Red List of South African Species

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Least Concern (LC)
Assessors: Stephanie Plön Vic Cockcroft
Contributors: Claire Relton Shanan Atkins Ken Findlay Mike Meyer Herman Oosthuizen Simon Elwen
Reviewers: Matthew Child

Rationale

The species is suspected to be widespread and abundant and there have been no reported population declines or major threats identified that could cause a range-wide decline. Globally, it has been listed as Least Concern and, within the assessment region, it is not a conservation priority and therefore, the regional change from Data Deficient to Least Concern reflects the lack of major threats to the species. The most prominent threat to this species globally may be incidental capture in fishing gear and, although this is not considered a major threat to this species in the assessment region, Fraser’s Dolphins have become entangled in anti-shark nets off South Africa’s east coast. This threat should be monitored.

Regional population effects: Fraser’s Dolphin has a widespread, pantropical distribution, and although its seasonal migration patterns in southern Africa remain inconclusive, no barriers to dispersal have been recognised, thus rescue effects are possible.

Distribution

The distribution of L. hosei is suggested to be pantropical (Robison & Craddock 1983), and is widespread across the Pacific and Atlantic Oceans (Ross 1984), and the species has been documented in the Indian Ocean off South Africa’s east coast (Perrin et al. 1973), in Sri Lanka (Leatherwood & Reeves 1989), Madagascar (Perrin et al. 1994) and the Maldives (Anderson 1996). Although, sightings and strandings records from the east coast of South Africa show a temporal pattern (the majority occurred in summer; Findlay et al. 1992), there is insufficient data to infer the seasonal movements of this species within the assessment region (Ross 1984). Generally, this species appears to be limited to tropical and subtropical regions between 30°N and 30°S (Jefferson & Leatherwood 1994; Dolar 2002) across the three major ocean basins, thus reports from temperate areas may be extralimital records associated with uncommon environmental conditions (Perrin et al. 1994), such as the global El Niño event in 1983–1984.

In South Africa, this species primarily inhabits deep (> 1,000 m) waters off the east coast (north of 34.3°S) beyond the shelf-edge; and possibly has a localized occurrence, which is strongly affiliated with the subtropical Agulhas Current (Findlay et al. 1992). Stranding records of 14 individuals from South Africa stretch along the coastline in a distribution slightly longer than that described by sightings records (Skinner & Chimimba 2005).

Population trend

Trend

No global estimates or trends are available for Fraser’s Dolphins, and although some regional estimates exist for other areas (for example, there are 289,000 CV = 34% in the eastern tropical Pacific; Perrin et al. 1994), there are none for the assessment region. However, based on fairly  regular stranding records between 1990 and 2009, this pelagic species is unlikely to be rare within South African waters and no major population decline is suspected. By 1986, ten stranding events, including a total of 14 individuals, had been recorded on South Africa’s east coast, associated with the subtropical Agulhas Current (Findlay et al. 1992). Since 1990, an additional 13 Fraser’s Dolphins have been reported, of which two were bycatch in shark nets. Taylor et al. (2007) estimated a generation period of 11.1 years.

Threats

Fraser’s Dolphins are taken incidentally in a variety of fishing gear globally, for example, this species is commonly caught as bycatch in the driftnet fishery off the Philippines (Dolar 1994), and in purse-seine fisheries of the eastern tropical Pacific. In South Africa there appears to be no significant fisheries involvement (Best 2007), although some are killed by anti-shark nets in South Africa (Cockcroft 1990; Perrin et al. 1994).

Considering that this is a deep-diving, offshore species, it is likely that this species may be vulnerable to the effects of marine noise pollution, for example, those produced by navy sonar and seismic exploration. Additionally, as cephalopods constitute a large proportion of the diet of Fraser’s Dolphins, it is likely that the increasing risk of plastic pollution may threaten this species due to accidental ingestion.

Uses and trade

Although Fraser’s Dolphins are exploited by small-scale subsistence fisheries in the Indo-Pacific, and in drive fisheries of Taiwan (Perrin et al. 1994), there is no trade or use of this species within the assessment region.

Conservation

Fraser’s Dolphins are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and this species is protected by the Marine Living Resources Act (No. 18 of 1998) of the national legislation. No species-specific conservation measures have been identified. However, estimates of population size and trends are needed to determine the status of this species in South African waters. Research is required to assess the impacts and trends of potential threats. This species may benefit from a reduction in the length, modification or compete removal of anti-shark nets off South Africa’s east coast, as recommended for Stenella spp.  

