Dolphin Research Institute (DRI)


What are Cetaceans?

All whales, dolphins and porpoises belong to a group of mammals, collectively known as "Cetaceans". In all there are approximately 81 species of cetaceans currently recognised. All species within the cetacean group are entirely aquatic, there are therefore no land-based representatives within this group.

Although cetaceans are usually referred to as whales, dolphins or porpoises, this division is problematic. In general, the larger species are referred to as whales, the smaller as porpoises or dolphins. This division is difficult when looking at the larger species of dolphin, such as the Orca (Killer Whale) which is actually a dolphin but is, in fact, larger than some whales. This general division is not based on scientific data and is therefore not generally used.

Scientists have instead divided cetaceans into two major groups based on similar characteristics within the groups. These two groups are the Mysticeti (Baleen Whales) and the Odontoceti (Toothed Whales).

Toothed whales (Odontocetes)

The toothed whales represent the largest group, containing 70 of the 81 cetacean species. All dolphin species are included in this group. This group is characterised by the presence of teeth, although the number, size and shape of the teeth of the various species can be quite variable. Some species within this group have hundreds of teeth, others only 2!

Unlike the mysticetes, odontocetes feed on "solitary" prey. All odontocetes hunt and catch a wide variety of individual fish, squid, crustaceans, and in some species, other mammals.

Baleen whales (Mysticetes)

Baleen whales do not have teeth. Instead of teeth, all Mysticetes have hundreds of comb-like baleen plates that are attached to their upper jaw. These plates are "furry" in appearance and are tightly packed. They hang from the upper jaw effectively acting as a strainer. As water moves across the plates, stiff hairs on the plates filter food out of the water.

Mysticetes feed by either gulping huge quantities of water from which they then filter out food, or by travelling along, "skimming" water and filtering food out that way. The main prey species consumed by the baleen whales are various species of zooplankton including tiny crustaceans such as krill, and other tiny plankton such as copepods. In the northern hemisphere, baleen whales have been observed feeding on schooling fish and molluscs such as squid.

Mysticetes also differ from Odontocetes since they have 2 blowholes located side by side. Odontocetes have only one.

Where do you find cetaceans?

Cetaceans can be found in all of the oceans of the world and in some rivers and estuarine areas. According to current information, the majority of cetacean species appear to have limited distributions.

Of the 81 species currently recognised, up to 46 of these are limited to rather small distributions or not enough is known of their distribution to be certain of the extent of their range. The latter is particularly true of cetaceans that inhabit only deep, open ocean areas.

Of the remaining 35 species, approximately 8 species can be found all around the world. Examples of these are the bottlenose dolphin and the common dolphin. Both of these species are widely distributed except for the polar regions.

There are also approximately 12 species of cetaceans that are widely distributed throughout tropical and sub-tropical regions and 6 species that live exclusively in the polar and sub-polar regions.

Most of the 11 species of baleen whales, such as humpback whales, are known to migrate between different regions, feeding in colder waters during summer before migrating to warmer waters to breed during winter. The exception to this is the Bryde's whale. This species remains in warmer waters all year round.

An unusual group of cetaceans are the river dolphins. Of the five species of river dolphin, 4 live exclusively in river systems, thus the name. The remaining species, the Franciscana, although grouped with the river dolphins, actually inhabits the shallow coastal waters off eastern South America. There is also at least one species of dolphin, the Tucuxi, that is not classified as a river dolphin but has entire populations that appear to live exclusively in river systems.

Cetacean Species found in Australia

Of the 81 species of cetacean currently recognised, a total of 44 of these have been observed in Australian waters (including Australian Territory waters, such as our Antarctic Territories). Of these, 31 are whale species and 12 are dolphin species. Only one species of porpoise, the spectacled porpoise, has been sighted in Australian territorial waters. This equates to 54% of all of the world's cetacean species being found in Australian waters.

Although a number of cetaceans are found within Australian waters, none of them can be considered endemic (ie only found in Australia) since they all have populations in other areas of the world.

The greatest diversity of cetacean species within Australia occurs around the coastline of Western Australia. A total of 37 different species have been observed off this coastline. This huge diversity is thought to be due to the range of habitats that are present along the vast West Australian coastline. The number of species found along the West Australian coastline is equivalent to the combined total of species found in Victoria, NSW and Queensland, which is not surprising when you consider that the West Australian coastline is the size of all these three states combined.

