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The blue whale (Balaenoptera musculus) is listed as endangered, and fin (Balaenoptera physalus) and sei (Balaenoptera borealis) whales are listed as vulnerable under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). This plan outlines the measures necessary to ensure recovery of the Australian populations of these species and is set out in accordance with Part 13, Division 5 of the EPBC Act.
Objectives for recovery
The objectives are:
the recovery of populations of blue, fin and sei whales utilising Australian waters so that the species can be considered secure in the wild; and
to maintain the protection of blue, fin and sei whales from human threats.
For the purposes of this plan ‘secure in the wild’ is defined qualitatively, recognising that stricter definitions are not yet available, but will be refined and where possible quantified during the life of this plan by work currently underway and identified in the actions of this plan.
‘Secure in the wild’ with respect to these species means: a population with sufficient geographic range and distribution, abundance, and genetic diversity to provide a stable population over long time scales.
Criteria to measure performance of the plan against the objectives
It is not anticipated that the objectives for recovery will be achieved during the life of this plan. However, the following criteria can be used to measure the ongoing performance of this plan against the objectives:
an indication of the population and recovery status of blue, fin and sei whale populations using Australian waters was developed; and
domestic and international protection regimes that support the recovery of the species were maintained and where possible improved.
Species information
Blue, fin and sei whales are baleen whales (order Cetacea, family Balaenopteridae). All are wide ranging oceanic species and the current scientific view suggests that the species show a general migration pattern of summer in higher latitudes and wintering in warmer tropical waters.
General information on the biology, population status, distribution and habitat of humpback whales can be found on the Species Profiles and Threats Database – www.deh.gov.au/sprat. This information is regularly updated to ensure that it reflects the most recent research.
Blue whales
Blue whales are the largest living animals, growing to a length of over 30m and weighing up to 180 tonnes. While the taxonomy is unclear, it is currently accepted that there are three subspecies of blue whale. Two are ‘true’ blue whales; the northern hemisphere Balaenoptera musculus musculus and the southern hemisphere Balaenoptera musculus intermedia. The third is the ‘pygmy’ blue whale Balaenoptera musculus brevicauda known mainly from the southern Indian Ocean, the eastern South Atlantic and the western South Pacific. Blue whales are extremely long-lived animals, with 'true' blue whales living up to 90 years and pygmy blue whales to around 50 years.
There are reported size and other morphological differences between ‘true’ and ‘pygmy’ blue whales, however, there is no confirmed set of features that make individuals of the two sub-species readily distinguishable from each other at sea. Studies have not yet conclusively distinguished differences between each subspecies, although recent acoustic research indicates segregation between the southern ocean populations. One notable differentiation is that during the southern hemisphere summer, ‘true’ blues are usually found south of 60°S, while ‘pygmy’ blues are usually found north of 55°S. The taxonomy of these different blue whales remains uncertain and may change with future genetic and behavioral work.
Blue whales were greatly over-exploited by commercial whalers in the 19th and 20th centuries. In 1960, the International Whaling Commission (IWC) banned the taking of blue whales in the North Atlantic, banned it entirely in the North Pacific in 1966, and in the southern hemisphere in 1967. However illegal unreported and unregulated hunting may have continued through to the early 1970’s. In 1985/86 the IWC declared a global moratorium on commercial whaling. Scientists have estimated that prior to whaling, southern hemisphere true blue whales numbered approximately 311,000 and pygmy blue whales approximately 10,000. In 2001 it was estimated between 500 and 2300 true blue whales were living in Antarctic waters. No agreed estimates of the number of pygmy blue whales exist. Recent data has shown an increase in the number of Antarctic blue whales, but the species remains at less than 1% of pre-whaling numbers.
In Australia, blue whales are found in the waters off Australia’s Antarctic Territory, and along the southern parts of the Australian coast including Western Australia, South Australia, Victoria, Tasmania, New South Wales through to southern Queensland. The majority of the most northerly sightings are likely to be pygmy blue whales.
