This paper was written as part of the 2002 Alaska Ocean Sciences Bowl high school competition. The conclusions in this report are solely those of the student authors.
Transient Orcas: A Dying Breed
As the muscular body catapults from the water, the crowd "oohs" and "aahs," straining against the rails to see the massive fluke slap against the waves. The stutter of camera clicks and flashes ceases, as the admirers wait anxiously for the next opportunity to record their great Alaskan adventure on film. As they continue their sightseeing, the tour guide informs the excited passengers about the killer whales, the mighty king of the seas. Each summer many vacationers migrate to Alaska to see the rugged scenery and magnificent wildlife. However, those occasional glimpses of the beautiful killer whale are becoming rarer and the question is "Why?"
Orcas (Orcinus orca) are the largest members of the family Dolphinidae, with males growing up to 27 ft (8.2 m) and females growing up to 23 ft (7 m) in length. Orcas are for a large part black, but have a white patch of above and behind the eyes, on the ventral side and a white or grey saddle behind the dorsal fin which is used to identify the individuals. There are two different types of orcas.1
The most common kind of orca, the resident orca, lives in pods of around 40 animals and travel in about the same area all of their lives. For this reason they are the easiest to study and more is known about them than either of the other two types of orcas. For the most part, residents eat salmon but will eat marine mammals if other food is not available.
Transient orcas live in very small pods of two to seven whales, and unlike resident pods, travel and hunt an area of up to 1,500 miles and have no known travel patterns which cause them to be very hard to study. Years can go by without seeing a particular orca. Transient orcas unlike residents prefer to eat marine mammals as opposed to fish.
Scientists believe that transients and residents are genetically as well as physically different. According to genetic studies, they have not breed for up to 100,000 years. This fact allows us to treat the transient whale as a separate species from the resident whales.
The transient orcas are affected by pollutants such as DDT's and PCB's. DDT's and PCB's mainly affect the males in the transient group, although they are transmitted through the females. The females transmit it to their off-spring through their milk. This belief may also be another reason why the males only live half as long as the females do.
The whales are getting these concentrated amounts of pollutants through the food chain. Since the whales are higher up in the food chain, they get higher concentrations of PCB's and DDT's. An example of how the PCB's get worse farther up the food chain is; a herring has about one part per million then the seals that eat the infected herring have about twenty parts per million, then the transient orcas that eat the infected seals have about 250 parts per million. This is bad news for the orcas in that they eat up to 200 pounds of food a day. PCB's stick in the whale's blubber stores and keep accumulating until these whales get killed by these pollutants or die of old age.
Most of the PCB's and the DDT's stay on the sea floor where fish and plankton pick it up and it works up the food chain until the pollutants get into the orcas.2
Another pollutant that has affected these whales is oil. When the Exxon Valdez hit ground in Prince William Sound some transient families lost up to half of their members. The Exxon Valdez Oil Spill impacted the environment greatly. Even after all the clean up efforts, a decade later, the ecosystem still suffers. To a tourist, Prince William Sound may appear to be normal and brimming with wildlife. However oil and toxins continue to contaminate the habitat of the marine species. The Office of Technology Assessment estimated that beach cleanup and oil skimming only recovered 3-4% of the Exxon Valdez spill. Transient orcas have been on a long-term downward population trend, and the Exxon Valdez oil spill only hurt by adding 14-22 killer whale deaths to the toll.
The diet of a transient killer whale mainly consists of marine mammals, whose populations have all been depressed at least since the Exxon Valdez oil spill. Pelagic marine ecosystems in the sub-Arctic have been changing during the past 30 years. The amount of fish, seabirds and marine mammals has shifted.3
One of the main staples of the orcas' diet is the Steller sea lion. Nesting in rookeries or cruising after Pollock schools, Steller sea lions have become infamous for their mysterious plummet in population. Their population has dropped 50-85%. The decline started in the 1960's, and since the 1970's documentation has increased. In 1989 it was estimated to be 116,000, only 39-48% of what it used to be 32 years before. In the central Gulf of Alaska the population has dropped 77% since 1976. In 1990, the Steller sea lion was placed on the Endangered Species Act list as threatened, and seven years later was changed to endangered.
However, with all the public concern the cause is still unknown. A popular hypothesis is the lack of food. Marine mammals' food in general has been limited. From the 70's to the 80's, 1-10 year old sea lions have become shorter, leaner, and lighter. Females birthing rates are 60-67% lower. In 1993, the Steller sea lion's main source of food, the herring, declined sharply in population. Now their new main diet, Pollock, has become more important to the fishing industry.