In 1996, "The Action Plan for Australian Cetaceans" was written for the Endangered Species Unit of the Australian Nature Conservation Agency (ANCA). The aim of this report was to develop a national overview of the conservation status of Australian cetaceans and to develop recommendations for research and management actions and conservation priorities.

For the majority of cetacean species, not enough was known to assign any category. Of those species that were assigned categories, only one species was determined, at that stage, to be endangered and that was the blue whale. Four species, the southern right whale, the humpback whale, the sei whale and the fin whale, were listed as vulnerable. A further four species were listed as "insufficiently known". These were the Indo-Pacific humpbacked dolphin, the Irrawaddy dolphin, the spinner dolphin, and the sperm whale.

Threats to Cetaceans

All cetacean species face a number of threats. Some of these are from natural causes such as predators but the majority of threats facing cetaceans today result from either direct or indirect human impacts.

Natural Threats - Predators

Cetaceans, like most animals are preyed upon by other predators. The main predators of cetaceans are sharks and Orcas (otherwise known as killer whales). False killer whales and pygmy killer whales are also known to prey on other species of cetacean.

As with many other species of animal, predators tend to prey on the very young, the old and the sick. In many cetacean species, strategies have been formed to deal with such attacks by predators. Most whales will attempt to defend their calves from the attack of a predator either by attempting to get away or by "fighting back".

The tendency of some cetaceans to travel in groups is also thought to be, at least in part, a defensive strategy against predators. By moving around in groups, cetaceans increase the chances of detecting a predator prior to any attack and successfully avoiding or surviving an attack.

Some Odontocetes have been observed to defend others within their group such as injured or very young individuals, from attack.

The Whaling Industry

The single greatest threat to cetaceans comes from the whaling industry. This industry came very close to wiping out entire species of the larger whales before a moratorium was declared in the early 1980's. Even so, entire populations of whales were wiped out before the moratorium came into effect. Even today, whales are not safe from whaling activities.

The History of Whaling

Humans have hunted whales throughout history. There are reports of whales being hunted as early as 1200. During the long history of whaling, whales have provided material for many products utilised by human populations. In many societies including Japan, Norway, Iceland and various indigenous communities around the world, cetaceans were valued for their meat.

In Europe and America, although whale meat was consumed, there was not the demand seen in other countries. Other whale products, however, were extensively used.

The blubber from whales contained oils that were used to make a bewildering range of products ranging from cosmetics and soaps through to crayons and paints. Whale oil was also used to make candles and as fuel in oil burners.

The baleen plates from the Mysticetes were also used to make a number of products including brushes, fishing rods and were even used as "whalebone" to stiffen the corsets worn by women in the nineteenth century.

As demand for whale-based products grew, so did the whaling industry. Advances in technology, especially the development of more advanced methods to track and harpoon whales, increased the number of whales which could be taken. Once located, a whale could be tracked for as long as necessary until it had to resurface for air. It was then harpooned. In the space of a few hundred years, whale hunting became a slaughter.

Fortunately, we no longer have any need for whale products in western society since we have found alternatives to replace them. Whale meat, however, is still valued as a source of food in some countries.

The End to Whaling? - Whaling and the IWC

Originally, whalers hunted the larger species of whale and as the stocks of each species became depleted, whalers would hunt another species. This continued until it became obvious that the pressure on whale populations around the world had become unsustainable.

In 1931, the first move to protect a species from commercial whaling occurred with the world-wide protection of the bowhead whale. In the same year, in an attempt to maintain the rapidly declining whaling industry, whalers adopted the Convention for the Regulation of Whaling. Fifteen years later, the International Whaling Commission (IWC) was established to manage the world-wide development of the whaling industry. IWC membership was and is composed of numerous Government representatives from many countries around the world.

When first established, the IWC attempted to manage the whaling industry by setting catch quotas. It soon became evident that this was not enough and, in 1986, 55 years after the first whale was protected from commercial whaling, a moratorium on whaling (voted on by the IWC in 1982) came into effect. In the period leading up to the IWC moratorium, there was also a massive, world-wide campaign by various environmental groups demanding an end to whaling.

This has not ended whaling throughout the world, however. Countries such as Norway and Japan, still hunt whales. Norway officially continues to object to the moratorium and under the rules of the IWC, is therefore legally able to continue whaling.

