REPRODUKSII KAN BELANAK (Mugil dussumieri) DIPERAIRAN UJUNG PANGKAH, JAWA TIMUR [Reproduction of Mullet (Mugil dussumieri) in Ujung Pangka Water, East Java] - Sulistiono Sulistiono; Mia Rahmatul Jannah; Yunizar Ernawati (Masyarakat Iktiologi Indonesia (Indonesian Ichthyological Society), 2001)
Penelitian dilakukan sejak Mei 2000 sampai April 2001, dengan menggunakan 3 macam jaring, yaitu jaring insang bermata jaring 1.5 dan 6,5 inchi; tegur bermata jaring 0,5 inchi dan experimental gillnet bermata jaring 1,25, 1,5, 1,75 dan 2 inci. Analisis dilakukan terhadap sex rasio, indeks kematangan gonad, tingkat kematangan gonad dan fekunditas. Kematangan gonad diduga secara morfologi. Hasil pengamatan menunjukkan bahwa rasio kelamin antara jantan dan betina tidak sama dengan 1:1. Berdasarkan tingkat kematangannya. ikan belanak M. Dussumieri yang memilki TKG III (maturing) dan IV (mature) ditemukan hampir setiap bulan dengan demikian dapat dikatakan bahwa ikan belanak memijah sepanjang tahun dengan puncak pemijahan pada bulan Juni dan Januari. Keadaan ini didukung pula oleli nilai indeks kematangan gonad yang tertinggi baik pada jantan maupun pada betina terdapat pada bulan Juni dan Januari. Fekunditas bervarisi tergantung pada tingkat kematangan dan ukuran yang berkisar antara 27.117-323.20. Penyebaran diameter telur juga bervariasi (0,03-0,63 mm) tergantung pada tingkat kematangan gonad. Berdasarkan pola penyebarannya pada TKG IV didapatkan bahwa pola penyebarannya memiliki lebih dari satu puncak yang berarti partial spawner.ABSTRACTStudy on the reproduction of mullet (Mugil dussumieri) in Ujung Pangkah, East Java was conducted from May 2000 to April 2001, using three kinds of fishing gears such as gillnet (mesh sized 1.5 inches and 6.5 inches, fixed trap net mesh sized 0.5 inches and experimental gillnet mesh sized 1 inch, 1.25 inches, 1,5 inches. 1.75 inches and 2 inches). Collected fish was preserved in formaldehyde 10%, measured for total body length (app. 0.1 mm) and weighted by electeronic balance (app. 0.01 g). Analysis was done to investigate sex ratio, gonado somatic index and fecundity. Gonad maturity stage was estimated according to the morphological characteristics. Sex ratio of the fish varied from 0.4 to 2.4 according to the sampling month and total body length. Based on chi square test, the sex ratio was significantly different with 1:1. According to gonad maturity stage, the fish with mature and maturing gonads increased during June (67% for male and 50% for female) and January (38% for male and 35% for female). These indicate that peak of spawning season were in June and January. This condition is supported by gonado somatic index which was higher during June and January. Fecundity varied according to gonad maturity and size which was from 27.117 to 323.200. Oocyte diameter varied from 0.03 to 0.63 mm according to gonad maturity. Based on the distribution pattern in mature gonad, oocyte distribution have more than one mode indicating a partial spawner.