In gathering information BEST should locate and solicit areas of concern by agencies or states. Incidents affect rare species. Incidents are well documented and well studied so extrapolation to other areas is possible. A recurrent pattern allows for extrapolation. A contaminant looms large relative to other issues.
Losses are from direct effects.
The presence of contaminants can be identified. Incident can be readily ascribed to the contaminant rather than other factors. Extrapolation is important, but it cannot be achieved from simple summaries of raw data. Someone must evaluate the data in relation to the area, contaminant, species, etc. The types of contaminants that will most likely be detected with mortality incident data are those that can be easily measured, leave a detectable residue, or have an acute effect on organisms.