Whales: Even Giants Aren't Safe

By Luisanna Carrillo-Rubio
April 2008

Figure 1: A Humpback Whale. Source

It is believed that we know more about the surface of the moon than about the depths of the oceans that cover 71% of our planet and contain between 300 and 500 million species of organisms. The importance of the oceans is not simply due to the enormous area of the Earth's surface they cover as well as the biodiversity they support, but also to their impacts on weather. With the warming of the oceans, the survival of all forms of life they contain — from phytoplankton or the tiny shrimp-like krill to the blue whale, the largest animal that has ever existed on earth (some weighing nearly 200 tons, twice the size of the largest dinosaur) — is being seriously threatened.

Even though whales are the largest mammals on the planet, they cannot escape another threat lurking in the shadows: anthropogenic climate change. In addition to climate change altering the ocean's ecology and coastal lands in ways that affect many whale species, whaling has also taken a toll among many whale populations. Even though commercial whaling has been banned since 1986 by the International Whaling Commission (http://www.iwcoffice.org/commission/iwcmain.htm), there is still some hunting of certain whale species. The oceans' ecosystem, though its vastness may make it appear inalterable, consists of a delicate balance that can be affected by small fluctuating surface temperatures.

The whale species that spend most of their lives in the Southern Ocean around Antarctica-for example, the right whales-are currently demonstrating what effects small increases in the ocean's surface temperature can unleash amongst all of the smallest organisms that feed the entire ecosystem. National Geographic News reported in 2006 the conclusions of scientists who investigated the correlation between rising global temperatures and the survival rate of right whale calves between 1983 and 2000.

Figure 2: A Right Whale. Source

In this study, scientists compared the sea's surface temperature in the southwest Atlantic to the index of surviving calves born off the coast of Argentina. According to Professor Charles H. Greene from Cornell University's Department of Earth and Atmospheric Science, "the authors [of the research] provide compelling evidence that South Atlantic right whale calving rates are correlated with climate variability" meaning that "as the water temperatures rise from the norm, calf output declines."

The reason for this correlation between the decline of calves' survival among right whales and increasing surface oceanic temperatures is most likely due to krill decline-a tiny shrimp-like marine animal or crustacean dependent on sea ice for its survival. Krill is a main element in the diet of many marine species including gentoo penguins, Antarctic fur seals, and right whales.

Figure 3: Photo of a krill, an essential part of many marine species' diets. Source

During years of increased sea surface temperatures, krill population has experienced a dramatic decline, with dire consequences on the pup survival rate for fur seals. Another whale that depends almost solely on enormous amounts of krill (up to 4 million a day) is the largest of the cetacean order, the blue whale, and whose numbers are, not surprisingly, also dwindling. This magnificent giant once had a healthy population of 300, 000 individuals. Today, less than 3 percent of that number remains in our vast oceans (according to the BBC documentary Planet Earth segment, Ocean Deep).

Figure 4: A blue whale with calf. Source

In another study released in March 2006, scientists reported the impacts of the recent years' ice loss in the Bering Sea (the sea between Siberia and Alaska) on whales and other wildlife species of the ecosystem. The Bering Sea is one of the world's most prolific feeding grounds for many species of sea birds, walruses and whales. The northern part used to be covered by a solid ice layer for seven months out of the year, but has been experiencing temperature increases and a weakening of the cold north winds in recent years. Nowadays, there is less amount of ice in general and, "the seasonal melt is starting earlier in the spring."

Marine Ecology expert Dr. Jacqueline Grebmeier has been tracking the impacts of climate change in the north of the Bering Sea since the 1980s. She explains that the "earlier ice melt and warming water is interfering with the life of the phytoplankton;" the ocean's starting link in its food chain and as a result, there are fewer worms, krill, shrimp, amphipods and clams on the seafloor. This reduction will affect adversely all the marine wildlife that feed on such seafloor dwelling creatures.

The changes in ice coverage and sea temperatures have serious impacts on the creatures that inhabit the ocean, as they have to migrate to different areas in search of food. For instance, as a result from this ice shrinkage, the gray whales that inhabit the Bering Sea are starting to move further north to stay in the colder waters in which they find their food. Some fish species, such as pink salmon and pollock, have also started to move northward to remain in cooler waters, when previously, remained predominantly further south of the Bering Sea (in the southeastern part). Some marine species which "feast on the sea's bottom-dwellers," such as walruses and bearded seals, "are struggling with a reduced food source, " according to the National Geographic News published report entitled, "Climate Change Harming Bering Sea Mammals, Birds, Study Shows."

