TYPE COMPOSITION OF EEL SEED (ANGUILLA SPP.) IN DUMOGA CREEK,

Dumoga River is one of the rivers in Bolaang Mongondow Regency disembogue to the Sulawesi Sea which becomes the entrance of glass eel from the sea. Glass eel that enters the river consists of several species. The purpose of this study was to study the species composition of glass eel that migrates to the creek of the Dumoga River. Glass eels were collected at the creek from 20th of April 2018, to 30th of May 2018 at 00:00 to 04:00. In a period of 40 days, there were 2,251 glass eels collected and consist of 3 species namely Anguilla marmorata (49.13%), Anguilla bicolor pacifica (37.94%), and Anguilla spp. (12.93%). Glass eels are stored in formalin for morphometric and meristic measurements. Morphometric was done by calculating the AD value (DA = 100 (LD-LA) LT-1) and the tail pigmentation structure. Meristic was done by calculating the eyelid spine. The result showed that the value of AD obtained ranged from (0-2.87) grouped in the type of bicolor pacifica, (14.90% 16.14%), grouped in the type A. marmorata and (6.85% 7.21%) grouped in the Anguilla sp.

(Coordinate 0.922556º E -124 catch is identified at Freshwater The materials used in this larvae phase. The eels' larvae cm sized-net. The collection (transects along 20 meters and the sample area of 200 m2 is The eels' larva obtained Morphometric measurements digital caliper with an accuracy camera and a computer for morphometric refers to Elis (1982) length (DL) and total length (TL), Based on the morphological River creek is divided into three 73.31 mm. In this study, it is obtained 0% -2.87%; 14.90% -16.14%; on AD values, it is suspected is Anguilla marmorata, Anguilla Anguilla sp.
The data presented in ano-dorsal vertebrae and the phylogenetic tree explains that obtained in this study is 111. Meanwhile, obtained the value of 105. The The calculation has obtained the The observations were also of the eel larvae reaching the marmorata eel type. The pigment RJOAS,8(80), August 2018 354 124.090733º E) at 00.00 -04.00 ICST. Glass Freshwater Aquaculture Laboratory (BPBAT) Tatelu.
this study consisted of 95% alcohol, 75% formalin larvae is collected at the edges of the river by shifting of the eel larvae is carried out by sweeping and 1 meter wide) by shifting for 10 times back obtained. obtained then fed into the formalin for morphological measurements and tail pigmentation determinations were accuracy of 0.01 mm under a stereomicroscope equipped for shooting. The determination of glass eel (1982) in Reveillac et al., (2009), are anal (TL), ano-dorsal value (AD) with the following equation:

RESULTS OF STUDY
morphological measurement, the total length of the glass three groups: group with total length of 49.3 mm; obtained the value of AD which is divided into 16.14%; and 6.85% -7.21%. Referring to the grouping that the type of eel that enters the mouth of Anguilla bicolor pacifica, and which has not Tables 1 and 2 show an association between the ano-dorsal length. Watanabe (2003) in the that the total vertebra of A. bicolor is 105-111 Meanwhile, the type A. marmorata is 103-110 he total number of vertebrates' type of Anguilla the value of 104 (Table 2).
orphometric measurements of eel in glass eel phase Meristic measurements of eel in glass eel phase also made on the structure of tail pigmentation. tip with a slightly rounded tail shape is categorized pigment in Anguilla bicolor pacifica is shaped like While in Anguilla sp., the shape of the tailbone is more similar to Anguilla marmorata with broom-shaped pigment as in Anguilla bicolor pacifica, but more pale and less dense.  Comparison of pre-anal and pre-dorsal distances also characterizes differentiation between species of eels. Figure 4 shows the long-fin type of Anguilla marmorata because the pre-anal distance is shorter than pre-dorsal. While the fin-type on Anguilla bicolor pacifica type can be seen in Figure 5.  The eel phase observed were thought to be Anguilla marmorata, were Anguilla.  Table   The waters quality data  Table 4. The data shows that environment of eel fish.  creek of the Dumoga accordance with the suitable as seeds for varied with no clear bicolor pacifica, it is also Anguilla sp. The following paragraphs will discuss the distribution of three species found at the mouth of the Dumoga River.
