PERAN IKAN LIAR YANG BERASOSIASI DENGAN KERAMBA JARING APUNG DALAM MEREDUKSI BUANGAN NUTRIEN PAKAN

Penelitian ini bertujuan untuk mengetahui peran ikan liar yang hidup di sekitar keramba jaring apung dalam meminimalisir buangan nutrien yang berasal dari kegiatan budidaya melalui pendekatan kecernaan ikan. Ikan sersan mayor Abudefduf vaigiensis dan capungan Sphaeramia orbicular yang dominan di keramba jaring apung ditangkap dan dipelihara selama dua bulan dan diberi pakan ikan kerapu komersial. Apparent Digestibility Coefficient (ADC) kemudian dihitung menggunakan metode tidak langsung dengan cara mencampurkan indikator khromium oksida (Cr2O3) ke dalam pakan. ADC ikan sersan mayor untuk N, P dan bahan kering berturut-turut sebesar 12,88%; 15,47%; dan 66,67%. Selanjutnya jumlah N dan P yang tersimpan dalam karkas ikan sebesar 19,90% dan 12,76%. Ikan sersan mayor dengan FCR 3,0 melepaskan N dan P ke perairan sebanyak 104,78 dan 42,66 gram setiap penambahan 1 kg bobot badan. Ikan capungan, dengan ADC terhadap N, P dan bahan kering pakan sebesar 12,52%; 59,07%; dan 62,15% menahan 16,76% N dan 11,71% P dalam karkasnya. Dengan FCR 5,0, ikan capungan mengeksresikan N sebanyak 181,46 gram dan 71,96 gram P ke perairan ketika terjadi peningkatan biomassa 1 kg. Ikan liar yang hidup di sekitar keramba jaring apung di Teluk Awerange dapat meminimalisir buangan limbah dari keramba jaring apung sebesar 10% – 20%. The study was aimed to point out the role of wild fishes associated with floating net cage in minimizing nutrient loading from fish farming through digestibility approach. Abudefduf vaigiensis and Sphaeramia orbicular as the dominant species around sea cage were caught and fed ad satiation with commercial grouper food for 2 months period. Apparent Digestibility Coefficient (ADC) was then calculated using indirect method by mixing indicator chromium oxide (Cr2O3) with fish food. ADC of A. vaigiensis for nitrogen (N), phosphate (P) and dry matter were 12.88%, 51.47%, and 66.67 % respectively. Moreover, N and P retained from fish carcass were 19.90% and 12.76%. Furthermore, these fishes with FCR of 3.0 release N and P to sea water as much as 104.78 gram and 42.66 g respectively when biomass increase to 1 kg. For Sphaeramia orbicularis, ADC for N, P and dry matter were 12.52%, 59.07%, and 62.15% respectively and retained 16.76% N and 11.71% P in their carcass. Moreover, with FCR of 5.0, these fishes excreted 181.46 gram of N and 71.96 gram of P into the environment when the biomass increases to 1 kg. Wild fishes associated with sea cage in Awarange bay have the potential of minimize released nutrient between 10%–20%