In short, Dr. Grebmeier warns that "the region is shifting from an Arctic ecosystem to one that looks more like the subarctic". Large pods of grey whales are known to make the longest journey of any other marine mammal, as they travel from Baja California in Mexico to the north of the Bering Sea in the fall. Whales are now heading further north, into the Chukchi Sea (above the Arctic Circle) in search of cooler waters to find amphipods, a shrimp-like crustacean, present at the bottom of very cold ocean waters.

Because of the warmer temperature, some whale species are more comfortable in the north, traveling only as far south as Kodiak, Alaska, rather than completing their full migration. As a result, they are moving into the territory of the bowhead whale, which is a quieter, less aggressive whale that also feeds on a crustacean, krill. Dr. Grebmeier expresses her concern over possible "space competition," especially if we take into account the fact that the nearly extinct North Pacific right whale, also swims to the north Bering Sea area to feed. This is more serious than it may appear, if we consider that there are as few as two dozen individuals of the North Pacific right whale remaining in the world, according to Dr. John Hildebrand, a professor at the University of California, San Diego, and Scripps Institution of Oceanography. "We need to make every effort possible to give them [the North Pacific right whale] a chance to survive," Dr. Hildebrand concluded. According to their endangered species profile, the future of the North Pacific right whales is a bleak one, if at all a possibility.

Figure 6: A North Pacific grey whale. Source

Along with the Bering Sea, the Pacific Ocean has also experienced a tremendous decline in its population of eastern gray whales, which at present is at 22,000 individuals. An article published by Stefan Lovgren, from the National Geographic on September 10th, 2007, pointed out that the Pacific whale population actually previously ranged between 76,000 to 118,000 individuals.

According to the report, "recent studies have shown that changing climate conditions in the Bering Sea and nearby areas have reduced prey populations for gray whales." The report further indicates that the estimate of "typical gray whale abundance suggests that recent problems in gray whale feeding-including reports of thin adults or high calf mortality-may result from changing conditions in northern feeding grounds." A dramatic drop in the numbers of gray whales "may be having a profound impact on the ocean's ecosystem," the report warns, since grey whales feed themselves in a very unique way. They "scoop up these gigantic mouthfuls of mud from the sea bottom," and by doing this, they stir up and bring a substantial amount of sea bottom sediment to the ocean surface. This manner of feeding is of great significance to the marine ecosystem, and when populations are in healthy numbers, they can help rake up to the surface enough food to nourish up to a million sea fowl, and countless other sea-dwelling species. A dramatic drop in the populations of gray whales would therefore impair the entire marine ecosystem further.

The World Wildlife Fund (WWF) and the Whale and Dolphin Conservation Society (WDCS) jointly issued a report concluding that "whales, dolphins and porpoises (cetaceans) are facing increasing threats from climate change." These animals "have some capacity to adapt to their changing environment," according to Mark Simmonds, the International Director of the WDCS. However, he points out that "the climate is now changing at such a fast pace that it is unclear to what extent whales and dolphins will be able to adjust and we believe many populations are very vulnerable to predicted changes." If the largest animals on earth are to survive, then the largest reduction possible in the emission of greenhouse gases has to occur soon. If not, whales, as well as so many other members of the marine ecosystem, will inevitably disappear, posing a threat to the lives of countless other marine species which are also a part of this balanced food chain. "Our planet is still full of wonders. As we explore them we gain not only understading, but power. It's not just the future of the whale that today lies on our hands. It's the survival of the natural world in all parts of the living planet. We can now destroy, or we can cherish. The choice is ours," wisely concludes the narrator of the BBC's Planet Earth series segment on the Deep Ocean.

Additional Information

For additional information on endangered or threatened species, you may visit the World Conservation Union's website

For information and footage on the planet's oceans and its wildlife, the Blue Planet BBC series offers spectacular insights

To understand the sea level rise phenomenon

To take action to protect whales

To take action to protect whales and marine wildlife, you may take action through the World Wildlife Fund activist webpage

For more information about the endangered status of the North Pacific right whale

For further information on whales and climate change: