1. Department of Biology, Memorial University of Newfoundland and Labrador, St. John's, NL A1B 3X7, Canada
2. Department of Ocean Sciences, Memorial University of Newfoundland and Labrador, St. John's, NL A1C 5S7, Canada
3. Ecological Sciences Section, Fisheries and Oceans Canada, St. John's, NL A1C 5X1, Canada
4. Alaska Fisheries Science Center, National Oceanographic and Atmospheric Administration, Newport, OR 97365, USA