Female philopatry in smalltooth sawfish Pristis pectinata: conservation and management implications

Abstract

Populations are more effectively managed with information on breeding and dispersal behavior, making the evaluation of these characteristics essential for effective conservation of a species. In the USA, 2 critical habitat units were designated in 2009 for the federally endangered smalltooth sawfish Pristis pectinata. Previous research in the Charlotte Harbor Estuary Unit (CHEU) of critical habitat shows that female smalltooth sawfish are polyandrous and highly philopatric to nursery grounds. However, these characteristics have not yet been examined in a larger area of designated critical habitat: the Ten Thousand Islands/Everglades Unit (TTIEU). We used microsatellite genotypes from 214 juvenile smalltooth sawfish to examine mating and dispersal behavior via sibship analyses and reconstruction of parental genotypes with the program COLONY. Parental reconstruction yielded 71 female and 117 male genotypes. Many females returned to the same region within TTIEU for parturition on a biennial cycle; however, at least 1 female switched parturition sites within TTIEU and at least 2 females produced litters in both TTIEU and CHEU over the study period. The maximum number of pups genetically assigned to 1 female was 12, a number that is consistent with that found for CHEU (8 pups), and within the litter size range reported (7 to 14) for the species. Confirmation of these mating behaviors and reproductive characteristics is important for understanding how the present population uses these protected habitats at different life stages, and for determining future habitat protection and population expansion strategies to restore smalltooth sawfish to previously occupied areas of their range.

Genomic evidence indicates small island-resident populations and sex-biased behaviors of Hawaiian reef Manta Rays

“…The combination of restricted female- and male-mediated migration provides evidence these populations are demographically isolated. This asymmetry in spatial genetic patterns between nuclear loci and mitochondrial haplotypes among reef manta rays is consistent with female philopatry and weak male-biased dispersal [ 45 , 46 ], which has been documented in batoids [ 47 – 50 ] and sharks [ 51 – 54 ]. Broadly, this molecular evidence for male-biased dispersal in reef manta rays adds further support to sex-biased dispersal as a recurrent pattern in viviparous elasmobranchs (reviewed in Phillips et al [ 55 ]).…”

“…Female reproductive philopatry is common among elasmobranchs and widespread across batoids including several species of stingrays [ 56 ], skates [ 56 , 57 ], and sawfish [ 47 , 50 , 55 ]. Previous studies (reviewed in Flowers et al [ 58 ]) have provided compelling evidence of site fidelity and residency in M. alfredi that are consistent with philopatry [ 6 , 8 – 10 , 12 , 15 , 59 – 62 ].…”

Impacts of trophy collection and commercial fisheries on sawfishes in Queensland, Australia

“…Successful conservation of endangered species includes maintaining genetic diversity across populations. Sawfishes are known to display reproductive philopatry with fine-scale ranges, and some species have male-biased dispersal , Feutry et al 2015, Green et al 2018, Feutry et al 2021, Smith et al 2021. Moreover, the 3 Pristis species have experienced population bottlenecks in the Gulf of Carpentaria (Phillips et al 2017).…”

Historical specimens and photographs reveal long‐term changes in Smalltooth Sawfish (Pristis pectinata) age class distribution and average size during U.S. population decline

“…Information on age class distribution from historical data sources can provide important insights into P. pectinata habitat use (e.g., nursery habitats and adult migratory routes). For instance, contemporary nursery areas for young‐of‐year (YOY) P. pectinata are designated in SWFL (Norton et al, 2012; Feldheim et al, 2017;Smith et al, 2021), but physical evidence of YOY from other locations would further corroborate the written historical accounts suggestive of historical nurseries in areas like Texas (Baughman, 1943; Bigelow & Schroeder, 1953), Alabama (Boschung, 1957) and the east coast of Florida (Goode, 1884;Evermann & Bean, 1898; Evermann & Marsh, 1900). Such information is critical to population recovery to ensure protection of key areas that were once biologically important to the species.…”