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Whales and Dolphins

Condition

Over 30 species of whales and dolphins visit or are resident in the Great Barrier Reef. Of these, two species of baleen whales, the humpback and the dwarf minke, are commonly seen during the winter. Bottlenose and spinner dolphins are also commonly seen and other whale and dolphin species reported from the Great Barrier Reef include Bryde’s whales, pan-tropical spotted dolphins, false killer whales, killer whales, short-finned pilot whales, sperm whales and various beaked whales. Very little is known of the status of these species in the Great Barrier Reef, other than their occurrence in the region. For instance, the occurrence of Longman's beaked whale in the Great Barrier Reef is known only from a single stranding near Mackay, even though it was recently shown to be widely distributed throughout the Indo-Pacific (Dalehout et al. 2003). The conservation status of two inshore dolphin species, the Australian snubfin and Indo-Pacific humpback dolphins, are of special concern (Parra, Corkeron and Marsh 2004).
 

For a comprehensive table listing all of the protected species of whales and dolphins known to occur in the Great Barrier Reef World Heritage Area and listed by the IUCN Red Data Books, or under Queensland or Australian Government legislation refer to Table 3 of the report “Fauna and Flora of the Great Barrier Reef World Heritage Area”. All cetacean species in the Great Barrier Reef are protected under the Australian Government’s Environment Protection and Biodiversity Conservation Act 1999 and under the Queensland Government’s Nature Conservation Act 1992, regardless of their conservation status.

All cetaceans exhibit similar biological characteristics, being long-lived animals that may take many years to reach sexual maturity and have few offspring. Most cetaceans only produce one calf per breeding season, with two to three years or longer between breeding seasons. These characteristics make whales and dolphins very susceptible to pressures that may reduce survival rates or reproductive success, so that the cumulative effects of apparently minor impacts may be considerable. Furthermore, declines may take many years to become evident by which time it is too late to address the pressures causing the decline. The inherent vulnerability of these species requires a management approach that, where-ever possible, minimises all pressures on these species, and carefully considers the potential for cumulative impact of seemingly minor pressures over long time scales. 

Detailed information on the current status of whales and dolphins can be found in the Whale and Dolphin Conservation Policy for the Great Barrier Reef Marine Park.

Condition: humpback whales

Since the early 1980’s there have been annual surveys of humpback whales as they migrate north to the Great Barrier Reef at the start of winter. While these surveys do not take place inside the Great Barrier Reef Marine Park, they still monitor the population of animals that inhabit the Area during winter. At this time of year, humpback whales are commonly seen in many parts of the Great Barrier Reef.

On a global, national and Queensland scale, the humpback whale is listed as being ‘vulnerable to extinction’. This means that this species is at ‘high risk of extinction in the medium-term future’. In Queensland, the humpback whale population is recovering from the large-scale, industrialised whaling activities that occurred between 1949 and 1962. The most recent population survey was in 1998. This estimated the population at  4000 animals, with an annual increase of 11% (Vang 2002). 

Condition: minke whales

Two different species of minke whale are found in Great Barrier Reef waters. The ‘dwarf’ minke is found throughout the area between March and October, with the largest number of records from the Cairns Section of the GBRMP (Arnold 1998, Birtles & Arnold 2002). The Antarctic (‘dark shoulder’) minke whale has rarely been seen in the GBRMP and is known primarily from strandings in the southern and central areas of the Great Barrier Reef. The minke whale was listed as 'common' in the Queensland Government’s Nature Conservation Act 1992. The 2002 IUCN Red List of Threatened Animals listed the dwarf minke whale as ‘lower risk-near threatened’, and the Antarctic minke whale as ‘lower risk-conservation dependant’. However, the Queensland Nature Conservation Act 1992 does not distinguish between the two species. The Action Plan for Australian Cetaceans (Bannister, Kemper & Warneke 1996) listed the Antarctic minke whale as ‘Secure’ and the dwarf minke as ’No category assigned because of insufficient information’.

Condition: inshore dolphins

Three species of dolphins from the Great Barrier Reef are classified as inshore species: Indo-Pacific hump-backed dolphins, Australian snubfin dolphins and bottlenose dolphins. Bottlenose dolphins are found throughout the Great Barrier Reef, not just inshore, and probably represent two distinct species (Stokes et al. 2002). The Indo-Pacific hump-backed dolphin and the Australian snubfin dolphin are listed as ‘rare’ under the Queensland Government’s Nature Conservation Act 1992. Both were listed in the Action Plan for Australian Cetaceans as “Insufficiently Known” but suspected to be endangered or vulnerable. Refer to Table 3 of the Fauna and Flora of the Great Barrier Reef World Heritage Area report. Recent research, including genetic studies, suggests that humpback and Australian snubfin dolphins in Australian waters may be subspecies or separate species to those elsewhere and, hence, Australia’s only endemic cetaceans (Beasley et al. 2002; Parra et al. 2004).

There is concern about apparent declines in populations of hump-backed dolphins and Australian snubfin dolphins (Smith et al. 2003) throughout their range including the Great Barrier Reef region. However, there is not enough information to make a robust assessment of the conservation status of these dolphins in the Great Barrier Reef. The only available information on numbers of groups of Indo-Pacific humpback dolphins (not actual population estimates) sighted during aerial surveys, suggests that the population is probably declining. There were even lower numbers of sightings of Australian snubfin dolphins in aerial surveys than humpback dolphins, suggesting either that they are relatively uncommon in Australian waters or that they are inadequately sampled by aerial surveys (Parra et al. 2002). Current research (G. Parra, James Cook University) is looking at populations in the central and northern GBR, using boat-based surveys. Hale (1997), Corkeron et al. (1997), Parra et al. (2002) and Parra, Corkeron & Marsh (2004) summarise existing data on the distribution, status and conservation of inshore dolphins in Australia.

Pressure

Whales and dolphins are subject to a wide variety of impacts from human activities, with different species being subject to different pressures. Key human-related impacts include boat strike and entanglement in nets (both commercial fishing and those set for bather protection), although very little is known about interactions with mesh nets.

Other impacts that may affect whales and dolphins are:

  • prey depletion
  • pollution
  • noise
  • habitat destruction from coastal development
  • whale watching (principally of humpback and dwarf minke whales),

Detailed information on the human activities likely to adversely impact on cetaceans can be found in the supporting document to the GBRMPA’s Whale and Dolphin Conservation Policy.

Pressure: whale watching and tourism

The annual migration of humpback whales along the east coast of Australia has led to the development of a tourist whale-watching industry, particularly in Hervey Bay, but also in the Whitsundays and Cairns areas. In the GBRMP, whale watching is primarily undertaken as an opportunistic activity on board vessels that focus on carrying passengers to specific reefs or islands in the Great Barrier Reef. Vessel activity from whale-watching operations has been shown to affect the behaviour of humpback whales. However, it is unknown whether whale watching has long-term detrimental effects such as changes in migration routes and habitat use or decreased reproductive success.

In addition to the whale-watching industry for humpbacks, there is a relatively new industry in watching and swimming with dwarf minke whales. This industry is located in the vicinity of the Ribbon Reefs, northeast of Port Douglas. The major difference between watching humpbacks and dwarf minkes is that all humpback watching occurs from on board a boat, whereas dwarf minke interactions often occur with the watchers in the water with the whales. This is such a new activity that the effects on the whales are not fully documented yet. Research into these effects is underway. Reports on the sustainable management of swimming with dwarf minke whales on the GBR are available (Birtles et al., 2002a, Birtles et al. 2002b).

Pressure: boat strike

The incidence of vessel strikes on whales and dolphins is believed to be low. Between 1998 and 2000, three cases of mortality attributable to boat strikes were recorded in the Marine Wildlife Stranding and Mortality Database. However, there are other incidences where known boat strikes have occurred and the fate of the animal is unknown. The increasing humpback whale population, and rising boat traffic in inshore areas suggest that boat strike incidences are likely to increase in the future.

Pressure: marine debris

Whales and dolphins may ingest foreign matter such as plastic bags which can lead to serious gastro-intestinal blockages, potentially causing the animal to starve. Whales and dolphins may also become entangled in debris which can hinder their movement and in severe cases cause them to drown. In 2000, a Bryde’s whale with almost six square metres of supermarket bags, food packaging, two-metre long plastic sheets and fragments of garbage bags stranded in Cairns.

Pressure: incidental catch

As for dugongs, stranding data suggest that mesh netting is a significant cause of mortality for inshore dolphin species and include confirmed cases of dolphin deaths from mesh net entanglement. However, information on actual numbers of dolphins killed in these nets is limited because entanglements are very rarely reported. For more information on the inshore net fishery see Management status – Fisheries.

Published data from the Queensland Shark Control Program (1962 to 1995) indicate that incidental catch for the Program included eight humpback whales, approximately 60 other whales, and 630 dolphins. Five of the eight humpback whales were released alive but their post release fate is unknown. On average, 19 dolphins and three whales were caught per year between 1962 and 1995 (Gribble, McPherson & Lane 1998). As there is little information about the population status for whales and dolphins in the Great Barrier Reef, it is unknown whether the mortality of whales and dolphins in shark control equipment has a significant impact on these populations. However, given the inherent susceptibility of these animals, and the cumulative stress of multiple pressures, a precautionary management approach is required. 

Response

Response: whale watching and tourism

Until it is established whether this activity has serious impacts on the whales, whale watching will continue to be managed in a precautionary manner to ensure that the whales are unharmed by human activities. In 2000, the Authority published a Whale and Dolphin Conservation Policy for the Great Barrier Reef Marine Park. This policy complements measures addressed in Queensland’s Nature Conservation (Whale and Dolphin) Conservation Plan 1997, and those of the Department of the Environment, Water Heritage and the Arts  including the Action Plan for Australian Cetaceans. Implementation of the Policy is proceeding especially in regard to:

  • whale-watching and swimming-with-dwarf minke whale requirements;
    • in 2003, nine permits were granted for swimming with dwarf minke whale activities in the Cairns area;
  • the development of regulations for interactions with whales and dolphins, including whale watching to complement those under the Environment Protection and Biodiversity Conservation Act 1999;
  • review and develop education programs to inform stakeholders and the public; and
  • the preparation and publishing of Best Environmental Practices for whale watching.

Response: boat strike and marine debris

A tri-agency (Queensland Parks and Wildlife Service, Department of Primary Industries, GBRMPA) approach is enabling close examination of whale and dolphin carcasses to establish the causes of mortality and obtain further information. The GBRMPA website enables the general public to subscribe to an Email Listserver that posts notices about each stranding soon after they are investigated.

The GBRMPA has prepared Best Environmental Practices to educate boaters on the risks vessels pose to marine wildlife and how to minimise the impacts of their activities. Voluntary transit lanes and speed restrictions are currently being trialled in the Hinchinbrook region.

In 2003 the Department of Environment and Heritage commissioned the preparation of a national recovery plan for Humpback Whales, Fin and Sei Whales, a national review of the conservation status of smaller whales and dolphins, and a national review for the coordination of sampling from live and dead stranded whales.

The disposal of waste at sea in the GBRMP is prohibited. While the runoff of litter into the GBRMP from the land is regulated by State and local government and is outside the jurisdiction of the GBRMPA, in recent years some local councils have taken steps to reduce the amount of litter washing into the GBRMP from local waterways and storm water drains. The GBRMPA is working with State and local governments on a wide range of water quality initiatives specifically designed to minimise the impacts of declining water quality on the marine environment (see Environmental status – water quality). The GBRMPA has also produced Best Environmental Practices to educate reef users about the correct disposal of waste. Education programs such as the Reef Guardians program educates school students about reducing the run off of litter into local waterways, and initiates actions to reduce litter at the local community level.

Response: incidental catch

Concern over catch of dolphins, as well as dugongs and turtles, in nets set in the Queensland Shark Control Program has led to many nets being replaced with baited hooks since 1992. Currently shark nets are only deployed at ten locations in the GBRWHA, five nets in Cairns and five nets in the Mackay area. Between 1992 and 1995 between 12 and 13 dolphins were caught each year, a reduction from the average of 19 animals per year between 1962 and 1992 (Gribble et al. 1998). Research into methods of reducing incidental catch of whales and dolphins using sonic alarms and pingers in underway in Cairns and on nets deployed outside the GBRMP in south-east Queensland.

Mesh-netting restrictions in Dugong Protection Areas may reduce the mortality of inshore dolphins. The assessment of these and alternative management activities will require better information on population levels and dynamics. Development of methods for targeted monitoring of populations of these species and research into effects of human pressures is under way. Until this information is available, a precautionary approach is required in management strategies.

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