Environ Biol Fish (2011) 90:287–299 DOI 10.1007/s10641-010-9742-6 Discriminant analysis as a tool to identify catfish (Ariidae) species of the excavated archaeological otoliths Weizhong Chen & Mohsen Al-Husaini & Mark Beech & Khlood Al-Enezi & Sara Rajab & Hanan Husain Received: 9 September 2009 /Accepted: 9 November 2010 /Published online: 4 December 2010 # Springer Science+Business Media B.V. 2010 Abstract Catfish otoliths excavated from two archae- of Kuwait Bay may not have changed much in the past ological sites in Kuwait, Sabiyah (ca. 7000 Years Before 7000 years. Present) and Al-Khidr, ca. 4000 YBP, were compared with those of Kuwait’smoderncatfish.Otolithsfrom Keywords Catfish . Species identification . Otolith . Kuwait’s four species of catfish, Netuma bilineata, N. Discriminant analysis thalassina, Plicofollis dussumieri,andP. tenuispinis were collected after recording total length and weight. Data recorded for both ancient and modern otoliths, Introduction including annual ring (age), weight, length and four otolith radii from transverse sections, were subject to Ubaid-related pottery of the fifth millennium BC discriminant analysis to differentiate among species (5000 BC) was among the preliminary findings of and develop classification functions for otoliths. excavations at site H3, known as Jazirat Dubaij Comparisons of the results from the ancient and (Dubaij Island) in Sabiyah, an area immediately modern otoliths showed that most of the excavated northeast of Kuwait Bay in the Arabian Gulf (Carter otoliths (78% from Sabiyah and 100% from Al-Khidr) et al. 1999) (Fig. 1). The pottery included painted and belong to the two presently dominate species N. plain shards from southern Mesopotamia, and helped bilineata and P. tenuispinis, indicating that ichthyofauna archaeologists to date the site, along with carbon dating, to the Neolithic Ubaid period. The H3 site is important because of its link between civilizations found in the region; it might have been a commercial * : : : W. Chen ( ) M. Al-Husaini S. Rajab H. Husain centre or a transit area for trade. Ubaid-related pottery Mariculture and Fisheries Department, Kuwait Institute for Scientific Research, has been found in other excavation locations in the 13109 Safat, Kuwait region including the Emirate of Sharjah and southern e-mail: [email protected] Iraq. Shell beads found at H3 were similar to those found at Ubaid-related sites in Sharjah, and on Abu M. Beech ’ Abu Dhabi Authority for Culture and Heritage, Dhabi s Dalma Island (Beech and Glover 2005) and Abu Dhabi, United Arab Emirates Umm al-Qaiwain in the United Arab Emirates (Phillips 2002). K. Al-Enezi Animal remains were also among the excavated Kuwait National Museum, National Council for Culture, Arts and Letters, artifacts. About 70% of the animal remains belonged Kuwait city, Kuwait to a mollusc, Lunella coronata, which usually inhabits 288 Environ Biol Fish (2011) 90:287–299 Fig. 1 Kuwait map illus- trating location of Sabiyah H3 site and Al-Khidr in Failakah Island the rocky shores of the Gulf. About 95% of the muddy bottoms. Many of these could have been caught recovered bones were from fish. Most of the fish bones in barrier traps or gill/seine nets, while the larger fish, recovered from the H3 site were caudal vertebrae caught in deeper waters, are more likely to have been belonging to several taxa: requiem sharks (Carcharhini- captured by hook and line or with basket traps. Small dae), sawfish (Pristidae), rays, groupers (Epinephelus slabs and chunks of bituminous material remains were sp.), jacks (Carangidae), seabreams (Sparidae), emperors recovered from the site, as fragments of the waterproof (Lethrinus sp.), flatheads (Platycephalidae), tuna coating used to cover a reed-bundle hull (Carter and (Euthynnus affinis) and sea catfishes (Ariidae) (Beech Crawford 2003). 2000; Beech and Al-Husaini 2005). Most of these Fishing equipment discovered at the H3 site fishes are shallow water inhabitants of sandy or sandy- (Beech 2001) consisted of notched pebbles made Environ Biol Fish (2011) 90:287–299 289 from stones (probably used as net sinkers), thick Arius bilineatus, A. thalassinus, A. dussumieri and A. pebbles that had a pecked shallow groove around tenuispinis before, Bawazeer 1985; Al-Hassan et al. them (probably used as fishing line sinkers), and bone 1988). The two species, N. bilineata and P. tenuispinis gorges identical to bone gorges discovered in other inhabit shallow coastal areas including islands, while excavated areas in the Arabian Gulf (Oman UAE). N. thalassina and P. dussumieri are larger in size and More than 240 ancient otoliths (inner ear bones) inhabit deeper and offshore waters (Al-Hassan et al. belonging to Ariidae (catfish) species were recovered, 1988). The speciation of the archaeological otoliths along with about 60 otoliths from other species, such could provide information related to fishing activities as Epinephelus sp., Sparidae and flat fish (Pleuro- (using hook and line) of ancient settlers at