Recommendations for managers and practitioners:
  • The severity of threats, as well as the potential synergistic effects of those threats on this species, requires investigation.
  • Sightings, strandings and bycatch data should be recorded, especially during ship-based surveys aimed at other cetacean species, as well as pelagic commercial fisheries and marine tour operators.
Research priorities:
  • Data on population size and trends, and on subpopulation substructure, could influence the listing of this species, and it may require reassessment as new data emerge.
  • Data pertaining to the species’ distribution patterns and the severity of potential threats that could affect the listing of this species.
Encouraged citizen actions:
  • Use information dispensed by the South African Sustainable Seafood Initiative (SASSI) to make good choices when buying fish in shops and restaurants, e.g. wwfsa.mobi, FishMS 0794998795.
  • Save electricity and fuel to mitigate CO2 emissions and hence rate of climate change.
  • Buy local products that have not been shipped.
  • Report sightings on virtual museum platforms (for example, iSpot and MammalMAP) to help with mapping geographical distribution.
  • Avoid using plastic bags.  

References 

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 author = {Skinner, J.D. and Chimimba, C.T.},
 publisher = {Cambridge University Press, United Kingdom},
 title = {The Mammals of the Southern African Subregion},
 year = {2005}
}
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 booktitle = {Minke Whales <i>Balaenoptera acutorostrata</i> and <i>B. bonaerensis</i>},
 editor = {Perrin, W.F. and Brownell, R.L},
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}
,@electronic{2474,
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 author = {Committee on Taxonomy},
 publisher = {Society for Marine Mammalogy},
 title = {List of marine mammal species and subspecies},
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}
,@techreport{2475,
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 title = {Generation length and percent mature estimates for IUCN assessments of cetaceans},
 year = {2007}
}
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 author = {Best, P.B.},
 publisher = {Cambridge University Press},
 title = {Whales and Dolphins of the Southern African Subregion},
 year = {2007}
}
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}
,@article{2762,
 author = {Findlay KP, Best PB, Ross GJB, Cockcroft VG.},
 journal = {South African Journal of Marine Science},
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 author = {},
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 editor = {Best, P.B. and Abernethy, R.B.},
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}
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 title = {Marine mammal research and conservation in Sri Lanka 1985– 1986.},
 year = {1989}
}
,@article{11140,
 author = {Dolar, M. L. L., Walker, W. A., Kooyman, G. L. and Perrin, W. F.},
 journal = {Marine Mammal Science},
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 pages = {1--19},
 title = {Comparative feeding ecology of spinner dolphins (<i>Stenella longirostris</i>) and Fraser's dolphins (<i>Lagenodelphis hosei</i>) in the Sulu Sea},
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}
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 journal = {Caribbean Journal of Science},
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}
,@article{11140,
 author = {Jefferson, T. A. and Leatherwood, S.},
 journal = {Mammalian Species},
 pages = {1--5},
 title = {<i>Lagenodelphis hosei</i>},
 volume = {470},
 year = {1994}
}
,@article{11140,
 author = {Anderson RC},
 journal = {Journal of South Asian Natural History},
 pages = {75--80},
 title = {First records of Fraser’s dolphin (<i>Lagenodelphis hosei</i>) from the Maldives},
 volume = {2},
 year = {1996}
}
,@article{11140,
 author = {Cockcroft VG},
 journal = {South African Journal of Wildlife Research},
 pages = {44--51},
 title = {Dolphin catches in the Natal shark nets, 1980–1988},
 volume = {20},
 year = {1990}
}
,@article{11140,
 author = {Dolar MLL},
 journal = {Report of the International Whaling Commission (Special Issue)},
 pages = {355--363},
 title = {Incidental takes of small cetaceans in fisheries in Palawan, central Visayas and northern Mindano in the Philippines},
 volume = {15},
 year = {1994}
}
,@phdthesis{11140,
 author = {Dolar MLL},
 school = {University of California},
 title = {Abundance, distribution and feeding ecology of small cetaceans in the eastern Sulu Sea and Tañon Strait, Philippines},
 year = {1999}
}
,@article{11140,
 author = {Perrin, W.F., Best, P., Dawbin, W.H., Balcomb, R., Gambell, R., and Ross, G.J.B.},
 journal = {Nature},
 pages = {345--350},
 title = {Rediscovery of Fraser’s dolphin <i>Lagenodelphis hosei</i>},
 volume = {241},
 year = {1973}
}
,@article{11140,
 author = {Robison BH, Craddock JE},
 journal = {Fishery Bulletin},
 pages = {283--289},
 title = {Mesopelagic fishes eaten by Fraser’s dolphin, <i>Lagenodelphis hosei</i>},
 volume = {81},
 year = {1983}
}
,@article{11140,
 author = {Tobayama TM, Nishiwaki M, Yang HC},
 journal = {Scientific Reports of the Whales Research Institute, Tokyo},
 pages = {251--263},
 title = {Records of Fraser’s Sarawak dolphin (<i>Lagenodelphis hosei</i>) in the western north Pacific},
 volume = {25},
 year = {1973}
}
,]
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