Effective Population Size and Genetic Diversity of a Species of Concern, the Sand Tiger Shark (Carcharias taurus) in Delaware Bay, USA

• Main Authors: Gray, Teagen K., Fox, Dewayne A., Wetherbee, Bradley M., Bernard, Andrea, Shivji, Mahmood S.
• Format: Conference Object
• Language: unknown
• Published: NSUWorks 2013
• Subjects: Marine Biology; Oceanography and Atmospheric Sciences and Meteorology; North Atlantic
• Online Access: https://nsuworks.nova.edu/occ_facpresentations/496; http://elasmo.org/2013-aes-abstracts

Genetic assessments can provide a conservation and management relevant perspective on the status of imperiled species including sand tigers, (Carcharias taurus). Sand tigers within the western North Atlantic were listed as a Species of Concern and thus prohibited from recreational and commercial fisheries in 1997 by the National Marine Fisheries Service. A previous global population study of sand tigers revealed the genetic isolation of individuals inhabiting the western North Atlantic from the remainder of this species' distribution. Here, we assess the genetic status, including effective population size and genetic diversity of sand tigers from an area of known high abundance: Delaware Bay (n=557). Eleven species-specific microsatellite markers were used to analyze temporal variation in effective population size and genetic diversity of sand tigers collected from 2007-2012. Total length was used to back-calculate age estimates for each sex using data from a previous age and growth study on sand tigers within this region. Individual sharks of similar estimated age were grouped together to form year classes. Preliminary results indicate little genetic differentiation among year classes with respect to genetic diversity and effective population size, suggesting relatively stable, recent temporal population dynamics for Delaware Bay sand tigers. Estimates of genetic diversity (allelic richness) of sand tigers captured within Delaware Bay were greater than the previous survey within the western North Atlantic, suggestive of recovery in this previously exploited population.