For more information on species & ecosystem science:

Wildlife Science

Fish Science

Habitat Science

Lead Scientists: Scott Pearson
  Monique Lance

Ecoregions: Puget Trough, Northwest Coast

Ecological Systems: Not Available for Research Area


The six marbled murrelet conservation zones


WDFW field biologists Ian Snider and Andrew Spees surveying marbled murrelets.


The six marbled murrelet conservation zones


Seabird Ecology

Marbled Murrelet Population Trends

Project Description

The Marbled Murrelet was listed as a Threatened species in California, Oregon and Washington in 1992 by U.S. Fish and Wildlife Service under the Endangered Species Act. A recovery plan was published in 1997 that outlined recovery strategies including developing and conducting standardized at-sea surveys. Along with federal and state researchers, Washington Department of Fish and Wildlife has participated in a program to estimate marbled murrelet population size and trends since 2000 and WDFW also participated in the testing of various survey methods prior to 2000. This at-sea monitoring program uses line transects (DISTANCE sampling) within 8 km of the Washington, Oregon, and northern California coastline in the area covered by the Northwest Forest Plan (see map). There are six marbled murrelet conservation zones but only zones 1-5 are monitored as part of this monitoring program. Two of these zones are located in Washington; Zone 1 includes the Strait of Juan de Fuca, Hood Canal and the San Juan Islands and is monitored by the Pacific Northwest Research Station, U.S.D.A. Forest Service; Zone 2 includes the Washington outer cost and is monitored by Washington Department of Fish and Wildlife.

This project is currently funded by U.S. Fish and Wildlife Service but has received funding from Washington Department of Natural Resources and WDFW.

Key Findings

  • Range-wide results (California, Oregon and Washington
    • The murrelet population estimate for the area extending from the United States border with British Columbia south to the Golden Gate of San Francisco Bay for 2013 was 19,617 birds (95 percent confidence interval: 15,396 to 23,838 birds

    • For the combined 5-conservation zone area for the 2001-2013 period, there was a weak downward trend (1.2% decline per year; P=0.16).

  • Washington results
    • The population estimate for Puget Sound and the Strait of Juan de Fuca in 2013 (Zone 1) was 4,395 birds (95% confidence interval = 2,275 – 6,740 birds) with a -3.88% (standard error = 1.73%) average annual rate of decline for the 2001-2013 period (p = 0.0499).

    • The population estimate for the Washington coast for 2013 (Zone 2) was 1,257 birds (95% confidence interval = 920 – 1,846 birds) with a -7.37% (standard error = 1.70%) average annual rate of decline for the 2001-2013 period (p = 0.0016).

    • For Washington State (Zones 1 and 2 combined) the estimate of annual rate of change in murrelet density was -4.65% (standard error = 1.33%) for the 2001-2013 period (p = 0.0059).