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.