Killer whales occur worldwide from the polar regions to the
tropics; they are the ocean’s top predator and the most intelligent
of all cetaceans. They are social, charismatic animals that live in family groups based on a matriarchal system, with adult females and their offspring enjoying the closest associations. Males may stay with their mothers for life. Their vocal repertoire is complex,
comprising echolocation pulses and communication calls with distinct dialects among different groups or populations. As a predator at the top of the marine food chain, killer whales consume a range of prey -- from small fishes to the enormous blue whale. Three known eco-types occur along the West Coast: residents, offshores (both of which eat fishes), and transients (which prey on marine mammals).
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| Killer whale holding down a gray whale. photo Nancy Black |
With such a high diversity of marine mammals inhabiting Monterey Bay, it’s not surprising that transient killer whales
frequent this area year-round. Over the past seventeen years, we have identified more than 150 different transient whales, based
on distinct markings, and have documented association patterns,
calving rates, behavior, and long-range movements. Some of
this information was gained through opportunistic photographs from our whale-watching vessels. Our team (which also includes Richard Ternullo, Alisa Schulman, Peggy Stap, and Sarah Graham) has also collected small biopsy samples (skin and blubber) from our dedicated research inflatable under permits in conjunction
with the National Marine Mammal Laboratory/National Marine Fisheries Service (NMFS). These samples have provided valuable data on genetics and organic pollutants.
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This yearly phenomenon of killer whales pursuing gray whales corresponds to the salmon-fishing season, often when there are hundreds of boaters out in the bay. While this is an exciting and once-in-a-lifetime event to witness, boaters must observe from a reasonable distance and not interfere with the whales. (While such an event may be
difficult for many to watch, it is not our place to intervene -- and, in fact, it is illegal to cause a change in behavior
of whales by our presence.)
All marine mammals are protected by the federal Marine Mammal Protection Act, and most large whales in the area are further protected under the federal Endangered Species Act. Under these acts, it is illegal to "harass, hunt, capture, or kill" any marine mammal. Prohibited conduct includes any "negligent or intentional act that results in the disturbing or molesting of marine mammals." Here are some basic guidelines for observing marine mammals:
- Do not approach a marine mammal closely enough to cause a change in behavior, such as causing resting sea otters to dive; seals or sea lions to enter the water from their haul-out area; or whales or dolphins to exhibit
evasive actions, quick dives, or abruptly stop the
behavior they are currently engaged in.
- Always approach whales slowly ("see a blow, take it slow"), without blocking their path of travel or boxing them in.
- Parallel their course and speed without drastic changes in engine speed, and do not approach head-on.
- If whales approach your boat, put engines in neutral and wait until they leave.
- Exit slowly from any areas where whales are present.
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Although killer whale occurrence is unpredictable, and the whales are seen between two and eight times per month, they are frequently seen in Monterey Bay during the spring, corresponding to the migration of mother gray whales and their calves. Gray whales undergo their yearly migration from feeding grounds in.
the Bering Sea to breeding areas along the west coast of Baja California. The migration is segregated by age and reproductive
status. Gray whales with recently born calves spend the most time in the lagoons and are the last whales to head back up to Alaska; these individuals pass through Monterey Bay during April and
May. The mothers and calves hug the coast closely as they travel north.
When the whales reach Monterey Bay, they generally cross the bay and the deep submarine canyon, where their migration path crosses the deep-water habitat of the killer whales. The killer whales patrol the canyon edges in search of the gray whale calves. When a gray whale calf is located, one of the most dramatic
predation events on earth occurs: several five-ton killer whales battling a forty-five-ton gray whale mother and her ten-ton calf for up to six hours. If successful, the killer whales gain a rich source of food for more than twenty whales.
Although this is a yearly event, the spring of 2004 was unprecedented as far as the frequency of killer whale sightings and the number of attacks and feeding events
on gray whales. After several years with relatively low
numbers of gray whale calves and a significant decrease in the
gray whale population, the number of calves born in 2004 was the highest since counts began ten years ago by the NMFS. Wayne Perryman, who heads these counts, believes that more calves
survive through full term and are successfully nursed during years when whales have an abundant and predictable food source in
the Bering Sea -- a situation that occurred during the summer of 2003. Last spring many calves passed through the bay each day, with a peak of around forty mother-calf pairs per day -- compared to less than ten in previous years.