Japan continues whaling under the guise of "scientific research", although many scientists have protested the validity of the research being conducted. Another aspect of this Japanese "research" which is contested is that once the whales have been captured, they are processed commercially on factory ships and the whale meat is sold.

Approximately 800 minke whales are still taken, each year, by Japan and Norway. There is also large-scale concern at the level of "pirate" whaling that is still occurring throughout the world. The number of whales taken during "pirate" operations is not known.

Indigenous whaling

The issue of indigenous whaling is a contentious one within the IWC. During the 51st meeting of the IWC in May, 1999, the renewal of a quota for the Bequian people of St Vincent and the Grenadines to take humpback whales was one of the most hotly debated issues of the meeting.

Indigenous communities and their governing bodies argue that they should be able to continue hunting cetaceans in order to maintain traditional practices, thus helping to alleviate some of the social problems facing these communities. The number of cetaceans taken during these hunts is also relatively small. At present, indigenous whaling quotas are set at approximately 165 whales per year. These quotas are divided between 6 indigenous groups spread around the world.

Many within the IWC argue the validity of the arguments for a continuation of quotas for some indigenous communities. It is alleged that some of these communities have embraced more modern lifestyles, no longer following many of their traditions and no longer hunt whales using traditional techniques.

After much debate, within the IWC, the Bequian quota was renewed at the 51st meeting with a number of conditions attached. One of these conditions is the preparation of a detailed "needs" statement detailing why the quota is needed. It seems likely that the issue of indigenous quotas is one that will continue to be debated at future IWC meetings.

Whaling and small cetaceans

The number of small cetaceans taken every year, is unknown. Small cetaceans do not come under the auspices of the IWC and, therefore, are not included in the IWC moratorium on commercial whaling. There are a number of nations who still continue to take commercial catches of small cetaceans such as dolphins and porpoises. It is known that smaller cetaceans are taken commercially in Japan and Peru. There are also other numerous cultures that carry out regular hunts. It has been estimated that perhaps hundreds of thousands of dolphins, if not more, are taken each year in these combined hunts. Recent attempts were made at the 51st IWC meeting to include the management of small cetaceans under the umbrella of the IWC. This attempt was hotly debated but was eventually unsuccessful.

Whales - How many are left?

It has been estimated that only between 5-10% of the original populations of whales remain. At the time the moratorium on commercial whaling was declared, it was thought to be inevitable that some species such as the blue whale would become extinct. The prognosis for many of these species, including the blue whale, is looking much better now. Although it will be a number of years before we know the fate of many cetacean species, it is clear that many species are showing signs of recovery. It is also clear, however, that most have a very reduced range from that originally recorded.

Many species appear to be recovering relatively quickly. These include, the grey whale, the blue whale (in some areas), humpbacks and the southern right whale (in some areas).

Sadly, species such as the northern right whale are not as fortunate. This species, although a protected species since 1935, is among the rarest of all the cetaceans and, even today, the total population is estimated at approximately 300 individuals.

The impacts of whaling activities on the smaller cetaceans are totally unknown, however it is highly likely that many populations around the world have also been severely depleted and this is still continuing today.

The future of whaling

During recent meetings of the IWC there has been a push to reinstate quotas for commercial whaling activities, particularly by countries such as Japan and Norway. More recently, at the 50th IWC meeting, Ireland put forward a proposal to allow limited coastal whaling. This proposal is under serious consideration by many IWC delegates and has caused some division amongst the "like-minded" delegates who, up to now, were opposed to whaling.

Countries such as Australia and a few others have countered the Irish approach by taking a different stance. They remain totally opposed to any resumption of commercial whaling and are lobbying strongly for the creation of several whale sanctuary areas around the world.

Commercial whaling: to be or not to be . . .

Until now, it has been easy to argue against commercial whaling based on knowledge of depleted whale stocks. What will happen, however as whale stocks continue to recover?

Although much of the anti-whaling arguments are based on sound ecological principles, some are based around ethical arguments. Many people see whales as being intelligent creatures that should not be hunted. Others see whaling as a cruel activity. Of this there is no doubt. During numerous IWC meetings, this issue has been discussed and as yet, no humane method exists of killing a whale. At the very best, it takes a whale a number of minutes to die, at worst, up to an hour. Usually the animal will have been in excruciating pain for much of that time.