The Distribution of Anguilla bicolor pacifica. Type A. bicolor is divided into two subspecies namely A. bicolor bicolor and A. bicolor pacifica. Allopathic isolation (geographical isolation) between two oceans may have split A. bicolor into two subspecies. A. bicolor pacifica is widely distributed but less abundant. According to Wouthuyzen et al., (2009) the spawning area of A. bicolor pacifica occurs in the North Sulawesi Sea. Arai et al., (1999) states that glass eel A. bicolor pacifica can only be sampled in January, March, April, October, and December. The spawning area of A. bicolor pacifica appears to be unidentified. However, the current species distribution map by Aoyama (2009) and Fahmi et al. (2102) shows that both A. marmorata and A. bicolor pacifica are carried from the Sulawesi Sea.
Analysis of the population structure of A. bicolor pacifica shows no significant genetic differences in the distribution of the South Pacific Ocean (Minegishi et al., 2012). The wide distribution of A. bicolor pacifica in the northeast of Indonesia may be due to the dispersive glass eel transport throughout eastern Indonesia. The dynamics of the water flow in eastern Indonesia are heavily influenced by the Indonesia River Flow, where these currents enter the Indonesian waters from the Pacific, flowing into the Indian Ocean via the western route of the Makassar Strait, then exit through the Lombok Strait. In this condition, the current can flow eastward into the Banda Sea. The saltier and denser waters of the South Pacific pass through the Banda Sea, where this mass of water will be mixed (Gardon, 2005). This current flow affects the local climate and helps the distribution of planktonic eggs and larvae.
The Distribution of Anguilla marmorata. The spawning areas that supply glass eels taken from the Dumoga River are not known with certainty. The existence of glass eel A. Based on the biological aspects of A. marmorata it is known that the current dynamics pattern is due to the effects of water entering from the North Pacific and the South Pacific. In addition, these waters cross the Wallacea line, which affects the pattern of species spread. There are some deep waters in eastern Indonesia that allow spawning, such as the Arafura Sea, Makassar Strait, Flores Sea, Sulawesi Sea, Tomini Bay and Bone Bay. Therefore, more research is needed on the structure of population A. marmorata in Indonesian waters, especially the eastern part of Indonesia.
Analysis of the population structure of A. bicolor pacifica showed no significant genetic differences in the distribution of the South Pacific Ocean (Minegishi et al., 2012). The wide distribution of A. bicolor pacifica in the northeast of Indonesia may be due to the dispersive glass eel transport throughout eastern Indonesia. The dynamics of the water flow in eastern Indonesia are heavily influenced by the Indonesia River Flow, where these currents enter the Indonesian waters from the Pacific, flowing into the Indian Ocean via the western route of the Makassar Strait, then exit through the Lombok Strait. In this condition, the current can flow eastward into the Banda Sea. The more salty and denser waters of the South Pacific pass through the Banda Sea, where this mass of water will be mixed (Gardon, 2005). This current flow affects the local climate and helps the distribution of planktonic eggs and larvae.
Distribution of Anguilla sp. The other types of eel (Anguilla sp.) in this research have an ADV range 6-7. However, its genetic is certainly not known yet. There are three species of tropical glass eel known to have anodorsal vertebrate between 6 and 12, which are A. celebesensis and A. borneensis (7-10 ADV). The glass eel from A. celebesensis and A. borneensis have been identified in the Makassar Strait (Wouthuyzen et al., 2009). The available information indicates that the spawning area of A. borneensis is likely to be in or close to Makassar Strait.