From April through mid-May, we documented sixty-five different killer whales involved in at least sixteen attacks on gray whale calves (including four escapes), compared to just a few attacks
over the past six years. The usual group size for transient killer whales averages three to eight whales, but during the spring season, several of these core or family groups gathered together in a
coordinated effort to hunt the gray whales and share the food.
Reproductively active females were most involved in the attacks. At least thirteen different core groups were found over this period, and four groups were present nearly 50 percent of the days, while some groups occurred just once or twice. It was surprising that some groups were involved so frequently, and we wondered if
they were binge-feeding by taking advantage of this huge food source over a short period of time.
Another function of pursuing gray whales is for adult female killer whales to teach their young how to hunt. A great deal of learning, cooperation, and communication is required to take down such a large animal.
We hope to continue monitoring the killer whales over many more years. As a keystone species, these whales act as health
indicators for the marine environment.
Nancy Black
Monterey Bay Cetacean Project
Humpback whales inhabit all of the world’s oceans. Like most
of the great whales, they undertake seasonal migrations between "high-latitude" summer feeding grounds and "low-latitude" winter mating and calving grounds. In the warm-water but unproductive wintering areas, they forego feeding and concentrate on finding mates, conceiving, and then giving birth the following winter.
This ability to store enough food reserves to allow the animals to fast for months, while traveling thousands of miles, is a remarkable adaptation that has apparently served them well through the inevitable natural variation in food and climate over tens of thousands of years. However, for scientists trying to understand, manage, and protect humpbacks, the
animals’ ability to use an entire ocean basin as their home seems an insurmountable obstacle. How does one apply
an ecosystem approach to protecting such a species?
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| The SPLASH Project is an unprecedented effort to coordinate research on humpback whales throughout the North Pacific Ocean. photo Ed Lyman/HIHWNMS/Fisheries Permit #782-1438 |
To address this challenge, the SPLASH (Structure
of Populations, Levels of Abundance, and Status of Humpbacks) Project was conceived. In order to gather systematic data from humpback whales in all of their known summer and wintering areas, within one of their largest ocean habitats, the SPLASH Project has formed a collaboration among virtually all of the humpback whale research teams working in the North Pacific Ocean. As
a result, approximately 130 researchers are gathering
data from the winter of 2004 through the winter of 2006, making the project the largest (in geography and participation) whale study ever attempted. The Hawaiian Islands Humpback Whale National Marine Sanctuary is at the center of much of the work in the winter, while most
sampling along the U.S. West Coast is focusing on the national marine sanctuaries there, including the Monterey Bay National Marine Sanctuary.
But even with this unprecedented geographic scope, one might wonder how a project that focuses on just one species will gain insight into that animal’s role in the ecosystem. Because most of the SPLASH teams will be working directly with individual whales from small vessels, the environmental data that can be collected
is limited. However, through images and tissue samples, some of the data collected from individual whales will tell us about the environments they inhabit.
The project’s basic methodology is to collect images and tissue samples from individual whales throughout the North Pacific Ocean. The black and white pattern on the underside of an animal’s tail flukes is, like a fingerprint, unique to each individual and allows it to be identified -- which can help researchers understand population structure, abundance, and movements. Moreover, images of each animal’s flanks and "tailstocks" allow for an examination (through scarring) of obvious physical impacts, like entanglements, vessel collisions, and predators. This analysis will give us an indirect look at some of the dangers the whales face in their different environments.
Finally, the tissue samples collected, using biopsy darts shot from a crossbow, will allow a suite of analyses that will give tremendous insight into how this species uses its ocean basin
habitat. The molecular determination of sex and genetic relatedness will allow a more complete understanding of population structure within the North Pacific and give insights into the species’ responses to global changes over thousands of years. But on a more timely scale, new analyses of the small bits of skin and blubber collected will allow a look at prey preferences (through fatty acids and stable isotopes), toxins, and -- as these analyses are perfected -- hormone assays, stress, and age. All of this, when combined with what we do know of its physical environment, will allow a tremendous advance in our understanding of the humpback whale’s place in the ocean-basin ecosystem.
This project is supported in part by National Oceanic and Atmospheric Administration (NOAA) Fisheries, NOAA's National Marine Sanctuary Program, the National Park Service, the Marine Mammal Commission, the North American Commission for Environmental Cooperation, the Department of Fisheries and Oceans (Canada), the National Fish and Wildlife Foundation, and the World Wildlife Fund.
For more information, start at:
http://hawaiihumpbackwhale. noaa.gov/special_offerings/sp_off/ splash/splash.html.
David Mattila
Hawaiian Islands Humpback Whale National Marine Sanctuary
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