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Use of Geographic Information Systems as a Forensic Tool to Investigate Sources of Marine Mammal Entanglement in Fisheries

NCJ Number
Journal of Forensic Sciences Volume: 52 Issue: 4 Dated: July 2007 Pages: 904-908
Leslie G. Burdett M.S.; Jeffrey D. Adams M.S.; Wayne E. McFee M.S.
Date Published
July 2007
5 pages
This paper describes an objective technique for using geographic information systems (GIS) to map the distinctive characteristics of fishing gear that inflicted wounds on dead marine mammals that were entangled in a fishery before being washed ashore without gear attached to their carcasses.
The findings show that GIS can be used to develop maps that identify the unique characteristics of fishing gear and entanglement wounds. Image processing tools within GIS provide a semiautomated approach to create these maps. This approach is more efficient and less subjective than the initial protocol of manually digitizing the outline of wound impressions. Future research will focus on case studies that match unknown entanglement wound patterns with specific fisheries. Currently, information on season, gear type, and location of commercial fisheries along the Atlantic coast is being stored in a database that will eventually be accessible to stranding networks. This database will also include outlines of specific fishing gear that have been developed with the technique described in this paper. For this study, tools within the Environmental Systems Research Institute, Inc. (ESRI) ArcMap GIS software were used to create maps that outline impressions that fishing gear leave on the epidermis of entangled marine mammals. It was necessary to extract only the pixels of images corresponding to the rope imprint on the carcass. A commonly used GIS approach for extracting feature information from image data is reclassification, a process in which pixels are grouped into classes. In order to extract the rope imprint pixels, the authors used a two-class Jenks optimization approach within ESRI's ArcGIS Spatial Analyst in order to explore the image data for a natural break in the distribution of the brightness values of the rope imprint's image. 5 figures and 30 references