Overview

Hyperoodon planifrons – Flower, 1882

ANIMALIA – CHORDATA – MAMMALIA – ARTIODACTYLA – ZIPHIIDAE – Hyperoodon – planifrons 

Common Names: Southern Bottlenose Whale, Antarctic Bottlenose Whale, Flatheaded Bottlenose Whale (English), Suidelike stompneuswalvis (Afrikaans), Ballena A Nariz De Botella Del Sur (Spanish; Castilian), Ballena Hocico De Botella Del Sur (Spanish; Castilian), Hyperoodon Austral (French), Hyperoodon austral (French), Minami Tokkuri Kujira (Japanese), Ploskolobye Butylkonos (Russian)
Synonyms: No Synonyms 

Taxonomic Note:  

The Southern Bottlenose Whale forms an antitropical species pair with the Northern Bottlenose Whale, Hyperoodon ampullatus. Intraspecific variation in mitochondrial control region sequences of two specimens from New Zealand was 4.12% higher than for all other cetacean species, and higher than between the antitropical species pair Berardius bairdii and B. arnuxii (3.78%) (Dalebout et al. 1998). Also, the skull characters are very distinct between the two species. 

Red List Status: LC – Least Concern, (IUCN version 3.1) 

Assessment Information

Assessors: James, B.S.¹ & da Silva, J.M.²

Reviewers: Purdon, J.^3,4 & Patel, T.⁵

Institutions: ¹University of Cape Town, ²South African National Biodiversity Institute ³TUT Nature Conservation, ⁴University of Pretoria, ⁵Endangered Wildlife Trust

Previous Assessors & Reviewers: Relton, C., Cockcroft, V. & Hofmeyr, G.J.G. 

Previous Contributors: Elwen, S., Findlay, K., Meÿer, M., Oosthuizen, H., Plön, S. & Child, M.F. 

Assessment Rationale 

There is no information pertaining to the population abundance of beaked whales within the assessment region, and they are generally considered to be naturally rare. The main threats to this species are climate change, whaling, entanglement, persistent organic pollutants and toxic metals. In addition, marine noise pollution, usually in the form of seismic surveys, navy operations and marine construction, as well as plastic pollution, have been identified as emerging and escalating threats to beaked whales. Anecdotal evidence suggests that beaked whales are more vulnerable to marine noise (particularly mid-frequency active sonar) than other cetaceans. The compounding influences of these threats could potentially cause beaked whale population declines. The Southern Bottlenose Whale is the most abundant of all Ziphiidae species within South African waters and is the second most commonly sighted beaked whale. Data from the IWC circumpolar surveys places the national population at between 50,000 and 70,000 individuals with an estimated stable population trend and no major threat that could cause population decline. Although, similarly for the other beaked whales, marine noise pollution is considered a major emerging and intensifying threat, it is not projected to cause significant population decline of this abundant species. Thus, we list this species as Least Concern. 

Regional population effects: Beaked whales are wide-ranging, seasonally migrating species. Those present within South African waters in summer presumably spend winters in the southern oceans, thus there are no barriers to dispersal, and rescue effects are possible. 

Reasons for Change 

Reason(s) for Change in Red List Category from the Previous Assessment: No change 

Red List Index 

Red List Index: No change

Recommended citation: James BS & da Silva JM. 2025. A conservation assessment of Hyperoodon planifrons. In Patel T, Smith C, Roxburgh L, da Silva JM & Raimondo D, editors. The Red List of Mammals of South Africa, Eswatini and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.

Regional Distribution and occurrence

Geographic Range

H. planifronsoccurs predominantly south of 30°S (Ross 1984) in the southern oceans off Chile, South Africa, New Zealand, the Falkland Islands and extensively throughout Antarctic waters. Their range extends south to the South Shetland Islands (65°S), but they have also been frequently sighted between 60°S and the ice edge (Kasamatsu et al. 1988). Several sighting records were documented from the south-western Indian Ocean off the coast of South Africa between 35°S and 40°S in summer (Gambell et al. 1975) but appear consistently absent from this region in winter. Peak sightings records off the coast of Durban in February may indicate a northward migration route from the Antarctic region in summer (Sekiguchi et al. 1993). Very few strandings of this species have been recorded on the South African coast (Hofmeyr et al. 2014). 

Elevation / Depth / Depth Zones 

Elevation Lower Limit (in metres above sea level): (Not specified) 

Elevation Upper Limit (in metres above sea level): (Not specified) 

Depth Lower Limit (in metres below sea level): (Not specified) 

Depth Upper Limit (in metres below sea level): (Not specified) 

Depth Zone: (Not specified) 

Map

Figure 1. Distribution records for Southern Bottlenose Whale (Hyperoodon planifrons) within the assessment region (South Africa, Eswatini and Lesotho). Note that distribution data is obtained from multiple sources and records have not all been individually verified.

