area. The daily activity space of P. pectinata was 0.7 km of river distance, which is similar to that of other demersal ray species. There was little evidence that P. pectinata left the river and returned; they remained in the nursery under a wide range of environmental conditions. The distribution of all P. pectinata combined was significantly related to 90-day lagged salinity; sawfish moved upriver as salinity increased. Salinity patterns within the river had a greater effect on the distribution (mean river position) of <1-year-old P. pectinata (90-day lagged salinity) than on that of older individuals (120-day lagged salinity). These results provide further evidence of the importance of this system as a nursery and provide specific habitat use patterns that will be useful in the development of management strategies for sawfishes and their habitats. [ABSTRACT FROM AUTHOR]

Endangered smalltooth sawfish (Pristis pectinata) were opportunistically sampled in south Florida and aged by counting opaque bands in sectioned vertebrae (n = 15). Small sample size precluded traditional age verification, but fish collected in spring and summer had translucent vertebrae margins, while fish collected in winter had opaque margins. Trends in Sr:Ca measured across vertebrae with laser ablation-inductively coupled plasma-mass spectrometry corresponded well to annual salinity trends observed in sawfish estuarine nursery habitats in south Florida, thus serve as a chemical marker verifying annual formation of opaque bands. Based on that finding and assumptions about mean birth date and timing of opaque band formation, estimated age ranged from 0.4 y for a 0.60 m total length (TL) male to 14.0 y for a 4.35 m TL female. Von Bertalanffy growth parameters computed from size at age data were 4.48 m for L∞, 0.219 y-1 for k, and -0.81 y for t0. Results of this study have important implications for sawfish conservation as well as for inferring habitat residency of euryhaline elasmobranchs via chemical analysis of vertebrae. [ABSTRACT FROM AUTHOR]

The article presents a study on the abiotic affinities of juvenile sawfish (Pristis pectinata) in Charlotte Harbor estuarine system in Florida. The study used gill nets and seines to capture and release the 137 juvenile sawfish in the nursery. It mentions that habitat suitability curves, logistic regression, and electivity indices were applied in plotting the locations of the captured sawfish. Results show the affinities of sawfish including its avoidance to water less than one meter deep.

To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically ,0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery. [ABSTRACT FROM AUTHOR]

The smalltooth sawfish, Pristis pectinata, is protected under the US Endangered Species Act (ESA) and all forms of international trade of this species are prohibited under Appendix I of the Convention on International Trade in Endangered Species of Flora and Fauna (CITES). Although it is illegal to land or trade P. pectinata within the US or across its borders, it is difficult to enforce these regulations for some sawfish body parts because they resemble legally-traded shark body parts (e.g. dried fins). There is also a growing need for conservation genetics research on this species and its relatives, including assessments of population structure and genetic diversity. Given these pressing trade monitoring and research needs, we developed: (1) a rapid PCR-based test to identify P. pectinata body parts in trade in the US and western Atlantic, (2) a DNA-barcode based on 520 bp of cytochrome b that resolves P. pectinata and five other extant sawfish species and (3) a suite of 11 polymorphic P. pectinata microsatellite markers that can be used in a variety of conservation genetics applications for this and other sawfish species. We anticipate that this suite of genetic tools will contribute to the conservation of this critically endangered species and its relatives by reinforcing landings and trade restrictions and by enabling future conservation genetics research. [ABSTRACT FROM AUTHOR]

The article discusses the use of life-history model in identifying the habitats used by juvenile common snook in Southwest Florida. A stratified-random sampling was used to determine the locations of snook habitat and to describe the changing habitat affinities through ontogeny. Results show that small juveniles occupy coastal-wetland pond and creek networks instead of riverine habitats as they grow. They subsequently inhabit creek mouths before dispersing in estuaries.

Abstract: Bycatch mortality in net fisheries was the major reason for the decline of the endangered smalltooth sawfish, Pristis pectinata, in the United States. These fisheries have been reduced or eliminated in some states including Florida—where most smalltooth sawfish are currently found in the United States. To determine whether other factors are still affecting this species, we obtained non-net fishery entanglement, injury, and mortality data by soliciting information from anyone who may have encountered this species. Smalltooth sawfish were damaged by marine pollution (e.g., polyvinyl chloride pipe, monofilament line, non-monofilament line) and injured by humans. Examples of injuries caused directly by humans include removal of rostra, shooting an individual with a powerhead, and shooting another with arrows. Many people are aware that the smalltooth sawfish is protected by state and federal laws, but some are still not aware of (or willing to accept) this status. The impacts of marine pollution and injuries directly caused by humans on this endangered species can be ameliorated by incorporating fisher education into the conservation and management processes. [Copyright &y& Elsevier]

Summary Facultative parthenogenesis — the ability of sexually reproducing species to sometimes produce offspring asexually — is known from a wide range of ordinarily sexually reproducing vertebrates in captivity, including some birds, reptiles and sharks [1–3] . Despite this, free-living parthenogens have never been observed in any of these taxa in the wild, although two free-living snakes were recently discovered each gestating a single parthenogen — one copperhead ( Agkistrodon contortrix ) and one cottonmouth ( Agkistrodon piscivorus ) [1] . Vertebrate parthenogens are characterized as being of the homogametic sex (e.g., females in sharks, males in birds) and by having elevated homozygosity compared to their mother [1–3] , which may reduce their viability [4] . Although it is unknown if either of the parthenogenetic snakes would have been carried to term or survived in the wild, facultative parthenogenesis might have adaptive significance [1] . If this is true, it is reasonable to hypothesize that parthenogenesis would be found most often at low population density, when females risk reproductive failure because finding mates is difficult [5] . Here, we document the first examples of viable parthenogens living in a normally sexually reproducing wild vertebrate, the smalltooth sawfish ( Pristis pectinata ). We also provide a simple approach to screen any microsatellite DNA database for parthenogens, which will enable hypothesis-driven research on the significance of vertebrate parthenogenesis in the wild. [ABSTRACT FROM AUTHOR]