Some reproductive biology aspects of bonylip barb (Osteochilus vittatus Valenciennes, 1842) in the waters of Benanga Reservoir, East Kalimantan

Abstract

Bonylip barb (Osteochilus vittatus Valenciennes, 1842) that belongs to the Cyprinidae family is one of the native freshwater fishes in Indonesian waters. Currently, status of this species in Benanga Reservoir, East Kalimantan is in over-exploited. Fish resources management, therefore, is needed to maintained fish stock in the reservoir based on fish reproductive biology aspects. The purpose of this study was to analyze some aspects of the reproductive biology including sex-ratio, gonad maturity, length at first gonad maturity, spawning season, fecundity, and spawning patterns as basic information for its management. Fish collection was carried out monthly on the third week from January to May 2019 at three stations. The fish samples were captured by using experimental gill nets with mesh size of 1; 1.5; 2; and 3 inches. A total of 278 bonylip barb was caught, consist of 92 males and 186 females. Sex ratio of male and female in the gonad mature stage was 1: 2.4. The average length at first gonad maturity in male and female were 136.08 mm and 137.38 mm, respectively. Peak of spawning occurs during the rainy season in May, with more than 90% of fish in mature stage with GSI in male and female were 6.88%, 13.16% respectively. Total fecundity ranged from 7312-22923 eggs individual-1 and egg diameter ranged from 0.6-1.94 mm. According to distribution of egg diameter, bonylip barb was categoried as a total spawner. Some management strategies that can be carried out are using fishing gears with mesh size above 2 inches, limiting fishing activities in the peak of the spawning season, prohibiting fishing gear using electric shocker and protection the reservoir from erosion.

Fekunditas dan Pola Pemijahan Ikan Sepat Rawa Trichopodus trichopterus (Pallas, 1770) dari Bendungan Lempake Samarinda, Kalimantan Timur

“…Subsampel gonad diletakan di dalam cawan petri berisi larutan NaCl 10% dan diaduk agar butir telurnya menyebar. Selanjutnya jumlah telur dihitung menggunakan alat colony counter merek Suntex Instrument 570 China (Jusmaldi et al, 2020).…”

“…Selanjutnya sebanyak 10 butir telur disusun di atas permukaan gelas objek dan diukur diameter telurnya menggunakan mikroskop yang telah dilengkapi dengan mikrometer okuler menggunakan perbesaran 40 kali. Pengukuran diameter telur diulang sebanyak tiga kali untuk masing-masing sampel gonad, sehingga jumlah total butir telur yang diukur diameternya adalah 900 butir telur (Jusmaldi et al, 2020).…”

“…Fekunditas ikan dihitung menggunakan rumus sebagai berikut: 𝐹 = 𝐺 𝑥 𝑓 𝑔 Keterangan: F = Fekunditas G = Bobot total gonad (g) f = Jumlah telur pada subsampel gonad (butir) g = Bobot subsampel gonad (g) (Brodziak, 2012) Hubungan fekunditas ikan dengan panjang total tubuh dan hubungan antara fekunditas ikan dengan bobot tubuh dianalisis dengan cara diregresikan. Jumlah kelas dan rentang panjang tubuh ikan ditentukan menggunakan rumus distribusi frekuensi kelas ukuran panjang ikan (Jusmaldi et al, 2020).…”

“…Dalam penelitian ini, ukuran panjang ikan sepat rawa yang tertangkap lebih kecil. Perbedaan ukuran panjang tubuh ini diduga karena adanya perbedaan kondisi lingkungan perairan seperti: ketersediaan sumber makanan dan kualitas air Jusmaldi et al (2020). menyatakan bahwa salah satu faktor utama penyebab berbedanya ukuran panjang dan bobot tubuh ikan dari lokasi geografis berbeda karena adanya perbedaan kualitas perairan seperti: suhu, oksigen terlarut dan pH.…”