Anne York, of National Marine Mammal Laboratory, using Mathematica, computer program, for statistical analysis and population modeling, searched for the reason for the problem. After researching survival and reproductive rates, she concluded the lower survival rate of the immature sea lions had caused the population decline. The juvenile sea lions depend on smaller Pollock than the adults, and there are theories that these have become scarce near the surface where the immature sea lions can reach them. Anne York reported, "I was able to solve some fairly complex equations and pinpoint a decrease in juvenile survival as the likely reason for the population decline that steered the biologists I work with to further study the feeding and diving habits of young animals. From that we learned that young sea lions do not dive as deeply as adult animals. They dive at a maximum of about 50 meters as opposed to the over 200 meter depths that adult sea lions dive." The biologists still aren't positive if the diving ability of young sea lions has caused the drop. They've hypothesized that oceanic conditions have fluctuated and now their prey have migrated to deeper waters and is less attainable. Some suspect however that it's because they're competing with the largest U.S. based fishery for pollock.4
Over fishing has been a problem for the Steller sea lions. Herring were previously an important prey for the Steller sea lion, but due to their drop the Steller sea lions have had to change their diet. No trawl zones have finally been established to protect their rookeries, but maybe the restrictions came too late. Many are asking if fishing is causing the decline in the Steller sea lion population, should fishing be decreased. If the problem continues the Endangered Species Act could mandate it.
Harbor seals are the other main staple in the orcas' diet. However, the killer whales can no longer rely on them either. Their population declined by 40% in Prince William Sound between 1984 and 1988. The population was further impacted by the Exxon Valdez Oil Spill; more than 300 harbor seals died, and the population hasn't recovered.
The problem might be based on the alterations in harbor seal's body condition. Fluctuations in their prey abundance have directly impacted the seals by changing their foraging. According to research done by Marine Sciences and Limnology and the Institute of Marine Science, male harbor seals showed slight variation in body mass over the season, but their core and blubber changed by 10-15%. Female's changes were much larger, corresponding with the birth weight of seal pups. Seals from 1972 were around 28% blubber; where as in the 1990's studies showed that it had dropped 17%. Biologists are still trying to refine their research and find out if this affects the energy and temperature controlling abilities for the seals.5
Alaska's coastal waters used to hold about 90% of the world's sea otters; however, in less than ten years sea otters have declined by 94% in the Aleutian Islands. 3,500 to 5,500 died in the Exxon Valdez Oil Spill, but that's minor compare to the plummet from 100,000 to 6,000, in 1992. Scientists didn't know about it, at least not the magnitude of the drop in population. Researchers today believe that the increase in temperature in the last ten years, which has been the warmest in this millennium and the effects, may be connected to the plummet in population. Besides the temperature scientists also believe that the killer whales caused the drop when they were forced to include sea otters in their diet because of lack of food elsewhere.
Charter boats and sightseeing play roles in the problem of pollution. Sightseeing is probably the larger of the two. Constantly whales are being pursued, even when they are swimming away from the boat. This is not only in sightseeing boats, there are numerous amounts of sport fishing vessels that will pursue whales while on there way out or back from the fishing grounds.
These guidelines set by NOAA (National Oceanic Atmospheric Administration) are supposed to help protect the whales and dolphins, but are being broken. A few of these guidelines are: Boats are to remain at least 100 yards away from any whale or dolphin unless it makes an advance towards the boat. Pursuit of whales and dolphins is prohibited by law.6
Factory trawlers fall under the category of fishing. Factory trawlers can range anywhere from 165 to 360 feet. They use enormous nets to catch their fish, some as long as four hundred yards. At each end of these nets is what they call a cod-end, these ends can hold anywhere from 5-150 tons of fish.
The reason they are called factory trawlers is they have large factories underneath the ships deck. This allows them to process and freeze as well as store the fish. The overall capacity for storing the processed fish, depends on the size of the vessel, but normally they hold anywhere from 300-1300 tons.7
Factory trawlers main source of fish is the pollock, and the pollock is the main diet of the Steller sea lion in the winter. Now all of this wouldn't have to do with transients, except that now transients are moving towards sea lions for their food supply.
The trawlers are a fleet of anywhere from 45-65 vessels. However, for there lack of ships they make up a large portion of the pollock industry. They make up for about 1/5 of the pollock caught in the recent years. The trawlers season has been shortened from year round to only 55 days a year. This has caused them to use very destructive fishing habits. Some 36,000 vessels account for the rest of the catch. Aleutian Island pollock (age 3+ biomass) has been at a steady decline since the 1980's. It appears to be at 20% of its earlier abundance.
The eastern Bering Sea pollock has declined by more than half of its population since the mid-1980's and by 40% from 1994-1997.
The Bering Sea pollock is the most abundant ground fish in that area. They account for more than 50-70% of the entire ground fish biomass. They are a primary prey for marine mammals in that area. The declines of major pollock predators, such as the Steller sea lion, in heavily fished areas of the Bering Sea, Aleutian Islands and Gulf of Alaska, suggests that large changes in the ecosystem have occurred since the advent of factory trawlers and industrial-scale fishing.8
One factor that may be affecting the decline of the transient orca is environmental changes, such as global warming. One way we think the warming of the oceans could effect the orcas is that the fish which the seals, and sea lions that the orcas eat would swim deeper to stay at the same water temperature. Therefore the sea lions and seals must swim deeper and use more energy to get the same amount of food. That would mean that the orcas would get less energy from each animal they eat. For that reason orcas might not produce as many offspring because of the lack of energy in there food. Also warmer temperatures might raise their metabolism rate and cause them to need more energy. On the other hand though because of the warmer water the orcas might not need as much fat to stay warm and therefore not need as much or as rich of food.
