Fisheries Research 84 (2007) 202–209 On fishing selectivity of hadrah (fixed stake trap) in the coastal waters of Kuwait Ali F. Al-Baz ∗ , W. Chen, J.M. Bishop, M. Al-Husaini, S.A. Al-Ayoub Mariculture and Fisheries Department, Kuwait Institute for Scientific Research, P.O. Box 1638, 22017 Salimyah, Kuwait Received 17 January 2005; received in revised form 29 October 2006; accepted 30 October 2006 Abstract The hadrah is an inter-tidal fixed stake trap, and a traditional fishing gear in Kuwait. The fishing selectivity of hadrah was investigated by comparative experiments in three locations in Kuwait’s coastal waters. At each location, one control hadrah with the standard mesh size and one comparative hadrah with a larger mesh size were built to collect fish samples. Length frequency data of the major fish species caught by the two hadrahs were used to fit to logistic fishing selectivity curve to obtain the 50% retention length (L 50 ) and to be compared by two values of the Akaike’s information criterion (AIC). The results showed that: among the 40 selected cases (pairs of length frequency data for different species and different locations), 31 cases showed no difference between the selectivity curves of the control and comparative hadrahs. Within the nine cases with different selectivity observations, six cases showed a positive difference in L 50 (the comparative hadrah having the larger L 50 ); these results were considered to be caused by the mesh-size differences between hadrahs. On the other hand, three cases showed negative difference (the comparative hadrah having smaller L 50 ), and these were not considered to be caused by the mesh size differences. The comparative hadrahs had limited selectivity variation in their catch compositions. The AIC method described in this paper detected all the large positive L 50 differences and should be a useful tool for comparing selectivity curves. © 2006 Elsevier B.V. All rights reserved. Keywords: Comparison of fishing selectivity; Fish trap; Hadrah; Kuwait 1. Introduction Throughout Southeast Asia, the inter-tidal stake trap is com- monly used gear for fish capture. In the Arabian Gulf, inter-tidal stake traps are known as hadrah and have been employed at least since the late 1800s (MacIvor, 1882). Inter-tidal stake traps remain an important component of Gulf countries’ fish- eries where laws permit. During the 8-year period from 1990 through 1997, hadrah catches contributed from 9% to 26% of Bahrain’s annual landings (Fisheries Statistical Section, 1998). The percent contribution by inter-tidal stake traps to Kuwait’s total landings is not known, but they are one of about five meth- ods used commercially to harvest fish and shellfish in Kuwait. Kuwait’s hadrah fishery has grown rapidly since the 1980s. In 1986, the number of hadrah counted from a helicopter survey was 137, of which 89 (65%) were concentrated in Kuwait Bay and the adjacent islands of Failakah and Mischan (Hakim et al., 1989). Seventeen years later, hadrah numbers had increased to ∗ Corresponding author. Tel.: +965 572 2966; fax: +965 571 1293. E-mail address: abaz@mfd.kisr.edu.kw (Ali F. Al-Baz). 355, a factor of 2.6, along Kuwait’s coast (Public Authority for Agriculture and Fisheries Resources, personal communication, March 2003). The reason for this rather dramatic rise in numbers was due to their positive economic return on investment. Equally important, inter-tidal stake traps are the only commercial fishing gear allowed to operate in Kuwait Bay and within the three-mile protected zone, which was established to protect fish breeding and nursery areas (Al-Mubarak et al., 1999). Because of their location, fish captured by hadrah are usually littoral species such as Klunzinger’s mullet (Liza klunzingeri), silver pomfret (Pampus argenteus), yellowfin seabream (Acan- thopagrus latus), and the tigertooth croaker (Otolithes ruber) (Morgan, 1985). Abou-Seedo (1992) reported that hadrah in Kuwait Bay captured a total of 76 species, representing 36 fam- ilies. Four species accounted for over 50% of the total catch for the years 1982 through 1984. These four species were Klun- zinger’s mullet (Abou Seedo’s L. caranata), bluespot mullet (Valamugil seheli), Hamilton’s thryssa (Thryssa hamiltonii) and Bloch’s gizzard shad (Nematalosa nasus). A large percentage of hadrah catches consists of juveniles of commercial species, and hadrah have come under increas- ing criticism from boat fishermen who believe their decreasing 0165-7836/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.fishres.2006.10.022