Piatt and Naslund 



Chapter 28 



Abundance, Distribution, and Population Status in Alaska 



these factors may also lead to underestimates of at-sea densities 

 (Ralph and Miller, this volume). Larger scale boat-based 

 surveys may overestimate populations as birds move within 

 the survey area and are recounted (Rodway and others, in 

 press). Continuous counting of flying birds during boat- 

 based surveys may significantly overestimate densities 

 (Gaston and others 1987; Varoujean and Williams, this 

 volume; Strong and others, this volume). Aerial surveys 

 provide a good synoptic picture of distribution, but may 

 underestimate densities at sea (Strong and others, this volume). 



Murrelet Distribution 



Piatt and Ford (1993) used ship-based census data 

 collected under the Outer Continental Shelf Environmental 

 Assessment Program (OCSEAP) to assess the abundance 

 and distribution of regional murrelet populations (figs. 1 and 



2, table 1). The relative distribution of important murrelet 

 habitat revealed by OCSEAP data is supported by fine-scale 

 surveys conducted in different areas of Alaska (Agler and 

 others 1994, Forsell and Gould 1981, Klosiewski and Laing 

 1994, Kuletz 1994, Piatt 1993). 



Although murrelets range widely in Alaska, they are 

 concentrated during the breeding season in three main areas: 

 the Kodiak Archipelago, Prince William Sound, and the 

 Alexander Archipelago (figs. 1 and 2, table 1). At a smaller 

 scale, areas of concentration (fig. 2) include in the Alexander 

 Archipelago: Stephens Passage, Lynn Canal, Sumner Strait, 

 Chatham Strait, Icy Strait, and Glacier Bay; on the outer 

 coast: Yakutat Bay, Icy Bay; all of western Prince William 

 Sound; along the south Kenai Peninsula; in lower Cook 

 Inlet: Kachemak Bay and Kamishak Bay; in the Kodiak 

 Archipelago: around Afognak Island, in Chiniak Bay and 



Marbled Murrelet 



densities in 



60' lat/long blocks 



February-October 



100 ZOO 300 400 500 600 700 800 



CHUKCHI SEA 



.000-.000/KraSq 

 .000-.500/KmSq 



ALASKA 



III .500-l.OO/KmSq 







1.00-2.00/KraSq 

 2.00-9.00/KmSq 

 200 m contour 



BERING SEA 



GULF OF ALASKA 



6600 62 00 1480014400 14000 U 00 152 



Figure 1 Distribution of Marbled Murrelets and survey coverage in 60' latitude-longitude blocks in Alaska (from 

 Piatt and Ford 1993). Data compiled for the months of February - October. Murrelet densities are scaled 

 geometrically. Similar analyses for breeding and non-breeding seasons were used for estimating population sizes 

 (table 1). Numbered areas are: 1 -Southeast Alaska (Alexander Archipelago), 2- Prince William Sound, 3- Cook 

 Inlet, 4- Kodiak Archipelago, 5- Alaska Peninsula, 6- Aleutian Islands. 



286 



USDA Forest Service Gen. Tech. Rep. PSW-152. 1995. 



