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The Petrus rupestris fishery has been closed since the implementation of a moratorium in 2012 (Department of Agriculture, Forest and Fisheries 2012). Petrus rupestris was historically an important recreational and commercial species in skiboat catches throughout its range (Penney et al. 1999, Griffiths 2000). In more recent years, this species formed a relatively small component of recreational and commercial skiboat catches in most areas except the Eastern Cape where it still comprised an important component if the catch (Smale and Buxton 1985, Hecht and Tilney 1989, Hecht and Buxton 1993, Penney and Wilke 1993, Fielding et al. 1994, Brouwer and Buxton 2002, Griffiths and Lamberth 2002, Fennessy et al. 2003, Donovan 2010). Historically, P. rupestris was taken by shore anglers in False Bay (Schoeman and Schoeman 1990) and taken on occasion by spearfishermen (van der Elst 1993). Petrus ruepstris has been reported in incidental catches from the inshore trawl fishery and shark longline fleet (DAFF unpublished data). Freezer vessels introduced in the early 1980s were equipped with high-precision navigational equipment and long-range capability and were able to effectively exploit previously unexploited populations of P. rupestris further offshore on the Agulhas Banks. This species rapidly became a highly prized fish and resulted in increased competition between vessels (S. Knobel and K. Kingma captains of freezer boats pers. comm.). Catch rates subsequently declined rapidly from about 15 kg per fisher per day in 1986 to around 2 kg per fisher per day since 1990 (Griffiths 2000).
CPUE declined by more than 90% throughout the 20th century (Griffiths 2000, Griffiths and Wilke 2002). A slight increase in CPUE was observed in the former Transkei between 1984 and 1992 (Hecht and Buxton 1993) but is thought that this was due to improved targeting on spawning aggregations on deep reefs (B. Mann, Oceanographic Research Institute pers. obs.). A similar increase in CPUE was recorded on the offshore Agulhas Banks during the 1980s and was due to improved targeting by larger freezer vessels but did not last long (Penney and Wilke 1993, Griffiths 2000, Griffiths and Wilke 2002). Nominal commercial skiboat CPUE data stored on the National Marine Linefish System showed a further 90% decline between 1985 and 2007 from 0.045 kg per man per hour to 0.005 kg per man per hour and commercial ski boat catches declined from 96 tonnes in 1991 to 1.9 tonnes in 2005 (National Marine Linefish System unpublished data). An additional analysis was conducted to corroborate these trends. Generalized Additive Models were fitted to standardize the probability of capturing P. rupestris along the South African coast by removing the effects of targeting and spatial and temporal variations (Winker and Attwood 2014). The modeling framework was based on approach described in Winker et al. (2013). The probability of capture is widely used for rare species and is considered to be more defensible than catch rates in weight because of it being less sensitive to management regulations such as catch restrictions by bag limits. The trends for the period 1985-2011 show that the capture probability of P.rupestris declined from 16% in 1985-86 to less than 1% 2010-2011 between Cape Point and Tsitsikamma and from 23% to less than 8% along the Eastern Cape and Kwazulu-Natal coast, corresponding to declines of more than 95% and 64% respectively. Percentage catch composition declined significantly in KwaZulu-Natal and Cape waters throughout the 20th century (Penney et al. 1999, Griffiths 2000). Catch composition of P. rupestris in the Port Alfred skiboat fishery indicated that this species declined from 44% to 3.3% to 9.9% for commercial catches and 15.3% to 4.6% to 5.1% for recreational fisheries for the periods 1985 to 1987, 1996 to 1998, and 2006 to 2008 for the "Sparid group" respectively (Hecht and Tilney 1989, Donovan 2010). Before 1970, a decline in the catch rates of adults was observed off northern Transkei and southern KwaZulu-Natal (van der Elst and Garratt 1984) and in the East London area (Winch 1999). Catch rates of higher trophic level reef fish declined substantially between the two fishery-independent surveys conducted from 1931 to 1933 and 1987 to 1993 off the Southern Cape with the decline in CPUE of P. rupestris at 84%. If the P. rupestris population had not been seeded by partially protected adult stocks on the offshore Agulhas Bank and Transkei, declines would have been much greater. Based on fishery-independent catch composition surveys from 1931 to 1933 conducted off the southern Cape, P. rupestris comprised 12% in the first survey and 6% in the second (Griffiths 2000).Petrus rupestris has undergone a coast-wise and seaward contraction in the range of adult abundance (Griffiths 2000). The status of the stock is <25% and is considered to be collapsed based on a CPUE decline >90% throughout the 20th century (Griffiths 2000, Griffiths and Wilke 2002) and it has been suggested that the P. rupestris stock has been reduced to <5% of the pristine level (Griffiths and Lamberth 2002). This species has also undergone a range contraction thought to be associated with a reduction in the population (van der Elst and Garratt 1984, van der Elst et al. 1992, Penney and Wilke 1993, Penney et al. 1999, Griffiths 2000). Large individuals of this species were commonly caught from the shore in the Southwestern Cape in the beginning of the 20th century, indicative of a seaward contraction in the adult distributional range (Biden 1930, Horne 1955, Burman 1989). Commercial fishermen along the South African coast have stated that catches of P. rupestris have declined dramatically in the past three decades (Smale 1988). Catch data from line-boats operating along the east coast and landing their catches in Durban support this overall decline (P.A. Garratt, Oceanographic Research Institute pers. comm.). During the early 1950s, P. rupestris became less abundant in the False Bay, Plettenberg Bay and Tsitsikamma areas (Schoeman 1957) which suggests that this trend was widely spread (Griffiths 2000). The Agulhas Banks provide spawning grounds for large adults and the demise of these individuals is likely to have had a negative impact on recruitment to the near-shore fishing grounds off the southern Cape and southwestern Cape (Griffiths 2000). Numbers of adult fish are still found in the Eastern Cape where they receive protection both in a number of MPAs and on deep reefs where they are difficult to access due to the strong prevailing Agulhas Current (Hecht and Buxton 1993).