Biogeographic Realms 

Biogeographic Realm: Afrotropical, Antarctic, Australasian, Neotropical 

Occurrence 

Countries of Occurrence 

Country	Presence	Origin	Formerly Bred	Seasonality
Antarctica	Extant	Native	–	–
Argentina	Extant	Native	–	–
Australia	Extant	Native	–	–
Brazil	Extant	Native	–	–
Chile	Extant	Native	–	–
Falkland Islands (Malvinas)	Extant	Native	–	–
New Zealand	Extant	Native	–	–
South Africa	Extant	Native	–	–
Uruguay	Extant	Native	–	–

Large Marine Ecosystems (LME) Occurrence 

Large Marine Ecosystems: (Not specified) 

FAO Area Occurrence 

	Presence	Origin	Formerly Bred	Seasonality
41. Atlantic – southwest	Extant	Native	–	–
47. Atlantic – southeast	Extant	Native	–	–
48. Atlantic – Antarctic	Extant	Native	–	–
51. Indian Ocean – western	Extant	Native	–	–
57. Indian Ocean – eastern	Extant	Native	–	–
58. Indian Ocean – Antarctic	Extant	Native	–	–
81. Pacific – southwest	Extant	Native	–	–
87. Pacific – southeast	Extant	Native	–	–
88. Pacific – Antarctic	Extant	Native	–	–

Climate change

The specific effects of climate change on Southern bottlenose whales is currently unknown however it has been suggested that similar to other cetaceans, beaked whales will likely undergo extensive range shift towards higher latitudes where they may be exposed to additional stressors such as increased noise exposure, interactions with fisheries, incidence of disease outbreaks and risk of ship strikes as well as reduced prey availability (Feyrer et al. 2024). Drastic reductions in suitable habitat and available prey for beaked whales due to climate change may result in future population declines, which would be difficult to quantify give the scarcity of abundance, life history and population level information we currently have for many beaked whale species. 

Population

H. planifrons is the most commonly sighted Ziphiidae species in Antarctic waters and is believed to be fairly abundant. In fact, of 599,300 (CV = 15%) beaked whales estimated south of the Antarctic Convergence in summer, the majority of these were probably Southern Bottlenose Whales (Kasamatsu & Joyce 1995). Furthermore, Barlow (1999) suggests that this abundance estimate is more than likely an underestimate, considering that the methods used for this estimate did not consider the deep-diving behaviour of this species nor their inconspicuous nature when surfacing. Within the assessment region, there are many records of this species in Durban, from whaling data and aerial sighting data (1972-1975). The IWC circumpolar surveys estimated an Antarctic population size of 55,000 in 1997/98. This species is thought to be the most abundant Ziphiid within the assessment region and the second most frequently sighted beaked whale globally.

Continuing decline in mature individuals? (Not specified) 

Extreme fluctuations in the number of subpopulations: (Not specified) 

Continuing decline in number of subpopulations: (Not specified) 

All individuals in one subpopulation: (Not specified) 

Number of mature individuals in largest subpopulation: (Not specified) 

Number of Subpopulations: (Not specified) 

Quantitative Analysis 

Probability of extinction in the wild within 3 generations or 10 years, whichever is longer, maximum 100 years: (Not specified) 

Probability of extinction in the wild within 5 generations or 20 years, whichever is longer, maximum 100 years: (Not specified) 

Probability of extinction in the wild within 100 years: (Not specified) 

Population Genetics

While phylogenetic investigations have been conducted on this species, no population genetic studies exist for species within the assessment region. It is however assumed to exist as a genetic metapopulation within the region.  

While outdated, population estimates suggest that over 55,000 individuals of this species exist in Antarctic waters. From this we can provide a broad estimate of the effective population size of the population using an Ne/Nc conversion ratio of 0.1-0.3. This yields a value of over 5,500 individuals, far exceeding the accepted Ne threshold of 500 to indicate a genetically healthy and stable population. 

It would be beneficial to confirm the genetic structure and diversity using finescale molecular techniques.  

Based on this information, two genetic diversity indicators in the Convention in Biological Diversity’s Global Biodiversity Framework can be quantified. The complementary indicator – proportion of populations remaining – would receive a score of 1.0 as 1/1 population remains (no genetically distinct subpopulations are noted or expected to have gone extinct), and the headline indicator – proportion of populations with an Ne > 500 – would also receive a score of 1.0, as the one population exceeds the 500 threshold based on proxy data for genetic diversity.  

Habitats and ecology

During the summer, H. planifrons is associated most frequently with regions within 100 km of the Antarctic ice edge. Generally, they prefer deep waters beyond the continental shelf, usually more than 1,000 m deep, and are considered rare in waters shallower than 200 m. They have also been documented in the steep thermocline, where the Agulhas Current and Antarctic waters meet (Cockcroft et al. 1990). Species occurrence models however suggest that there is a high probability of occurrence for H. planifrons along much of the South African east coast primarily linked to sea surface temperature, chlorophyll α concentration, bathymetry and distance to shore (Purdon et al. 2020). Analyses of the stomach contents of this species have revealed that squid forms the major constituent of their diets (Ross 1984; Sekiguchi et al. 1993; Slip et al. 1995). Sekiguchi et al. (1993) found the remains of four Antarctic squid and four subantarctic squid in the stomachs of two individuals stranded in January, which indicated a recent migration from the Southern Ocean to South African waters in summer. Stable isotope analyses suggests that this species may also be consuming Antarctic benthopelagic fish in addition to squid (Riccialdelli et al. 2017). Sightings of calves, approximately 3.5 m long, in January suggests that calving may take pace during the early summer months (Ross 1984).  

IUCN Habitats Classification Scheme 

Habitat	Season	Suitability	Major Importance?
10.1. Marine Oceanic -> Marine Oceanic – Epipelagic (0-200m)	–	Marginal	–
10.2. Marine Oceanic -> Marine Oceanic – Mesopelagic (200-1000m)	–	Suitable	Yes
10.3. Marine Oceanic -> Marine Oceanic – Bathypelagic (1000-4000m)	–	Suitable	Yes

Life History 

(Best, 2007) 

Generation Length: (Not specified) 

Age at Maturity: Female or unspecified: (Not specified) 

Age at Maturity: Male: (Not specified) 

Size at Maturity (in cms): Female: (Not specified) 

Size at Maturity (in cms): Male: (Not specified) 

Longevity: (Not specified) 

Average Reproductive Age: (Not specified) 

Maximum Size (in cms): (Not specified) 

Size at Birth (in cms): (320 cm) 

Gestation Time: (12 months) 

Reproductive Periodicity: (Not specified) 

Average Annual Fecundity or Litter Size: (Not specified) 

Natural Mortality: (Not specified) 

Does the species lay eggs? (Not specified) 

Does the species give birth to live young: (Not specified) 

Does the species exhibit parthenogenesis: (Not specified) 

Does the species have a free-living larval stage? (Not specified) 

Does the species require water for breeding? (Not specified) 

Movement Patterns 

Movement Patterns: (Not specified) 

Congregatory: (Not specified) 

Systems 

System: Marine 

General Use and Trade Information

In general, beaked whales in the southern hemisphere are not utilised or traded commercially. Additionally, a limited number of B. arnuxii and H. planifrons specimens have been taken for the purpose of scientific research (Jefferson et al. 1993). 

Local Livelihood: (Not specified) 

National Commercial Value: (Not specified) 

International Commercial Value: (Not specified) 

End Use: (Not specified) 

Is there harvest from captive/cultivated sources of this species? (Not specified) 

Harvest Trend Comments: (Not specified) 

Threats

There appear to be no widely distributed major threats to beaked whales. The impact of potential threats are unknown but, considering that most Ziphiidae species are naturally rare, especially within the assessment region, they may have unsustainable impacts on local populations and further research is required. According to Feyrer et al. (2024), the threats that southern bottlenose whales face are from climate change, whaling, entanglement, persistent organic pollutants and toxic metals. Even though beaked whales occur in remote habitats they are exposed to many threats which cumulatively could have a significant impact. 

Anthropogenic noise pollution has become an increasing and well-known threat to beaked whales, as they appear to be more vulnerable to high frequency noise pollution than other cetacean species (Dalebout et al. 2005). Several mass stranding events involving beaked whales have been attributed to high-powered navy sonar (Simmonds & Lopez-Jurado 1991; Mignucci-Giannoni 1996; Frantzis 1998, 2004; Balcomb & Claridge 2001; Jepson et al. 2003; Cox et al. 2006). Although the exact mechanistic causes are not clearly understood, the formation of gas bubbles (Fernández et al. 2005), appears to be attributed to sonar activities and noise pollution (Cox et al. 2006). Jepson et al. (2003) described the physiological damage, including acute and chronic tissue damage, inflicted on beaked whales by the deployment of military sonar at the Canary Islands. In 2004 a moratorium on naval activities in the Canary Islands was enforced by the Spanish government, and since then no mass stranding events have occurred in this area (Fernández et al. 2013). Within the assessment region, marine noise pollution is intensifying due to coastal industrial development, shipping traffic and energy exploration, and thus represents a potential threat. 

