World Applied Sciences Journal 28 (11): 1514-1517, 2013 ISSN 1818-4952 © IDOSI Publications, 2013 DOI: 10.5829/idosi.wasj.2013.28.11.1848

First Documented Occurrence of the Giant Mottled , Anguilla marmorata in Peninsular Malaysia, Malaysia

12Takaomi Arai and Ryon Siow

1Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia 2Freshwater Research Center, Fisheries Research Institute, Glami Lemi, Titi, 71650 Jelebu, Negeri Sembilan, Malaysia

Abstract: Previous studies had reported the occurrence of a tropical eel species Anguilla marmorata (Quoy and Gaimard, 1824) in Peninsular Malaysia without the validation of its true identification. Because seven species or subspecies occur in the western Pacific around and Malaysia and morphological key characters are overlapping between species, comprehensive identification on the species is needed. Actually, after re-examination of a number of key morphological characters of a preserved specimen of A. marmorata, the species was identified as bengalensis (Gray, 1831). In the present study, an anguillid eel found in Peninsular Malaysia were identified as A. marmorata, as revealed by the valid morphological key characters. The present study showed the first documented occurrence of the giant , Anguilla marmorata in the Peninsular Malaysia. No reports on anguillid including A. marmorata recruited to the eastern coast of the peninsular facing South Sea. Thus, the discovery indicates a possible existence of another population (South China Sea region) in addition to four different populations (North Pacific, South Pacific, , Guam region) revealed recently.

Key words:Anguilld eel Anguilla marmorata Distribution Malaysia Population South China Sea Tropical eel

INTRODUCTION major landmasses, it is clearly not likely to comprise a single panmictic population as found in temperate The , Anguilla marmorata Quoy and anguillid species such as Anguilla japonica Temminck Gaimard 1824, is a tropical anguillid that reaches large and Schlegel 1847 [5], Anguilla rostrata (Lesueur 1817) sizes of almost 2 m in length with a maximum weight of 21 [6], Anguilla anguilla (Linnaeus 1758) [7, 8] and more kg [1]. Like all catadromous species, A. marmorata migrate recently for the tropical anguillid, Anguilla reinhardtii between inland or coastal growth habitats and oceanic Steindachner 1867 [9]. Based on a population genetic spawning areas. This species has the widest geographic study, A. marmorata has been shown to consist of at distribution of the 19 species of Anguilla from the least four genetically isolated populations (North Pacific, western Indian Ocean to the North Pacific and South South Pacific, Indian Ocean, Guam region) [10]. Pacific oceans [2]. Recently, this species was found at the Recently, we had reported Anguilla bicolor bicolor Palmyra Atoll in the central Pacific [3] and even farther to McClelland 1844 in the western parts of Peninsula the east in the Galapagos Islands [4], which may indicate Malaysia as a new distribution range in the species [11]. that it has an even wider geographic range than Furthermore, occurrence of A. bengalensis bengalensis previously thought. Because of the wide geographic Gray 1831 was also recorded in Malaysian waters, as range of A. marmorata, which is separated by several revealed by both morphological and molecular genetic

Corresponding Author: Takaomi Arai, Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia. Tel: +60 9668 3960; Fax: +60 9669 2166.

1514 World Appl. Sci. J., 28 (11): 1514-1517, 2013 analyses [12]. In the present study, we discovered A. marmorata in the eastern part of the peninsular where is more unique distribution range because there was no report regarding the distribution of the species throughout Peninsular Malaysia and from the western part of Borneo Island. This is the first formal record of A. marmorata found in native waters of Peninsular Malaysia. This finding also suggests the possible existence of the further populations in the species.

MATERIALS AND METHODS

An anguillid eel was collected by local fishermen in the Tembeling River in Jerantut of Pahang state where is located 180 km from Kuantan in the eastern coast of Peninsular Malaysia, in the region of the central peninsular (4°18’ N, 102°36’E) on 31 January 2007 (Fig. 1). Tembeling River is a main tributary of Pahang River that is the longest river on the peninsular with 459 km in length and drains into the South China Sea (eastern coast of the peninsular). The eel was collected by hook and line. After Fig. 1: The distribution of Anguilla marmorata (thick collection, the eel was brought alive to Freshwater lines) by Ege (1939) with the new finding in Fisheries Research Center (FFRC) in Malaysia and was Peninsular Malaysia in the present study (star). cultured until died in the aquarium on 9 July 2010. The dead specimen was preserved in 10% formalin and was deposited in the FFRC (UT048). The external morphometric characters were measures followed by Ege [2] and Watanabe et al. [13] and the data are shown in Table 1. A. marmorata has the largest range of total number of vertebrae (TV) of any species of the

