The Stock Potency of Demersal Fish Resource at the Coastal Zone, East Kutai District in East Kalimantan

The objective of this research was to estimate the potency of demersal fish resource spread over three sub-districts i.e. Sangkulirang, Sandaran and Kaliorang in Kutai district, East Kalimantan province. The result showed that the highest total biomass was produced by aquatic zone of Sandaran sub-district with 1,763,713.6 ton/zone and the density stock was 13,566.5 kg/km2. It was followed by Sangkulirang sub-district with 264,653.3 ton/zone and 6,640.4 kg/km2, respectively and then by Kaliorang sub-district with 58.086,5 ton/zone and 2,768.0 kg/km2, respectively. In term of species particularly from crustaseaae family, the most economic aquatic zone was found in Sangkulirang sub-district. The export product species Penaeus sp was obtained from Penaeus monodon, Metapenaeus monoceros, Metapenaeus sp, Parapenaeopsis sculptilis, Penaeus sp, and lobster which was accounted by 3,381.6 tons/zone, 83,199 tons/zone, 14,492.7 tons/zone, 24,691.3 tons/zone, 41,331.1 tons/zone, and 1,073.5 tons/zone, respectively. It was followed by Sandaran sub-district with export product species was Penaeus merguensis 33,495.7 tons/zone and non-export products were Parapenaeopsis sculptilis 63,641.7 tons/zone, Penaeus sp 16,747.8 tons/zone, Metapenaeus sp 1.674,8 tons/zone, Caridina sp 1.562.572,2 tons/zone, and Scylla serrata 3,349.6 tons/zone. Next was Kaliorang sub-district which accounted by Penaeus merguensis 62.2 tons/zone and Metapenaeus monoceros 49.7 tons/zone. In situ measurement on seven physical-chemical quality parameters of water which compared to the standardized of sea water showed that water quality found in coastal zone of Kaliorang, Sangkulirang and Sandaran sub-district, East Kutai province was suitable and feasible for the aquatic and living of marine habitats


I. INTRODUCTION
Coastal zone has abundant potency of fishery resource, but somehow hasn't reached the optimum exploration (Charles, 2001). Thus, appropriate effort should be addressed in order to manage and explore those resources. Coastal zone is the transition or interface between land and ocean ecosystem (Blankenship and Leber, 1995). Biologically, this zone is very productive and potential for Demersal fish catchment (Blanchard, 2001).
Fishing can be carried out in coastal zone and off-shore zone. Fishing catchment in coastal zone is carried out by small fishermen using simple technology. They catch different kinds of skinny fish, mollusk and plant protein such as mangrove vegetation, algae, sea weed and so on (Sorensen et al., 1984). While fishing catchment in off shore zone, besides of small fishers, capital-intensive fishers play the most significant role (Soede, 2000).
Local community highly depend their livelihoods on the sustainability of coastal zone in East Kalimantan. It has been known from a long time ago that coastal zone with its all potency has been utilized by local community especially for economic reason (Suyatna et al., 2010).
Villages of East Kutai in East Kalimantan province particularly located in Kaliorang, Sangkulirang and Sandaran sub-district have fisheries resources that can be utilized and managed by local community as the main livelihood and sideline to improve their prosperity and economy. However, fishing catchment activity has not yet given significant yield for East Kutai district. Mean while, abundance coastal potency spreading over seven subdistricts is very potential for further fishing exploration by utilizing fishing device such as hand line, tonda, purse seine, guidding barrier, gillnet, trammel net and trawl (East Kalimantan Statistical Bureau, 2012).
The biophysical characteristic of coastal zone located in East Kutai depicts viable fisheries condition for the development of fishing catchment activity of Demersal fish. The slope profile of coast is very practicable for utilization of fishing device including dogol, trawl, trammel net, belat, jermal and rawai dasar. However, it has limitation on the geographically aspect in which the zone is freely exposed to stream and wave of north and south season. Technical modifications on the catchment technology system and uses of stable ship/boats used for fishing are some efforts that could be done to minimizing the limitation (Purwaka and Sunoto, 1999). In spite of this, the limiting factor that cannot be avoided is regulation concerning on the spatial planning excluding fisheries sector (Stobutzki et al., 2006).

II. RESEARCH METHOD
Research was carried out in two months covered three sub-districts i.e.: Kaliorang, Sangkulirang, and Sandaran. According to English et al. (1985), there are at least five fishing gears for sampling fish species living surround mangrove forest, one of them is trawl. Fish sampling technique was performed by lowering fish net called setting. When the net already reached the bottom, the ship was operated to capture all the existing biota in the bottom for 30 minutes. Then, the net was hauled using the method of Line tracking Fish sampling was conducted out in two months period. A period of sampling consisted of one week for two trips so the total sampling was 32 times (with towing period by 30 minutes). According to Ricker (1967), Swept Zone Analysis and Total Biomass are two frequently-used procedures to identify fish types. Theoretically, CPUE is written as: Cw/a (Cw = weight of the catch; a = swept zone or effective path swept of each hauling so that a = D. h. X (D = length of the path and h is the length of the upper head-rope or width of the path swept by the trawl, X = varies from 0.4 to 0.66. Generally, X value is 0.4.D or Di could be specifically written as: Lat1= latitude at the start of haul (degree), Lat2 = latitude at the end of haul (degree); andLon1 = longitude at the start of haul (degree), Lon2 = longitude at the end of haul (degree) (Spare and Veneme, 1992 in Can et al.., 2005).

