Population trend
Trend
Currently, the Chrysoblephus puniceus stock in South Africa is considered to by optimally exploited and is showing recovery from severe depletion in the in the early 1990s. Since the reduction in commercial fishing effort between 2003-2006 this species has shown a c. 30% recovery in biomass (Winker et al. 2012).
Historic data show that commercial linefish catches off KwaZulu-Natal declined during the 20th Century from approximately 1,600 tonnes per annum in the early 1900s to around 800 tonnes per annum in the 1990s, despite substantial increases in fishing effort (Penney et al. 1999). Over the same period the overall catch per unit effort (CPUE) declined from around six tonnes/man/year to under one tonne/man/year (Penney et al. 1999). Through sequential target switching, more prized species in the South African linefishery such as Polysteganus undulosus and Petrus rupestris declined and C. puniceus gradually increased in percentage composition (Penney et al. 1999). Stock status indicators such as skewing of M:F sex ratios and a decline in mean size of C. puniceus throughout their distribution suggest that this species was overexploited. This has to a large extent been confirmed through per-recruit stock assessments (Punt et al. 1993, Lichucha 2001). The shared C. puniceus stock between KwaZulu-Natal and southern Mozambique (Duncan 2014) was heavily overexploited by the 1990s, with per-recruit assessments suggesting that spawning biomass per recruit (SBPR) had been reduced to 14-16% off KwaZulu-Natal (Punt et al. 1993), while off southern Mozambique SBPR was reduced to ~37% (Lichucha 2001). CPUE between 1985 and 2000 in the KwaZulu-Natal commercial linefishery was relatively stable at approximately one kg/man/hour but following the emergency declared in the South African linefishery in 2000 and the reduction in commercial effort from 2003 to 2006, standardized CPUE showed an increasing trend from one kg/man/hour to 1.4 kg/man/hour (Winker et al. 2012). Catch rates in the KwaZulu-Natal recreational ski-boat fishery have also shown an increase from 0.3 fish and 0.2 kg/outing (1994–1996) to 0.9 fish and 0.7 kg/outing (2008–2009) (Mann et al. 1997, Dunlop and Mann 2013). However, CPUE in southern Mozambique has continued to decline and some of the fishing fleet effort has moved northwards (Fennessy et al. 2012), beyond the distribution of this species, because of declining catch rates.
Mean size of C. puniceus in KwaZulu-Natal appears to have remained similar between 1979–1981 and 2007–2011 (Garratt 1985a, B. Mann ORI unpublished data). In southern Mozambique, however, a decrease in mean and modal size has been observed (Lichucha et al. 1999, Lichucha 2001, Fennessy et al. 2012).
This species contributes approximately 25% to 50% of the total commercial linefish catch and 10% to 15% of the recreational skiboat catch in KwaZulu-Natal (Mann et al. 1997, Penney et al. 1999, Dunlop and Mann 2013). This amounts to a total estimated catch of approximately 250 tonnes per annum (commercial and recreational combined). During the 1990s it also comprised approximately 11–21% of the total commercial catch in southern Mozambique taken by lineboats operating out of Maputo (van der Elst et al. 1994, Lichucha et al. 1999). The total C. puniceus catch in southern Mozambique would therefore be approximately 150 tonnes per annum (Lichucha et al. 1999).
Male:Female sex ratio is strongly skewed in favour of females, particularly in KwaZulu-Natal (1:19), which is thought to be a result of over-fishing (Garratt et al. 1993). In southern Mozambique the M:F sex ratio was less skewed between 1997 and 1999 with a ratio of 1:7 (Lichucha 2001) but it had changed considerably from that recorded by Garratt (1985a) in southern Mozambique between 1979 and 1981 which was 1:2.3.
Commercial data show that since 2000 commercial fishing effort has declined dramatically in the whole South African linefishery 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).
