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Cymatoceps nasutus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Sparidae

Scientific Name: Cymatoceps nasutus
Species Authority: (Castelnau, 1861)
Common Name(s):
English Black Musselcracker, Musselcracker, Poenskop Seabream
French Spare Nasique
Spanish Sargo Narigón
Synonym(s):
Chrysophrys nasutus Castelnau, 1861
Pagrus nigripinnis Boulenger, 1903

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2bd ver 3.1
Year Published: 2014
Date Assessed: 2009-11-15
Assessor(s): Mann, B.Q., Buxton, C.D. & Carpenter, K.E.
Reviewer(s): Russell, B. & Pollard, D.
Facilitator/Compiler(s): Gorman, C. & Comeros-Raynal, M.
Justification:
Cymatoceps nasutus is a South African endemic that inhabits inshore and offshore reefs to 80 m depth. This species exhibits many life history traits that make it vulnerable to overexploitation, including longevity, slow growth, limited range, hermaphroditism, large bodied, apex predator, and high residency. This species was heavily exploited throughout the 20th century and has experienced population decline, decrease in mean size, and skewed sex ratios as a result of the removal of large males. Although C. nasutus only comprises a small component of the commercial line-fishery, significant declines in catch and CPUE have been observed. MPAs play a major role in the conservation of this species as indicated by the increasing trend in abundance of C. nasutus in protected areas. The de-commercialization of C. nasutus, implementation of a slot size limit, and the retention of no-take status in the existing MPA network are recommended. Targeted commercial effort data indicate that CPUE and catch declined significantly from the mid 1980s to the early 2000s and are indicative of a population decline of over 30% within three generation lengths (48 years). Although a formal stock assessment has not been conducted for this species, it is clear that this species has experienced significant declines in less than three generation lengths, and given the life history traits of this species, heavily skewed sex ratios and its dependence on MPAs, this species is at a higher risk of extinction. It is therefore assessed as Vulnerable under A2bd.

Geographic Range [top]

Range Description:Cymatoceps nasutus is endemic to South Africa and is found from Cape Agulhas, Western Cape to St. Lucia in KwaZulu-Natal (Fisher and Bianchi 1984, Smith and Heemstra 1991, B. Mann pers obs.). The depth range for this species is <10 m to 80 m (Buxton and Clarke 1989, King and Fraser 2001, B. Trow pers. comm.). In the Transkei, this species usually occurs in shallow water less than 40 m depth while in KwaZulu-Natal it is caught in deeper water between 40 m and 80 m depth (P. Garratt pers. comm.). The estimated area of occupancy (AOO) for this species is 23,139 km2.

This species was recorded to occur as far north as Maputo, Mozambique (van der Elst 1988); however, C. nasutus was not recorded in the commercial line-fishery or trap fishery in southern Mozambique in 1997 (Lichucha et al. 1999). It was also not recorded in the St Lucia and Maputaland Marine Reserves (Chater et al. 1993) but has been observed in commercial catches off St Lucia just south of the St Lucia Marine Reserve (B. Mann pers. obs.)
Countries occurrence:
Native:
Mozambique; South Africa
FAO Marine Fishing Areas:
Native:
Atlantic – southeast; Indian Ocean – western
Additional data:
Estimated area of occupancy (AOO) - km2:23139
Lower depth limit (metres):80
Upper depth limit (metres):10
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Cymatoceps nasutus was heavily exploited throughout the 20th century which has led to a decrease in abundance and mean size (Penney et al. 1999, Maggs et al. 2013). Although a formal stock assessment has not been undertaken for Cymatoceps nasutus, the trend in catch per unit effort (CPUE) has declined significantly in KwaZulu-Natal (Penney et al. 1999) and it is estimated that the stocks have declined to ~20% of their historical values (Griffiths and Lamberth 2002). CPUE of C. nasutus in Tsitskamma National Park showed an increase from 1998 to 2005 CPUE (Götz et al. 2008) while CPUE in the no-take zones of the Pondoland Marine Protected Area (MPA) was higher (0.37 fish/angler/hr) than in the adjacent exploited area (0.23 fish/angler/hr) from 2006 to 2011 (Maggs et al. 2013). Using targeted commercial effort data, there has been a significant decline in CPUE from 0.43 kg/man/hr in 1985 to 0.33 kg/man/hr in 2007 (National Marine Linefish System unpublished data). Increasing mean annual CPUE (~55%) over the last eight years (between 1998 and 2005) in Tsitsikamma National Park was recorded (James et al. 2012); however, this figure should be viewed with caution as the generation time for C. nasutus is 16 years. 

There was little change in total commercial catch between 1930–1933 (10 tonnes) and 1986–1987 (12 tonnes) in KwaZulu-Natal (Buxton and Clarke 1989). However, the total reported commercial catch for this species has declined from a peak of 25 tonnes in 1987 to less than four tonnes in 2003–2007 (National Marine Linefish System unpublished data). 

The trend in catch composition is also thought to have declined in KwaZulu-Natal similarly to other large, slow growing, endemic sparids (Penney et al. 1999). A significant decline in catch composition was recorded in the Transkei between 1984 and 1992 due to voluntary cessation of catch by commercial fishers (Hecht and Buxton 1993). 

Male to female sex ratios in the Eastern Cape were reported to be strongly biased in favour of females (1:6) (Buxton and Clarke 1989). Mean size of C. nasutus has decreased, with almost 100% of the current catch weighing less than five kg and catches of trophy fish by coastal recreational anglers that were once common are now extremely rare (Murray and Cowley 2012). Mean size of C. nasutus was significantly larger in the Pondoland MOA (41.7 cm FL) compared to the adjacent exploited area (38.0 cm FL) (Maggs et al. 2013). 