Fin whales
Fin whales are large whales growing to a maximum of approximately 26m. The biology and life history of the species is poorly known. Most fin whale populations were severely depleted by modern whaling from the early 1900’s until protection in 1975. The fin whale was second to the blue whale in commercial importance because of its size and wide ranging distribution. In the southern hemisphere the pre-exploitation abundance was estimated at around 500,000 and may have been reduced to as few as 25,000. There are no estimates of current fin whale abundance for the southern hemisphere or for Australian waters.
Fin whales are widely distributed in both hemispheres between latitudes 20-75°. The species is more common in temperate waters, and the Arctic and Antarctic Oceans. Areas of upwelling and interfaces between mixed and stratified waters may be an important feature of fin whale feeding habitat. In the Antarctic the species is seen feeding both at the ice edge and further to the north in areas of complex bathymetry.
In Australia, there are confirmed records of fin whales for all coastal waters except in New South Wales and the Northern Territory, but the available information suggests that the species is more commonly present in deeper water.
Sei whales
Sei whales are moderately large whales growing up to 18m. The biology and life history of the species are less well known than for blue and fin whales. Sei whales were hunted by modern whalers primarily after other whale species (such as blue, fin and right whales) had been depleted. Most populations of sei whales were reduced by extensive whaling from the 1950’s until the 1970’s. International protection was afforded in 1977 for this species.
The sei whale is one of the less well studied great whales and the current status of most populations is poorly known. The original southern hemisphere population may have numbered around 100,000. There is no accepted current abundance estimate for sei whales in the southern hemisphere and no estimate for Australian waters.
The movements and distributions of sei whales are unpredictable and not well documented. Sei whales are similar in appearance to Bryde’s whales which has resulted in confusion about distributional limits and frequency of occurrence, particularly in warmer waters where Bryde’s whales are more common. The available information suggests that sei whales have the same general pattern of migration as most other baleen whales including blue and fin whales, although the timing is generally later and the current scientific view is that the species does not go to such high latitudes. There is evidence from catch data of a pronounced segregation of the sexes during migration, where the pregnant females generally arrive and depart from feeding areas earlier than males.
Sei whales are not often found near coasts and the species is infrequently recorded in Australian waters, with records only occurring from Western Australia, South Australia, Tasmania and Queensland.
Habitat critical to the survival of blue, fin and sei whales
It is not currently possible to define habitat critical to the survival of blue, fin and sei whales. Due to the limited knowledge about the distribution and abundance of these species, little is currently known about the location and characteristics of these habitats. To date the best information relates to aggregation areas (in particular feeding areas) for blue whales. These areas can be considered important to the survival of blue whales as they seasonally support significant aggregations of whales, and those ecosystem processes on which blue whales rely.
Australian Antarctic waters are known to support feeding for all three species and should be considered as important to conserve. In Australian coastal waters, a number of areas are known to support aggregations of blue whales. Known feeding areas are listed in Table 1. Fin and sei whales have also been sighted in some of these areas but not enough information currently exists to suggest that they are important to the survival of these species. Significant aggregations of blue whales are also found at Geographe Bay in Western Australia, although the reasons for this are not currently known. Figure 1 illustrates the recognised aggregation areas for blue whales utilising Australian waters. It should be noted that the boundaries presented on the map are indicative only and there is inherent variability in the movements of the species.
Table 1: known feeding areas for blue whales within Australia’s main Exclusive Economic Zone.
Location
Feeding observed
Bonney upwelling, southeast SA to western Victorian waters
November to April
Duntroon Basin, SA
November to April
Perth Canyon off Rottnest Island, WA
December to April
True blues appear to feed mainly, if not exclusively, in the Antarctic. Pygmy blues, however, are not generally found in the Antarctic, and appear to feed in more temperate latitudes. It is more than likely that Australian records of blue whales, almost entirely in summer, are of pygmy blue whales.
Division BLUE, FIN AND SEI WHALE - Blue, Fin and Sei Whale Recovery Plan 2005-2010 - BLUE, FIN AND SEI WHALE | Zoe