At the opposite end of the scale, pro-whaling groups see whales as a food source or simply as a resource to be exploited. They appear to have none of the ethical concerns expressed by the anti-whaling nations and argue that whale meat is a traditional part of their culture.

Some whale stocks, such as the Minke whale are now considered secure. During the next decade, the debate over whaling is likely to escalate as other species continue to recover. The pro-whaling nations will continue to push for the resumption of legal whaling, based on the recovered stocks and their traditional cultural "need" for a whaling industry.

Another argument used by the pro-whaling nations, especially Japan is the potential impact of increasing whale stocks on the world's fisheries. To this end, a paper titled "Estimation of Total Food Consumption by Cetaceans in the World's Oceans" was presented by Japan at the 51st IWC meeting. A major inference of this paper was that whales have a significant impact on commercial fisheries. Australia also tabled a paper, produced by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) on whale-fish interactions which refuted the Japanese paper. This issue is far from over and has been referred to the scientific committee of the IWC for consideration at the 2000 meeting held in Adelaide in June/July.

The anti-whaling lobby will continue to put forward arguments based around conservation and management issues. Central to these will be our ability to manage species such as whales that range over such large areas. It should not be forgotten that attempts to manage the whaling industry, prior to the moratorium, failed spectacularly. We still do not know enough of most species of whales to manage populations effectively. Many anti-whaling proponents also argue against the role of whale meat in many societies, arguing that it is not an essential part of the diet for many of the larger whaling nations.

If whale stocks continue to recover at the present rate, this issue promises to be one of the biggest issues facing conservationists and management authorities alike in the next decade.

Fishing and Cetaceans

Over the years, many fishing practices have been identified which have a catastrophic effect on ocean ecosystems. Although many species of cetaceans are affected by various fishing practices, it is by far the smaller cetaceans on which the effect is most devastating.


This method of fishing has been referred to as "vacuuming" the ocean by one author and as "the most indiscriminate method of fishing ever devised", by another. Drift nets are huge nets, tens of kilometres in length which are released onto the ocean and allowed to drift until retrieval at a later stage. These nets are very difficult to detect in the water and they catch almost everything they encounter. They are not only responsible for the death of large numbers of cetaceans, particularly dolphins, but also other sea life such as turtles, sharks and vast quantities of fish species. In the early 1990's steps were taken to set a maximum total size of the nets used (2.5km). These nets are still extensively used, however throughout the world and even at 2.5km, continue to pose a significant threat to all marine life.

Tuna Fishing

The tuna fishing industry has been responsible for more dolphin deaths than any other human activity. The reason for this huge mortality rate lies with the behaviour of dolphins and tuna. Certain species of dolphin and yellowfin tuna often swim together in the open ocean.

Because many of these dolphin species such as the spinner dolphin, the spotted dolphin and the common dolphin travel in huge groups, often numbering thousands of individuals, they are very easy to spot when they surface to breathe. During the 1960's and 1970's tuna fishermen began using dolphins to find tuna. A type of net known as a purse-seine net was then placed around the dolphins and the tuna. This net was then drawn up to form a bag, trapping the dolphins and tuna. Millions of dolphins were caught and died in this way.

As the public found out about this huge mortality rate, there was a massive outcry. This initially resulted in the labelling of many tuna products with the label "dolphin safe". This label, however, did not mean that no dolphins were accidentally caught. It simply means that the fishers did not intentionally encircle dolphins to catch tuna.

In the past two decades, tuna fishers have taken steps to limit the accidental capture of dolphins, including placing divers in the nets to help dolphins escape.

In 1992, many governments signed the La Jolla Agreement. This set dolphin mortality limits for individual vessels participating in the Eastern Tropical Pacific Ocean (ETP) tuna fishery. Unfortunately, although the numbers of dolphins caught has reduced significantly, tuna is still not completely "dolphin safe". The US, in 1996 drafted a bill designed to ensure that tuna could only be labelled "dolphin safe" if no dolphins were killed in the capture of the tuna. This will only apply to tuna caught in the ETP.

Unfortunately, the ETP is not the only part of the world in which tuna is caught and there are huge concerns for dolphins in other tuna fishing areas around the world. As of 1996, no fishing method designed to eliminate dolphin mortality, without significantly increasing the mortality of other species, had been found.


