1. Marine Mammal Laboratory; NOAA-NMFS Alaska Fisheries Science Center; 7600 Sand Point Way NE Seattle Washington 98115 USA
2. ARC Centre for Excellence in Mathematical and Statistical Frontiers (ACEMS); The Institute for Future Environments; Queensland University of Technology; Brisbane Australia
3. U.S. Geological Survey; Colorado Cooperative Fish and Wildlife Research Unit; Fort Collins Colorado 80523 USA
4. Department of Fish, Wildlife, and Conservation Biology; Colorado State University; Fort Collins Colorado 80523 USA
5. Department of Statistics; Colorado State University; Fort Collins Colorado 80523 USA
6. Department of Statistics; The Pennsylvania State University; State College; Pennsylvania 16802 USA
7. Department of Ecology and Evolutionary Biology; University of Toronto; 25 Willcocks St. Toronto Ontario M5S 3B2 Canada