Plastic pollution is a large-scale and increasing problem in all marine environments. The ingestion of plastic marine pollution has been documented in several species of beaked whales and may eventually lead to mortality as a result of choking, a reduction in appetite or starvation (e.g. Scott et al. 2001).  

Accidental entanglement of beaked whales in fisheries is widespread, particularly in deep-water gillnets, although the number of recorded mortalities is not high. However, Southern Bottlenose Whales have been caught as bycatch in driftnet fisheries in the Tasmanian Sea (Jefferson et al. 1993). Extensive gillnet and longline fishing practises throughout the ranges of many beaked whales may become an increasing risk to these species as a result of accidental entrapment and drowning. 

The expansion of high-latitude fisheries, such as those directed at Antarctic Toothfish (Dissostichus mawsoni), which are largely unregulated and illegal, threaten the food stocks available for large cetaceans such as beaked whales. There is substantial evidence of large-scale reductions in many predatory fish populations (Baum et al. 2003, 2005; Polacheck 2006; Sibert et al. 2006), over-fishing and the collapse of several important “prey” fish stocks world-wide (e.g. Jackson et al. 2001). Although the effects of anthropogenic fish exploitation and the subsequent ecosystem changes on beaked whales is considered to be fairly low in comparison to other cetaceans in the Pacific Ocean (Trites et al. 1997), the degree of impact associated with high-latitude fisheries world-wide is largely unknown and could result in population declines. 

The marine-related threats associated with global climate change may pose unquantified and complex threats to beaked whales, particularly within cool temperate and cold Antarctic habitats (Learmonth et al. 2006). Increasing ocean temperatures may result in range shifts or contractions (Learmonth et al. 2006); however, no direct predictions pertaining to the direction or size of these shifts in range are currently known. 

Unlike many whale species, beaked whales have not experienced large-scale historic or recent exploitation for meat or other products. This may be attributed to their general scarcity and inconspicuous nature, deep-sea distributions and/or deep-diving behaviour. 

Conservation

More research into the distribution, abundance, migration patterns, bycatch rate and diet of beaked whales is essential for the effective development of species-specific mitigation measures for these species in South African waters. Mitigation measures associated with anthropogenic marine noise is probably most vital for Ziphiidae species locally and world-wide. The avoidance of beaked whale habitats in South African waters is currently challenging due to their wide distribution, and the lack of data pertaining to habitat preferences and geographical extent across this region. 

Passive acoustic monitoring is a valuable technique used to detect marine mammals to modify marine activities to avoid the animals, decrease the amplitude or temporarily stop the source of sound when animals are within a critical distance (Barlow & Gisiner 2006). Although beaked whales are acoustically difficult to detect, all species are assumed to give off echolocation clicks, some may also produce whistles (Dawson et al. 1998; MacLeod & D’Amico 2006). Generally, the clicks of Ziphiidae species are more narrow-banded than those of other marine mammals of a similar frequency, thus electronic filtering methods may be more effective than other methods (Barlow & Gisiner 2006). 

Maintaining sightings records of beaked whales, during ship-based surveys directed at other species, is a valuable means with which to monitor the distribution and abundance of these cryptic and unknown species in South African waters. 

All Ziphiidae species within the assessment region are listed either on Appendix I or II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Recommendations for managers and practitioners:  

• Critical beaked whale habitats, and areas of high beaked whale concentration should be identified, so as to effectively mitigate the effects of noise pollution.  
• Although species-specific monitoring is deemed unnecessary for Ziphiidae species in the assessment region, sightings data should be recorded during systematic monitoring of other cetacean species.  
• Establish a nationwide strandings network and databases (comprised of whale-watching operators, coastal protected areas, police stations, hotels, etc.) to gather and pool information.  

Research priorities:  

• Population size and trend estimates.  
• Effects of marine noise pollution and plastic pollution on beaked whale populations.  
• The identification of high concentration areas in South African waters, including distributional limits, seasonal movements and diving behaviour.  
• Diet, reproduction and general biology.  

Encouraged citizen actions:  

• Report strandings east of Mossel Bay to the Port Elizabeth Museum, and west of Mossel Bay to Iziko Museums, Cape Town.  
• Report sightings on virtual museum platforms (for example, iNaturalist and MammalMAP) to help with mapping geographical distribution.  
• Avoid using plastic bags.  
• Save electricity and fuel to mitigate CO₂ emissions and hence the rate of climate change.  

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