188 
Fishery Bulletin 1 14(2) 
Map of the study area and its location within the Tracy Arm-Fords Terror Wilderness area 
in southeastern Alaska where harbor seals (Phoca vitulina) rest and nurse their pups on 
ice calved from glaciers. Observation point 1 (upper inset), from which seals were studied, 
is located at 57.857°N, 133.135°W. We recorded the time when boats entered and left sec- 
tions A and B (upper inset). Observation point 2 was used beginning in 2005 after the South 
Sawyer Glacier had receded so far that observation point 1 no longer provided a good view 
of the seals. 
thinning and retreating (Larson et al., 2007). Endicott 
Arm also has tidewater glaciers. Tracy Arm is 72 km 
south of Juneau, a major cruise ship port (CLAA 7 ) and 
the capital of Alaska. The proximity of this fjord to Ju- 
neau results in hundreds of cruise ships (7 visits/week 
on average; Nuka Research and Planning Group 3 ), tour 
boats, other commercial vessels, and private vessels 
visiting Tracy Arm each year. Unlike vessel traffic in 
GBNP, where numbers and speed are restricted, vessel 
traffic is currently unregulated in Tracy Arm. 
We conducted our study in Tracy Arm from 2001 
to 2006 and conducted more intensive sampling (e.g., 
more days of sampling and more types of data collect- 
ed) in 2001 than in later years. We monitored seals and 
vessels from an elevated observation point (OP1) ini- 
tially -500 m from the face of the South Sawyer Gla- 
cier (Fig. 1). Tracy Arm is approximately 1 km wide 
at OP1, which afforded an unobstructed view of the 
7 CLAA (Cruise Line Agencies of Alaska). 2015. Cruise ship 
calendar for 2016. CLAA, Ketchikan, AK. Available at 
website.] 
areas of greatest seal and ice concentration (Fig. 1). 
From July 2004 through August 2005, the South Saw- 
yer Glacier receded dramatically such that the face of 
the glacier was >1.6 km farther from OP1. Because of 
that change, a second observation point (OP2) was used 
late in the 2006 season (Fig. 1), but the use of OP2 had 
little direct effect on the type of data collected (i.e., 
counts from shore and from behavioral sampling) dur- 
ing this period. We refer to the area visible from OP1 
and OP2 as “the study site” or “the inlet.” 
Seal counts 
From 27 May through 30 June 2001, harbor seals were 
counted from OP1 with tripod-mounted 10x42 binoc- 
ulars. Whenever possible, 2 observers counted simul- 
taneously. Each day between 0700 and 2000 h, 3-6 
counts (1-4 of which were paired counts) were made; 
the median time interval for conducting a count was 
22 min (range: 7-39 min). Each day, we attempted to 
obtain at least 1 count before vessel disturbance (i.e., 
before vessels entered the study site). 
