Feeding preferences and diet overlap of sciaenids fishes in Pabean Bay, Indramayu

Abstract

The trophic ecology of Sciaenid fishes, one group of the demersal fishes in Pabean Bay, Indramayu is described in our study. A total of 14 types of prey were identified belonging to three groups (Decapod Crustacean, Mollusca, and Bony fishes) to analyze the feeding preferences and diet breadth overlap. The preferred prey items of Johnius belangerii (Belanger's croaker) were Calappidae (Ii = 16.12), followed by Squilla sp. (15.5), and Penaeus sp. (14.6); while Johnius borneensis (Sharpnose hammer croaker) were Penaeus sp. (Ii = 86.5), followed by Calappidae (3.45), and Acetes sp. (1.38); Johnius macropterus (Largefin croaker) were Penaeus sp. (Ii = 35), followed by Callapidae (5); Nibea soldado (Soldier croaker) were Penaeus sp. (Ii = 25.63) followed by Squilla sp. (23.98), and Charybdis sp. (16.42); Otolithes ruber (Tigertooth croaker) was Penaeus sp. (Ii = 25.63). The diet breadth (BA) values indicate that Sharpnose hammer croaker (BA = 0.06) and Tigertooth croaker (BA = 0.07) are high specialist consumers, while Belanger's croaker (BA = 0.36) and Soldier croaker (BA =0.34) are considered as non-specialized feeders. Our study showed that sciaenid fishes have overlapping trophic niches intra and inter-specific due to their common feeding on decapod crustaceans. The high trophic overlap between predators suggests that Sciaenid fishes in Pabean Bay are competing with each other when food resources are limited.
 Abstrak
 Ekologi trofik famili Sciaenidae, salah satu kelompok ikan demersal di perairan Teluk Pabean, Indramayu dideskripsikan melalui studi ini. Sebanyak 14 jenis makanan dari tiga kelompok utama (Krustasea Decapoda, Moluska, dan ikan bertulang sejati) berhasil diidentifikasi untuk analisis preferensi dan tumpang tindih relung makanan ikan Sciaenidae. Mangsa yang diminati oleh ikan Johnius belangerii (Belanger's croaker) adalah Calappidae (Ii = 16,12), diikuti oleh Squilla sp. (15,5), dan Penaeus sp. (14,6); sementara ikan Johnius borneensis (Sharpnose hammer croaker) menyukai Penaeus sp. (Ii = 86,5), disusul oleh Calappidae (3,45), dan Acetes sp. (1,38); ikan Johnius macropterus (Largefin croaker) menyenangi Penaeus sp. (Ii = 35), diikuti oleh Callapidae (5); sedangkan ikan Nibea soldado (Soldier croaker) cenderung memilikih Penaeus sp. (Ii = 25,63), Squilla sp. (23,98), dan Charybdis sp. (16,42); sedangkan Otolithes ruber (Tigertooth croaker) lebih banyak mengonsumsi Penaeus sp. (Ii = 25,63). Nilai relung makanan (BA) mengindikasikan bahwa ikan Sharpnose hammer croaker (BA = 0,06) dan Tigertooth croaker (BA = 0,07) adalah termasuk pemangsa yang spesialis, sedangkan Belanger's croaker (BA = 0,36) dan Soldier croaker (BA = 0,34) lebih cenderung sebagai pemangsa yang bukan spesialis. Tumpang tindih relung makanan khususnya jenis krustasea decapoda terjadi baik antarspesies maupun antar individu dari spesies yang sama, termasuk antar kelompok ukuran. Tumpang tindih relung makanan yang tinggi antar ikan predator menunjukkan bahwa kelompok ikan Sciaenidae di Teluk Paben berkompetisi memperebutkan makanan saat terjadi kelangkaan sumberdaya makanan.