Abstract
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−1for 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.
Highlights
Assessment of the population viability or threat of extinction for endangered species requires information on population dynamics, including vital rates of growth and mortality
Vertebrae from 15 smalltooth sawfish collected in south Florida between 2003 and 2012 were made available for use in this study
Opaque bands were clear and easy to discern in smalltooth sawfish vertebrae sections
Summary
Assessment of the population viability or threat of extinction for endangered species requires information on population dynamics, including vital rates of growth and mortality. The population declined by approximately 95% in the 20th Century, primarily due to fisheries bycatch and habitat loss, and today individuals are only regularly encountered in south Florida [5,6,7,8]. Because of this large population decline and range reduction, the U.S distinct population segment of smalltooth sawfish was listed as endangered under the Endangered Species Act (ESA) in 2003 following a formal status review by the US National Marine Fisheries Service [9]. A recovery plan was produced by scientists and managers that outlined specific recommendations to promote conservation and recovery of the remaining population and critical habitats were designated for juveniles [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
