Aspek Bioekologi Ikan Bilih (Mystacoleucus padangensis Bleeker.) di Perairan Danau Toba, Sumatera Utara

Abstract

A study was made on Bioecological Aspects of Ikan Bilih (Mystacoleucus padangeensis Bleeker.) of Lake Toba, North Sumatra. Facilities in this research such as some aspects of ikan bilih’s growth, biological aspect, Echo Sounder and Physical and Chemical factors studied were have been developed. The results showed the highest frequency distribution of ikan bilih length and weight in near cages are 9 cm (18,38%) and 7 g (7,86%). The highest frequency distribution of ikan bilih length and weight in the estuary are 9 cm (25,90%) and 7 g (13,10%). Value of ikan bilih length and weight relationships is 2,92 so the pattern of ikan bilih is negative allometrik where the growth of length is faster than weight. Bilih fish around cages found in higher number of male (78,74%) and females (21,26%), while in the estuary, most of ikan bilih are female (67,66%) and male (32,34%). TKG female in tilapia cages dominated by TKG V (34,00%) and estuary by TKG V (41,84%). Combined Factors Condition amounted to 1,137 which means the body of ikan bilih is flat. Stomach contents of ikan bilih in tilapia cages 70% in brownish substance similar with tilapia fish and stomach contents of ikan bilih in river estuaries 70% of light yellowish substance in the form of phytoplankton. With Echo Sounder instrument is known that ikan bilih still found below the cage until 30 meter. Based on statistical regression analysis found that water physical and chemical factors of Lake Toba (Temperature, Light Penetration, DO, BOD, COD, pH) did not significantly influence the growth of Ikan Bilih.

Suatu kajian telah dibuat tentang Aspek Bioekologi Ikan Bilih (Mystacoleucus padangeensis Bleeker.) di Perairan Danau Toba, Sumatera Utara. Beberapa aspek pertumbuhan ikan bilih, aspek biologi, faktor fisika kimia dan Echo Sounder telah dibina. Distribusi frekuensi panjang dan berat ikan bilih tertinggi pada keramba jaring apung adalah 9 cm (18,38%) dan 7 g (7,86%). Distribusi frekuensi panjang dan berat ikan bilih tertinggi pada muara sungai adalah 9 cm (25,90%) dan 7 g (13,10%). Nilai hubungan panjang dan berat ikan bilih adalah 2.92 sehingga pola pertumbuhan ikan bilih bersifat allometrik negatif dimana pertambahan panjang lebih cepat daripada pertambahan berat. Ikan bilih yang berada di sekitar keramba jaring apung didominasi jantan (78,74 %) dan betina (21,26 %), sedangkan di Muara Sungai sebagian besar ikan bilih adalah betina (67,66 %) dan jantan (32,34 %). TKG betina di keramba jaring apung didominasi TKG V (34,00%) dan di muara sungai TKG V (41,84%). Faktor Kondisi gabungan sebesar 1,137 berarti badan ikan bilih agak pipih. Isi perut ikan bilih di keramba jaring apung 70% berupa substansi kecoklatan seperti isi perut ikan nila dan isi perut ikan bilih di muara sungai 70% berupa substansi halus kekuningan berupa fitoplankton. Dengan alat Echo Sounder diketahui bahwa ikan bilih terdapat di dekat keramba jaring apung sampai kedalaman 30 meter. Berdasarkan analisa statistik regresi diketahui bahwa faktor fisika kimia perairan Danau Toba (Temperatur, Penetrasi Cahaya, DO, BOD, COD, pH) tidak berpengaruh secara signifikan terhadap pertumbuhan ikan bilih.