III. RESULT AND DISCUSSION
The result of swept analysis was about the species of demersal fish, a potential resource for coastal fishery in East Kutai District. The analyzed fish were from the commonly-consumed species. Based on the result of potential analysis per unit zone in Kaliorang sub-district, it was obtained that the number of pepetek fish (Leiognathus sp)was much larger than other species, with total biomass 39,793.8 tons/zone, whereas fish from around 26 tax a ranged from 24.9 -746.1 tons/zone, except for family Pomadasys kaakan which was 5,347.3 tons/are, Terapon theraps was 2,014.6 tons/zone, Johnius amblycephalus 1,517.1 ton/zone and Sardinella fimbriata 1,243.6 ton/zone. For export shrimp commodity (Penaeus sp) especially Penaeus merguensis was 62.2 tons/zone and Metapenaeus monoceros was 49.7 tons/zone. Overall, total biomass in Kaliorang aquatic zone was 58,086.5 tons/zone and total density of stock was 2,768.0 kg/km2.
According to the result of potential analysis per unit zone in Sangkulirang sub-district, it was obtained that the number of Johnius amblycephalus was much larger than other species, with total biomass was about 23.617,8 tons/zone, whereas fish from 19 tax a ranged from 53. Rapid development shave brought negative impacts on the quality of the environment. One of the attempts to save the environment is to minimize the effect of an activity that will cause water quality degradation. Review of water quality parameters requires an adequate knowledge and understanding of the definition (terminology) of water quality parameters, the relationship between parameters, the causative relationship between parameters and the role of these parameters in the balance of aquatic environments.
Given the importance of the presence of water resources quality, the quality should be preserved and maintained, so that the utilization could be sustained. Due to many activities occur in coastal zones of Kaliorang subdistrict, Sangkulirang sub-district, and Sandaran subdistrict, possible impacts that occur on water quality also need to be considered in order to avoid changes in water quality and pollution of sea water.
Water quality samplings were conducted on sunny days, each sampling started from 7:30 am until 1:10 pm (Indonesia Central Time). Water quality parameters were measured and observed in situ consists of seven parameters of water quality, which were: DO (Dissolved Oxygen), conductivity, turbidity, pH, temperature, salinity and TSS (suspended solids). The results of the sea water quality measurement at nine observation stations around the coastal waters of Kaliorang sub-district, Sangkulirang sub-district, and Sandaran sub-district, East Kutai district, are presented in Table 4. The quality of the aquatic environment is an aquatic environmental feasibility for sustaining life and growth of aquatic organisms whose value is expressed in a certain range. Meanwhile, an ideal aquatic zone is an zone that supports the life of organisms in completing their life cycles (Boyd, 1982 The measurement results at all observation stations in coastal waters of Kaliorang sub-district, Sangkulirang subdistrict, and Sandaran sub-districtshowed that most measured sea water quality were still in the approved limit according to Sea Water Quality Standard in Minister of Environment Decree No. 51 in 2004 Appendix I for Ports Water and Appendix III for Marine Life. However, in general, there were wo parameters beyond the approved limit, such as: Turbidity and Dissolved Oxygen. According to Yosiaki et al. (1988), the process of photosynthesis caused an increase in dissolved oxygen during the day and reached its maximum in the afternoon, and then the concentration of dissolved oxygen decreased from evening until the next morning due to the respiration activity of organisms and decomposition of organic matter Dissolved oxygen is an important parameter of water quality for marine life because it is closely related to respiration process in the water. In general, the quality of sea water in coastal zones of Kaliorang sub-district, Sangkulirang sub-district, and Sandaran sub-district contained DO ranged from 4.16-4.52 mg/l. If we compare to Sea Water Quality Standard in Minister of Environment Decree No. 51 in 2004 Appendix I for Ports Water and Appendix III for Marine Life, measured DO level in all zones were under the required range, more than 5 mg/l.
The results of turbidity measurements showed that turbidity parameter as an indicator of sea water quality at all observation stations in coastal zones of Kaliorang subdistrict, Sangkulirang sub-district, and Sandaran sub-district had exceeded the limit of Sea Water Standard in Minister of Environment Decree No 2004 Appendix I for Ports Water and Appendix Marine Life. Measured sea water turbidity at al ranged from 15-983 NTU and had exceeded the pe quality standard which is 5 NTU. Odum (1971) su that turbidity was caused mainly by siltatio sediment particles. Turbidity is often importan limiting factor. On the contrary, if the turbidity is by organisms (plankton) or organic materials, the turbidity is an indication of water productivity. Turbidity is caused by both organic and in materials suspended or dissolved such as mu organic and inorganic materials such as plankto other microorganisms. High turbidity value do mean as the indication of high pollution rate, it jus light penetration that might reduce the level of p productivity in marine life. Coastal aquatic ecosyst still heavily influenced by the land and the rivers th into the sea, in addition to other influences such stirring waters by waves and currents, they a influenced by microorganisms such as planktons.
