Penelitian dilakukan dari bulan Januari sampai Desember 2012 di Tegal, Jawa Tengah. Tujuan penelitian ini untuk mengkaji aspek perikanan meliputi : armada dan teknik penangkapan, daerah penangkapan, komposisi hasil tangkapan dan CPUE ( Catch per unit effort ); aspek biologi yang meliputi sebaran frekuensi panjang, hubungan panjang berat, nisbah kelamin, tingkat kematangan gonad, ukuran pertama kali tertangkap, ukuran pertama kali matang gonad,fekunditas dan diameter telur, Indeks Kematangan Gonad, Musim memijah dan kebiasaan makan. Metode pengumpulan sampel yaitu diambil secara acak dari hasil tangkapan pukat cincin mini dan jaring insang. Hasil penelitian menunjukkan sebaran frekuensi panjang ikan tongkol batik hasil tangkapan pukat cincin mini 13-55 cm dengan modus 25 cm, hasil tangkapan jaring insang 22-49 cm dengan modus 37 cm. Pertumbuhan bersifat isometrik. Nisbah kelamin dalam kondisi seimbang. Ukuran pertama kali matang gonad = 33,7 cm. Ukuran pertama kali tertangkap (Lc) dengan pukat cincin = 31,75 cm, sedangkan Lc dengan jaring insang = 38,85 cm. Fekunditas ikan tongkol batik berkisar 225.760 ? 2.601.500 butir telur, diameter telur berkisar antara 0,11? 0,65 mm, paling banyak pada ukuran 0,44 mm. Pola pemijahannya adalah memijah beberapa kali (partial spawner). Musim memijah ikan tongkol batik di Laut Jawa pada bulan Juni sampai Agustus. Ikan tongkol batik tergolong ikan karnivora yang mangsanya meliputi berbagai jenis ikan dan moluska.

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The study conducted from January to December 2012 in Tegal, Central Java. The purpose of this study to assess the fisheries aspects that include : fleet and fishing techniques, fishing ground, catch composition and CPUE ( Catch Per Unit Effort ); and aspects of biology that includes the length frequency distribution, length weight relationship, sex ratio, gonad maturity level, length at first capture, length at first maturity, gonad size, fecundity and egg diameter, Gonado Somatic Index, spawning season and food habits. Samples were collected random from the catches of mini purse seiner and gill nets.

The results showed that the distribution frequencies of kawakawa (tongkol batik, Euthynnus affinis) was caught by mini purse seine were 13-55 cm, with mode 25 cm, and those was caught by gill net were 22-49 cm, with mode 37 cm. Growth was isometric. Sex ratio was in equilibrium condition. The length at first capture of mini purse seine was = 31.75 cm, length at first capture of gill net was = 38.85 cm, length at first maturity = 33.7 cm. Fecundities of kawakawa were 225,760 - 2,601,500 eggs, egg diameter ranged from 0.11 - 0.65 mm, mode 0.44 mm. Spawning pattern was partial spawner. The spawning season of kawakawa in the Java Sea in June to August. kawakawa was classified as carnivores that the prey various types of fish and mollusks.