Ikan tongkol lurik Euthynnus affinis, (Scombridae) merupakan ikan besar yang banyak tertangkap di perairan Laut Jawa. Penelitian ini bertujuan untuk mengetahui komposisi sebaran ukuran ikan tongkol, panjang pertama kali tertangkap, hubungan panjang-berat, pola pertumbuhan, kebiasaan makanan, nisbah kelamin, Tingkat Kematangan Gonad (TKG), Indeks Kematangan Gonad, fekunditas dan diameter telur ikan tongkol yang didaratkan di PPI Labuan. Pengambilan sampel dilakukan pada bulan Mei, Juni, dan September 2012.Hasil penelitian menunjukkan bahwa sebaran frekuensi panjang cagak ikan tongkol yang ditangkap berkisar 38-69 cm ( x = 50 cm). Ukuran pertama kali tertangkap 47,8 cm dengan panjang cagak ikan yang paling banyak tertangkap berkisar 49-51 cm. Hubungan panjang-berat ikan tongkol bersifat allometrik negatif. Ikan tongkol memakan ikan pelagis kecil, cumi dan teri. Nisbah kelamin antara ikan jantan : betina (1:1,4). Tingkat Kematangan Gonad ikan termasuk TKG III dan IV hal ini menunjukkan bahwa ikan dalam masa pemijahan. Indeks Kematangan Gonad rata-rata adalah 4,55%. Faktor kondisi berkisar antara 1,38-2,22. Fekunditas telur berkisar antara 852.000 - 2.056.609 butir dengan rata-rata 1.352.382 butir. Sedangkan diameter telur berkisar 1,28 - 1,8 mm.

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Eastern little tuna Euthynnus affinis (Scombridae) is a pelagic fish which caught excessively in the Java Sea waters. The objective of this research is to determine the composition of these tuna size distribution, lenght at first capture, length-weight relationship, growth pattern, food content, sex ratio, gonad maturity level, gonado stomatic index, fecundity and eggs with diameter of their kind of fish caught and landed in PPP Labuan. Sampling was conducted in May, June and September 2012.The results showed that the frequency distribution of fork lenght caught ranged 38-69 cm (x =50 cm). Size of lenght at first capture is 47.8 cm and most of them ranging from 49-51 cm. Length-weight relationship is allometric negative. The food of this fish species are small pelagic fish, squid and anchovies. Sex ratio the male: female (1:1.4). Gonad maturity level of fish at TKG III and IV indicating that the fishes are in the spawning seasons. Gonad Maturity Index is 4.55%. The condition factor ranged from 1.38 to 2.22. Fecundity ranged from 852,000 - 2,056,609 eggs (average 1,352,382 eggs). While the eggs diameter ranged from 1.28 to 1.8 mm.