Fall through spring 2018/2019 Marbled Murrelet At-Sea Densities In Five Strata Associated with U.S. Navy Facilities in Washington State: Annual Research Progress Report 2019


Published: October 2019

Pages: 16

Author(s): Pearson, S.F. and M.M. Lance


The goal of this project is to estimate on-the-water marbled murrelet (Brachyramphus marmoratus) densities during the fall-spring seasons (September - April) adjacent to the following facilities: (1) Naval Air Station Whidbey Island (Crescent Harbor); (2) Manchester Fuel Department; (3) Naval Base Kitsap at Bangor, Zelatched Point, Toandos, Keyport and Bremerton; (4) Naval Magazine Indian Island; and (5) Naval Station Everett. These surveys have been conducted annually since September of 2012 and, now that we have seven years of survey effort, we can begin to examine murrelet trends during the non-breeding season. Because the nearshore marine environment and murrelet densities adjacent to any one of these facilities is too small to derive reliable site-specific at-sea murrelet densities, Washington Department of Fish and Wildlife (WDFW) used a stratified sampling approach outlined in Pearson and Lance (2012, updated 31 October 2013) to derive stratum specific density estimates. This approach uses line-transect or distance sampling methods (Buckland et al. 1993) to derive murrelet density estimates for four strata using nearshore and offshore transects placed in 32 primary sampling units (PSUs) (Figure 1). Note that the coastal unit (Pacific Beach) was not surveyed this year.

Suggested citation

Pearson, S.F. and M.M. Lance. 2019. Fall-spring 2018/2019 Marbled Murrelet At-Sea Densities for Four Strata Associated with U.S. Navy Facilities: Annual Research Progress Report. Washington Department of Fish and Wildlife, Wildlife Science Division, Olympia, WA.