NSW Scientific Committee - final determination
The Scientific Committee has found that:
1. The Southern Right Whale Eubalaena australis (Desmoulins, 1822) (family Balaenidae) is a large baleen whale growing to 18 m in length with mature females often slightly larger than males (Bannister et al. 1996). It has a dark grey to black body, white belly and distinguishable callosities on the head and lower jaw, which appear white due to large colonies of whale lice (cyamids). The head is large and narrow with a highly arched jawline that begins above the eye (Jefferson et al. 1993). The round body tapers to a relatively narrow tail stock, then extends into a broad tail, with flukes which form a wide triangle. Pectoral fins are short and paddle like and the species lacks a dorsal fin. Southern Right Whales have two completely separate blowholes which produce a distinctive V-shaped blow (DEH 2005). The smooth finless back and callosities make the Southern Right Whale distinguishable from other whale species also found in southern waters (DEH 2005).
2. Southern Right Whales migrate seasonally between summer feeding grounds in Antarctica and winter breeding (i.e. mating and calving) grounds around the coasts of southern Australia, New Zealand, South Africa and South America (DEH 2005). In Australia, Southern Right Whales are present between winter and spring along the southern coastline of mainland Australia (generally from Perth to Sydney) and around the entire Tasmanian coast, with the majority of whales occurring between Albany, WA, and Head of Bight, SA (DEH 2005). In eastern Australia there are occasional sightings from as far north as Hervey Bay, Queensland (Franklin & Burns 2005), perhaps representing a re-population of the species’ historic distribution (Allen & Bejder 2003; DEWHA 2010). The distribution of Southern Right Whales in Australian off-shore waters is not known (DEH 2005).
3. In NSW, the Southern Right Whale has been frequently observed close to shore, with the majority of sightings occurring from July to September around the southern and central NSW coastline (south of Newcastle) (Smith 2001; NSW Wildlife Atlas accessed April 2011).
4. The overall habitat requirements of Southern Right Whales are not well known (DEH 2005). Although poorly studied, foraging habitat for Southern Right Whales is thought to be the deeper, high productivity waters of the Southern Ocean from the sub-Antarctic to locations south of 60°S (Goodall & Galeazzi 1986; Ohsumi & Kasamatsu 1986; Bannister et al. 1997; Bannister et al. 1999). The species feeds on Antarctic krill Euphausia superba, copepods and the decapod Munida gregaria by filtering water through their baleen (Bannister et al. 1996). Southern Right Whales demonstrate fidelity to feeding sites, which is thought to limit or delay dispersal (DEH 2005; Valenzuela et al. 2009).
5. Observations of females with calves suggest breeding habitat is characterised by shallower waters (a depth of less than 5 m) with a sandy bottom (Payne 1986; Elwen & Best 2004a; Elwen & Best 2004b). However, current spatial patterns for calving in Australia are considered to be those of a remnant population and so occupied habitat may not represent preferentially selected locations (Pirzl 2008).
6. Large groups of Southern Right Whales may congregate in breeding areas, where whales that are not accompanied by calves engage in mating and socialising behaviours (Payne 1986; Burnell 2001). Reports of Southern Right Whales mating in NSW waters are rare (G. Ross pers. comm. 2010). Several records of suspected mating appear in the NSW Wildlife Atlas, including off Bermagui in 1993 and off Perpendicular Point (mid north coast of NSW) in 1999, however the only mating recorded with any certainty was observed in Sydney Harbour in 2004 (G. Ross pers. comm. 2010).
7. Southern Right Whales show a strong tendency to return to the same coastal sites to calve (Payne 1986; Burnell 2001; Pirzl 2008). Each year the majority (>90%) of calving in Australia occurs along the south-western Australian coast (from Cape Leeuwin, WA to Ceduna, SA), with less than 10% of the Australian population of females calving off the coasts of Tasmania, Victoria, New South Wales and eastern South Australia (Kemper et al. 1997). In NSW, Twofold Bay, Eden is considered to have been an important historic calving ground (Pirzl 2008). Intermittent calving (based on observations of mothers with very young calves) is still known to occur in Twofold Bay (DEH 2005) and there have been many records of new-born calves travelling with cows in NSW waters, including a sighting as far north as Woolgoolga (Smith 2001). However, there are no longer any sites in NSW that are considered to be regular calving grounds for the species (Pirzl 2008).
