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The Chrysoblephus cristiceps stock is currently considered to be collapsed (Buxton and Mann 2013). Per-recruit assessment showed that the C. cristiceps population off the Port Elizabeth area in the Eastern Cape had already collapsed in 1986 with a spawning biomass per recruit (SBPR) of ~5% in the Port Elizabeth area while SBPR was ~54% in the Tsitsikamma Coastal National Park (TCNP) (Buxton 1993). There is strong evidence to suggest that the catch per unit effort (CPUE) for C. cristiceps has declined throughout their distributional range except in the TCNP (Crawford and Crous 1982, Hecht and Tilney 1989, Buxton 1993, Griffiths 2000). Commercial linefish catches throughout the range of C. cristiceps from 1984 to 2007 indicate a decline in excess of 50% over a period of 23 years (National Marine Linefish System unpublished data). CPUE in the Port Alfred commercial linefishery declined significantly from 0.69 kg per fisher per hr to less than 0.1 kg per fisher per hr (decline of ~85%) from 1998 to 2007. The decline after 2005 is believed to be primarily due to the implementation of stricter fishing regulations including an increased minimum size limit of 40 cm TL and a reduced daily bag limit of one fish per person per day applying to both recreational and commercial fishers (Donovan 2010). For this reason, an additional analysis was conducted using Generalized Additive Models to standardize the probability of capturing C. cristiceps along the South African coast (Winker et al. 2014). The modelling framework was based on an approach described in Winker et al. (2013), which was developed to correct abundance index for the effects of targeting and spatial and seasonal variations. The probability of capture is widely used for rare species and is considered to be more defendable 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 1985-2010 show that the capture probability of C. cristiceps declined from 8% in 1985 to less than 0.1% in 2011 between Cape Point and Tsitsikamma, and from 24% to less than 0.1% along the Eastern Cape and KwaZulu-Natal coast, corresponding to declines of more than 95% across its South African range.
There has also been a drastic decline in the percentage composition by mass from ~65% from the 1940s to the 1960s to 2.5% in 1987 in the Port Alfred linefishery (Hecht and Tilney 1989). Similar declines have been observed in the southern Cape such as 11% in 1931 to 1933, to 2% in 1987 to 1993 (Griffiths 2000). A further decline in catch composition was also observed in the Port Alfred linefishery with C. cristiceps decreasing from an average of 28% of the sparid group from 1985 to 2001 to 8.5% between 2002 and 2007. The decrease in catch composition was partially a result of the increase in minimum landing size and the decrease in commercial and recreational bag limits in 2005 (Donovan 2010). Recent data show that the total commercial catch for this species has declined since 1992 from approximately 25 tonnes/annum to a current level of less than one tonne/annum since 2004.
There is strong evidence for growth overfishing in the form of a decrease in mean size and age-at-sex change in exploited areas (Hecht and Tilney 1989, Buxton 1993) as fish are recruited into the fishery before maturity. Buxton (1993) showed that sex ratio was skewed towards females and mean size was lower in exploited areas. The adult M:I:F sex ratio from 1978-1986 was 1:0.2:2.3 (East London area), 1:0.2:4.4 (Woody Cape to St Croix), 1:0.6:3.8 (Tsitskamma National Park) and 1:0:24 (Knsyna to Mossel bay) (Buxton 1993).
Chrysoblephus cristiceps is important to commercial and recreational skiboat linefisheries in the Eastern and Western Cape (Crawford and Crous 1982, Smale and Buxton 1985, Hecht and Tilney 1989). However, a decline in abundance and strict species-specific regulations have reduced the importance of this species in the commercial linefishery (Donovan 2010). This species is also taken by spearfishers that dive on deep reefs below 20 m depth (B. Mann, ORI pers. obs.).
The current fisheries regulations for Chrysoblephus cristiceps include a daily bag limit of one fish per person per day for both commercial and recreational fishers and a minimum size limit of 40 cm TL (Department of Agriculture, Forestry, and Fisheries 2012). This species is afforded some protection in several no-take MPAs on the South African coast including De Hoop, Goukamma, Tsitsikamma, Bird Island, East London MPAs, Dwesa-Cwebe and the Pondoland MPA (World Database of Protected Areas, accessed March 2014). The Tsitsikamma National Park has been shown to protect a higher abundance and a larger mean size of C. cristiceps than adjacent exploited areas (Buxton and Smale 1989; Buxton 1992, 1993). The De Hoop Marine Reserve and MPAs off East London probably also assist in protecting a portion of the C. cristiceps stock (Griffiths and Wilke 2002; M. Smale, PEM, pers. comm.). SBPR in an unexploited MPA was estimated to be ~54% while in an exploited area SBPR was estimated at ~5% (Buxton 1993) which indicates that MPAs can be effective tools in the protection of this species.