Threats to Whales
Humankind’s activities have severe consequences for the many species that live in the oceans. Climate change, the destruction of the ozone layer, pollution from toxic wastes and over-fishing all play their role in destroying the whales’ home.
The topics covered in this section are just a glimpse of some of the threats facing whales today. The overall effects these threats have on whales are a sign of the total effects they have on all life on Earth.
Whales and Ozone Depletion
In 1985, British scientists discovered that the Earth’s protective ozone layer had developed a large hole. They soon realised the hole was being caused by man-made chemicals: chlorofluorocarbons, otherwise known as CFCs. CFCs are now banned from use in many industries. But so much has already been produced, and released into the atmosphere, that they will continue to damage the ozone layer for many more years to come.
The ozone’s hole has caused increased levels of Ultraviolet B (UV-B) radiation to reach the earths surface. Increased UV-B is believed to have bad effects on all ecosystems.
Organisms at the bottom of the food web are most affected by UV-B. In the southern oceans of Antarctica, the ozone hole led to a 6-12% decrease of marine phytoplankton. Phytoplankton is the basis of the marine food web. This in turn would lead to a reduction in the food available to other species, higher in the food web, such as marine mammals. Baleen whales, which feed directly on plankton, may experience a considerably reduced food supply.
UV-B radiation will not only affect whales’ food supply. Whales themselves are already beginning to feel the direct impacts of decreased ozone. Southern Right whales, which migrate to Peninsula Valdes (South America) each year, spend a lot of time resting on the surface. Pox-like markings have been recently appearing on the backs of these animals. These are being attributed to increased UV-B radiation.
Whales and Climate Change/Global Warming
Global warming, or climate change, results from a build up of greenhouse gases in the Earth’s atmosphere. More heat is trapped close to the earth, much like an ever-thickening blanket.
Greenhouse gases are: carbon dioxide (CO2); methane (CH4); nitrous oxide (N2O); and hydrocarbons such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). These gases are largely produced from the burning of fossil fuels, such as coal, oil and gas.
Global warming radically and rapidly changes the Earth’s climate. This will have severe implications for the entire planet. The marine phytoplankton (microscopic plants), which are prevalent in the Southern Oceans, play a pivotal role in the climate change scenario. They naturally break down carbon dioxide through photosynthesis. If the numbers of phtyoplankton are reduced because of global warming, the remainder cannot use up the excess CO2. The warming process will then speed up and Earth will literally cook itself.
Clearly, weather patterns, water temperature, currents, and nutrient cycles in the oceans will all be influenced by climate change. The results of climate change on the marine food web will impact every level through a series of knock on effects. If one species is affected, they, in turn, will effect other species.
Whales and Organochlorine Pollution
Today there are so many human-made pollutants entering the world’s oceans that there are no longer any areas which can be classified as “untouched.”
Some of the most deadly and widespread of these pollutants are human-made chemicals containing carbon and chlorine, called organochlorines. They include: PCBs (Polychlorinated biphenyls), DDT, PCPs (Polychlorinated phenyls), atrazine, simazine, dieldrin and dioxins.Such chemicals are used as pesticides and herbicides, in the dry cleaning industry, in tanneries, and in electrical equipment.
Organochlorines have been found all over the planet, from organisms living under 11,000 feet of water, to the snow and ice of the Arctic and Antarctic, to the islands of the Pacific.
The threat from these chemicals affects all forms of life on Earth. Organochlorines are lipophilic. They accumulate in fats and oil rather than air or water. Therefore, they tend to build up in the fatty tissues of marine organisms such as whales. Usual biological processes do not break them down. Because of this, they are very persistent in the environment and will bio-accumulate up the food chain (increasing in concentration with each level). In the oceans, organochlorines reach their highest levels in the top predators, which are marine mammals, sharks and human beings. We endanger our lives and the lives of our children by eating the fish we have indirectly poisoned.