these sites nectiformes) (Beech 2001). The Ariidae ancient and as well as their paleo-environmental distribution in otoliths are well preserved and were chosen for the the northern Arabian Gulf. present investigation because of their abundance in comparison to other species. Another important archaeological site (Al-Khidr) Materials and methods was recently excavated on the north-western shore of Failakah Island. Dating from the late third to early Modern otoliths second millennium BC, the site dates from Dilmun period i.e. Bronze Age (Benediková and Barta 2009) Catfish samples were collected monthly from both (Fig 1). The site is rich in zoo-archaeological sea surveys and fishermen at the fish markets materials, with the majority being of ichthyological from February 2005 through March 2007. These origin. Among these fish remains were vertebrae and samples were mainly from trawls, gill nets, and otoliths, the majority of which were from Ariidae gargoors (hemispherical wire traps) and were (Hajnalová et al. 2009). Preliminary analysis has confined to Kuwait waters. The collected catfish identified at least three mammalian species (cattle, samples were identified to different species based on sheep, and goat) and 12 species of fish representing the morphological methods described by Al-Hassan ten different families (Carcharhinidae, Pristidae, Ariidae, et al. (1988), Carpenter et al. (1997), and Froese and Serranidae, Carangidae, Haemulidae, Letherinidae, Pauly (2009). For N. bilineata, two different distinct Sparidae, Scaridae, and Sphyraenidae). The most abun- types or populations were identified. Although dant metal finds all across the site were fish hooks (Barta morphologically they are one species and the L-W et al. 2008). These hooks were with long shanks made relationships are same, the otolith weight and fish from round or hammered rods. body length correlation and the length-at-age data Archaeozoological studies aim to shed light on show two patterns. The segregation of the two human activity in these settlements, including food groups was based on distribution patterns of otolith production, animal husbandry practices, site sea- weight against fish length, length-at-age data and sonality, and information about the local and annuli widths for age 2–6. For example, the mean regional palaeoenvironment. annulus width of age 3 type 1 is 893 μm while that Marginal increment analysis of ancient fish otoliths for type 2 is 1312 μm. For fish of the same body have been used in palaeontology and palaeocology to size, N. bilineata type 1 had a larger otolith with determine season of human occupation (Hales and more annual rings (older) than type 2; for fish of Reitz 1992; Andrus and Crowe 2000; Higham and same age, N. bilineata type 1 exhibited a smaller Horn 2000; Van Neer et al. 2002) and as a source of body size. In total, 1446 individuals of N. bilineata paleoclimate data using isotopes (Patterson et al. [including both type 1 (Nb1) and type 2 (Nb2)], 157 1993; Patterson 1998; Andrus et al. 2002; Surge and N. thalassina (Nt), 245 P. dussumieri (Pd) and 2506 Walker 2005). P. tenuispinis (Pt) were obtained. The sampled The aim of this study was to investigate the Ariidae fishes were measured to nearest cm in total length species whose remains were excavated from the two (TL) and weighed to the nearest g for total weight. settlements. Four species of Ariidae are reported from Otoliths were removed from the specimen by the Arabian Gulf: Netuma bilineata, N. thalassina, cutting through the posterior region of the skull to Plicofollis dussumieri and P. tenuispinis (referred as expose otic chamber where the lapillus otoliths (the 290 Environ Biol Fish (2011) 90:287–299 largest otolith) were dissected out, cleaned with Otoliths were sectioned transversely (Fig. 3) near water, dried at room temperature, and stored in the middle of the long axis using an Isomet saw paper envelopes with the appropriate data. The (Buehler Inc, USA). The primordium (nucleus) is shapes of otolith from four species are basically located on outer margin of the dorsal side along 1/3 of thesame(Fig.2). They are circular, thick and the proximal-distal axis from the distal side; the bulbous in shape with a distinct round end rostrum sulcus acusticus is absent from catfish lapillus (anterior) and an indistinct pseudo-rostrum (poste- otoliths. rior). The sizes of otoliths differ depending on Each catfish otolith annulus in transverse section is species groups. At a similar body size, Nb 1, Nt composed of a thin opaque zone that is most easily and Pt have relative larger otoliths than the other discerned and read under transmitted light, while the twogroups,andNb1andPtarealsomucholder translucent zone is lighter than the opaque zone as (have more annual rings) than those of the other shown in Fig. 3. The primordial regions (nucleus) are three groups. terminal in these sections and were opaque in most otoliths. Otolith accretion occurs along the axis from the otolith dorsal to the ventral side.