8. In Australia, peak breeding periods of the Southern Right Whale are from mid-July through to August (Burnell 2001). Gestation has been calculated as 11 to 12 months (Burnell 2001), but it may be up to two years (Payne 1986). Southern Right Whales generally have one calf every three years (Bannister et al. 1996). Calves are dependent on cows for 11 to 12 months after birth (Bannister et al. 1996). Age at sexual maturity for female Southern Right Whales is estimated to be eight years and life expectancy is estimated to be 57 years (Taylor et al. 2007). Generation length (IUCN 2010) for the Southern Right Whale has been estimated at around 29 years (Taylor et al. 2007).
9. During migration, Southern Right Whales are usually solitary, or cows may be accompanied by a dependent calf or occasionally a yearling offspring (Payne 1986; Burnell 2001). Migrations are known to occur over vast distances between feeding grounds and coastal calving and mating grounds (Bannister 2008). Movements east to west along the Australian south coast have also been documented (Hart et al. 1842; Burnell 2001). Habitat requirements of Southern Right Whales during migration are not known (DEH 2005), but the broad-scale range and occupancy patterns of southern right whales indicate that the entire coastline within their Australian range is an important movement corridor, despite some areas being less utilised (Pirzl 2008).
10. Southern Right Whales were subject to severe depletion across their range due to whaling in the late 18th and early 19th centuries (Braham & Rice 1984; Dawbin 1986; Tormosov et al. 1998), resulting in a very large reduction in abundance, and a contraction in range (DEH 2005; Pirzl 2008). Prior to harvesting, global populations of Southern Right Whales were estimated at between 60 000 and 100 000 animals (adults and calves) (IWC 2001; IWC 2009). In 1997, the global population was estimated at about 7000 (IWC 2001). Currently, due largely to apparently strong recovery off the coasts of Argentina/Brazil, South Africa and Australia, the global population is estimated to be around 16 000 (IWC 2010), or 16 to 27% of pre-exploitation levels. The current rate of increase in the Australian population has been estimated at about 7-8% per annum (Bannister 2008). However, this is based on work in south-western Australia where human population density and near-shore activity and infrastructure is low compared with south-eastern Australia. Southern Right Whales in New South Wales belong to south-eastern Australian stocks, which show significant genetic differentiation from south-western stocks, and should be considered as separate populations (Patenaude & Harcourt 2006; Carroll 2009; Carroll et al. in press). The south-eastern population is very small and is not considered to be recovering at the same rate as the south-western population (DEWHA 2010; R. Pirzl pers. comm. 2011).
11. There are no reliable data with which to determine current population trends in NSW. Based on aerial surveys conducted in the early 1990’s, and the known distribution of Southern Right Whales in eastern Australia, Smith (2001) has estimated the total number of Southern Right Whales now visiting NSW in any one year to be less than ten. However, in August 2010 an opportunistic aerial survey, in response to Southern Right Whale sightings in southern NSW, recorded 14 individuals (males, females and calves) in one day between Moruya and Narooma (G. Ross pers. comm. 2010). Although such observations are considered rare in NSW waters (G. Ross pers. comm. 2010), it suggests the population may be greater than 10. Nevertheless, based on other surveys in the NSW, incidental sightings, and comparing survey results from other areas across the species’ Australian range, the population in NSW is thought to be very low, not exceeding 100 mature individuals (G. Ross pers. comm. 2010; R. Harcourt pers. comm. 2010).
12. Calving range and occupancy of calving grounds has remained restricted, with whales not yet re-colonising many historically used sites, particularly in NSW (e.g. Twofold Bay) (Pirzl 2008; DEWHA 2010). The current Australian calving range shows an east-west and north-south contraction representing less than 25% of the species’ likely former calving range (Pirzl 2008). An estimated 26 to 34 coastal locations across Australia were regularly occupied historically, compared to five locations that are occupied now, a reduction of around 80–85%. No established calving grounds now occur in NSW (Pirzl 2008). As a result of strong philopatry and aggregation tendencies (Payne 1986, Burnell 2001; Pirzl 2008) the ability of Southern Right Whales to establish new calving sites is constrained and there has been no evidence of expansion in calving range since the end of exploitation (Pirzl 2008).
13. A limited calving range is likely to place the population at higher risk of impacts. Southern Right Whales are vulnerable to entanglement of marine debris as they spend around half the year migrating through coastal waters where there is much fishing activity (Clapham et al. 1999). Entanglements occur from a range of fishing techniques, including droplines, longlines, finfish farms, lines or ropes associated with traps and pots set to catch crustaceans, floats/buoys, floating fish cages and boat mooring lines (Best et al. 2001; Knowlton & Kraus 2001; Kemper et al. 2003; Shaughnessy et al. 2003; Kemper et al. 2008). ‘Entanglement in or ingestion of anthropogenic debris in marine and estuarine environments’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
14. In Australia, shark/bather protection netting is used seasonally in New South Wales and throughout the year in Queensland (north of the main distribution of the Southern Right Whale). There have been no recorded entanglements of Southern Right Whales in bather protection netting in Australia (Kempler et al. 2008), but Best et al. (2001) recorded one fatal and three nonfatal Southern Right Whale entanglements in similar netting in South Africa. ‘Death or injury to marine species following capture in shark control programs on ocean beaches’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
15. The Southern Right Whale is particularly susceptible to vessel collision, as the species sits low in the water, is difficult to see and spends much time in areas with high commercial and recreational marine traffic (G. Ross pers. comm. 2010). In 2009, a Southern Right Whale calf was killed when it was struck by a recreational boat user in Jervis Bay (G. Ross pers. comm. 2010).
16. Threats to the Southern Right Whale at breeding grounds include increased disturbance due to increases in commercial whale watching; construction of marinas, wharves or aquaculture infrastructure in sheltered areas; changes in water quality (e.g. from agricultural runoff or oil spills) and water flow regimes (e.g. altered currents at inshore habitat from dredging) (Smith 2001; DEH 2005). Although there is no information on the impact that human activities may be having on population recovery at calving grounds, none of the used grounds are located in areas of heavy infrastructure. By contrast, around 70% of the historically used calving grounds are currently associated with some form of infrastructure, including Twofold Bay (the only known historic calving ground in NSW), now the site of major industrial and shipping activity (Pirzl 2008).
17. Other potential threats to the Southern Right Whale include ingestion of marine debris such as plastic, and acoustic pollution (e.g. noise from marine vessels and seismic survey activity) which affects cetacean reactions, and may also disrupt the connectivity of coastal habitat, but the impact is not well researched in Southern Right Whales (Richardson et al. 1995; Smith 2001; DEH 2005). Hunting may pose a future potential threat to the species given the current pressure for the resumption of commercial whaling and/or the expansion of scientific whaling.
18. Climate and oceanographic change may affect habitat and food availability for the Southern Right Whale. The Southern Right Whale is most likely to be affected by climate change through the changes in sea ice extent and duration, which will subsequently affect the distribution and abundance of their main food source, krill and a rise in sea level may result in loss of coastal habitat such as nursery grounds and sheltering areas (IWC 2009). ‘Anthropogenic Climate Change’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
19. Although commercial harvesting of the Southern Right Whale has ceased, and populations both globally and in south-western Australia appear to be stable or increasing, the south-eastern Australian stock of Southern Right Whales has not shown the same level of recovery, and the breeding biology of the species means that any recovery will be protracted. Furthermore, there is no indication that the area of occupancy for calving grounds is anywhere near pre-exploitation levels, with predictions that the species may take at least a century to recover (Braham & Rice 1984). In addition, fishing, aquaculture, shipping and boating activities are expanding within the range of the species and it is inevitable that such activities will increasingly affect Southern Right Whales in the future.
20. Southern Right Whale Eubalaena australis (Desmoulins, 1822) is not eligible to be listed as a Critically Endangered species.
21. Southern Right Whale Eubalaena australis (Desmoulins, 1822) is eligible to be listed as an Endangered species as, in the opinion of the Scientific Committee, it is facing a very high risk of extinction in New South Wales in the near future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2010:
Clause 9 Low number of mature individuals of species
The total number of mature individuals of the species is observed, estimated or inferred to be:
|
(b) |
very low. |
Associate Professor Michelle Leishman
Chairperson
Scientific Committee
Proposed Gazettal date: 04/05/12
Exhibition period: 04/05/12 - 29/06/12
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