Cherry Point,WA Regional Ecologial Risk Assessment
Overview of the Cherry Point area looking to the south
Eggs of the Pacific Herring that spawn at Cherry Point
Beach at Cherry Point
Pacific Herring Risk Assessment
The Pacific Herring stock that spawns at Cherry Point, west of Bellingham, WA, has undergone a dramatic decline in the last 20 years. The Cherry Point region has associated with it two oil refineries and an aluminum smelting operation. Fishing for herring roe and eggs has occurred in the past, but is now banned in the region. Our charge from the Washington State Department of Natural Resources was to evaluate the risk factors to Herring posed by the Cherry Point region in order to manage the site.
We conducted a regional ecological risk assessment using the relative risk model (RRM) to investigate the causes of the current decline, current risks to the population, and the outcomes of future management options. The RRM incorporates geographic location and multiple anthropogenic and natural stressors into estimating risk. The population decline of the herring, corresponds with a collapse of the age structure, although survivorship of eggs to the Age 2 class has not diminished. The range of spawning areas has also declined, with the area of Point Whitehorn as the principal location.
The retrospective risk assessment identified climate change, as expressed by the warmer sea surface temperatures associated with a warm Pacific Decadal Oscillation (PDO), and exploitation as important risk factors. The warmer water also changes patterns in food resources, predators, and water quality. Contaminants have the potential for impact, but exposure to the eggs, hatchlings and fry has not been demonstrated at Cherry Point. Exposure to contaminants to adults during migration may occur and has been included into our assessment. Modeling of the population age versus fecundity curves and survivorship data indicate that the current population of Age 2 and 3 fish can not be self sustaining without the survivorship or immigration of Age 4 and older fish.
Current risk factors to the reduced population center on the destruction of the spawning habitat at Whitehorn Point from spills, development, and natural alterations to the environment due to the PDO and other climate change factors. Included in our assessments are testable risk hypotheses and estimates of uncertainty.
Since herring are transitory, alternate indicators of the ecological resources need to be developed to effectively manage the Cherry Point region. eelgrass, Dungeness crab, surf smelt and sand lance, shellfish, blue and Great Blue Heron, are recommended as alternative endpoints to effectively manage the ecological resources in the region.
We made a series of recommendations for future research in the area. These include understanding the loss of older age class fish, determining contaminant loadings in adult fish, the use of alternative endpoints, and preserving the existing habitat as the herring populations increase as the PDO shifts to a cooler period.
Risk Assessment of the Alternative Endpoints
We conducted a regional ecological risk assessment for the Cherry Point region in northern Whatcom County, WA using the Relative Risk Model. The objectives of this study were twofold: (1) to analyze cumulative impacts from multiple sources of stress to assess risk to multiple biological endpoints that utilize the region and (2) to determine the applicability of the Relative Risk Model in the study area.
We used geographic information systems to compile and compare spatial data for sources of stressors and habitats in sub-regions within the study area. These data determined the ranks for each sub-region. By quantitatively integrating ranks with exposure and effects filters as defined in a conceptual model, we estimated relative risk in sub-regions, relative contribution of risk from sources, risk in habitat types and assessment endpoints most at risk within the Cherry Point area. Finally, we used Monte Carlo techniques to perform uncertainty analysis and applied an alternative ranking scheme to evaluate the effects of model and parameter uncertainty on the risk predictions.The Relative Risk Model and uncertainty analysis results suggest the major contributors of risk in the region are commercial and recreational vessel traffic, upland urban and agricultural land use and shoreline recreational activities. The biological endpoints most likely to be at risk are great blue heron and juvenile Dungeness crab. The majority of risk occurs in sandy inter-tidal, eelgrass and macro-algae habitats. The sub-regions where the most risk occurs are Lummi Bay, Drayton Harbor and Cherry Point.
Weight of Evidence for Regional Ecological Risk Assessments
A classic problem in environmental decision making is the estimation of the causes of impacts observed in aquatic populations and communities at regional scales. I applied a weight of evidence (WoE) and path analysis approach based upon our relative risk model in order to estimate the cause of the decline of the Cherry Point Pacific herring. This WoE approach is based upon a risk assessment type conceptual model in order to link the paths of potential sources of stressors to the effects seen in the population. Ranking criteria and regressions are used to assign weights to the potential sources and stressors. A Monte Carlo analysis is applied to represent the uncertainty in each of the ranks, correlations and filters and to estimate the uncertainty of the analysis. This technique results in a series of multinomial distributions representing the likelihood of a stressor causing an impact. In the case of the Cherry Point herring, climate change, habitat alteration and contamination at a landscape scale were identified as important stressors. This case study demonstrates that a clearly derived and quantified WoE and path analysis is a useful approach to investigating casual links at regional scales.
Papers resulting from this research
Landis W. G., Hart Hayes, E., Markiewicz, A. M. 2005. Chapter 12. Retrospective Regional Risk Assessment Predictions and the Application of a Monte Carlo Analysis for the Decline of the Cherry Point Herring Stock. In W. G. Landis editor Regional Scale Ecological Risk Assessment Using the Relative Risk Model. CRC Press Boca Raton pp 245-256.Hart Hayes, E., Landis W. G. 2005. Chapter 13. The Ecological Risk Assessment Using the Relative Risk Model and Incorporating a Monte Carlo Uncertainty Analysis. In W. G. Landis editor Regional Scale Ecological Risk Assessment Using the Relative Risk Model. CRC Press Boca Raton pp 257-290
Hart Hayes, E. and Landis WG. 2004. Regional ecological risk assessment of a nearshore marine environment: Cherry Point, WA. Human and Ecological Risk Assessment. 10: 299-325.
Landis, W. G, P. B. Duncan, E. Hart Hayes, A. J. Markiewicz, J. F. Thomas. 2004 . A regional assessment of the potential stressors causing the decline of the Cherry Point Pacific herring run and alternative management endpoints for the Cherry Point Reserve (Washington, USA). Human and Ecological Risk Assessment 10: 271-297
Landis, W. G., E. Hart Hayes and A. M. Markiewicz. 2003. Weight of Evidence and Path Analysis Applied to the Identification of Causes of the Cherry Point Pacific Herring Decline.. Droscher, Toni and David A. Fraser (eds.) 2003 Georgia Basin/Puget Sound Research Conference, March 31-April 3, 2003, Vancouver, British Columbia -Proceedings (December 2003). Document Link
Landis WG, Markiewicz, AJ, Thomas JF, Hart Hayes E. 2002. Regional risk assessment predictions for the decline and future management of the Cherry Point Herring Stock and region. Proceedings of the 2001 Puget Sound Research Conference. T. Droscher, editor. Puget Sound Water Quality Action Team. Olympia, Washington.
This research was managed by the Washington State Department of Natural Resources with funding from Washington State Department of Natural Resources and British Petroleum Cherry Point Refinery