Burger 



Chapter 29 



Marine Distribution, Abundance, Habitats in British Columbia 



1989 D 1990 M 1991 1992 



1993 



A Nearshore shoreline surveys 



61.8 32.9 



5! 8 - 



> ^ i *^ *N ^ 



B Open water surveys 



Week starting on date shown 



30 

 25 

 20 

 15 



5 

 



C Annual means (26 April - 30 June) 



Nearshore Open water 



6 



1989 



1990 



1991 



1992 



1993 



Figure? Densities of Marbled Murrelets in Laskeek Bay, Queen Charlotte Islands, showing seasonal patterns in nearshore surveys 

 (A) and those in open water (B); and inter-year variations in mean densities (C). No open water surveys were made in 1 989. Sample 

 sizes show numbers of surveys used to calculate the mean values for the period 26 April through 30 June. Error bars show standard 

 deviations (inverted for 1993 nearshore). Transect widths were 400 m throughout (Lawrence, pers. comm.). 



and jack-mackerel (Trachurus symmetricus), which eat prey 

 similar to that taken by murrelets, and significantly low densities 

 of euphausiids and juvenile herring (Hargraves, pers. comm.; 

 Tanasichuk, pers. comm.). Murrelet surveys in the Broken 

 Islands showed no effects of these changes in 1992, relative 

 to 1991, but in 1993 many murrelets appeared to leave the 

 Broken Islands and the Deer Island-Trevor Channel area in 

 June, at least a month before their usual departure (fig. 8). 



Abundance and Distribution Relative to Distribution 

 of Forest Stands 



There are insufficient data for coarse-scale comparisons 

 between murrelet densities at sea and rates of detections in 

 adjacent forests. Murrelet detection frequencies in forest 

 surveys on the east coast of Vancouver Island, which has 

 been extensively logged, were much lower than on the west 

 coast (Savard and Lemon in press), and this corresponds to 



304 



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