Organochlorines in whales have the potential to disrupt a variety of biochemical and physiological processes. Organochlorines concentrate in whales’ large blubber reserves. At times, when they are migrating, whales will not feed and so will live off these reserves. If the reserves are contaminated with pollutants it may cause the animal to become ill. In addition to this, organochlorines are transferred from mother to calf during lactation, or nursing.
Body burdens of organochlorine pollution are higher in the toothed whales than the baleen whales cause they feed higher up the food chain. In addition to this species that inhabit coastal waters have higher levels than those that live in the open ocean.
Beluga whales, in the St Lawrence river, have toxin levels so high that when dead Belugas are found washed up, they are classified by world health standards as toxic waste and must be incinerated rather than buried. Organochlorines severely inhibit the reproductive processes of whales and can lead to infertility, birth defects, tumors and lesions, tooth decay, adrenal gland cysts, a high percentage of malignant growths, and carcinogens.
Whales can become entangled in various fishing gear designed to catch crabs and lobsters and once entangled can drag the lines, ropes, traps and floats for months, slowing the whale down reducing it’s potential to dive, feed, and migrate effectively. The ropes typically cut into the whales flesh and cause serious wounds, sometimes removing entire tail flukes or pectoral fins. These eventuate in the whale becoming weak and increase the potential for predation from sharks and killer whales.
Many dolphin species associate with tuna. The tuna fishing industry killed hundreds of thousands of dolphins in the eastern tropical pacific by netting on the dolphins in order to catch the tuna underneath and in this way some populations of spinner, spotted and stripped dolphins have been reduced to 25% of their initial abundance.
Whales and Toxic Algal Blooms
Toxic algal blooms are a natural occurrences in oceans at certain times of year. However, they can cause mass mortalities of marine organisms because they deplete oxygen or produce poisonous toxins. Toxic algal blooms are responsible for mass mortalities such as the humpbacks found dead after consuming Atlantic mackerel. The mackerel contained toxins the same as those that cause paralytic shellfish poisoning in humans.
Although not lethal in themselves, long-term low doses of toxins from contaminated fish may stress whales physiologically, making them more susceptible to fatal bacterial and viral pathogens.
Whales and oil spills
Whales have no way of avoiding oil spills. As they surface to breathe they inhale the volatile and carcinogenic components of the oil that sit just above the water’s surface.
The health of the whale is a measure of the health of the whole ocean / planet habitat. Their bodies are records of what is going on between the atmosphere and the seas.
The International Whaling Commission
The International Whaling Commission was established in Washington USA in 1946. Its aim was to achieve the maximum sustainable utilisation of whale stocks, and protect the future of stocks as a resource.
Since 1949, the IWC has met annually, where it has assessed population statistics and set limits and quotas on catches. Unfortunately, it has no powers of enforcement, and some countries either refuse to sign recommendations, or leave the commission when they disagree with it. Over the years, the stance of the IWC has changed as some of its members adopted more conservation-oriented views and positions on whaling.
The majority of the IWC member countries no longer hunt whales commercially since synthetic products became available, replacing whales traditional uses.
The IWC is responsible for the establishment of both the Indian Ocean Whale Sanctuary in 1979, and the Southern Ocean Whale Sanctuary in 1994. Today the IWC is comprised of around 50 member nations: a few are still whaling nations; several are former whaling nations; and several others are countries who never hunted whales, but joined to support improved conservation measures for whales.
Southern Ocean Whale Sanctuary
In May 1994, the IWC met in Mexico City where, by 23 votes to one, the Commission agreed to establish the Southern Ocean Whale Sanctuary. This signalled a major victory for the environment! The Sanctuary covers an area stretching south from 40oS latitude (excluding the tip of South America). A little more than halfway from the South Pole to the equator, it is basically the “bowl” at the bottom of the earth. The sanctuary protects the great whales when they are in their feeding grounds during the summer. It overlaps with the Indian Ocean Sanctuary which protects whales in their winter breeding grounds, thus ensuring that at least one population of each species will be protected throughout its complete life cycle. The Southern Ocean provides the main feeding grounds for sperm and all of the baleen whales (except for Bryde’s whale) in the southern hemisphere. The establishment of the Southern Ocean Whale Sanctuary signals to whaling nations that their industry is dead. By denying whalers access to the largest remaining concentration of baleen whales, the sanctuary will prevent the revival of a major international trade in whale meat that would hide the products of illegal whaling.
