Population trend
Trend
Grandcourt et al. (2004) compiled size frequency data for Argyrops spinifer in the southern Persian Gulf from commercial catches made off the coast of Emirate of Abu Dhabi in UAE between September 2000 and March 2003. Biological data were collected from individuals purchased from commercial catches between June 2002 and May 2003. Grandcourt et al. (2004) determined the mean size and age at first sexual maturity for females to be 26.9 cm LF and 2.4 years and for males, 26.7 cm LF and 2.4 years, respectively. Mean size at first capture was 12.1 cm LF, which was smaller than the size at which maximum yield per recruit occurs (27.4 cm LF) (Grandcourt et al. 2004). The size at which the probability of capture was 100% for Argyrops spinifer was estimated to be 20.5 cm (LF). Juvenile retention was estimated to be 66.9%. Grandcourt et al. (2004) estimated the natural, fishing and total mortality rates for Argyrops spinifer to be 0.573 per year, 0.394 per year and 0.967 per year, respectively. The estimated exploitation rate of 0.407 per year, was comparable to what was estimated to be a safe harvest level at F0.1 (0.407 per year). Grandcourt et al. (2004) concluded that Argyrops spinifer is exploited at a safe level; however, the differences between the mean size at first capture that would maximize yield per recruit (27.4 cm LF) and the high juvenile retention rate (66.9%), suggests that the trap fishery's mesh size regulations should be reviewed.
Argyrops spinifer and Acanthopagrus bifasciatus form a small component of landings in the southern Persian Gulf representing about 2.5% of the total annual catch. During 2002, 120 tonnes of A. spinifer were landed in the Emirate of Abu Dhabi (Grandcourt et al. 2004). FAO landings for this species show increases in total catches for the Persian Gulf from 1980 through 2007 (FAO 2009). Since 1994, landings of sparids (including A. spinifer) have shown a general trend for increasing annual catches and in 2006, 6,185 tonnes of sparids (including A. spinifer) were landed accounting for 16.5% of demersal fish landings in Omani waters (Al-Mamry et al. 2009). The Argyrops spinifer stock appears to be in a healthy condition in the Arabian Sea, as a wide range of size and age classes were caught in the hand-line (Al-Mamry et al. 2009) and industrial trawl fisheries (McIlwain et al. 2006). By comparison, A. spinifer caught in the trap-fishery in the southern Persian Gulf tend to be smaller (14–40 cm LT) and younger (under five years old) (Grandcourt et al. 2004). However, this is probably a reflection of the fishing gear used, since fishing traps used in Omani coastal waters similarly catch smaller-sized A. spinifer (25–45 cm LT) (Al-Mamry 2006). Valinassab et al. (2006) conducted a trawl survey in the Persian Gulf from 2003–2004 to assess the abundance of demersal fish resources in the Persian Gulf and Oman Sea. Argyrops spinifer contributed 1.36% of the total biomass from the Persian Gulf and 2.30% from the Oman Sea.
Elsewhere in the Western Indian Ocean, Argyrops spinifer is found off Mozambique and KwaZulu-Natal extending north to Kenya, but is not plentiful in these countries (Mann and Fennessy 2000). However, it is one of the most common marine fish species seen in fish markets in southeast Madagascar and some of the catch from here and from the Tamatave region is exported from Madagascar (S. Fennessy, Oceanographic Research Institute pers. comm.). In Taiwan, Argyrops spinifer is common but not abundant and found mainly on the southwest coast including Penghu Island (K.-T. Shao, Biodiversity Research Center, Academia Sinica pers. comm. 2009).
FAO capture production figures for this species in 2007 were: Qatar - 1,158 tonnes, Saudi Arabia - 2,260 tonnes and United Arab Emirates - 5,800 tonnes. Landings of A. spinifer are not reported from Kuwait (J. Bishop, Kuwait Institute for Scientific Research pers. comm. 2013), but landings from Qatar were 626.1 tonnes, 1,030.3 tonnes, 1157.2 tonnes, 1171 tonnes, 630.6 tonnes, 535 tonnes, 687.8 tonnes from 2005–2011 (one of the dominant species in the catch ~ 5% of total).
Bushehr (Iran) Shrimp Fisheries By-catch Study
Between 2001–2002, Paighambari and Daliri (2012) sampled shrimp trawl fisheries by-catch composition in the Bushehr province (Iranian waters). Argyrops spinifer occurred in 88% of trawls with a mean biomass of 0.9 kg/h (+/- 0.1 S.E.) and a mean catch rate of 0.7 individuals/h (+/- 0.11 S.E.) (Raeisi et al. 2011). Argyrops spinifer contribution to the by-catch in Bushehr waters was 0.9% in weight and 0.1% in the number of individuals collected (Raeisi et al. 2011).
Studies of By-catch in the Cutlassfish (Trichiurus lepturus) trawl fishery (2009-2010)
In Hormozgan waters of the northern Persian Gulf, Argyrops spinifer occurred in 20% of trawls (Hosseini et al. 2012).
Study of the retained and discarded by-catch of Kuwait's shrimp fishery:
Between September 2010-January 2011, Chen et al. (2013) sampled 17 tows from Kuwait's shrimp fishery for retained and discarded bycatch. Chen et al. (2013) noted between zero to 11 kg of Argyrops spinifer were collected as by-catch, in which zero to 10 kg were discarded. The remainder (zero to one kg) were kept as retained by-catch.
FAO Regional Commission for Fisheries (RECOFI) Capture Production (1986-2011) in the Persian Gulf
FAO RECOFI aggregate landings show an overall increasing trend from 2,024 tonnes in 1986 to 6,039 tonnes in 2011. A peak of 8,439 tonnes was collected in 2003.
FAO Global Capture Production (1982-2011)
FAO global aggregate landings show an overall increasing trend from 910 tonnes in 1986 to 6,487 tonnes in 2011. A peak of 9,688 tonnes was collected in 2004.
Annual Catch Statistics Report for Abu Dhabi Emirate Fisheries (2005-2012)
Abu Dhabi Emirate fisheries landed, on average, 33.15 tonnes of Argyrops spinifer between 2005-2012. A peak of 55.5 tonnes were collected in 2005, followed by a decline to 10.3 tonnes in 2011. In 2012, there was a slight increase to 13.7 tonnes (Marine Environment Research Center 2005, 2012).
