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2005 At-Sea Marbled Murrelet Population Monitoring

Category: Wildlife Research and Management - Wildlife Research

Date Published: November 28, 2005

Number of Pages: 12

Author(s): Monique M. Lance and Scott F. Pearson

Prepared For: U.S. Fish and Wildlife Service (Section 6 Federal Aid Report) and Washington Department of Natural Resources


In 1992, the Marbled Murrelet was listed under the Federal Endangered Species Act of 1973 as a Threatened species in California, Oregon and Washington. A recovery plan was published in 1997 (U.S. Fish and Wildlife Service 1977) that outlined recovery strategies including developing and conducting standardized at-sea surveys. These surveys were viewed as critical to the recovery of the Marbled Murrelet because they allow researchers to model population trends and demographics and because detecting changes in populations is critical to the evaluation of recovery actions and ultimately to the determination of recovery success or failure. In response to this recovery goal, the U.S. Fish and Wildlife Service, U.S. Forest Service and state wildlife agencies initiated a Marbled Murrelet monitoring strategy in 2000 (Raphael et al. 1999, 2004, Miller et al. 2005). The goal of this monitoring strategy is to estimate Murrelet population size and changes in population size for the area between the Washington – Canada border and San Francisco. Results will be used to evaluate any USFWS incidental take criteria and to facilitate the Recovery Plan development and evaluation. In addition to meeting the requirements of the Endangered Species Act, long-term Marbled Murrelet monitoring is required to evaluate the effectiveness of the Northwest Forest Plan (Madsen et al. 1999). This plan is a large-scale ecosystem management plan for Federal lands in the Pacific Northwest. The Murrelet was identified as a conservation and monitoring target for evaluating the effectiveness of this plan.

Since 2000, Washington Department of Fish and Wildlife along with researchers from the US Forest Service, US Fish and Wildlife Service, Crescent Coastal Research, and the University of California Berkeley have been estimating Murrelet population size and trends using at sea line transects within 8 km of the Washington, Oregon, and northern California coastline. These transects cover ~8,800 km2. This area of coastline has been subdivided into the five Marbled Murrelet Conservation Zones identified in the Marbled Murrelet Recovery Plan (Figure 1; US Fish and Wildlife Service 1997). Washington Department of Fish and Wildlife has been responsible for monitoring the outer Washington coast (Figure 2; Zone 2 - from the northwest tip of the state to the mouth of the Columbia River). The first four years of monitoring have been summarized for the entire Washington to California region in Miller et al. (2005). Preliminary results indicate that for all zones combined, we will be able to detect an annual population change of 2% in 15 years (with 95% power) or a 3% annual population change over 10 years (with 80% power). These results suggest that long-term monitoring is required to confidently detect changes in population size.

Here we summarize the methodology, sampling and results for the 2005 at-sea monitoring on Washington’s outer coast (Cape Flattery to the south jetty of the Columbia River).

Suggested Citation:
Lance, M.M., and S.F. Pearson. 2005. 2005 at-sea Marbled Murrelet population monitoring. Washington Department of Fish and Wildlife, Olympia, WA. 11 pp.