GAP Program Regional Risk Analysis Project Summary
Integration of Ecological Risk Assessment and the GAP Analysis Program: Assessing Risk to Salmon in Small Streams
Wayne G. Landis, Jessica A. Ellis, Laurel A. Kaminski, and April J. Markiewicz
The results of this pilot project demonstrate that a regional-scale ecological risk assessment (ERA) methodology can be used in conjunction with the GAP Analysis Program process to organize site-specific data and information, and assist in management decisions. A series of creeks and their watersheds in and around Bellingham, WA that are used for spawning by several species of salmon were selected as the study sites. Although in close proximity to one another, the creeks and their watersheds vary in the type of land uses and resource management actions applied to them. Data for these sites that were used in this ERA were obtained from state and local governments, as well as a local non-governmental agency. The ERA methodology used was the updated Relative Risk Model (RRM) originally developed by Wiegers et al. (1998) that also uses Monte Carlo analysis to describe uncertainty. The ecological endpoint assessed was total smolt production, since that was identified by the stakeholders as a socially valued attribute and smolt data existed for each of the creeks.
The completed ERA identified multiple stressors as major contributors of risk to the watersheds. The top ranked stressors were toxicants, reduced land cover, reduced wetland area, and altered stream flow as most important, with each contributing approximately the same to the overall risk score. The highest ranked sources of these stressors were residential areas, roads and chemical industries. In the analysis of individual stressors and sources none stood apart as a management priority, but rather a broad range of factors need to be managed to reduce risk. An analysis of the risks posed by GAP stewardship areas 2, 3 and 4 indicated that they only contribute 17 percent of the risk in the study area, i.e., even if all risks to salmon were eliminated from these regions, 83 percent of the risks would still remain. A data-mining exercise was also conducted to examine whether there was a correspondence between land uses in each watershed and smolt production, but no significant relationships were found. Uncertainty and sensitivity analyses results indicated that the data were not of sufficient statistical power to identify relationships even though multiple years of data existed for some of the sites.
In conclusion, regional-scale ERA methodology can be applied to the management of natural resources under GAP Analysis Program. An ERA can identify potential stressors, sources, and areas where more data need to be collected. It can also be used to examine the effects of management actions on the overall risks to the species or assessment endpoint of interest. Finally, risk assessment can be used to estimate the statistical power needed for data collected from field studies.
Project Funding from the U. S. Geological Survey GAP Program.