The measurement results of the degree of acid at all observation stations in coastal waters of sub-district, Sangkulirang sub-district, and Sandar district ranged between 7.75 and 8:37. The results measurements in all zones generally were still in th required by Sea Water Quality Standard in Min Environment Decree No. 51 in 2004 Appendix I fo Water and Appendix III for Marine Life which is 6.5-8.5.
Every organism has an optimum pH for its ideal pH for phytoplankton is 6.5-8.0. In waters w less than six, phytoplankton cannot live well. W waters with pH 9.5 can cause the death of organisms and reduce productivity (Weber, 1991    The measurement results of water tem observation stations in coastal zones of district, Sangkulirang sub-district, and district ranged from 29 -30.8 °C. The res were still in the limit according to Sea Standard in Minister of Environment De 2004 Appendix I for Ports Water and A Marine Life which required Water Temper range with variation less than 3°C. A temperature are likely to affect many che which occur simultaneously in plant and thus also affecting the biota as a whole. temperature, the higher metabolism of orga the waters will occur. It will increase oxyg but the ability of hemoglobin to bind ox Walk et al., (2000) stated that high te directly affect the metabolic processes of a The measurement results of total susp all stations in coastal zones of Kaliora Sangkulirang sub-district, and Sandar ranged from 28 mg/l to 57 mg/l . In gene TSS or suspended solids measured at stations were still in the limit accordin Quality Standard in Minister of Environm 51 in 2004 Appendix I for Ports Water a for Marine Life which required total su (TSS) or dissolved residues less than content of TSS generally is influenced by w from coastal and sea water which are ope and lotic water resulting in water move stir the silt contained in the bottom 4 particles to move towards the surface through process and abrasion (soil erosion on the shore).  Based on the measurement results of the el conductivity value (EC) at nine sampling stati Kaliorang sub-district, Sangkulirang sub-distri Sandaran sub-districtranged from 18.3 to 50.2 ms/ lowest value of DHL was found in Muara Susu station which was 18.3 ms/cm. Its value was muc than in Muara Selangkau which was 91 ms/cm. Electric conductivity (EC) describes the el charge contained in a water body due to the pres dissolved ions in the waters, thus the DHL value proportional to the concentration of dissolved sub which form ions in the water. The higher concentr ions contained in the water, the higher conductivity will be gained (Boyd, 1982).  Due to the distribution of coastal eco lamun, coral reefs, and mangroves a ecosystem based on the types such as estu water) and sea water, the management o in East Kutai especially in three observ namely Kaliorang, Sangkulirang, and San wide variation.
Based on the results of fishing using bo fish and shrimp with economically signi size is big enough) were caught within th coastline between two and three km. shrimp caught in the zone less than 2 km smaller size. Therefore, this zone can be r a fishing zone (fishing ground) for local fis Related to the type and fish size as we ecosystems, the three groups interacte especially the interaction between fish ecosystem (Lamun, Mangroves and Coral R small fish congregated in the estuary mangrove is found, even only with mangr of groups was found. In this zone, they easily as feeding ground and even as the and therefore the estuarine fish produ highest, while the diversity of types was fo reef ecosystem. For recommendations, mouths should be prohibited from using reduce the amount of larvae and small fi net should be also prohibited. For fisheri (sustainable management), prohibition shrimp fishing in some places are very ne (Marine Protected Zones), but this needs determine the locations . The results of th that Sangkulirang sub-district and Sanda had the highest potential and diversity Kaliorangsub-district. Therefore, those su attention to be used as a marine protecte km from the coastline must be served as zone and it is necessary to study the m fishing gear.

CONCLUSION
The highest total biomass of demers was found at Sandaran sub-district a 1,763,713.6 ton/zone and density stoc kg/km2, followed by Sangkulirang aq 264,653.3 ton/zone and 6,640.4 kg/km2, Kaliorang aquatic zone by 58,086.5 ton/ kg/km 2 , respectively.
According to the biomass production family, the most economic aquatic zo

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Nine Sampling Stations oastal ecosystem such as groves as well as the uch as estuaries (brackish agement of fish resources ee observed sub-districts, g, and Sandaran, will give g using bottom mini trawl, cally significant size (fish within the sea zone from ree km. While fish and than 2 km commonly have can be recommended as or local fishers. size as well as the types of interacted each other, een fish and the coastal nd Coral Reefs). Generally, e estuary waters where ith mangroves, small form , they could find food en as the nursery ground, ish productivity was the pes was found in the coral ations, zones in the river m using dogol as it would d small fish. Small fishing For fisheries management rohibitions in fish and re very necessary as MPAs this needs further study to sults of the study showed and Sandaran sub-district d diversity compared to , those sub-districts need e protected zone. Above 5 served as pelagic fishing tudy the most economical f demersal fish resource district aquatic zone by nsity stock by 13,566.