Title Indonesian Journal of Environmental Management and Sustainability e-ISSN:2598-6279 p-ISSN:2598-6260 Research Paper Species Composition and Length-Weight Relationship of Anguillid Eels Habited in Bengkulu Waters, Indonesia Ni Komang Suryati1,2, Fauziyah3*, Ngudiantoro4, 1 Graduate school of Resources Management, Universitas Sriwijaya, Indonesia 2 Research Institute for inland Fisheries and Fisheries Extension 3 Marine Science Program Study, Universitas Sriwijaya, Indonesia 4 Mathematic Study Program, Universitas Sriwijaya, Indonesia *Corresponding author e-mail: Siti_fauziyah@yahoo.com Abstract Management of euryhaline species, such as Anguillid eel, is very important. Anguillid eel is an important economic fish which the partly of its life cycle spent in inland waters then migrates into the ocean for spawning. The objective of this study is to identify the morphological diversity and length-weight relationship of Anguillid eels in this province. The total of 148 individuals of elver and adult Anguillid eels were caught was identified using the comparison of ano-dorsal with total length parameter. Cluster analysis was obtained based on measurement of morphometric parameter. The current work used cluster analysis and dendrogram to group the population characteristic of Anguilla eel. It revealed that in the Jenggalu, Kungkai and Manna rivers of Bengkulu province, there are two groups of Anguilla eel with significant difference of ano-dorsal length. The value of the ano-dorsal varied from 2.56 ± 1.54 and 17.78 ± 1.33 for A.bicolor bicolor and A.marmorata, respectively. The length-weight relationships between total length (TL) and weight (W) for Anguilla bicolor and A.marmorata were found to be highly significant (r2 > 0.94, p < 0.001). The average value of ’b’ for length and weight were higher than 3, i.e., 3.2677 and 3.4821 in A.bicolor and A.marmorata respectively which indicated a positive allometric growth trend of this species in the studied area. Keywords Anodorsal length, LWR, Anguillid eel, Bengkulu Received: 23 February 2018, Accepted: 15 April 2018 https://doi.org/10.26554/ijems.2018.2.2.48-53 1. INTRODUCTION Management of euryhaline species, such as Anguillid eel, is very important. Anguillid eel is an important economic �sh which the partly of its life cycle spent in inland waters then migrates into the ocean for spawning. Commercial eel �shery activity is distributed all over the world (De Leo and Gatto, 2001). Based on data from Food and Agriculture Organization, United Nations (FAO), Eel’s production signi�cantly increases from 17,775 t in 1950 (only 3% from aquaculture) to 280,000 t in 2007 (96% from aquaculture) and its production stabilized since 2008 to 2010. There are 19 species/subspesies of Anguillid eel distribute all over the world covering Indopaci�c, Atlantic and Oceania. Indonesia has 10 species such as Anguilla bicolor bicolor (Indone- sian short �n eel), Anguilla bicolor pasi�ca, Anguilla marmorata, Anguilla nebulosa nebulosa, Anguilla borneensis, Anguilla celebescen- cis Anguilla megastoma, and Anguilla interioris (Fahmi, 2015; Sugeha and Suharti, 2008). The geographical position of rivers in the Bengkulu Province which face directly to Indian Ocean is the potential habitat for Anguillid eels. Kungkai, Jenggalu and Manna river are located in the Bengkulu. There are �owing into Indian Ocean directly. Research on the existence and distribution of Anguillid eel in Indonesia has been conducted widely, generally in the Java Island. Whereas in the other areas such as Bengkulu is limited. The existence of Anguillid eel in Bengkulu province results in the high demand of eel seeds from eel farm in the Java Island. Therefore, it is necessary to manage the Anguillid eel resources for its sustainability. Certainty taxonomy is required for managing the Anguil- lid eels resources. Therefore, morphological identi�cation is needed for Anguillid eels species in Bengkulu. Furthermore, the knowledge on quantitative aspects such as length-weight relationship, condition factor, growth, and recruitment are im- portant tools for the adequate management of for this species (King, 2007; Ndome et al., 2012). The length-weight rela- tionships also help to �gure out the condition, reproduction history, life history, and the general health of �shing species https://doi.org/10.26554/ijems.2018.2.2.48-53 Suryati et. al. Indonesian Journal of Environmental Management and Sustainability, 2 (2018) 48-53 Figure 1. The Sampling site of Anguillid eels in Bengkulu Province, Indonesia (Nikolsky, 1963; Wootton, 1990, 1992; Pauly, 1993) and is also useful in local and interregional morphological and life historical comparisons in species and populations. Therefore, the length-length relations of species under various environ- mental conditions should be known. The objective of this study is to identify the morphological diversity and length-weight relationship of Anguillid eels in this province. 