The area Transient orca whales are affected by pollutants such as DDT's and PCB's. These pollutants stay in the whale's fat or blubber stores and take longer to break down. DDT's and PCB's mainly affect the males in the transient group, although they are transmitted through the females. The females transmit it to their off-spring through their milk. This belief is may also be another reason why the males only live half as long as the females do.
Another pollutant that has affected these whales is oil. When the Exxon Valdez hit ground in Prince William Sound some transient families lost up to half of their members. The diet of a transient killer whale mainly consists of marine mammals, whose population has been depressed since the Exxon Valdez oil spill and before. Pelagic marine ecosystems in the sub-Arctic have been changing during the past 30 years, which has been indicated by declining or shifting abundances of fish, seabirds and marine mammals. Some of these changes have been alarming, as well as well publicized. To the naked eye, Prince William Sound may appear "normal." However, looking just beneath the surface, oil continues to contaminate beaches, national parks, and designated wilderness. The Office of Technology Assessment estimated that beach cleanup and oil skimming only recovered 3-4% of the Exxon Valdez spill.
A decade later, the ecosystem still suffers. Substantial contamination of mussel beds persists contributing to the decline of marine mammals.
Transients often cruise close to shorelines, looking for unwary harbor seals and sea otters. Both species have been in a long-term population decline. In Alaska, more marine mammals and birds died than in any other oil spill, including estimated 14-22 killer whales.
Killer whales and sharks are the main predators of the food chain. Killer whale populations do not seem to have increased. Pollock have become more important relative to herring and other fish. Juvenile sea lions may rely on smaller pollock than do adults. Most deaths apparently occur when the sea lions are at sea and unobserved. Sea lions tend to bioaccumulate toxins. However, there is no evidence of toxic and pollutant levels in affected areas (except Prince William Sound).
Some seals and sea lions are killed by entanglement in fishing gear and other jetsam, but probably not enough to account for the declines.
Human activities (mainly fisheries) and/or natural environmental change may have caused a change in food supply.
For example, herring have declined severely in the Bering Sea, which may be due at least in part to over fishing. Herring formerly were an important prey item.
Current fishing activities (trawling) may reduce prey availability. "No-trawl-zones" have been established near some rookeries.
If fishing is impacting the Steller sea lion, should fishing be curtailed? This could be mandated by the provisions of the Endangered Species Act.
Steller sea lion populations have decline sharply, probably beginning in the 1960s. These declines have been well-documented since the mid-1970s.
To reduce the severity of the problem and keep orcas off the endangered species list, we must look to the international community for assistance. To solve our local crisis, we propose these solutions-
One way to stop pollution from Asia is to let China into the World Trade Organization (WTO) return they will stop producing DDT's & PCB's in their country. If they start to produce PCB's and DDT's again, their place in the WTO will become void, and we not be allowed back on until production has ceased. Another way to help the Eastern Asian countries is to give them grants to help them pay for their research to help control their use of DDTs and PCBs and hopefully get rid of them all together.
Ways to stop trawlers from causing so much damage to our ecosystem is to: Lengthen the season but not the quota amounts. In theory, if we lengthen the season hopefully if would cause the fishermen to have safer fishing habits. Also if we made the fishing limits larger than they are right now, maybe it would help to pollock population rise, as well as the sea lion population. If we also made the fines for the trawlers more extreme, in theory it would also increase there safer fishing habits and make them more cautious of their fish weight.
If the world cleans up its factories, power plants, transportation emissions global warming might slow down. There is no way to stop global warming, it is a natural process, all we can do it slow it down. So if we produce cleaner burning cars, convert mechanical machines to either water or possibly a cleaner fossil fuel such as natural gas and propane, it will slow that natural occurring process.
If we applied for a grant through governments, corporations, and international organizations, the money could possibly help in the research and aid of the orcas. Craig Matkin, a local scientist, whose studies are focused on orcas, is constantly asking for help and aid, including donations. Getting grants or donations from individual corporations is also a possibility.9 There is so much research being done in the world, and so many people need funding, just like so many projects, not many people give money to the studies of sciences.
There is currently in state legislature, a proposal for a state income tax. For this reason, we feel that if this bill is passed, .05% of this tax be designated to the research and restoration of Alaskan killer whales.
What we have concluded from our research and investigations is that transient orcas differ from resident orcas both genetically and physically and that they have very different habitat and food needs. To accommodate these needs and differences we suggest that transient orcas be listed and classified as a separate species. Because of the difficulty of counting and studying these animals, it is hard to tell what their health conditions and population numbers are. Therefore, we suggest taking the precaution of placing them on the endangered species list and putting more efforts and funding into studying and protecting transient orcas.