Glacier Bay National Park & PreservePage 59 of 97
Counting Close Calls Between Cruise Ships and Humpback Whales in Glacier Bay
Over 49 trips in 2008 and 2009, a shipboard observer standing at the bow of cruise ships recorded more than 300 encounters with humpback whales in and around Glacier Bay National Park and Preserve. Most were at distances over 100 yards (90 m); the close ones clustered at the park entrance and in the lower bay. Karin Harris and Scott Gende describe the study in the National Park Service's Alaska Park Science.
The observer was stationed inside a gated area at the center of the bow (NPS photo).
Why it matters
Knowing how often and how close ships meet humpbacks helps managers decide how many ships to allow and write policies that protect the whales while letting visitors enjoy them. The park now limits cruise ships to no more than 2 a day and no more than 153 in the June to August peak season, and enforces speed restrictions where whales are likely. Two lethal injuries from ship strikes have been confirmed in the park: in 2001 a large cruise ship collided with and killed an adult humpback, and in 2004 a calf washed ashore with injuries attributed to a vessel collision. Reports of ship and whale collisions in Southeast Alaska have increased, but few data record how often or how severely ships and whales meet. The study built on a shipboard observer project begun in the park in 2006; a University of Washington graduate student was given the chance to ride cruise ships in 2008 and 2009 and document the frequency (how often) and severity (how close) of encounters, inside and outside the park.
How the observations were made
From May to September of both years the observer rode six different Holland America ships, spending two nights aboard, boarding in Skagway or Juneau the day before a ship's arrival in the park and leaving in Ketchikan or Sitka. The observer worked out boarding and leaving with agents from the cruise line, Cruise Line Agencies of Alaska and U.S. Customs and Border Protection. Ships from Juneau followed the same route to Sitka throughout, while ships from Skagway took different routes to Ketchikan: inside waters in 2008 and outside waters in 2009.
| Day | What happened |
|---|---|
| 1 | Aboard, the observer got a hand-held radio from the chief officer to warn the bridge if a whale strike looked imminent |
| 2 | From the bow, starting in Icy Strait as early as 4 am depending on light, the observer used laser range finder binoculars and ordinary binoculars to find whales, a hand-held GPS to log the ship's track and position, and a datasheet for each whale's distance and bearing, later entered in a database. Observations continued in Cross Sound or Chatham Strait depending on the route, but not north of Composite Island in the upper west arm, where whales are rarely seen |
| 3 | Arrival in Ketchikan or Sitka and a meeting with customs and cruise agents before disembarking |
Range finder binoculars and a hand-held GPS unit were used to record the distance and location of whales surfacing near ships (NPS photo).
An encounter closer than 100 yards (90 m) counted as close.
What they found
The 49 trips gave more than 300 hours of observation in all kinds of weather. Ships typically spent nine to ten hours in the park. More than 300 encounters were recorded, and most were at distances greater than 100 yards. The close encounters happened in Icy Strait near the park entrance and in the lower parts of Glacier Bay, which are hotspots of whale abundance. The authors call this a first step toward showing managers where measures can best be applied to protect the whales.
What comes next
Future analysis will look for factors behind close encounters, the whales' response times as ships approach, and where and when whales surface in front of a ship's bow. That should help show where in the park whales are most at risk, when in the season close encounters happen most, and what steps cruise operators and managers can take.
Sources
- Karin Harris and Scott Gende, Cruise Ship – Humpback Whale Encounters In and Around Glacier Bay National Park and Preserve, Alaska, Alaska Park Science, National Park Service; rewritten in hubnx's own words.