2. EXPERIMENTAL SECTION 2.1 Description of research location The research location of Anguillid eel �sh was conducted in three locations which is the eel’s �shing ground. There were Kungkai, Jenggalu and Manna river in Bengkulu province (Fig. 1). Anguillid eel’s sampling was done by using bamboo traps and pole and line (warm bait) in June and July 2016. Labo- ratory analysis was conducted at the �sh biology laboratory, Research Institute for Inland Fisheries. 2.2 Sample analysis Anguillid eel’s samples were collected from the �shermen in each river. There was only yellow eel’s stage which was caught and no glass eel found in the research. Glass eel is a seed that has no pigmentation development in the body. The glass eel will become yellow eel when entering the river and rapidly develop pigmentation which stay in freshwater for growth for many years before they become mature as “silver eel” and migrate back to the ocean for spawning. All of samples were preserved by using 90% alcohol for subsequent analysis in the Laboratory of Research Institute for Inland Fisheries. Morphological identi�cation for freshwater eel is one of the technical requirements for identi�cation. Species determina- tion used the key identi�cation based on literature i.e (Arai and Takaomi, 2016; Tesch et al., 2003; Silfvergrip, 2009). A sharp- jawed vernier caliper graded to 0.1 mm used for measuring the morphological character such as total length (TL), Head Figure 2. Morphological character of Anguillid eels (TL: Total Length; HL : Head Length; PD : Predorsal Length; PA: Preanal length (Tesch, 2003)) Figure 3. Characteristics of Anodorsal distance measurements on anguilla eel (Hakim, 2015) Length (HL), Predorsal Head Length (PDHL), Pre Anal Head Length (PAHL), Pre Dorsal length (PDL), Pre Anal Length (PAL) and Anodorsal length (AD) (Fig. 2). Equation to distinguish the species for adult eel is ano- dorsal length (AD) (Reveillac et al., 2009; Rovara and Amarul- lah., 2007). The characteristic expressed by Ege’s in 1939 have been widely accepted now. This study used species identi�- cation by using the Ano-dorsal parameter which cheaper and faster. According to that equation, anguillid eel classi�ed into two group as follows, long �n and short �n. Long �n is the anguillid eel which has the long ano-dorsal length, while short �n is the opposite. Based on di�erences in ano- dorsal length, body coloration, number of vertebrae combined with genetic cluster, there are 16 species of Anguillid eel in the world (Arai and Takaomi, 2016). In addition to the color pattern, other species distinguishing characteristics in all anguillid eel stadia are performed by measuring ano dorsal parameter which is divided by total lengths as the following equations (Reveillac et al., 2009; Rovara and Amarullah., 2007): A−D%= (LD−LA) LT ·100 (1) Where LT is the Total length, LD is the Length of dorsal �n and LA is the Length of anal �n. Short�n has ano dorsal value 0-5 while long�n 7-17 (Rovara and Amarullah., 2007). More speci�c [14] AD/TL for Anguilla bicolor bicolor is ranged from 0-3, A. nebulosa 7-13 and A. mar- morata 14-17. The length-weight relationships for weight were calculated using the equation, W = aLb (Ricker, 1979), where ‘a’ is a coe�- cient related to body form and ‘b’ is an exponent indicating iso- © 2018 The Authors. Page 49 of 53 Suryati et. al. Indonesian Journal of Environmental Management and Sustainability, 2 (2018) 48-53 Figure 4. Frequency distribution of ano-dorsal to total length (AD/TL) % Anguilla bicolor bicolor and Anguilla marmorata in Bengkulu province metric growth when equal to 3. The statistical signi�cance level of r2 was estimated by linear regressions on the transformed equation, LogBW = log a + b * logTL. The length-weight relationship between males and females were not calculated separately. All statistical analyses were evaluated at p < 0.05 signi�cance level. 2.3 Cluster Analysis Morphometric measurement on anguillid eel is used to decide its population character. Cluster analysis was obtained based on each parameter value on morphometric measurement. This analysis was performed using STATISTICA software. Figure 5. Cluster analysis based on morphometric characterize between A.bicolor bicolor and A.marmorata in Bengkulu province 3. RESULTS AND DISCUSSION The total number of samples for this study is 148 individuals of anguillid eel in three locations. Then, the samples identi�ed based on morphological characters such as body coloration and ano-dorsal parameter that determines whether the samples are long �n or short �n. The result of initial identi�cation indicated that there are two species of Anguillid eel in Bengkulu which have di�erent characteristic. Table 