Ecoregional Assessment of Biological Diversity in East Kalimantan

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East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems ‣ Fishermen who work illegally with electric prods, frequently focus on Pesut feeding grounds and use the presence of Pesut to identify favorable places to fish. Most of these illegal fishermen are Banjar transmigrants and tend not to be local Kutai people who have a stake in maintaining viable populations of these native fishes. 4. Pollution from gold mining upstream, which commenced about 1980. Because Pesut eat fish and prawns that may spend part of their time upstream in the areas more contaminated by mercury and arsenic, they are likely to have increased loads of these heavy metals. The effect of these metals on reproduction and health of Pesut can only be speculated upon at this time, but is likely to be detrimental to the health, productivity and longevity of affected individuals. 5. Siltation in these lakes is caused not only by erosion from the Mahakam’s upper catchment area (due to extensive logging since the early eighties), but also by the accumulation of dead aquatic plants, which are over abundant in the lakes and whose growth is supported by the high nutrient input to the water (eutrophication) from agriculture, fish cage farming and settlements surrounding the lakes (Hardwinarto et al. 1999; Suryadiptra et al. (2002). 6. There has been a major increase in the amount of aquatic vegetation (mainly Eicchornia crassipes and Mimosa pigra) in the lakes, which may have arisen from eutrophication due to nutrient enrichment from fish farming in the rivers and lakes or from agricultural activities surrounding the lakes. The presence of increased aquatic vegetation is in turn increasing the rate of siltation in the lakes by trapping more suspended material in the river. Not only does fish-farming lead to nutrient enrichment in the lakes but it probably contributes directly to the physical siltation process, through large amounts of waste food falling to the riverbed and being washed into the lakes (Suryadiptra et al. 2000). 7. Danielle Kreb (pers. com.) also strongly recommends the immediate establishment of conservation areas in major Pesut habitat, namely, 1) the confluence area of Muara Kaman and tributary Kedang Rantau, 2) the Pela tributary and southern part of Lake Semayang, and 3) the confluence area of Muara Pahu and Kedang Pahu tributary until Bolowan. She considers that, within these areas, it is important to increase awareness of local residents, install speed limit regulation for speedboats, gillnet-setting regulations, and step up active patrolling and law-enforcement of illegal fishing techniques and dolphin catches. Additionally, Suryadiptra et al. (2000) indicate the need for an integrated management plan for the Mahakam lakes and their upper catchment areas by involving various/relevant stakeholders and to restore some of the lakes (e.g., Lakes Tawar and Perian) by removing aquatic plants and sediment. 55
East Kalimantan Ecoregional Assessment: Chapter 2 – Target Ecological Systems Occurrence Determination Significant Major Rivers and Lakes were identified first using LandSat imagery to locate them in the East Kalimantan province. The ECA team then consulted with individual experts and literature sources, followed by a ground or aerial check for those rivers proposed for inclusion in the portfolio. Major river systems in East Kalimantan are defined in this report as those having complex deltas at their terminus, usually with Mangrove Forest or Freshwater Forest adjoining. In East Kalimantan, this ECA recognized the following 12 major river systems: Stratigraphic Unit 1 Stratigraphic Unit 3 Sungai Sebuku Sungai Kinjau Sungai Sembakung Sungai Belayan Sungai Sesayap Sungai Mahakam Sungai Kayan Stratigraphic Unit 2 Stratigraphic Unit 4 Sungai Segah Sungai Kerang Sungai Kelai Sungai Karangan Sungai Kedang Kepala Condition Condition of the above rivers was ranked based upon a cumulative score of three separate ranks assigned the major segments of the river system, namely the Upper Catchment Area, Mid-stream Buffer Zone, and the Terminal Delta. These individual segments were ranked accordingly: Prime upper catchment area- identified by flow accumulation of the watershed and its polygon defined by an aggregation of the sub-watershed area boundaries. The condition was ranked as Very good, Good, Poor, or Very Poor. Mid stream buffer zone – identified as the belt zone within 500 meters on either side of the river, ranked according to the same condition criteria used to rate the Lowland Rainforest system. The conditions were ranked asVery good, Good, Poor, or Very Poor. Terminal Delta – identified as the forested area at the mouth of each river, usually defined by the zone of perennial inundation, and ranked according to the same condition ratings given Mangrove Swamp and Freshwater Swamp system types. The conditions were ranked as Very good, Good, Poor, or Very Poor. 56
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Ecoregional Assessment of Biological Diversity in East Kalimantan

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