title: Modeling the distribution of illicit oily discharges detected by aerial surveillance in western Canadian marine waters.
abstract: Oily discharges from vessel operations have been documented in Canada's Pacific region by the National Aerial Surveillance Program (NASP) since the early 1990s. We explored a number of regression methods to explain the distribution and counts per grid cell of oily discharges detected from 1998 to 2007 using independent predictor variables, while trying to address the large number of zeros present in the data. Best-fit models indicate that discharges are generally concentrated close to shore typically in association with small harbours, and with major commercial and tourist centers. Oily discharges were also concentrated in Barkley Sound and at the entrance of Juan de Fuca Strait. The identification of important factors associated with discharge patterns, and predicting discharge rates in areas with surveillance effort can be used to inform future surveillance. Model output can also be used as inputs for risk models for existing conditions and as baseline for future scenarios.
authors.affiliation: Department of Geography, University of Victoria, Victoria, BC V8W 3P5, Canada. Electronic address: normaserra@gmail.ca.
authors.forename: Norma
authors.initials: N
authors.lastname: Serra-Sogas
authors.affiliation: Canadian Wildlife Services, c/o Institute of Oceans Science, Sidney, BC V8L 4B2, Canada; Department of Biology, University of Victoria, Victoria, BC V8W 3P5, Canada.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: O'Hara
authors.affiliation: Department of Geography, University of Victoria, Victoria, BC V8W 3P5, Canada.
authors.forename: Rosaline
authors.initials: R
authors.lastname: Canessa
mesh_terms: D002170:Canada; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D008962:Models, Theoretical; D010140:Pacific Ocean; D059392:Petroleum Pollution / Q000032:analysis*; D012623:Seawater; D012767:Ships; D014874:Water Pollutants, Chemical; D014877:Water Pollution, Chemical
chemical_list: D014874:Water Pollutants, Chemical
keywords: Aerial surveillance; Canadian West Coast; Chronic oil pollution; Detection; Marine pollution; Zero-inflated models