The application of GIS and spatiotemporal analyses to investigations of unusual marine mammal strandings and mortality events

Stephanie A. Norman, Jessie Huggins, Tim Carpenter, James Case, Dyanna M. Lambourn, Jim Rice, John Calambokidis, Joseph K. Gaydos, M. Bradley Hanson, Deborah A. Duffield, Sandra Dubpernell, Susan Berta, Matt Klope

Research output: Contribution to journalArticle

11 Scopus citations


In 2006-2007, an unusually high number of harbor porpoises (Phocoena phocoena) stranded along the Washington and Oregon coastlines. Spatiotemporal analyses were used to examine their ability to detect clusters of porpoise strandings during an unusual mortality event (UME) in the Pacific Northwest using stranding location data. Strandings were evaluated as two separate populations, outer coast and inland waters. The presence of global clustering was evaluated using the Knox spatiotemporal test, and the presence of local clusters was investigated using a spatiotemporal scan statistic (space-time permutation). There was evidence of global clustering, but no local clustering, supporting the hypothesis that strandings were due to more varied etiologies instead of localized causes. Further analyses at subregional levels, and concurrently assessing environmental factors, might reveal additional geographic distribution patterns. This article describes the spatial analytical tools applied in this study and how they can help elucidate the spatiotemporal epidemiology of other UMEs and assist in determining their causes. More than one spatial analytical technique should be used if the study objective is to detect and describe clustering in time and space and to generate hypotheses regarding causation of marine mammal disease and stranding events.

Original languageEnglish (US)
JournalMarine Mammal Science
Issue number3
StatePublished - Jul 1 2012



  • Epidemiology
  • GIS
  • Harbor porpoise
  • Phocoena phocoena
  • Spatiotemporal analyses
  • Unusual mortality event

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science

Cite this

Norman, S. A., Huggins, J., Carpenter, T., Case, J., Lambourn, D. M., Rice, J., Calambokidis, J., Gaydos, J. K., Hanson, M. B., Duffield, D. A., Dubpernell, S., Berta, S., & Klope, M. (2012). The application of GIS and spatiotemporal analyses to investigations of unusual marine mammal strandings and mortality events. Marine Mammal Science, 28(3).