There are numerous road culverts that impede passage of fish in the Pacific Northwest and no consistent procedure for prioritization. Priorities are essential because the cost of restoration is large. For example, the GAO estimates the cost of fish passage restoration to be at least $375 million for just public lands in Oregon and Washington. The state of Oregon has invested over $28 million alone in the past decade to restore passage.
Using Netica software, a decision support tool was developed in the form of a Bayesian Network (BN) to assist prioritization of fish passage restoration. The BN incorporates empirical evidence and expert opinion to depict factors affecting the decision to replace a barrier. Major factors in the BN include potential habitat quality, likelihood of fish using habitats above a barrier, degree of passage impairment, and cost. The BN combines these considerations to inform a decision to replace a culvert or not.
We are adapting this generalized model to the specific case of ESA listed winter-run steelhead trout (Oncorhynchus mykiss) in the Santiam Basin Oregon. Lessons learned from this case application will be applied to prioritizing fish passage restoration in the Santiam Basin, and to refining the BN for more widespread application.
