1. Department of Environmental Conservation, University of Massachusetts Amherst 1 , Amherst, MA 01003-9285 , USA
2. National Research Council under contract to Fisheries Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration 2 , La Jolla, CA 92037-1508 , USA
3. Fisheries Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration 3 , La Jolla 92037-1508, CA , USA
4. Department of Wildlife, Fish, and Conservation Biology, University of California, Davis 4 , Davis, CA 95616 , USA
5. US Geological Survey, Eastern Ecological Science Center at the S. O. Conte Research Laboratory 5 , Turners Falls, MA 01376-1000 , USA