Mammals > Marine mammals > About marine mammals

Issues

• Whaling
• Strandings
• Rescue
• Seals
• Conservation

Whaling

Indigenous whaling

Many indigenous people around the world have hunted marine mammals over thousands of years. In some parts of the world, including Australia, these practices still continue but not without some controversy. From a conservation point of view however this subsistence taking probably had little impact on the populations of the target species.

Commerical whaling

Large-scale commercial whale and seal hunting by western countries began in the late 18^th and 19^th century. But it was the mechanised killing involving factory boats in the first half of the 20^th century, even as late as the 1970s that really plunged some whale species to the brink of extinction. A few like the Northern Right Whale, the Bowhead and the Blue Whale were reduced to less than 10% of their former population. These species have still not returned to anywhere near their pre-whaling numbers. Pressures both natural and from human impact on the marine environment are probably hindering this recovery.

During the peak of the sailing and stream driven whaling industry, products obtained from whales had general use in western culture. The most valuable was Sperm Whale oil, but also included:

• other whale oil
• whalebone
• whale meat

Seals did not escape this slaughter, especially sea lions and fur seals whose valuable fur pelts were in high demand. Seals were hunted when they congregated on shore, usually during the breeding season. Many colonies were effectively wiped out within a few years. Seals populations around Australia, with a few exceptions, have recovered.

Whaling in Australia

The impact of the Australian whaling industry on whale populations was probably relatively minor. There were a number of land-based operations and one in Albany, Western Australia operated until the mid 1970s. During the peak of the industry they generally relied on long boats rowed from shore, which limited the numbers of whales caught. Australia contributed to the Southern Hemisphere slaughter by allowing whaling fleets from other nations to use our ports. Ships off loaded their catch for shipment to Europe and North America, then after being resupplied, returned to the whaling grounds.

Banning Whaling

Despite a voluntary world ban on commercial hunting of whales, instituted by the International Whaling Commission (IWC), the issue still causes controversy. To some cultures, especially in Asia and northern Europe, whales are no different from fish. They are viewed as a traditional food resource that should be exploited if in sufficient numbers. To most western nations, especially the English-speaking ones however the resumption of whaling for whatever reason, scientific, commercial or indigenous needs is strongly opposed. The reasons are a mixture of conservation and animal welfare concerns as well as a cultural attitude which see these animals as having a special status. Each year at IWC meetings the resumption of commercial whaling for meat is discussed. The target species, the Minke Whale was ignored by the whaling industry because it was too small, so its numbers are quite large. On this basis Japan continues to hunt it under a scientific licence. The prime concern of the anti-whaling nations is that the great whales might become vulnerable should any commercial hunting resume.

Strandings

Of all the issues associated with marine mammals, the apparently deliberate stranding on shore of whales and dolphins is the most curious and mystifying. It can involve the slow death of hundreds of animals, although on average probably only 10 - 20 are involved in any one stranding. As each event is different, the reasons behind them have proved difficult to determine. There are however certain conditions that are present at many of the strandings.

Only about four or five species are known to mass strand and all are normally only found in the open ocean. This would suggest that unfamiliarity with coastal area is a factor. Strandings seem to occur at the same site time after time so it is clear that landform plays some part in confusing these animals. The other characteristic these vulnerable species have in common is that they are very social animals and live in a group or pod. It is possible that a mistake or illness of one individual might cause it to strand. Its distress calls appear to cause the rest of the school to follow it onto the beach. These theories have been tested by some rescue strategies. Surviving individuals have been removed to another beach before being pushed out to sea. This approach has been successful in a few cases and would appear to eliminate the possible causal influence of landform and the social pressure of other individuals in the pod.

The species involved in strandings are reasonably common and while the deaths are stressful there is little impact on the overall populations. It is also a natural event that has been occurring for thousands of years so human activity is not a contributing factor. Unfortunately most rescue efforts are unsuccessful and even if animals are pushed out to sea, there is some evidence to suggest that their long-term life expectancy is reduced by the stress of the stranding.

There are now some instances of mass strandings thought to have been caused by human activity, namely underwater seismic and weapons testing. Sound or pressure waves caused by explosions can be extremely damaging to animals such as cetaceans that are so dependent on hearing. Recent deaths of beaked whales species normally not known to mass strand, off Africa and the United States coast, suggest this as the cause of their deaths.

Rescue

What can you do if you come across stranded animals?

• Notifying authorities such as the local national parks or wildlife office, local council or natural history museum is an important first step.
• Coordinating of rescue efforts is a complicated operation and usually requires experienced management.
• Photographing the situation is also useful, especially if you are present at the beginning of a stranding event.
• The biggest enemy of beached whales apart from their own weight is heat stress and dehydration. They need protection from both by constant wetting of their skin and protection from the sun. It is much easier and more effective when assisting these animals if as much of their body as possible is in the water. This will help keep them upright and able to breathe.
• The most useful action you can take is to be guided by experienced authorities and ensure your own safety when standing near or assisting with what are usually quite large and very stressed animals.

Seals

Occasionally individual seals will be seen on shore. Often they are very young and inexperience, and prevailing currents can force them well out of their normal range. Seals seen by themselves on shore is not necessarily a situation that requires human intervention. If there are obvious signs of severe injury than authorities may organise veterinarian assistance. Otherwise all seals should be left alone. They can move a lot faster on land especially sand, than the average person. It is generally thought that most of these animals have come ashore to rest.

Some species, such as the Australian Fur Seal, are natural inhabitants of our coastal areas and their appearance in place like Sydney Harbour is not unusual.

Conservation

There are many issues of human activity that do pose a threat to seals and other marine life. Competition with the fishing industry probably represents the greatest threat and it comes in two forms. It is estimated that probably hundreds of seals are drowned each year by being caught in nets. Some regulations are in force to modify the shape of nets to allow seals to escape but there is little monitoring of the industry. Direct competition between the fishing industry and seals poses a threat to seal populations.

For some of the larger whales PCB and heavy metal poisoning is becoming a problem.

Marine pollution is an ongoing threat. Entanglement in discarded nets, ropes and plastic bags is a problem for seals and whales, especially the young. At best they can prevent the animal feeding efficiently, at worst, ropes can cause slow strangulation.

Shark meshing nets off beaches especially in Queensland are known to result in significant number of dolphin and Dugong deaths each year. Unlike accidental netting instances shark meshing nets puts marine mammal conservation in direct conflict with the perception that meshing prevents shark attacks on people. Dugongs also face increasing problems with pollution of their food supply, the seagrass beds, thought to be caused by land clearing and the resultant soil runoff.

Over the last 30 - 40 years, Dugong numbers have declined markedly along the east coast of Queensland probably through a combination of environmental factors and human activity.

• Dugong Deaths
  Great Barrier Reef Marine Park
  http://www.gbrmpa.gov.au/corp_site/info_services/
  publications/sotr/mammals_frame.html)

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