|Scientific Name:||Pachymetopon grande Günther, 1859|
Pachymetopon glaucum Norman, 1935
Pachymetopon guentheri Steindachner, 1869
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Mann, B.Q., Buxton, C.D. & Carpenter, K.E.|
|Reviewer(s):||Russell, B. & Pollard, D.|
|Contributor(s):||Gorman, C. & Comeros-Raynal, M.|
The bronze seabream (Pachymetopon grande) is a South African endemic that inhabits shallow intertidal rocky shores and reefs to 25 m depth. This species exhibits life history characteristics that exacerbate its vulnerability to overexploitation, including slow growth, late maturation, longevity, high residency, and limited geographical range. Pachymetopon grande is targeted by recreational and subsistence fisheries but is prohibited for commercial fishers (no sale). It is afforded some protection by the established Marine Protected Area (MPA) network which has proven to be a very effective in the conservation of this species. Independent fishery survey data in the Eastern Cape indicated a decline of almost 30% in seven years; however, as available data are somewhat sparse, these trends should be viewed with caution. CPUE from 1998 to 2005 fluctuated in Tsitsikamma National Park MPA with a 55.5% decline recorded from 2001 to 2002, fluctuating in subsequent years as well. This species experienced declines of almost 30% in seven years and appears to have been relatively stable since then. Therefore, we infer that this species experienced declines approaching 30% within three generation lengths (33 years), almost reaching the thresholds of Vulnerable under criterion A2bd, and may be subject to habitat degradation as P. grande inhabits shallow water environments. It is therefore listed at Near Threatened.
|Range Description:||Pachymetopon grande is endemic to southern Africa and is currently known from the southern Mozambique to Struisbaai, Western Cape (Fischer and Bianchi 1984, Smith and Heemstra 1991, van der Elst 1993, Heemstra and Heemstra 2004). Reports of this species from Madagascar need to be verified (Heemstra and Heemstra 2004). Fishing records and underwater fish visual census surveys have not recorded this species further north than Richards Bay, KwaZulu-Natal, and show the southern distribution is as far south as Cape Agulhas (B. Mann pers. comm. 2009). The depth range for P. grande is from shallow intertidal areas down to 25 m (Buxton and Clarke 1992).|
|FAO Marine Fishing Areas:|
Atlantic – southeast; Indian Ocean – western
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||A 29% reduction in catch per unit effort (CPUE) for P. grande was observed in the Port Elizabeth area from 12.6 g/person/hour in 1989 (Clarke and Buxton 1989) to nine g/person/hour in 1996 (Brouwer 1997 ). Recreational catch data from the National Marine Linefish System (NMLS) shore patrols in KwaZulu-Natal from 1985 to 2008 show a slight decline in from 0.003 to 0.002 fish/angler/day (NMLS unpublished data). However, these data are relatively sparse and should be viewed with caution. CPUE in the Tsitsikamma National Park is 4.8 times higher than CPUE in exploited areas of the Eastern Cape (Cowley et al. 2002). Mean CPUE caught by research anglers in the Tsitikamma National Park MPA for the years from 1998 through 2005 fluctuated ranging from 0.028 fish angler–1 h–1 (1998 and 2002) to 0.063 fish angler–1 h–1 (2001) (James et al. 2012); indicating a 55.5% decline in CPUE from 2001 to 2002 but slightly increased in 2003 and then fluctuated in subsequent years. CPUE from the spearfishery in KwaZulu-Natal from 1989 to 1987 and 2002 to 2007 at Ballito and Scottburgh did not show significant changes in abundance (Lloyd et al. 2012). |
The increase observed in annual contribution to catch by competitive shore anglers in KwaZulu-Natal and Transkei from 1977 to 2000 is attributed to a shift in targeting and changes in fishing techniques (Pradervand 2004, 2007). Pachymetopon grande was the most important species in terms of biomass in the shore fishery along the Transkei coast, accounting for 26% of the catches of 760 fishers checked (Mann et al. 2003). Pachymetopon grande was one of the most abundant species caught in the Dwesa-Cwebe MPA (Venter and Mann 2012). Pachymetopon grande was one of the most common species by number in angler's catches from Angling Week competitions between 1999 and 2010 with a catch composition of 9.6% with 99.6% of the catch mature. This species was one of the few that exhibited a decreasing trend in CPUE (Dicken et al. 2012).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
Pachymetopon grande is a highly resident species (Cowley 1999, Cowley et al. 2002, ORI Tagging project unpublished data) that inhabits shallow intertidal rocky shores and reefs to 25 m depth (Beckley and Buxton 1989, Buxton and Clarke 1992, Mann et al. 2006). Juveniles of this species inhabit subtidal gullies and shallow subtidal reefs <10 m (Beckley and Buxton 1989, Smale and Buxton 1989, Buxton and Clarke 1992, Heemstra and Heemstra 2004, Mann et al. 2006). This species is an omnivorous browser that feeds on algae and small invertebrates (Smith and Heemstra 1991, King and Fraser 2002), while juveniles have a similar diet but also feed on small crustaceans, including amphipods, which comprise a major component of the juvenile diet (Clarke 1988, Buxton and Clarke 1992).
