A Molecular Analysis of Atlantic Menhaden (Brevoortia tyrannus) Stock Structure

• Main Author: Lynch, Abigail J.
• Format: Others
• Language: English
• Published: W&M ScholarWorks 2008
• Subjects: Fresh Water Studies; Molecular Biology; Oceanography
• Online Access: https://scholarworks.wm.edu/etd/1539617866; https://scholarworks.wm.edu/cgi/viewcontent.cgi?article=2996&context=etd

Atlantic menhaden is an ecologically and economically important species along the U.S. east coast. As a filter-feeder and key prey fish, it provides a critical link between primary production, phytoplankton, and larger piscivorous predators, such as striped bass, bluefish, and weakfish. The species is also the target of one of the largest commercial fisheries in the country. Menhaden are assessed as a single, coastwide stock, and recent assessments indicate that it is not overfished. However, there is very limited population genetics data to support the assumption of a single stock. Additionally, the recent consolidation of the fishery and localization of harvests within and around Chesapeake Bay have raised concerns over the possibility of ‘localized depletion’ of the species in this area. This study used rapidly evolving molecular markers to examine Atlantic menhaden stock structure along the U.S. Atlantic coast, specifically to determine the potential for the loss of unique genetic variation resulting from concentrated fishing pressure in and around Chesapeake Bay. Samples were collected from up to three cohorts of Atlantic menhaden (2005, 2006, and 2007 year classes), at four geographic locations along the U.S. Atlantic coast (New England, mid-Atlantic, Chesapeake Bay, and U.S. south Atlantic) in 2006 and 2007. Two independent classes of molecular markers were surveyed: the mitochondrial cytochrome c oxidase subunit I (COI) gene region and seven nuclear microsatellite loci. All markers revealed considerable genetic variation. Hierarchical analyses of molecular variance (AMOVA) and examination of pairwise ΦST, FST, and RST estimates indicate a homogeneous distribution of genetic variation within Atlantic menhaden (all region AMOVAs: ΦST = -0.00873, FST = 0.00515 (FST method), FST = -0.00666 (RST method); p>0.05). The genetic connectivity between the regional collections suggests that concentrated fishing pressure in and around Chesapeake Bay will not result in a significant loss of unique genetic variation.