Population trend
Trend
Sarpa salpa is considered to be underexploited in KwaZulu-Natal (van der Walt and Govender 1996). Catch per unit effort (CPUE) in KwaZulu-Natal increased between 1975–1977 and 1994-1996 from 0.22 fish/angler/day to 0.51 fish/angler/day but declined during 2009–2010 to 0.34 fish/angler/day (Joubert 1981, Mann et al. 1997, Dunlop 2011). However, this may be a result of subtle differences in survey design in the mentioned studies rather than a decrease in abundance (Dunlop 2011) and should therefore be viewed with caution. An increase in CPUE was also recorded on the Eastern Cape coast between 1985–1986 and 1994–1996 from 8.98 g/fisher/hr to 13.4 g/fisher/hr (Clarke and Buxton 1989, Brouwer 1997). Unpublished data from long-term monitoring of shore anglers' catches in KwaZulu-Natal (National Marine Linefish System) revealed a decrease in CPUE from 1985–2008 from 0.25 fish/angler to 0.1 fish/angler but this trend is likely to have been at least partially effected by the introduction of a daily bag limit of ten fish per angler per day introduced in 2005 (Mann and Dunlop 2013).
Fishing mortality was recorded at F=0.81 year-1 in Kwazulu-Natal from 1994-1995 with SBPR at 60% (van der Walt and Govender 1996). There was an increase in catch composition between 1975–1977 (20.3%) and 1994–1996 (42.9%) in Kwazulu-Natal but a subsequent decline from 2009–2010 (34%) (Joubert 1981, Mann et al. 1997, Dunlop 2011). As mentioned previously, minor differences in survey design by these studies may have resulted in the observed changes in percentage composition (Dunlop 2011). A slight increase was recorded between 1985-86 (21.5%) and 1994–1996 (23.1%) in the Southeastern Cape (Clarke and Buxton 1989, Brouwer 1997). A sex ratio (M:F) of 1.1:1 was recorded in KwaZulu-Natal from 1975–1977 (Joubert 1981) but a ratio of 1.6:1 was later recorded from 1994–1995 in KwaZulu-Natal (van der Walt and Mann 1998).
FAO landing statistics for the Mediterranean Sea show a steady increase over the last 50 years, with a peak in the early 1990s at around 4,000 tonnes and stabilizing at around 2,000 tonnes during the period from 1996 to 2005. This species is very common and very abundant in suitable habitats throughout its range in the Mediterranean Sea. In a study by Akyol and Ertosluk (2010), captures from the sea-cage farms along the coast of the Turkish Aegean Sea, were determined with the use of a special cage trap and trammel net. Hand or longlines and underwater harpoons, although rare, were also in use. This species was dominant and accounted for 10.2% of the total weight of one fish farm from 2004–2008. In the eastern Mediterranean Sea, there is some circumstantial evidence that this species is being displaced and out-competed by Siganus luridus and S. rivuluatus, both of which are herbivores and very successful Lessepsian migrants from the Red Sea (Lundberg et al. 2004). Sarpa salpa has since become very rare along the Lebanese coast despite the large numbers existing there in the 1930s (Bariche et al. 2004).