1 showed the morphological identi�cation of Anguillid eel sample in Bengkulu province. The �rst species, A. bicolor bicolor, showed characteristics of the body coloration is plain (without pattern/un marbled) and has short �n which was found in the Kungkai and Jenggalu Rivers (Northern part of Bengkulu province. A. marmorata, second species, was characterized by marbled body color and has a long �n and was found in the Manna River (southern part of Bengkulu). The result of initial identi�cation based on morphological identi�cation is the initial process to facilitate the next steps for identi�cation the species. Table 2 showed that A. bicolor bicolor in Kungkai and Jeng- galu river has the same characteristics of morphometric such as head length (HL) 0.2 to 9.1 (in average: 4.25±1.01) cm, pre dorsal length (PDL) 5.8 to 27.5 (in average: 12.99±2.98) cm, pre anal length (PAL) 7.9 to 29 (in average: 13.89±3.08) cm and ano dorsal length (AD) 0.3 to 4.9 (in average: 2.56±1.54) cm. While A. marmorata in Manna river showed the char- acterize as follows head lenght (HL) 5.1 to 6.1 (in average: 5.58±0.27) cm, pre dorsal length (PDL) 7.5 to 14.6 (in aver- age: 10.90±1.96) cm, pre anal length (PAL) 12.6 to 294.7 (in average: 18.03±3.07) cm and ano dorsal length (AD) 15.5 to 20.8 (in average: 17.78±1.33) cm. Comparison of ano dorsal length (AD) to total lenght (TL) used to di�erentiate the anguillid eel species (Reveillac et al., 2009; Rovara and Amarullah., 2007). Matsui (Rovara and Amarullah., 2007) has devided the anguillid eel into two groups based on the length of the �n as follows, short�n which 0 to 5 and long�n 7-17. More detailed on (Reveillac et al., 2009) showed that AD/TL for species A. bicolor bicolor is 0 to 3, A. nebulosa 7-13 and A. marmorata 14-17. The result showed that there were two ano-dorsal length groups in this study. First group was A.bicolor bicolor which has 0.3 to 4.9 of anodorsal lenght. Other groups was showed the result 15.5 to 20.8 as A.marmorata. Figure 2 described the distribution frequency for that species in this study. The total © 2018 The Authors. Page 50 of 53 Suryati et. al. Indonesian Journal of Environmental Management and Sustainability, 2 (2018) 48-53 Table 1. Morphological identi�cation of Anguillid eel in Bengkulu province Location Local name Common name Scienti�c name Characteristic Kungkai river Sidat Indonesian short�n eel A.bicolor bicolor Body color is no pattern/un-marbled and has short �n Jenggalu river Sidat Indonesian short�n eel A.bicolor bicolor Body color is no pattern/un-marbled and has short �n Manna river Pelus Giant mottled eel A.marmorata Body color is marbled and has long �n Table 2. Characteristics of two species of Anguilla eels in Bengkulu Species Site N (ind) Character HL (cm) PDL (cm) PAL (cm) AD/TL(%) A. bicolor bicolor Kungkai 91 Range 0.2 – 6.8 7.2 – 19.3 7.9 - 22 0.3 – 4.5 Average± SD 4.17 ± 0.87 12.92 ± 2.40 13.68 ± 2.6 2.99 ± 0.93 Jenggalu 34 Range 3 – 9.1 5.8 – 27.5 Oct-29 1.4 – 4.9 Average± SD 4.84 ± 1.89 14.25 ± 5.82 15.40 ± 5.33 3.08 ± 1.02 TOTAL 125 Range 0.2 – 9.1 5.8 – 27.5 7.9 – 29 0.3 – 4.9 Average± SD 4.25± 1.01 12.99 ± 2.98 13.89 ± 3.08 2.56 ± 1.54 A. marmorata Manna 23 Range 5.1 – 6.1 7.5 – 14.6 12.6 – 24.7 15.5 – 20.8 Average± SD 5.58 ± 0.27 10.90 ± 1.96 18.03 ± 3.07 17.78 ± 1.33 125 individual of anguillid eel was A.bicolor bicolor with per- centage of ano-dorsal length 2.56 % and 23 individual sample of A.marmorata with the ano-dorsal length 17.78 %. Percentage of ano-dorsal length 2 was dominant with the frequency 44 individual. While for A.marmorata species is dominated by 16 of ano-dorsal length with the total number of individual 6 (Figure 4). There are 3 species of Anguilla eel in Bengkulu (Fahmi, 2015) such as A. bicolor bicolor, A.marmorata dan A. nebulosa nebulosa by using the analysis of the glass eel/juvenile stage. Meanwhile, there are only two species of anguilla eel which are identi�ed by elver and yellow eel stage which morphological identi�ed based on ano-dorsal length (AD/TL) as A.bicolor bicolor and A.marmorata. AD/TL is the useful for distinguish the species of anguilla eel in the rivers that leads to Palabuhan Ratu bay (Sugeha et al., 2001). It was supported by this study that this method can also be applied to distinguish the anguillid species in Bengkulu province. Overlap of the AD/TL percentage did not occur on this study because between A. bicolor bicolor and A. marmorata has signi�cant di�erence on this characteristic. The examples of the overlapping on this character occur between two sub species A.bicolor bicolor and A.bicolor pasi�ca (Sugeha and Suharti, 2008). Therefore, Watanabe (Watanabe and Tsukamoto., 2004) sug- gested that identi�cation based on Ege must be supported by the existence of geographic data information. Geographical in- formation of the