Overview

Mesoplodon hectori – (Gray, 1871)

ANIMALIA – CHORDATA – MAMMALIA – ARTIODACTYLA – ZIPHIIDAE – Mesoplodon – hectori 

Common Names: Hector’s Beaked Whale, New Zealand Beaked Whale, Skew-beaked Whale (English), Hector se Snoetwalvis (Afrikaans), Ballena De Pico De Héctor, Zifio De Héctor (Spanish; Castilian), Mésoplodon De Hector (French)
Synonyms: No Synonyms 

Taxonomic Note:  

Mitochondrial DNA evidence revealed that stranded specimens from the eastern North Pacific previously identified as M. hectori were a new species of Mesoplodon subsequently described as M. perrini (Dalebout et al.2002).  

Red List Status: DD – Data Deficient, (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 current threats to this species include climate change, whaling and vessel strikes. 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. Except for the Southern Bottlenose Whale, beaked whales in the assessment region are listed as Data Deficient, which highlights the need for additional research, specifically on assessments of abundance, changes in abundance, distribution and anthropogenic threats, including marine noise pollution.  

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 Mesoplodon hectori. 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

M.hectori has been documented (mostly via strandings data) within temperate waters from southern South America, New Zealand, Tasmania, southern Australia, the Falkland Islands and South Africa. Their distribution is expected to be continuous in the Atlantic and Indian Oceans, although there appears to be a discontinuity in their range from the central and eastern Pacific Ocean. Previous stranding records of this species in the eastern North Pacific (Mead 1981; Rice 1998), have now been reclassified as M. perrini (Perrin’s Beaked Whale), thus it is no longer considered present within the northern hemisphere (Dalebout et al. 2002). Within the assessment region, the only formally documented records are from two immature individuals from the Lottering River mouth, near Plettenberg Bay (Ross 1970), and a stranding on Sedgefield beach in April 1987 (V. Cockcroft unpubl. data). 

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 Hector’s Beaked Whale (Mesoplodon hectori) 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, Australasian, Neotropical 

Occurrence 

Countries of Occurrence 

Country	Presence	Origin	Formerly Bred	Seasonality
Argentina	Extant	Native	–	–
Argentina -> Chubut	Extant	Native	–	–
Australia	Extant	Native	–	–
Australia -> Coral Sea Is. Territory	Extant	Native	–	–
Australia -> Lord Howe Is.	Extant	Native	–	–
Australia -> Tasmania	Extant	Native	–	–
Brazil	Extant	Native	–	–
Brazil -> Rio Grande do Sul	Extant	Native	–	–
Chile	Extant	Native	–	–
Falkland Islands (Malvinas)	Extant	Native	–	–
New Zealand	Extant	Native	–	–
New Zealand -> Antipodean Is.	Extant	Native	–	–
New Zealand -> Chatham Is.	Extant	Native	–	–
New Zealand -> Kermadec Is.	Extant	Native	–	–
New Zealand -> North Is.	Extant	Native	–	–
New Zealand -> South Is.	Extant	Native	–	–
South Africa	Extant	Native	–	–
South Africa -> Eastern Cape Province	Extant	Native	–	–
South Africa -> Western Cape	Extant	Native	–	–
United States of America	Extant	Native	–	–
United States of America -> California	Extant	Native	–	–
Uruguay	Extant	Vagrant	–	–

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	–	–
57. Indian Ocean – eastern	Extant	Native	–	–
77. Pacific – eastern central	Extant	Native	–	–
81. Pacific – southwest	Extant	Native	–	–
87. Pacific – southeast	Extant	Native	–	–

Climate change

The specific effects of climate change on Hector’s beaked 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 information

There is very little information pertaining to the population abundances and trends of M. hectori as they are rarely sighted at sea. They are, however, considered fairly common in New Zealand waters, but uncommon elsewhere in the southern hemisphere.

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 analyses confirm the designation of this species within the genus, no population genetic studies have been undertaken. Despite this, its structure may be informed by what has been uncovered in other species within the genus, with the absence of population structure, especially within the assessment region, likely to be found. From this, one of the two genetic indicators in the Convention of Biological Diversity’s Global Biodiversity Framework can be quantified – the complementary indicator- proportion of populations maintained with a species. One population is anticipated for the region and no other subpopulations are thought to have gone extinct, therefore this indicator would receive a value of 1.0 (1/1 population remains) 

Habitats and ecology

Mesoplodon species occur commonly in deep-waters and along continental slopes, where prey availability may be enhanced by the interactions between ocean currents and topography (MacLeod & Zuur 2005). Beaked whales are believed to be suction feeders (Heyning & Mead 1996), feeding predominantly on squid and deep-water fish. Very low stable isotope concentrations of δ13C and δ15N for M. hectori suggest it occupies a similar ecological niche to Berardius arnuxii (Riccialdelli et al. 2017).  

Ecosystem and cultural services: Marine mammals integrate and reflect ecological variation across large spatial and long temporal scales, and therefore they are prime sentinels of marine ecosystem change; migratory whales may be used to investigate broad-scale shifts in ecosystems (Moore 2008). 

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 

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): (Not specified) 

Gestation Time: (Not specified) 

Reproductive Periodicity: (Not specified) 

Average Annual Fecundity or Litter Size: (Not specified) 

Natural Mortality: (Not specified) 

Breeding Strategy 

Does the species lay eggs?

No

 

Does the species give birth to live young

Yes

 

Does the species exhibit parthenogenesis

No

 

Does the species have a free-living larval stage?

No

 

Does the species require water for breeding?

Yes

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.  

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. The current threats to this species include climate change, whaling and vessel strikes (Feyrer et al. 2024). 

Anthropogenic noise pollution has become an increasing and well-known threat to beaked whales, as they appear to be more vulnerable to noise pollution than other cetacean species (Dalebout et al. 2005). A number of 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 potentially severe 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 because 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 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 shift or contraction (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 in order to modify marine activities so as 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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