Hubungan antara dayadukung pembentuk- an biomassa dan tingkat pemanfaatan stok ikan teri merah (Encrasicholina heteroloba) di Teluk Ambon Bagian Dalam

Abstract

The objectives of this research were to identify and to evaluate the potency capacity of biomass formation, recruitment and growth as well as level of stock biomass utilization of shorthead anchovy (Encrasicholina heteroloba) in Inner Ambon Bay. A year sampling was conducted in three sites of Inner Ambon bay i.e. in the front (zone I), in the middle (Zone II) and in the back (zone III), in order to examine the habitat characteristics, stock distribution as well as fishing intensity and catch in both full and half-moon. The results showed that habitat characteristics which consist of hydro-oceanography factors and water quality were suitable for growth and distribution of shorthead anchovy. Capacity of biomass formation in zone I, II and III reached a maximum level in June, July and August (east monsoon) and subsequently declined in September untill November (transition II of monsoon), and relatively stable in December till/up to May (west monsoon and transition I). It was indicated that utilization level of beach seine and lift net at zones I, II and III had not exceeded capacity of stock, however capacity of eliminated stock had exceeded in a particular months or season. From 23 times sampling within one year period, it was found that stock utilization level which do not exceed eliminating carring capacity (under exploited) were 9, 8, and 9 times at zone I, II, and III consecutively. Whilst stock utilization level that exceed exploitation (over explotation) were 14, 15, and 14 at zone I, II, and III consecutively. It can be concluded that Inner Ambon Bay is a semi enclose waters that connected to Outer Ambon Bay through a ridge/sill. This area has biomass carring capacity which has experienced similar exchange i.e. increase at east monsoon, decrease at 2nd monsoon, and stable during west monsoon up to 1st transition monsoon. Stock biomass utilization level has exceeded biomass formation carring capacity that causes decrease in stock sustainability or currently this stock is under over exploitation level . From this study it was suggested that management of shorthead anchovy should be based on capacity of biomass formation and elimination with the consideration of optimal utilization level towards stock potency (stock availability and capacity of stock) up to achievable sustainability levels.

Perikanan ikan umpan merupakan salah satu perikanan ikan pelagis kecil di Teluk Ambon Dalam (TAD) yang telah lama dilakukan. Perikanan ikan umpan menunjang perikanan cakalang (Pole and liner fisheries) dalam menyediakan umpan dalam pengoperasiannya. Salah satu jenis ikan umpan yang dominan tertangkap adalah ikan teri merah (Encrasicholina heteroloba). Belakangan ini, penurunan produksi maupun hasil tangkapan per unit alat tangkap ikan umpan mengalami degradasi. Penurunan tersebut diperkirakan sehubungan dengan perubahan daya dukung pembentukan biomassa, tingkat eksploitasi dan keluar masuknya ikan di Teluk Ambon Dalam. Tujuan penelitian ini adalah untuk mengidentifikasi potensi daya dukung pembentukan biomassa rekrutmen dan pertumbuhan serta tingkat pemanfaatan biomassa stok ikan teri merah. Penelitian dilakukan di TAD dengan pembagian segmen (zonasi) atas bagian mulut teluk (zona I), tengah teluk (Zona II) dan bagian terdalam (zona III). Pengambilan contoh dilakukan terhadap karakteristik habitat, distribusi stok serta intensitas dan hasil tangkapan selama setahun pada bulan gelap maupun terang di masing-masing zona. Hasil penelitian didapatkan bahwa karakteristik habitat yang meliputi faktor hidro-oseanografi dan kualitas air masih layak bagi pertumbuhan dan distribusi ikan teri merah. Daya dukung pembentukan biomassa di zona I, II dan III meningkat mencapai maksimum pada bulan Juni-Agustus (musim timur), menurun dari bulan September sampai Nopember (musim peralihan II), dan berfluktuasi mantap pada bulan Desember sampai Mei (musim barat dan peralihan I). Tingkat pemanfaatan biomassa stok di zona I dan II dan III tercermin dari total hasil tangkapan jaring pantai dan bagan belum melampui daya dukung biomassa. Pada saat daya dukung maksimum (di zona I sebesar 29.60 ton, di zona II sebesar 327.27 ton dan zona III sebesar 211. 94 ton), tingkat pemanfaatan hanya mencapai 20% pada zona I, 29% pada zona II dan 21% pada zona III. Tingkat pemanfaatan daya dukung pembentukan biomassa tereliminasi, sebagian besar (dari 23 kali pengambilan contoh selama setahun) telah terlampaui, di zona I sebanyak 14 kali, zona II sebanyak 15 kali dan zona III sebanyak 14 kali. Bahwa tingkat pemanfaatan tidak memperhatikan daya dukung tereliminasi, sehingga pada waktu atau musim tertentu tingkat pemanfaatan melampaui daya dukung tereliminasi