Untitled

Abstract

This study demonstrates the comparative pattern of reproductive parameters viz. sex ratio, size at first gonadal maturity, gonadosomatic index (GSI), fecundity, egg dimension of O. bimaculatus analyzed from 13 different rivers during 2011-2013. It was observed that females start to mature earlier than males and mean size at first maturity in male and female varied considerably between the different populations. The reproductive period of fish were extended from April -August while in Southern rivers it was extended from March to July. The results indicated three types of reproductive patterns of O. bimaculatus in terms of age at first sexual maturity and absolute fecundity and distinct variation was observed across different rivers. The meanabsolute fecundity varied significantly between the rivers and was grouped in to three categories: (i) high absolute fecundity (ii) medium fecundity and (iii) low fecundity. The results indicated significant and positive correlation between absolute fecundity and total length, body weight and ovary weight in all the rivers (P<0.05). The oocyte distribution during the maturity season was consistent within the ovary but more fluctuations were observed within different population. This study provides quantitative account in to the comparative reproductive potential and inter-population reproductive strategies for the first time.

Growth Pattern, Sex Ratio and Distribution of Humpback Fish (Hemisilurus heterorhynchus, Bleeker 1854) in the Flooded River Basin, Kampar Kiri, Riau Province

“…Hasil tangkapan ikan dari bulan Oktober -Maret memberikan nilai nisbah kelamin 1.16:1, walaupun jumlah ikan jantan lebih banyak 6 ekor daripada betina, nisbah kelamin sudah mendekati pola seimbang dengan perbandingan 1:1, artinya ada keseimbangan populasi antara ikan janta dan betina. Hasil serupa juga ditemukan pada ikan Ompok bimaculatus yang diperoleh di enam sungai tropis Ganges basin, India (Praveen et al, 2017) dan 13 sungai berbeda yang ada di india yaitu (Sarkar et al, 2017) Keseimbangan nisbah kelamin ikan dapat menggambarkan keidealan suatu populasi ikan dalam mempertahankan kelestariannya, maka diharapkan perbandingan ikan jantan dan betina seimbang disetiap ikan yang sedang diteliti (Romimohtarto dan Juwana, 2001). Nisbah kelamin juga memiliki pengaruh terhadap proses pemijahan.…”

Perkembangan gonad, fekunditas dan diameter telur Hemisilurus heterorhynchus, Bleeker 1854 di sungai paparan banjir, Desa Mentulik, Kampar Kiri, Riau

“…Hal yang sama juga ditemukan pada ikan dari famili Siluridae lainnya seperti ikan Ompok bimaculatusyang ditemukan pada enam sungai di India, dimana fekunditas memiliki hubungan yang erat terhadap panjang tubuh, berat tubuh dan berat gonad (Praveen et al, 2017). Ompok pabdayang di Mymensingh, Bangladesh (Roy et al, 2021), Ompok bimaculatus di beberapa sungai di India (Sarkar et al, 2017).Ompok pabo di Tripua, India (Bhattacharya & Banik, 2015), Ompok bimaculatus di Tripura, India (Malla & Banik, 2015)…”