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Holohalaelurus regani

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES CARCHARHINIFORMES SCYLIORHINIDAE

Scientific Name: Holohalaelurus regani
Species Authority: (Gilchrist, 1922)
Common Name(s):
English Izak Catshark
Synonym(s):
Scylliorhinus regani Gilchrist, 1922
Taxonomic Notes: The taxonomy of this genus has recently been reviewed (Human 2006) and there has been much confusion historically with other species of this genus in northeastern South Africa and southern Mozambique (with H. punctatus and a newly recognized species, H. favus Human 2006). Holohalaelurus favus was previously considered to be a subspecies of H. regani, however, it is distinct from H. regani. Holohalaelurus regani is treated here as it was originally described by Regan, with a distribution as defined below.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2009
Date Assessed: 2007-01-17
Assessor(s): Human, B.
Reviewer(s): Cavanagh, R.D., Fowler, S.L., Stevens, J.D., Pollard, D., Dudley, S. & Valenti, S.V. (Shark Red List Authority)
Justification:
This catshark, endemic to Namibia and South Africa, is one of the few chondrichthyan species to show an increase in estimated population size in the presence of commercial fishing pressure, and as such, is assessed as Least Concern. Occurs on the continental shelf at depths of 100–500 m, and exceptionally from 40–910 m. This likely highly fecund species is present as a regular discarded bycatch (probably with high survival rates) in the trawl fishery that operates throughout its geographical range (although not throughout its entire depth range). Population monitoring of this species is essential however, because it is a regional endemic confined to a relatively limited range.

Geographic Range [top]

Range Description: Southern African endemic: ranging southwards from approximately 27°S (south of Lüderitz) in the southeast Atlantic off Namibia, continuing southwards and eastwards around South Africa and into the Western Indian Ocean, off Durban, South Africa (Bass et al. 1975, Compagno et al. 1991, Human 2006, Richardson et al. 2000).
Countries:
Native:
Namibia; South Africa
FAO Marine Fishing Areas:
Native:
Atlantic – southeast; Indian Ocean – western
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The Izak Catshark appears to have a minor seasonal migration occurring on the southernmost tip of the Algulhas Bank, South Africa, with sharks migrating closer inshore in autumn (and possibly summer?). On the west coast of South Africa, the mean biomass of H. regani increased from 1,606 t (for the period 1986–1993) to 3,012 t (1994–1999) as determined by periodic research trawl surveys in the area (Richardson et al. 2000). Biomass estimates for the south coast of South Africa are less well known due to non-periodic research trawl surveys in this area. Highest densities of this shark occur in areas where the continental shelf is broad.
Population Trend: Increasing

Habitat and Ecology [top]

Habitat and Ecology: H. regani is a benthic shark that occurs on the continental shelf from a depth of approx. 100–500 m, and exceptionally from 40–910 m (Human 2006, Richardson et al. 2000). There is marked sexual dimorphism in this species and the male is significantly larger than the female, an oddity in chondrichthyan fishes, where the opposite is normally true. Females mature between 40.0–45.0 cm total length (TL) and males mature between 45.0–50.0 cm TL. A single eggcase is found in each uterus in gravid females (single oviparity) and gravid females are present at all times of the year. Ovulation occurs when the ova reach 11 mm in diameter. Richardson et al. (2000) speculated that female fecundity may be high, with other species within the family Scyliorhinidae able to lay one egg pair every 15 days, this however remains to be confirmed for this species. Abundance of this species suggests that H. regani is highly fecund.
Systems: Marine

Threats [top]

Major Threat(s): There appear to be no threats for this species in the immediate future. A demersal trawl fishery for hake exists within the known range of H. regani, fishing between 200 and 600 m on the Agulhas Bank, south of Cape Town, South Africa. The Izak Catshark is a discarded bycatch species of this fishery. Survival rates are likely to be high due to the increase in biomass, in the presence of this trawl fishery, reported for this species by Richardson et al. (2000). Although biomass of H. regani has increased in recent times, it is endemic to a small area and could therefore be threatened by habitat degradation and localised catastrophic events.

Conservation Actions [top]

Conservation Actions: Appropriate monitoring of this species in the research trawl surveys that are regularly conducted in the area are sufficient at this time. Currently no specific management for this species is in place, although, under the FAO International Plan of Action for the conservation and management of sharks (IPOA-Sharks), development of a shark management plan for all chondrichthyans is currently being considered in South Africa (finalisation and implementation of this plan should be considered a matter of priority and great urgency) and a shark management plan has recently been implemented in Namibia (Anon 2004).

Citation: Human, B. 2009. Holohalaelurus regani. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 02 August 2014.
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