Commercial data show that since 2000, commercial fishing effort has declined dramatically in the South African line-fishery from approximately 3,000 to 450 vessels, in line with the long-term fisheries rights allocation process implemented in 2006 (Department of Agriculture, Forestry and Fisheries 2012).

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Cymatoceps nasutus is a solitary species with a generalist diet consisting primarily of molluscs, crustaceans, and echinoderms as adults (Buxton and Clarke 1989, Heemstra and Heemstra 2004). Adults of this species occur on deeper high-profile inshore and offshore reefs (Buxton and Smale 1984, Buxton and Clarke 1989, King and Fraser 2001) while juveniles use shallow sub-tidal reefs <10 m depth as nursery habitats (Buxton and Clarke 1989, Mann et al. 2006). Tag recapture data have shown that juveniles and sub-adults are extremely resident and, although limited, data on movements of larger adults does suggest an easterly movement up the coast (ORI Tagging Project unpublished data). Growth studies based on age determination of otoliths show that C. nasutus is slow growing and long lived with the oldest recorded age being 45.5 years (Buxton and Clarke 1989). The maximum length recorded for this species is 109.9 cm FL (Buxton and Clarke 1989) with a maximum weight of 37.8 kg (South African Deep Sea Angling Association 2012). 

Reproduction

Cymatoceps nasutus is assumed to be a protogynous hermaphrodite (Buxton and Clarke 1989) and data suggest that spawning occurs between May and October in Transkei waters (Buxton and Clarke 1989). The absence of reproductively active adults in the Western Cape suggests that there may be a northeasterly movement up the coast to Transkei and KwaZulu-Natal (Buxton and Clarke 1989). Size at 50% maturity is unknown for this species but the smallest reproductively active female collected by Buxton and Clarke (1989) was 53 cm FL, and age at 50% maturity is estimated to be ~10 years based on observed size at maturity. Sex change presumably takes place at approximately 70 cm FL and an age of ~18 years, with all individuals >95 cm FL being males (Buxton and Clarke 1989).

Generation length for C. nasutus is estimated to be 16 years, using the following equation for a protogynous fish species: Generation length =SR* (Σxlxmx/Σlxmx)+(Σlxmx/Σlxmx)
Systems:Marine
Generation Length (years):16

Use and Trade [top]

Use and Trade: Cymatoceps nasutus is caught by shore anglers and spearfishers, as well as recreational and commercial skiboat linefishers throughout its distribution (Coetzee and Baird 1981, Smale and Buxton 1985, Hecht and Tilney 1989, Mann et al. 1997, Brouwer and Buxton 2002, Fennessy et al. 2003, Mann et al. 2003). This species is sought after by recreational fishers but is of little commercial importance due to its low abundance, except in the Transkei where it comprised ~16% of total commercial landings in the Coffee Bay linefishery in 1985 (Smale and Buxton 1985, Clarke 1988, Buxton and Clarke 1989, Brouwer and Buxton 2002, Murray and Cowley 2012). In 1992, this figure dropped to less than 1%, which is most likely due to a voluntary abeyance of catch by commercial fishers (Smale and Buxton 1985, Hecht and Buxton 1993). Cymatoceps nasutus comprised ~0.25% of ski-boat catches in the southern parts of the Eastern Cape from 1979–1980 (Smale and Buxton 1985), with little change in the period 1994–1996 (0.14%) (Brouwer and Buxton 2002).

Threats [top]

Major Threat(s): Cymatoceps nasutus is extremely vulnerable to overexploitation due to its life history characteristics, including high residency, slow growth, late maturity, longevity, and hermaphroditism (Buxton and Clarke 1989). Their aggressive nature as dominant reef predators further accentuates their vulnerability to capture. Male and female sex ratios are heavily biased towards females, which is exacerbated by the removal of large males from the population (Murray and Cowley 2012). Although not known, is it suspected that females may be changing sex at a smaller length and a younger age as a result of overexploitation (T. Murray DIFS pers obs.).

Conservation Actions [top]

Conservation Actions: Cymatoceps nasutus is currently managed with a minimum size limit of 50 cm TL and a daily bag limit of one fish per person per day for all fishery sectors (Department of Agriculture, Forestry, and Fisheries 2012). This species also occurs in several large no-take MPAs on the South African coast including De Hoop, Goukamma, Tsitsikamma, Sardinia Bay, Bird Island, Dwesa and the Pondoland MPAs. The Tsitsikamma National Park has been shown to provide an important refuge for juveniles and sub-adults of C. nasutus (Buxton and Smale 1989, Götz et al. 2008). As the adults probably spawn in the area between East London and St Lucia, the only MPAs which provide protection for adults of this species are the Amathole MPA, Dwesa-Cwebe MPA and the Pondoland MPA (B. Mann ORI unpublished data). MPAs are extremely important for the conservation of this species, especially due to the highly resident behaviour exhibited by juveniles and sub-adults (Murray and Cowley 2012). Data from no-take MPAs show that C. nasutus is significantly more abundant and of a larger mean size than in adjacent exploited areas (Maggs et al. 2013), further supporting the importance of MPAs for the protection of this species. 

The consideration of de-commercializing C. nasutus is suggested due to its low importance in the commercial fishery. Also recommended is the introduction of a slot size limit between 50 cm to 70 cm TL, to protect small resident individuals <50 cm TL and large mature adults >70 cm TL (Murray and Cowley 2012).

Citation: Mann, B.Q., Buxton, C.D. & Carpenter, K.E. 2014. Cymatoceps nasutus. The IUCN Red List of Threatened Species 2014: e.T170204A1292756. . Downloaded on 17 August 2017.
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