Gillnets are widely used around the world to catch a variety of fish species. Like drift nets, they are almost impossible to detect in the water. They are also used in relatively shallow, coastal waters and are responsible for high levels of by-catch of some cetaceans in some parts of the world. This fishing practice has become an issue in some areas where harbour porpoise populations are suffering huge losses to these nets. It has been suggested that the large number of fish present in the nets may actually attract small cetaceans who then become entangled. Scientists have been working on various techniques to stop cetaceans from becoming entangled. One such experiment is the use of acoustical devices known as "pingers" which are designed to warn dolphins of the presence of the nets. This method is still being tested at this time.


As the human need for ocean fisheries resources increases, so does the level of competition between cetaceans and humans. At present, there are countless fisheries around the world which are in danger or decline as a result of overfishing. Also the enormous by-catch of other species of fish, associated with many fishing practices is likely to impact on species other than those targeted for human consumption. The indirect effects of such practices on cetacean populations have not been estimated.

One of the major areas of concern is the Japanese krill fishery industry in Antarctica. Krill is a major part of the ecosystem in Antarctic waters. It forms the main diet of many species of whales and penguins and other animals in Antarctica. Every year, Japanese vessels take huge quantities of krill from this system, the effects of this harvest on this resource are unknown, but many scientists have grave concerns.

Another aspect to competition is more worrying. In many parts of the world, some cetaceans are deliberately killed by fishers since they are perceived as competition for scarce resources.

Habitat degradation

This is a major issue facing all species that live in the world's oceans. Habitat degradation can come from a number of sources, these include pollution, physical changes and increased noise.

For many years, we have been indiscriminately pouring various pollutants into our oceans. In some cases, such as in the case of highly toxic waste, or oil spills, the effects on cetaceans and other sea life are immediate, often swiftly resulting in death. In the case of continued pollution from other, more subtle sources, the effects may not be as obvious. Some toxins may accumulate in the tissues of cetaceans over a number of years, eventually resulting in the death of the animal. At present, some toxins have been identified as contributing to weakened immune systems and lowering the fertility of certain species of cetacean. Unfortunately, the effects of many pollutants are more subtle and may not be known for a number of years.

Another example of a type of pollution which can severely affect cetaceans is noise pollution. This can come from several vectors including boat traffic, underwater exploration and mining operations. Very little research has been conducted on the effects of increased noise pollution at this time, however the extent of any effects appears to be dependent on the frequency and duration of the noise.

In the short term, the species most likely to be affected by habitat degradation are the riverine, estuarine and coastal species. Such species are living very close to humans. Probably the most poignant of these is the Baiji otherwise known as the Yangtze River dolphin. This animal is only found in the Yangtze River. The habitat of the Baiji has become so degraded from pollution, development, industrial activities and boat traffic, that numbers of this unusual cetacean have declined alarmingly. Although a protected species since 1975, attempts to protect this species have largely failed. The chances of saving this species from extinction appear slim.


Over the past two decades, the cetacean-based tourism industry has increased dramatically. It is now a major industry in many parts of the world. Although such tours provide operators with a unique opportunity to educate patrons about cetaceans, including conservation, they are also becoming a significant impact in some areas. Throughout the world, most of the better known species of cetacean have been targeted, especially migratory species such as humpback whales and right whales. Many of the smaller species, especially coastal populations of dolphins have also been targeted. Whale watching operations that focus on the larger species of whale during migratory periods, often focus on the smaller species outside of these periods.

In recent years, the rapid growth of the industry has started to lead to some problems. In the US recently, two whales were struck by whale watching vessels, one fatally. In other areas, large numbers of vessels "jostle" for access to a limited number of whales. In the majority of cases, these tours run in a completely unregulated environment.

The impacts of tourism activities are largely unknown . Some studies have demonstrated that animals can become disturbed in the short term, however the long-term impacts are still to be determined. Various scientists around the world are currently trying to understand the impacts of this industry on the various species of cetacean on which these tours are currently focussed.

References Used

Bannister, J.L; Kemper, C.M & Warneke, R (1996) The Action Plan for Australian Cetaceans. Australian Nature Conservation Agency.

Carwardine, M (1996) The Book of Dolphins. Dragon's World Ltd.

Carwardine, M; Hoyt, E; Fordyce, R.E & Gill, P (1998) Whales, Dolphins and Porpoises. Reader's Digest.

Environment Australia (1999) Delegation Report - 51st Meeting of the International Whaling Commission, Grenada 25-29 May, 1999.

Watson, L (1985) Whales of the World. Hutchison & Co.