1. Organismic and Evolutionary Biology Program, University of Massachusetts Amherst, 230 Stockbridge Road, 204C French Hall, Amherst, MA 01003, USA
2. US Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Center, One Migratory Way, Turners Falls, MA 01376, USA
3. Environmental Conservation Department, University of Massachusetts Amherst, 160 Holdsworth Way, 225 Holdsworth Hall, Amherst, MA 01003, USA
4. Commercial Fisheries Research Foundation, PO Box 278, Saunderstown, RI 02874, USA