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FINAL Gray Whale Migration Update: May 17, 2000
Today's Report Includes:
- Latest Highlights from the Gray Whale Observation Posts
- Link to Susan Payne's Full Report
- This Week's Migration Data
- Why So Many Strandings?
- Orcas in the Arctic
- Where's the Ice?
- Fill in the Blanks! Answers for Challenge Questions #19, #20, and #21
- Year-End Evalution: Please Share Your Thoughts
- Have a Whale of a Summer!
Latest Highlights from the Gray Whale Observation Posts
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Gray whales are still plowing north, but in smaller numbers, reaching as far Kuskokwim Bay (59.67N, 162.33W). The American Cetacean Society census taken at Long Point (33.74.N, -118.39W) ended on May 15 with lower numbers than in 1999. The northbound total as of May 14 was 1039 gray whales, including 19 cow/calf pairs. Unless lots of cow/calf pairs swam past the census point on May 15, this count is down from the 34 cow/calf pairs in 1998/99 and the 174 cow/calves in 1997/98. Total northbound numbers will be lower than last year, when 1383 northbound grays were counted. Why are whale numbers down? Susan Payne offers some ideas later in this Update.
For more sighting stories from the migration trail, including orca sightings, where to see data from the spring migration on the Oregon Coast, and details about the autopsy of a stranded gray whale, see Susan's full report:
Why So Many Strandings?
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"I do not yet have the official numbers from the 1999 stranding report being compiled by the National Marine Mammal Laboratory, but from the news it appears that unusually high numbers of strandings happened in both years, and that some of these animals have been emaciated. This report from the Oregonian, and other reports point to food limitations in the Bering Sea. Environmental changes could be the cause. Another possibility is depletion of prey items by a large gray whale population.
Dr. Donald Schell is Director of the Institute of Marine Science at the University of Alaska, Fairbanks. Dr. Schell did a recent study that indicates environmental changes in the Bering Sea ecosystem have taken place. Dr. Schell spoke at Whale Fest Kodiak about his work. His topic was "Using Bowhead whales as indicators of environmental change in the Bering Sea" .
Dr. Schell looks at the atomic composition along the length of the bowhead whale's baleen. He compares the ratio of Carbon 13 to the more abundant Carbon 12 isotope. The isotope ratios measure what's accumulated in the keratin being deposited on the baleen, assimilated in the bowhead's food--primarily euphausiids and large calanoid copepods. Not only can Dr. Schell tell the whale's age with this technique, but also how productive the ocean has been over the whale's lifetime. From 1947 to 1997, Dr. Schell sees in these baleen readings that ocean productivity in the Bering Sea (the bowheads' winter feeding grounds) has fallen to its lowest point in 50 years. The latest samples, from 1994 through 1997, suggest that ocean productivity has decreased 35 to 40 percent since its peak around 1965. Dr Schell explained that "a 40 percent decline in the primary production of the ecosystem is going to have profound effects on the top consumers."
An adequate food supply in the Bering and Chukchi Seas is important to the gray whale because it is widely believed that most whales do not appear to eat significant amounts of food during either their southbound or northbound migrations. It has been estimated that the whales gain 16-30% of their body weight while on their northern feeding grounds, and this reserve must sustain them during both legs of their migration. In the three years that I have contributed to Journey North reports, we have consistently had reports of feeding whales along the migration route. These feeding whales included both migrating whales and seasonal residents. For the first time in peoples' memories here in Kodiak, more gray whales are staying year round in the Narrow Cape area. We will have to see if this use continues in the future, but it may be another sign that the Bering Sea is no longer an optimum feeding area, and the gray whale must find food resources in other places.
What do you think this would mean for the migration? For the whale population? Time will tell.
Orcas in the Arctic
Journey North received a letter this week from Larry Dickerson in the Arctic. Pull out a map and see if you can locate Larry's site from the description he wrote. Here's what Larry told us about his work and gray whale sightings in the far north:
Dear Journey North,
I am a marine wildlife biologist for the US Fish and Wildlife Service's Marine Mammals Management. I am temporarily stationed on St. Lawrence Island in the Siberian Yupik village of Gambell, AK (63.78 N,-171.70W). I am here until June 15th, conducting polar bear and walrus tissue sampling and hunter kill information, but I'm sending you a few comments about gray whales this year.
We received our first report of gray whales on May 2nd from Savoonga bowhead whale hunters who were encamped on the South Side of St. Lawrence. Spotting gray whales is a general signal to these Siberian Yupik hunters that the bowhead whaling season is almost over. I spotted three gray whales on May 4th from the beaches of Gambell, which is located on the NW tip of the island. The whale hunters from Gambell did not strike a bowhead this year and have now given up and turned their efforts towards walrus. Here in Gambell, the sighting of gray whales also signals that the end of whaling season is near.
Two years ago, a pod of 5 killer whales killed a gray whale calf, just yards from the Gambell beaches, where it was witnessed by many of the villagers and myself. The entire act took about 20 minutes. Also, many hunters from here have told me they often find small whales or gray whale calves washed upon the beaches of the island. The villagers say that when the dead whales have their tongues missing, it is a sure sign of killer whale depredation, as orcas prefer the tongue and often only remove this from the unfortunate victim.
Larry Dickerson
No wonder the network of observers along the migration trail includes orca sightings in their reports to Susan
Payne.
Where's the Ice?
Even if some of the news seems grim, we can still celebrate the numbers of whales that are still plowing north, or happily feeding in the icy seas. You might want to see for yourself how far the whales can go this week in their Arctic feeding grounds. See:
Fill in the Blanks!
Answer for Challenge Question #19
"It is uncommon to see such a large group of transient orcas unless they have been feeding on a gray whale."
Answer for Challenge Question #20
"Of the 1011 Northbound gray whales counted by the ACS Census, the percentage of cow/calf pairs is 1.58%."
Answer for Challenge Question #21
"More than 500 northbound whales were sighted on these two April dates: 18 and 26."
A Whale-sized Thanks!
Migration data and observations in our gray whale reports are contributed by Susan Payne's network of wonderful
observers and organizations. Meet them all:
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Journey North |
Have a Whale of a Summer!
This is the FINAL Gray Whale Migration Update for Spring 2000. The gray whales' journey has been an exciting story.
We celebrate that one big obstacle they faced this year, the proposed saltworks factory in San Ignacio, is no longer
a threat. We're happy to hear from researchers like Sheyna Wisdom, who shared what she's learning about gray whale
sounds and habits. Next year will bring different whale numbers, more research, and new tales about the whales
people love to watch. Have a wonderful summer as you keep an ear out for news of gray whales. We hope you'll be
back with us for the gray whales' journey in 2001!
Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form
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