KEMELIMPAHAN KOMUNITAS IKAN HASIL TANGKAPAN NELAYAN JARING INSANG DI PANTAI BARON GUNUNGKIDUL, YOGYAKARTA

AGNITA NUNUNG NUGROHO WULANADJI, Dr. Tjut Sugandawaty Djohan, M.Sc.

2013 | Tesis | S2 Biologi

Penelitian variasi komunitas ikan dipelajari berdasarkan ikan hasil tangkapan nelayan Baron di perairan antara Sundak dan Ngrenehan. Ikan ditangkap di jeluk 51-100 m, dengan menggunakan jaring insang. Jaring ditebarkan antara 1-2,5 jam. Penelitian dilakukan secara temporal selama dua belas bulan mulai September 2011 sampai dengan Agustus 2012. Setiap bulan, sampel diambil pada salah satu masa puncak tangkapan. Sampel berupa hasil tangkapan dari lima perahu bermotor, sebagai lima ulangan. Setiap populasi dihitung densitas dan biomasanya. Komunitas ikan dibedakan menjadi dua. ikan pelagik dan demersal. Komunitas ikan demersal dibedakan lagi menjadi demersal karang dan bukan karang. Analisis ordinasi menunjukkan adanya kecenderungan perbedaan populasi penyusun komunitas antara musim kemarau dan musim hujan. Musim kemarau didominasi ikan pelagik yaitu Sarda orientalis dan Auxis rochei rochei, sedangkan musim hujan adalah ikan demersal, Lepturacanthus savala. Populasi Selar crumenophthalmus ditangkap sepanjang tahun. Variasi populasi penyusun komunitas menunjukkan adanya refleksi pengaruh angin monsoon yang terjadi di Laut Selatan Jawa.

Research of variation of fish was studied based on gillnetting fishermen recruitment along the coasts between Sundak and Ngrenehan. Gillnetting was carried out monthly from September 2011 to August 2012, at depth ranging from 50 to 100 m. Sampling was replicated five times using the fish taken from five fisheries boats. Data on observed fish species density was analyzed using catch per unit effort. The trend of community shifted was analyzed with Bray and Curtis ordination. Ordination analysis showed that there was seasonal shifted community. Fish community from fishermen catch was distinguished into two groups; pelagic fish and demersal fish. Pelagic fish was codominant in the dry season and demersal fish in the wet season. Species codominant in dry season was Sarda orientalisand Auxis rochei rochei; and in wet, Lepturacanthus savala. Both were economical fishes. There were some species catches throughout the year, Selar crumenophthalmus. The community shift was regulated by monsoon at southern ocean of Java.

Kata Kunci : ikan pelagik, ikan demersal, migrasi, makanan, umur ikan, musim kemarau , musim hujan, air sungai