SANBI

Rationale

Porcostoma dentata is of little commercial or recreational fishing importance with stable incidental CPUE over the last 22 years. It is commonly observed in underwater surveys and is present in several no-take marine protected areas and subject to effort controls. It is therefore listed as Least Concern.

Distribution

Porcostoma dentata is endemic to southern Africa and is known mainly between Beira in central Mozambique and Port St. John's on the east coast of South Africa from 10 to 120 m depth (Fischer and Bianchi 1984, Fennessy and Mann 2013). Strays reach as far south as Algoa Bay and small juveniles have occasionally been found as far south as Knysna in the Western Cape (Mann and Fennessy 2000, Heemstra and Heemstra 2004). It is most common on the southern Mozambique, KwaZulu-Natal and former Transkei coasts (Fennessy et al. 2003, Mann et al. 2006, Dunlop 2011)

Habitat View more ecological information

Population trend

Trend

Porcostoma dentata appears fairly regularly in the commercial and recreational skiboat catches along the KwaZulu-Natal and former Transkei skiboat fisheries (Fennessy et al. 2003, Dunlop 2011, Dunlop and Mann 2013). Little change has been observed in the KwaZulu-Natal recreational skiboat catches, having retained catch rates of 0.04 fish and 0.01 kg per outing from 1994 to 1996 and 0.02 fish and 0.01 kg per outing from 2008 to 2009 (Mann et al. 1997, Dunlop 2011). A slight decline was recorded in the KwaZulu-Natal commercial skiboat catches from 1985 (0.15 kg/man/hour) to 2007 (0.1 kg/man/hour) (South African National Marine Linefish System unpublished data). Catch composition remained fairly stable in the KwaZulu-Natal recreational ski-boat catches from 1994–1996 (0.5% by number and 0.1% by weight) to 2008–2009 (0.75% by number and 0.2% by weight). Proportions in commercial skiboat catches from KwaZulu-Natal declined from 1994–1996 (0.8% by number and 0.3% by weight) to 2008–2009 (0.01% by number and 0.01% by weight); however, the sample size was very small in the 1994–1996 study (Mann et al. 1997, Dunlop 2011). Commercial data show that since 2000 commercial fishing effort has declined dramatically in the South African linefishery from approximately 3,000 to 450 vessels as part of the long-term rights allocation process in 2006 (Department of Agriculture, Forestry and Fisheries 2012).

Threats

There are no major threats identified for this species.

Uses and trade

Small numbers of this species are commonly caught in the commercial and recreational skiboat linefishery in Mozambique, KwaZulu-Natal and the Eastern Cape, but because of its small size, it is of little importance (van der Elst 1988). It is often retained as a “take home” fish by the crew on commercial skiboats (S. Fennessy, ORI pers. obs.) and is often returned to the water by recreational skiboat anglers, and is therefore underrepresented in surveys of catches. Porcostoma dentata is not targeted, due to its small size, but is a common bycatch in catches made by the commercial and recreational ski-boat fisheries in KwaZulu-Natal and the former Transkei (Fennessy et al. 2003, Dunlop 2011). Although this species has not been recorded in the Mozambique semi-industrial or recreational fisheries, it probably does occur (S. Fennessy Oceanographic Research Institute pers. comm.).

Conservation

In South Africa, Porcostoma dentata was first included in the national linefish regulations in 1992 in terms of the Sea Fisheries (Act No. 12 of 1988) with a daily bag limit of five fish per person per day for recreational and subsistence fishers. This legislation was implemented as a precautionary measure but is unlimited for the commercial sector (Department of Agriculture, Forestry and Fisheries 2012). The establishment of large no-take MPAs such as the St Lucia and Maputaland MPAs in KwaZulu-Natal and the Pondoland MPA in the Eastern Cape, have also undoubtedly provided some protection for this species (Mann et al. 2006). It probably also receives some protection in the Ponta do Ouro Partial Marine Reserve in Mozambique (Fennessy and Mann 2013). Despite its reasonably small range this is a fairly common species which is still not specifically targeted due to its small size. The decline in commercial catch rates and catch composition may be an aberration in the data, which is confounded by lumping this species with other "red fish" in landed catches. All catches should be monitored as part of observer programs for all fisheries in which it occurs; fisheries-independent surveys (e.g. using baited cameras) may give a better idea of abundances since this species is not always recorded in formal landed catches (Fennessy and Mann 2013).

There is a need for additional information on the biology of this species.

References

[@techreport{2060,
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 author = {Mann, B.Q.},
 institution = {Southern African Association for Marine Biological Research Oceanographic Research Institute},
 title = {Southern African Marine Linefish Species Profiles},
 year = {2013}
}
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 address = {Cape Town},
 author = {van der Elst, R.},
 publisher = {Struik Publishers},
 title = {A guide to the common sea fishes of Southern Africa (2nd edition)},
 year = {1988}
}
,@inbook{12137,
 author = {},
 booktitle = {<i>Lithognathus lithognathus</i>},
 editor = {Lamberth, S.J.},
 pages = {156--158},
 publisher = {Special Publication Oceanographic Research Institute 7},
 title = {Southern African Marine Linefish Status Reports},
 year = {2000}
}
,@techreport{12137,
 author = {Mann, B.Q., Beckley, L.E. and R.P. van der Elst},
 institution = {Oceanographic Research Institute Unpublished Report 134},
 title = {Evaluation of linefishery participation and management along the KwaZulu-Natal coast},
 year = {1997}
}
,@techreport{12137,
 address = {Staatskoerant},
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 year = {2012}
}
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 author = {Dunlop, M.I.},
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}
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}
,@article{170184,
 author = {Fennessy, S.T., McDonald, A.M., Mann, B.Q. and Everett, B.I.},
 journal = {African Journal of Marine Science},
 pages = {61--78},
 title = {An assessment of the recreational and commercial skiboat fishery in the Transkei},
 volume = {25},
 year = {2003}
}
,@article{170184,
 author = {Dunlop, S.W. and Mann, B.Q.},
 journal = {African Journal of Marine Science},
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 pages = {79--97},
 title = {An assessment of the offshore boat-based linefishery in KwaZulu-Natal, South Africa},
 volume = {35},
 year = {2013}
}
,@article{170185,
 author = {Beckley, L.E. and Buxton, C.D.},
 journal = {Transactions of the Royal Society of Southern Africa},
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 title = {Underwater observations of reef fish in and around Algoa Bay, South Africa},
 volume = {47},
 year = {1989}
}
,]

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