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

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

Historical specimens and photographs reveal long-term changes in Smalltooth Sawfish (Pristis pectinata) age class distribution and average size during US population decline

1. Population-level, historical studies can provide insights on the distribution, abundance and demographic characteristics of imperiled species prior to human exploitation, habitat modification or climate change. These studies provide a baseline for contemporary data, which often shape successful management and recovery. 2. The smalltooth sawfish (Pristis pectinata) occupies similar to 20% of its historical range due to declines driven primarily by mortalities in fisheries and coastal habitat loss over the last century. As a result, they are listed as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species and as Endangered federally in the United States (U.S.). 3. Because P. pectinata grow to a large size and have a toothed rostrum, many historical photographs and specimens are archived in natural history collections. Metadata and morphometric data were collected and analysed from P. pectinata photographs (n = 84) and specimens (n = 429) to evaluate temporal changes in average size and historical distribution of five age classes in U.S. waters. 4. Historically, smaller age classes were well-distributed throughout the northern Gulf of Mexico, while only larger age classes were recorded on the U.S. east coast, north of Florida. All age classes were found in both Florida and Texas historically, but records from Texas decline after the 1980s and remain persistent in Florida, indicative of a strong-hold for the U.S. population. Regardless of origin, individuals in three of the five age classes were larger on average historically than those observed today. 5. Understanding which age classes used previously occupied areas will help direct habitat restoration efforts and support recovery, especially in the face of climate change. Non-traditional data sources, such as those used here, may often be the only means of providing historical context to modern research on imperiled species, ultimately guiding restoration and conservation efforts