Blue whale - endangered species listing

NSW Scientific Committee - final determination



The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Blue Whale,Balaenoptera musculus(Linnaeus, 1758), as an ENDANGERED SPECIES on Part 1 of Schedule 1 of the Act, and as a consequence, omit reference to the Blue Whale subspeciesBalaenoptera musculus musculus as an Endangered Species. Listing of Endangered species is provided for by Part 1 of the Act.

The Scientific Committee has found that:

1. The Blue Whale subspeciesBalaenoptera musculus musculus is currently listed as an Endangered Species on Schedule 1 Part 1 of the Threatened Species Conservation Act.

2. Recent authors recognise three Blue Whale subspecies (e.g. Clapham et al. 1999): in the Northern Hemisphere,B. m. musculus; and in the Southern Hemisphere, B. m. intermedia and the Pygmy Blue Whale, B. m. brevicauda. The 'true' Blue Whale subspecies musculus and intermedia are spatially disjunct, with each population migrating annually from winter breeding grounds in tropical and subtropical waters to summer feeding grounds in polar and subpolar waters (Yochem and Leatherwood 1985; Reilly and Thayer 1990). The Pygmy Blue Whale is known mainly from the southern Indian Ocean, the eastern South Atlantic and the western South Pacific (Kato et al. 1995). Blue Whales are extremely long-lived animals, with 'true' Blue Whales living up to 90 years and Pygmy Blue Whales to around 50 years (Warneke 1995).

3. There has been only one recorded Blue Whale stranding in New South Wales (NSW), that of a 'true' Blue Whale at Twofold Bay in 1908 (Mead 1985). Blue Whales have been sighted in or near NSW waters on several other occasions, mostly between Green Cape and Bermagui in October and November (Smith 2001). There are no confirmed records of Pygmy Blue Whales in NSW waters. However, it is likely that some of the Blue Whale sightings off the NSW coastline have been of Pygmy Blue Whales as it is the more common subspecies in adjacent Victorian waters (Warneke 1995).

4. Blue Whale populations have been severely depleted by whaling. Approximately 360 000 Blue Whales were taken in the Southern Hemisphere during the 20th century (Clapham et al. 1999). It was previously thought that Pygmy Blue Whales had been less depleted by whaling than other Blue Whale subspecies. Recent studies of the records of the Soviet pelagic whaling fleet have found that 9 359 Pygmy Blue Whales were harvested between 1946 to 1972 with only 10 reported to the International Whaling Commission (Zemsky et al. 1995; Mikhalev 1997).

5. The pre-whaling abundance of Blue Whales in the Southern Hemisphere has been estimated at between 150 000 to 240 000 (Gambell 1976; Butterworth and De Decker 1989). The current Southern Hemisphere 'true' Blue Whale and Pygmy Blue Whale populations have been estimated at 610 and 4 300 (respectively) (Butterworth et al. 1995). However, the deficiency of data for each subspecies limits the accuracy of these estimates.

6. Threats to Blue Whales that visit NSW waters include: collisions with large vessels; entanglement in fishing gear; pollution of habitat; bioaccumulation of toxins in body tissues; military operations; anthropogenic climate change; and competition with other krill-feeders such as Minke Whales, Balaenoptera acutorostrata (Smith 2001). Moreover, and despite the cessation of commercial whaling as a threat, Blue Whale numbers have been so severely depleted as to exacerbate their vulnerability to other threats.

In view of the above points, the Scientific Committee is of the opinion that the Blue Whale, Balaenoptera musculus, is likely to become extinct in nature in New South Wales unless the circumstances and factors threatening its survival or evolutionary development cease to operate.

Proposed Gazettal date: 24/05/02

Exhibition period: 24/05/02 - 28/06/02

References

Butterworth, D.S. and De Decker, J.B. (1989). 'Estimates of abundance for Antarctic Blue, Fin, Sei, Sperm, Humpback, Killer and Pilot Whales from the 1978/79 to 1985/86 IWC/IDCR sighting survey cruises. Report SC/41/020.' (International Whaling Commission Scientific Committee: Cambridge.)

Butterworth, D.S., Borchers, D.L., Chalis, S. and De Decker, J.B. (1995). 'Estimates of Abundance for Southern Hemisphere Blue, Fin, Sei, Humpback, Sperm, Killer and Pilot Whales From the 1978/79 to 1990/91 IWC/IDCR Sighting Survey Cruises, With Extrapolations to the Area South of 30°S for the First Five Species Based On Japanese Scouting Vessel Data. Report SC/46/SH24.' (International Whaling Commission Scientific Committee: Cambridge.)

Clapham, P.J., Young, S.B. and Brownell, R.L., Jr (1999). Baleen whales: conservation issues and the status of the most endangered populations. Mammal Review 29, 35-60.

Gambell, R. (1976). World whale stocks. Mammal Review 5, 41-53.

Kato, H., Miyashita, T. and Shimada, H. (1995). Segregation of two sub-species of the blue whale in the Southern Hemisphere. Report of the International Whaling Commission 45, 273-83.

Mead, T. (1985). 'Killers of Eden: The Killer Whales of Twofold Bay.' (Angus and Robertson: Sydney.)

Mikhalev, Y.A. (1997). Additional information about the catches of Soviet whaling fleet Sovietskaya Ukraina. Report of the International Whaling Commission 47, 147-50.

Reilly, S.B. and Thayer, V.G. (1990). Blue whale (Balaenoptera musculus) distribution in the eastern tropical Pacific. Marine Mammal Science 6, 265-77.

Smith, P. (2001). Review of the conservation status of marine mammals in New South Wales. Report to the NSW Scientific Committee.

Warneke, R.M. (1995). Other rorqual whales. In 'Mammals of Victoria: Distribution, Ecology and Conservation'. (Ed. P.W. Menkhorst.) pp. 304-6. (Oxford University Press: Melbourne.)

Yochem, P.K. and Leatherwood, S. (1985). Blue whale Balaenoptera musculus (Linnaeus 1758). In 'Handbook of Marine Mammals, Volume 3, The Sirenians and Baleen Whales'. (Eds S.H. Ridgway and R. Harrison.) pp. 193-240. (Academic Press: London.)

Zemsky, V.A., Berzin, A.A., Mikhalev, Y.A. and Tormosov, D.D. (1995). Soviet Antarctic pelagic whaling after WWII: review of actual catch data. Report of the International Whaling Commission 45, 131-5.

About the NSW Scientific Committee

Page last updated: 28 February 2011