VARIASI UKURAN DAN JENIS MANGSA DARI IKAN MADIDIHANG MUDA (IMMATURE) DAN DEWASA (MATURE)

Abstract

Penelitian ini bertujuan untuk mengetahui hubungan antara mangsa dan pemangsa (ikan madidihang) di perairan Marisa. Pengambilan contoh dilakukan di Marisa, Provinsi Gorontalo, pada perusahaan fillet ikan tuna. Pengamatan isi lambung dilakukan secara visual. Hasil penelitian menunjukan bahwa tidak terdapat hubungan antara pertambahan ukuran mangsa dengan ukuran ikan pemangsa (madidihang), tapi terdapat hubungan antara jenis mangsa dengan ukuran ikan pemangsa. Ikan madidihang yang berukuran besar (matang gonad) memakan tuna kecil (Auxis rochei) dan ikan pelagis kecil (Brama dussumieri dan Selar crumenopthalmus), sedangkan ikan madidihang yang belum matang gonad banyak memakan Canthigaster spp., Monacanthidae, dan Balistidae. Kanibalisme tidak terjadi di perairan Teluk Tomini.

The objective of this research was to study on the relationship between predator and prey for yellowfin tuna in Tomini Bay. Sampling site were located at Marisa, Gorontalo Province in 2007. Prey composition of yellowfin tuna was visually determined. The results showed that there was no relationship between the size of yellowfin tuna and their preys, however, there was indication that different size of yellowfin tuna feed on different item of foods. Adults yellowfin tuna feed little tuna (Auxis rochei) and small pelagic fish Brama dussumieri and Selar cromenopthalmus), while immature yellowfin tuna feed mostly Canthigaster spp., Monacanthidae and Balistidae.