Monterey Bay Whale Watch - December 2000 Feature


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Gray Whales Headed South
By Nancy Black

As winter approaches, we look forward to the annual migration of the Gray Whale. These whales are now a success story, having recovered from near extinction. They are the first marine mammal ever to be removed from the endangered species list.

Click for larger Gray Whale photo As of early December, most of the Gray Whales have left their summer feeding grounds and are now making their way down the west coast to their breeding and calving areas off Baja California. Off Monterey, we have already spotted a few early migrators. Their numbers will increase through December and January on the southbound migration. Then during mid-February, with some whales still headed south, the first northbounders will be passing by. Their numbers will increase through March. Since the population of Gray Whales is now more than 26,000, we expect to see Grays passing our coast each day from mid-December through April and into May.

Although the Gray Whale has recovered, they are still being monitored. For many years the National Marine Mammal Lab (part of NOAA) has monitored the Gray Whales by operating a count station just a few miles south of Monterey. The whales migrate within a few miles of shore near Monterey so they can easily be counted, and then an accurate population estimate can be derived. In addition, another crew from the National Marine Fisheries Service counts the number of mother/calf pairs as they migrate north in spring. This is an excellent indicator of how the population is fairing.

Some interesting findings have occurred over last few years. Last year was the lowest mother/calf pair count since the surveys were begun over five years ago. Wayne Perryman, a scientist with NMFS, has attributed the low number of calves over the last two years to poor feeding seasons for the Gray Whales during summer in the Bering Sea. Longer periods of ice covering the whales' feeding areas, due to colder ocean temperatures associated with La Nina (the cold water period after an El Nino), have prevented females from feeding throughout the season and building up enough reserves to successfully support their calves, resulting in a lower reproductive rate. Other things may be a factor, such as an overall decline in the productivity of the Bering Sea, which could affect the amphipods the Gray Whales feed on. Normally these little animals that bury in the mud are extremely abundant, but the changing ecology of the Bering Sea with lower production may result in less food for the whales.

In addition, the population may have reached carrying capacity, and there may not be enough feeding areas to support such a large number of whales, which would naturally result in lowering the population. There is some indication that this is taking place; over the last two years, a number of Gray Whales have washed up along the beaches on the northern migration, possibly a result of not feeding well enough the previous summer. The Gray Whales feed during the summer and for the most part spend the migration period and wintering period fasting while living off the blubber layer they gained from summer.

Something we are following closely is the predator/prey relationship between the increasing Gray Whale population and their predator, the Killer Whale. We have been studying the Killer Whales in Monterey Bay for close to 15 years, and now focus our research most intensively during the spring when the Gray Whales migrate north with their calves. At this time, Killer Whales are often hunting for them in Monterey Bay. We will continue to work with the National Geographic Society for a third year on this research, which will also result in a feature film. We have found a correlation between the number of calves for a season and the number of Killer Whale attacks on Gray Whales. Last year, the lowest calf year, we saw no predation events. This predator/prey relation is an amazing event of nature that has been occurring for thousands of years. Just over the last ten years, we've begun to learn more about how the Killer Whales work as a coordinated group to overcome these larger whales and teach the Killer Whale calves to hunt.

During 1997, the BBC Natural History Unit in England accompanied us during our research and for the first time filmed this incredible event. This will be part of a television series entitled the Blue Planet (similar to Trials of Life), scheduled for broadcast in the U.K. in January 2001 and in the U.S. in fall 2001.

Click for larger Gray Whale photo Our Gray Whale trips will begin December 15 and continue daily until April 30 (except for Christmas and Easter). Although we can celebrate the recovery of the Gray Whale, as we are rewarded while watching the many pods migrate past our coast, we must continue to protect their habitats and monitor their population in years to come. We hope our endangered population of Humpback and Blue Whales, which feed in Monterey Bay during the summer and fall, will enjoy a similar recovery.


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U R Here Features -- December 2000

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Monterey Bay Whale Watch, LLC
84 Fisherman's Wharf
Monterey, CA 93940
Phone 831-375-4658  

Copyright © 2000 Monterey Bay Whale Watch. All rights reserved.
Photos by Grace Atkins and Nancy Black.

Last updated December 5, 2000