Large scale whaling will no longer be a profitable investment and the Southern Ocean whales will have a chance to rebuild their numbers in peace. Even though Japan registered an official protest against the Sanctuary, they could not gain enough support to prevent it from becoming a reality.
The Continuing Struggle
The Plight of the Forgotten Whales: Little Whales Under Threat The great whales may now be protected, but we cannot forget that some whalers are now turning to the smaller species of cetaceans to satisfy their appetites: Examples are:
- Dall’s porpoise (found exclusively in Japanese waters, California and to the Bering Sea): between 1986 and 1990 at least 111,000 were slaughtered in Japan. Some of the meat is sold on the black market as whale meat to inflate prices;
- Striped dolphins: are the second most exploited whales in Japanese waters. Fortunately, they are not exclusive to this area, but are found distributed in tropical and temperate waters;
- Commerson’s dolphin: in Chilean waters are slaughtered by fishermen for crab bait;
- Pilot whales: are continually being slaughtered in large numbers by the people of the Faroe Islands. Other species are slaughtered because they are caught in fishing gear etc or their habitat is under direct threat: For example
- The Vaquita is the most endangered of all marine cetaceans. Its population can only be found in a 30 mile radius in the Upper Gulf of California in Mexico. The current level of Vaquita mortalities due to gillnet fishing operations almost guarantees its extinction within four to five years
- Baiji / Yangtze River dolphin is the most threatened of all cetaceans. Its habitat is being destroyed by a series of dam projects on the Yangtze River. It is also caught in fishing gear, poisoned by pollution (including PCBs and organochlorines), endangered by industrial development, and starved for food
- Harbour porpoises inhabiting coastal waters in many parts of the northern hemisphere are seriously endangered by the threat of drowning through entanglement in fishing gear. Populations in Canadian waters are currently listed as threatened and are likely to be changed to endangered
Generally there are two categories of strandings. The first is solitary strandings, which normally involve only one whale. The majority of single strandings involve ill or already dead animals. If these animals are refloated they will usually strand again or die at sea shortly after release as the weight of their body mass can crush their own internal organs if they are on the beach for an extended period.
The second category is mass strandings, which consist of three or more Animals, usually toothed whales such as pilot whales. Several theories have been put forward to explain mass strandings. These range from the likely to the ridiculous. The likely are explained below, the ridiculous will not be discussed.
Strandings occur for the following reasons:
- The whales’ navigational senses are disrupted and they cannot use the Earth’s magnetic field to navigate migration routes
- The toothed species of whales are those most likely to strand en mass
- Strandings usually occur on gently sloping sandy or muddy shores
- In mass strandings the majority of animals are healthy except for one or two individuals
- Social bonds between animals will cause others in the pod to strand when responding to the call of sick animals or following the leader into shallow water
- Atmospheric disturbances such as storms or even a full moon increase the likelihood of strandings occurring
If you find a stranded whale, here are some good ideas about what to do:
- If the animal is completely out of the water, keep it upright. This minimises the risk of drowning as the tide returns, and reduces the animals disorientation when it is refloated
- If the animal is laying on its flippers, dig them free as these and the flukes are areas where they lose most of their body heat
- Do not touch or cover the blowhole and keep water away from it, it is extremely sensitive
- Keep the animal cool - beached cetaceans usually die of heat exhaustion. The body’s thick layer of blubber holds the heat like a thermos flask. If not kept wet, the delicate skin soon dries out, cracking and peeling in the sun
- Make sure the animal’s skin is kept wet. If possible cover the skin with a light-coloured towel or sheet and keep this wet
- Do not tug on flippers or flukes as cetaceans are very fragile. Using a sling or canvas sheet gently lift or drag the animal to the water
- Once back in water do not push the animal out to sea immediately. allow some time for the animal to cool down and reorient itself. After a while guide the animal seaward