Ikan karang kategori mayor adalah ikan yang mempunyai jumlah dan jenis paling banyak di ekosistem terumbu karang, sehingga keberadaannya berkaitan erat dengan keberadaan terumbu karang. Penelitian ini bertujuan untuk mengetahui tutupan terumbu karang serta keanekaragaman, kemerataan, dominansi, dan kelimpahan ikan kategori mayor di ekosistem terumbu karang Perairan Sebalang Kabupaten Lampung Selatan. Pengambilan data dilaksanakan pada bulan Mei 2018. Lokasi pengambilan data dipilih berdasarkan perbedaan karakter lingkungan, ditetapkan sebanyak 3 stasiun, pada kedalaman 3 meter dan 8 meter. Terumbu karang diamati dengan metode Line Intercept Transect (LIT), sedangkan populasi ikan mayor diamati dengan metode Underwater Visual Census (UVC). Transek pengamatan sepanjang 100 meter, dengan batas pengamatan dari transek sebelah kiri 2,5 meter dan kanan 2,5 meter. Hasil penelitian menunjukkan tutupan terumbu karang hidup berkisar antara 5,5-39,5%. Ikan mayor yang diperoleh terdiri dari 15 famili dan sebanyak 62 spesies. Indeks biologi terdiri dari indeks keanekaragaman (H') berkisar antara 2,02-2,97, indeks kemerataan (E) berkisar antara 0,78-0,95, indeks dominansi (D) berkisar antara 0,06-0,22, dan indeks kelimpahan (X) berkisar antara 0,11-0,56 individu/meter2. Jenis ikan mayor yang paling banyak ditemukan adalah dari famili Pomacentridae spesies Abudefduf vaigiensis dengan persentase 8,49%.

Major reef fish category is the fish that has most abundant number and most typically inhabit in coral reef ecosystems, so their existence is closely related to the presence of coral reefs. The aims of this study were to determine coral reef cover and diversity, evenness, dominance, abundance of fish major category in the coral reef ecosystem of Sebalang Waters, South Lampung Regency. The observation was conducted in May 2018. The location for observation was decided in 3 stations, with a depth of 3 meters and 8 meters. Coral reefs cover and type was observed following to Line Intercept Transect (LIT) method, while the major fish with the Underwater Visual Census (UVC) method. The transect was used a 100-meter line scale, and limited 2.5 meters to both left and right along transect. The results showed that coral reef covers about 5.5-39.5%. Major fish showed that there were 15 families and composed 62 species. The biological index obtained was the diversity index (H') were 2.02-2.97, the evenness index (E) were 0.78-0.95, the dominance index (D) were 0.06-0.22, and the abundance index (X) were 0.11-0.56 individuals/meter2. The most commonly found major fish species are families of Pomacentridae species Abudefduf vaigiensis with percentage 8.49%.

Kata Kunci : ekosistem, karang, konservasi, Pomacentridae/conservation, coral, ecosystem, Pomacentridae