Analisis Daya Dukung Perairan Danau Toba terhadap Kegiatan Perikanan sebagai Dasar dalam Pengendalian Pencemaran Keramba Jaring Apung

Abstract

Lake Toba is the biggest lake in Indonesia and also the largest vulcanic lake in the world with categorized as oligotrophic lake with a low supply of plant nutrients and a long habitation time. Lake Toba has been utilized for fish farming, agriculture, settlement, livestock, and tourism. Fish farming industry has started since 1986 and there has been a sharp increase in the number of fish cages afterwards. In 2008, the number of fish cages in Lake Toba amounted to 6,269 units. Growth in the fish farming activities needs to be analyzed to see the possibility of addition or reduction. Therefore, there is a need for an Analysis of the Carrying Capacity of Lake Toba Waters Towards Fish Farming as the Basis for Controlling the Pollution of the Fish Cages. The analysis is conducted based on the existence of Phosphorus in Lake Toba waters considering that the basic measurement is the Phosphorus parameter itself. The primary aims of this study are to analyze the existence of Phosphorus in Lake Toba, to analyze the carrying capacity of Lake Toba waters on the basis of Phosphorus existence, and to recommend feasible in the number of fish cages as a way of controlling the pollution caused by the fish cages in Lake Toba. For that purpose, this research employs a method of water quality measurement towards Phosphorus parameter, as well as the application of Dillon and Ridgler; Beveridge; Pulatsu and the Ministry of Environment s methods of determining the carrying capacity of Lake Toba waters towards the fish farming activities. The results of Lake Toba water quality measurement show an average concentration of Phosphorus (0.172 mg/L) and as excess amount of Phosphorus in several point above the level of quality standard (0.2 mg/L) based on the Governor Regulation No.1 in the year 2009 concerning the Quality Standard of Lake Toba water in the vicinity of Sibaganding, Simanindo, Ambarita, Silima Lombu and Haranggaol as fish farming centers. And the carrying capacity of Lake Toba towards fish farming activities amounts to 8,357.011 tonnes of fish/year or as many as 2,228 units fish cages. As results 4,041 fish cages need to be reduced in lake Toba waters. Therefore, certain measures regarding the carrying capacity of Lake Toba towards the floating net fish cages need to be specified through local regulations based on the environmental carrying capacity by considering the hidrological factors of Lake Toba, the flushing rate of water quality existence as well as Lake Toba share.

Danau Toba merupakan danau terbesar di Indonesia dan juga merupakan Danau vulkanik terbesar di dunia, dengan kategori sebagai danau oligotrofik dengan ciri khas miskin akan unsur hara, memiliki waktu tinggal yang cukup lama. Perairan Danau Toba dimanfaatkan untuk kegiatan perikanan, pertanian, pemukiman, peternakan dan pariwisata. Khusus untuk kegiatan perikanan telah dimulai sejak Tahun 1986 dan terus mengalami peningkatan yang tajam hingga Tahun 2008 terdapat 6.269 unit keramba di perairan Danau Toba. Pertumbuhan kegiatan perikanan di Danau Toba perlu dianalisis apakah masih memungkinkan untuk di tambah atau dikurangi. Untuk itu perlu dilakukan Analisis Daya Dukung Perairan Danau Toba Terhadap Kegiatan Perikanan Sebagai Dasar Dalam Pengedalian Pencemaran Keramba Jaring Apung. Analisis dilakukan berdasarkan keberadaan Fosfor di Perairan Danau Toba mengingat dasar perhitungannya adalah parameter Fosfor. Tujuan utama dari penelitian ini adalah menganalisis keberadaan Fosfor di perairan Danau Toba, mengenalisis daya dukung perairan Danau Toba berdasarkan status trofik atau keberadaan unsur Fosfor dan menyarankan kapasitas keramba yang ideal untuk pengendalian pencemaran perairan Danau akibat kegiatan keramba jaring apung. Untuk mencapai tujuan tersebut dilakukan pengukuran kualitas air terhadap parameter Fosfor dan penerapan metode atau rumus Dillon dan Ridgler; Beveridge;Pulatsu dan Kementerian Lingkungan Hidup dalam menetapkan kapasitas daya dukung perairan Danau Toba terhadap kegiatan perikanan. Hasil pengukuran kualitas air Danau Toba menunjukkan rata-rata Fosfor 0.172 mg/L dan di beberapa titik telah melebihi Baku Mutu yaitu 0,2 mg/L sesuai dengan Peraturan Gubernur Nomor 1 Tahun 2009 tentang Baku Mutu Air Danau Toba yaitu Sibaganding, Simanindo, Ambarita, Silima Lombu dan Haranggaol yang merupakan pusat kegiatan perikanan. Sedangkan kapasitas daya dukung perairan Danau Toba terhadap kegiatan perikanan adalah sebesar 8.357,011 ton ikan/tahun atau sebanyak 2.228 Unit keramba. Sehingga perlu pengurangan sebanyak 4.041 unit keramba di perairan Danau Toba. Oleh karena itu perlu penetapan daya dukung perairan Danau Toba terhadap kegiatan keramba jaring apung melalui peraturan daerah berdasarkan daya dukung lingkungan dengan mempertimbangkan faktor hidrologi Danau Toba, laju penggelontoran eksisting kualitas air serta peruntukan Danau Toba.