source of the Anguillid eels makes it easier to identify the species of the Anguillid eels. For instance, A.bicolor bicolor distributed on Indian ocean coast from South Africa, The Arabian peninsula, Srilanka to the west of Indonesia and the western part of Australia (Robinet et al., 2003). This species is thought to be spawning in the eastern Indian Ocean precisely on the west cost of Sumatera island. Cluster analysis by using the dendrogram showed that there were 2 groups of Anguilla eel based on grouping of charac- terized population. These characteristics described by the line which divided the sample into two groups of population. Cluster analysis showed (Fig.5) that A.bicolor bicolor has sig- ni�cant di�erence on percentage of anodorsal (AD/TL) with A.marmorata. This result was supported by the Dendrogram that there was one group of A.bicolor bicolor in Jenggalu and Kungkai River. This indicated that sample from the adjacent rivers will have the same morphological characters. Meanwhile, the sample from Manna river which is located far apart from another station show di�erent species of Anguilla, A.marmorata. The di�erences are also related to the habitat characteristics of the three rivers. Length-weight relationships for anguillid eesl and the total sample population were determined and shown in Table 3 and Figure 6. Analysis of covariance revealed signi�cant di�erences between sexes for the slopes (b) of the regression lines (p < 0.05). © 2018 The Authors. Page 51 of 53 Suryati et. al. Indonesian Journal of Environmental Management and Sustainability, 2 (2018) 48-53 Figure 6. Length-Weight Relationship A.bicolor bicolor and A.marmorata in Bengkulu province Table 3. Add caption Species N Total Length (cm) Total Weight (g) Relationship parameter Range Mean±SD Range Mean±SD a b r A.bicolor bi- color 125 16.5-63.5 32.1±6.6 6.0-420.9 50.3±47.7 0.0005 3.2677 0.9453 A.marmorata 23 28.1-56.8 40.0±7.6 38-477 161.2±118.2 0.0004 3.4821 0.9623 According to Le Cren (1951) since fat and water content of �sh may vary according to temperature therefore the length- weight relationships in �shes are related to the seasonal vari- ation. Sinha (1973) stated that the change in ’b’ value shows allometric growth of the body due to the in�uence of numerous factors such as seasonal �uctuations, changes in physiological condition during spawning periods, gonad development, sex, physicochemical conditions of the environment and nutrition conditions of the environment. Sekharan (1998) have also observed an inter speci�c for ’b’ that remains constant at ’3.0’ for an ideal �sh. The result showed that values for ’b’ for length and weight were higher than 3, i.e., 3.2677 and 3.4821 in A.bicolor bicolor and A.marmorata respectively, which were of expected range and indicated that the growth is almost posi- tive allometric on Anguillid eels. However, Wootton (1992) opined that b < 3 indicates that the �sh gets relatively thin- ner as they grow larger while b > 3, it is plumper as it grows larger. The values of coe�cient of determination (r2) calcu- lated for LWR relationships TL-Wt A.bicolor bicolor and A. marmorata (Tables 3) were 0.9453 and 0.9623, respectively which are highly signi�cant (p < 0.001). Regression coe�cients obtained from length-weight relationships (L-W) which are indicatives of isometric or allometric growths di�er not only between species but sometimes also between stocks of same species. The development of �sh involves several stages, each of which has its own length-weight relationships. There may also be di�erences in the relationships due to sex, maturity, season, and environmental conditions (e.g. pollution). 4. CONCLUSIONS The current work successfully used cluster analysis and den- drogram to group the population characteristic of Anguilla eel. It revealed that in the Jenggalu, Kungkai and Manna rivers of Bengkulu province, there are two groups of Anguilla eel with signi�cant di�erence of ano-dorsal length. The value of the ano-dorsal varied from 2.56 ± 1.54 and 17.78 ± 1.33 for A.bicolor bicolor and A.marmorata, respectively. Furthermore, the present study provides an important contribution to base- line data on the length-weight relationships of the A.bicolor and A.marmorata which are important tools for the adequate management of the �sh stocks and populations. The provided data on the LWR would be bene�cial for �shery biologist’s managers to impose suitable regulations for sustainable �shery management and conservation programs in the region. 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Ecol- ogy, 73(3); 981–991 Wootton, R. J. (1990). Ecology of teleost �shes. Chapman and Hall, London, 404 © 2018 The Authors. Page 53 of 53 INTRODUCTION EXPERIMENTAL SECTION Description of research location Sample analysis Cluster Analysis RESULTS AND DISCUSSION CONCLUSIONS