1. National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole Laboratory Woods Hole Massachusetts 02543 USA
2. Department of Biological Sciences University of New Hampshire Durham New Hampshire 03824 USA
3. IBSS, under contract with National Marine Fisheries Serivce, Northeast Fisheries Science Center Silver Spring Maryland 20910 USA
4. Massachusetts Division of Marine Fisheries, Annisquam River Marine Fisheries Station Gloucester Massachusetts 01930 USA
5. Department of Biology, Dalhousie University Halifax Nova Scotia B3H 4R2 Canada