Pachymetopon grande is a slow growing species that can reach an age in excess of 38 years (Buxton and Clarke 1992) and has a maximum recorded length of 74 cm TL (Booth and Attwood 2000). The maximum recorded weight for this species is 5.4 kg (SAUFF 2012).
ReproductionPachymetopon grande is a late gonochorist, rudimentary hermaphrodite (Buxton and Garratt 1990, Buxton and Clarke 1992) with 50% maturity attained at around 5.5 years of age for both sexes and a length of 30 cm FL (Buxton and Clarke 1992). This species has a restricted breeding season between January and June in the Eastern Cape while spawning in KwaZulu-Natal takes place in winter (Connell 2012). Pachymetopon grande probably spawns in groups and spawning may take place in the early morning and evening (Connell 2012). Spawning probably occurs throughout the species' distribution inside the 30 m depth contour (Buxton and Clarke 1992, Mann et al. 2006, Connell 2012). This species exhibits characteristics that suggests group spawning; however, this is not confirmed (Buxton and Clarke 1992)
Generation length for P. grande is estimated to be 11 years, using the following equation for a gonochoristic fish species: Generation length = Σxlxmx/Σlxmx
|Generation Length (years):||11|
|Use and Trade:||Pachymetopon grande is an important species in the recreational shore fishery (Clarke and Buxton 1989, Brouwer et al. 1997, Mann et al. 2003, Pradervand and Govender 2003, Pradervand 2007), spearfishery (Mann et al. 1997, Lloyd et al. 2012), and is occasionally caught in the skiboat fishery (Fennessy et al. 2003). This species is particularly important in recreational and subsistence fisheries along the Transkei and southeastern Cape coasts (Brouwer and Buxton 2002, Mann et al. 2003, Pradervand 2004). Pachymetopon grande was ranked third in terms of landed biomass by shore-anglers in the Eastern Cape (Brouwer et al. 1997), and was ranked the second most targeted species, comprising 21% of the catch, by spear-fishers in the Eastern Cape and Western Cape (Mann et al. 1997).|
|Major Threat(s):||Although P. grande is not exploited commercially, it is heavily targeted by the recreational shore angling fishery and spearfishery (Clarke and Buxton 1989). It is also an important component of subsistence fisheries along the Eastern Cape coast (Brouwer 1997, Mann et al. 2003). This species has experienced population declines of almost 30% over around seven years, (Clarke and Buxton 1989, Brouwer 1997) and the intrinsic life history characteristics exhibited by P. grande, including late maturation, slow growth, high residency, and longevity, exacerbate this species' vulnerability to overexploitation. This species may also be vulnerable to habitat degradation from pollution and sedimentation, particularly in metropolitan areas.|
Current fisheries regulations for P. grande include a minimum size 30 cm TL and a daily bag limit two fish per person per day for both recreational and subsistence fishers (Department of Agriculture, Forestry, and Fisheries 2012). This species is present in several large MPAs on the South African coast, including de Hoop, Goukamma, Tsitsikamma, Sardinia Bay, Amathole, Dwesa-Cwebe and Pondoland MPAs (World Database of Protected Areas, accessed March 2014). MPAs are considered to be one of the most effective conservation tools for protecting stocks of this species (Buxton and Clarke 1992, Cowley et al. 2002, Venter and Mann 2012).
The role of the Tsitsikamma National Parkin the management of four important shore-angling fish, including P. grande, was evaluated by comparing shore angling catches along the southeastern Cape coast of South Africa with research catches (tag and release) in the park. Size frequency analyses revealed that the mean individual length and mass of the four species was significantly higher in Tsitsikamma than in the open access areas. CPUE data suggest that the P. grande was five times more abundant in Tsitsikamma while analysis of anglers' daily catches revealed that the current bag limits (five per person per day) were seldom reached or exceeded even within Tsitsikamma, indicating the ineffective nature of this restriction. This study confirms the value of marine protected areas as an effective tool for the management of these and other resident reef-associated fish that are vulnerable to overexploitation (Cowley et al. 2002).
Improved law enforcement is recommended to ensure regulation compliance as well as more focus on comprehensive catch and effort monitoring of this species, especially in the Eastern and Western Cape (Mwale and Cowley 2012).
|Citation:||Mann, B.Q., Buxton, C.D. & Carpenter, K.E. 2014. Pachymetopon grande. The IUCN Red List of Threatened Species 2014: e.T170208A1293651.Downloaded on 15 October 2018.|
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