A. celebesensis is one of the endemic tropical eel species in Sulawesi. The glass eel species are collected in two different seasons and in two different regions (Sulawesi Sea and Tomini Bay). Glass eel in Tomini Bay was discovered in May, while leptocephalus in the Sulawesi Sea was discovered in February (Aoyama et al., 2003;Wouthuyzen et al., 2009). However, in a research conducted in April-May, this endemic species was still found in the Dumoga estuary since the spawning and growth area of A. celebesensis are considered to be in Tomini Bay. Therefore, it indicates that the migration distance of A. celebesensis is the shortest one of the genus Anguilla since the approximate migration distance is 80 km.
In addition to the Sulawesi Sea, the spawning area of A. celebesensis is also located in Tomini Bay (Aoyama et al., 2003). At least, the larvae can be carried out from the bay by the water flow that will eventually join the Indonesian Throughflow and enter the Makassar Strait. This suggests that eels, such as A. marmorata and A. celebesensis may have more than one spawning area.
The other A. borneensis endemic tropical species is taken from Celebes Sea (Aoyama et al., 2003). A. borneensis growth habitat is limited to the eastern Borneo and the Celebes Sea. In this research, A. borneensis specimen is allegedly found since the research location has a direct contact with the Celebes Sea and Makassar Strait. The migration distance of A. borneensis glass eel is at least 450-650 km from the spawning area (Aoyama et al., 2003).
The tropical eel has a unique distribution and migration patterns such as short migration distance, short metamorphosis duration, spawning throughout the year and some of them spread widely, while some others spread closely. The spreading behavior pattern is an important factor in the separation of eel types, because, in leptocephalus stadia, the eel will swim passively following the flow pattern. However, the re-migration of the eel depends largely on its ability and oceanographic condition.
The occurrence of abundance variation (absolute and relative) is caused by the combination of several factors discussed by Kuroki et al., (2012). Factors that may affect the uptake of each glass eel species are affected by the survival rate, the time and spawning result as well as the transport of glass eel larvae following the ocean flow as a glass eel and the metamorphosis process into glass eel stage. Righton et al., (2012) state that the eel migration may be affected by factors related to climate. The survival and migration route of glass eel larvae can be affected by multi-decade trends in ocean circulation and pattern changes affected by the climate. There is a temporal pattern in taking the glass eels in the Dumoga River over a period of years or even decades that cannot be detected based on the short duration of the data. It is also possible that the pattern changes or will change due to the global shift in climate and ocean circulation.
Seen from the biodiversity perspective, the existence of Anguilla sp. species in small quantity with ADV of 6-12 are still considered important to ensure that glass eels survive during the migration. Therefore, it is suggested to let the glass eel of ADV group of 6-12 go and return it to the wild. The spot observation and distribution variability of ADV numbers reinforce the opinion that there may be more than one species with ADV ranges of 6-12 taken from the Dumoga estuary. Furthermore, the difference in glass eel size is due to the presence of two (or more) species and/or the existence of glass eels from different ages (from different spawning activities or even laying spots) taken at the same time.
Three species taken from the Dumoga estuary with ADV numbers in the range of 6-12 are important from biodiversity and biogeography perspective in order to identify the species that actually exist. Identification of glass eels based on DNA from one or more recent species has been developed by Fahmi et al., (2013). Seasonal and annual variability needs to be observed in the recruitment. The sample selection should include full ADV range and fat least few months (ideally over a period of one or more years) to ensure complete identification of existing species.

CONCLUSION
During the research period, three species of Dumoga estuary have been collected. The species composition is dominated by Anguilla Marmorata and Anguilla bicolor Pacifica, both of which are commercially valuable. In addition, a species that cannot be accurately identified using ADV and tail pigmentation method was found. However, from the aspects of conservation and biodiversity, it is considered very important. A genetic analysis method is required to identify this species in order to know the whole composition of glass eel species collected from the Dumoga River.