Table 1: Morphometric characters of Anguilla marmorata (UT048) collected in the eastern part of Peninsular Malaysia Measurements (mm) Total length (Lt) 1230 Body weight (g) 4200 Head length (HL) 152 Predorsal length (PD) 325 Preanal length (PA) 529 Distance between verticals through anus and origin of (PA) 204 Predorsal length without head length (PDH) 173 Preanal length without head length (TR) 381 Distance from tip of lower jaw to corner of mouth (LG) 42.4 Fig. 2: Anterior and medial regions of Anguilla FDI (%) 16.6 marmorata, 1230 mm total length (UT048). PA/Lt (%) 43.0 HL/Lt (%) 12.4 genus Anguilla [2, 13]. The TV is overlapped with a TR/Lt (%) 31.0 number of other species and TV is not a useful taxonomic PDH/Lt (%) 14.1 character in the anguillid [2, 13]. Thus, we did not conduct Patten of color marking of skin variegated the vertebrae counting in the present study.

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The fin difference index (IFD), which is the distance of Indonesia to of ) and (iv) Guam between the verticals from beginning of the dorsal fin (Z) (including Micronesia) populations. However, only one to the anus (ano-dorsal length) relative to the total length spawning area of this species has been estimated based

(LT) [2], was calculated as follows: on the otolith analyses with oceanic currents, which is located offshore in the western North Pacific to the west 1 IFD = 100 Z LT . of Guam [15-17]. The spawning area might be also quite far from the eastern coast of Peninsular Malaysia based After Ege [2] and Watanabe et al. [13], the specimen on the age at recruitment of the species (4-6 months) [16, was identified as A. marmorata using characters of color 17]. These results suggest that A. marmorata might have (variegated) markings and ratio of FDI. further populations around South China Sea region. Further intensive sampling should be undertaken, along RESULTS AND DISCUSSION with molecular genetic studies, in order to better understand the details of the distribution and population This is the first description of the occurrence and structure in the species. distribution of A. marmorata in Peninsular Malaysia. No The present results all lead to conclude that this is or commercial fisheries are known for eels in the first record of the occurrence of Anguilla marmorata the regions of Peninsular Malaysia studied here and there in Peninsular Malaysia. There was no eel aquaculture have been no reports of the release of eels into natural around the eel habitats. Thus, A. marmotrata is a native waters in Malaysia. It seems quite impossible, therefore, eel species in Peninsular Malaysia. The results are also that A. marmorata is an introduced, exotic species in the suggesting a possible existence of another population in country. Recently, we discovered A. bicolor bicolor in addition to four different populations reported. the western and northern parts of the peninsular [11]. Interestingly, A. marmorata recruited to the eastern coast ACKNOWLEDGEMENTS of the peninsular facing South China Sea and settled before capture because no report in the species This study was financially supported by the Ministry throughout the peninsular and the western parts of of Higher Education Malaysia under the Fundamental Boreneo Island. It is possible to suppose that A. Research Grant Scheme, with reference to marmorata distributes in the western parts of the FRGS/1/2013/STWN04/UMT/02/3 (Vot No. 59281). The peninsular like A. bicolor bicolor. According to Jespersen Higher Institution Centre of Excellence (HICoE) Research [14], the occurrence of preleptocephalus to Grant, under the Institute of Oceanography and metamorphosing stages in anguillds in waters off Sumatra Environment (INOS), also jointly supported this study. supports the populations of the eels that are distributed in Java and Sumatra may have their spawning area REFERENCES situated off the south-western coast of Sumatra, close to the distribution area of the freshwater stage (Fig. 1). A. 1. Castle, P.H.J., 1984. , pp: 34-37. marmorata in the western coast of Malaysia might In: Checklist of the Freshwater of Africa originate from spawning areas from off Sumatra. However, (CLOFFA) Volume 1. J. Daget, J.P. Grosse and the distance between the spawning area and recruitment D.F.E. Thys van den Audenaerde (eds.). ORSTOM, area in the eastern Peninsular Malaysia and the western Paris. Borneo Island is considerably longer than the distance 2. Ege, V. 1939. A revision of the Genus Anguilla Shaw. between the islands of Java and Sumatra and there are no Dana Rep., 16: 8-256. oceanic current transporting larvae to the eastern coast 3. Handler, A. and S.A. James, 2006. from off Sumatra [14]. No distribution of A. marmorata in Anguilla marmorata (giant mottled eel) discovered the eastern Sumatra supports the supposition (Fig. 1). A. in a new location: natural range expansion or recent marmorata has been shown to have a multiple population human introduction? Pac. Sci., 60: 109-115. structure consisting of four genetically isolated 4. McCosker, J.E., R.H. Bustamante and populations [10], i. e. (i) the North Pacific (from Japan to G.M. Wellington, 2003. The freshwater eel, Sulawesi of Indonesia), (ii) the South Pacific (from Papua Anguilla marmorata, discovered at Galapagos. New Guinea to Tahiti), (iii) the Indian Ocean (from Sumatra Noticias de Galapagos, 62: 2-6.

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