Jurnal Iktiologi Indonesia

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. . — 2022-06-29

Pre-settlement small pelagic larvae in Ambon Bay based on length distribution

Grace Hutubessy — 2022-06-29

Larval occurrence in Ambon Bay is related to the larval settlement and indirectly affects the population of pelagic species which have nursery ground in Ambon Bay. The objective of this study is to analyze the factors that influence larval fish occurrence in Ambon Bay based on the length distribution. A lift net assisted by 6 LED lights was operated during the dark to catch larval fish and data was collected from 2016-2018 at Hative Besar, Ambon City. Length frequency with a 5 mm interval was set following the sampling dates. Two variables: length frequency and the number of new individuals (<20mm) together with information on tides and moon phase obtained from the website were collected for further analysis. The larval occurrence was associated with 4 moon phases (dark, first quarter, full and third quarter) and with 2 types of tides: semi-diurnal and mixed semi-diurnal. The normality test (Kolmogorov–Smirnov test) showed normal distribution on length data and the ANOVA showed no significant difference in larval occurrence among the moon phases (F=1.223, P=0.318) but between semi-diurnal and mixed semi-diurnal, and larval recruitment was significantly different (F=3.07; P=0.003), small size larvae were abundance during semi-diurnal tides while large larvae during mixed semi-diurnal tides. It is concluded that small pelagic larval occurred throughout the year and the new cohort occurred by the influence of the tidal current to Ambon bay. Our findings highlight the biological impacts of lift net siru-siru as priorities for the management of fisheries in Ambon bay.

Abstrak

Pola kehadiran larva ikan di Teluk Ambon berkaitan erat dengan proses menetap dan secara tidak langsung berkaitan juga dengan dinamika populasi ikan pelagis yang memilih daerah pembesaran di dalam Teluk Ambon. Penelitian ini bertujuan untuk menganalisis faktor lingkungan yang memengaruhi kehadiran pra-menetap larva ikan pelagis kecilberdasarkan frekuensi panjang. Larva ikan ditangkap dengan menggunakan siru-siru dengan bantuan lampu di malam hari. Sampling dilaksanakan dari tahun 2016 hingga 2018 di Negeri Hative Besar, Ambon. Frekuensi panjang total larva ditabulasi dalam bentuk histogram dengan kisaran 5 mm untuk setiap tanggal sampling. Dua variabel: panjang dan jumlah individu baru (≤ 20mm) bersama dengan hari bulan dan pasang surut digunakan untuk analisis selanjutnya. Kehadiran larva dihubungkan dengan hari bulan (4 fase: bulan baru, kwartir pertama, purnama dan kwartir terakhir) dan tipe pasang surut (harian ganda dan tipe campuran). Uji normalitas Kolmogorov–Smirnov test menunjukkan sebaran data panjang normal (P=0.20). Selanjutnya hasil ANOVA menunjukkan kehadiran pra-menetap larva di Teluk Ambon tidak dipengaruhi hari bulan (F=1,223, P=0,318), tetapi dipengaruhi oleh pasang surut (F=3,07; P=0,003) ketika larva berukuran kecil lebih banyak tertangkap pada tipe harian ganda, sedangkan larva yang lebih besar pada tipe campuran. Kehadiran pra-menetap larva ikan pelagis kecil terjadi sepanjang tahun dan kehadiran individu baru di Teluk Ambon dipengaruhi oleh arus pasang surut. Hasil penelitian ini menyorot dampak biologis dari perikanan siru-siru sebagai prioritas pengelolaan perikanan di Teluk Ambon.

Community structure and genetic variation of freshwater fishes in stream and standing water in the Brantas River, Malang Regency

Restu Fitriani — 2022-06-29

Anthropogenic activities along the Brantas River may affect the community structure and cause changes in the genetic variation of native fishes. This study aimed to analyze and compare the community structure and the genetic diversity of fishes in the standing and streamwater areas of the Brantas River. The sampling method was purposive sampling and fish samples were collected using a gill net with a horizontal transect technique. Genetic variation analysis was conducted through DNA isolation, PCR, amplification, and sequencing. A total of 14 fish species represented six families namely Chanidae, Cyprinidae, Cichlidae, Butidae, Channidae, and Mastacembelidae were recorded. Fish community structure was categorized as a moderate level of diversity with values of 1.62 and 1.88; moderate evenness with values of 0.61 and 0.75; low species richness with values of 1.86 and 1.69; and low dominance with values of 0.34 and 0.19. The Hutcheson’s T-test found significant differences in the diversity between standing water and stream water locations. The results of genetic variation analysis using the COI gene in low-abundance fish species obtained genetic differences in the Mystacoleucus marginatus sequence in standing water, shown by the substitution of three nucleotides bases at 363, 381, and 601. Meanwhile, Macrognathus aculeatus samples from this study had a 99% nucleotide similarity percentage with Macrognathus aculeatus samples in the GenBank.

Abstrak

Aktivitas antropogenik yang dilakukan di Sungai Brantas dapat memengaruhi struktur komunitas dan menyebabkan perubahan variasi genetik ikan asli Sungai Brantas. Penelitian ini bertujuan untuk menganalisis dan membandingkan struktur komunitas ikan, serta membedakan variasi genetik ikan di daerah mengalir dan menggenang Sungai Brantas. Metode pengambilan sampel untuk struktur komunitas secara purposive sampling menggunakan alat tangkap jaring insang dengan teknik transek horizontal. Analisis variasi genetik dengan cara isolasi DNA, PCR, amplifikasi, dan skuensing. Penelitian ini berhasil memperoleh 14 jenis ikan dari enam suku, yaitu Chanidae, Cyprinidae, Cichlidae, Butidae, Channidae, dan Mastacembelidae. Struktur komunitas di Sungai Brantas Kabupaten Malang dapat dikategorikan dengan tingkat keanekaragaman sedang dengan nilai 1,62 dan 1,88, kemerataan yang sedang dengan nilai 0,61 dan 0,75, kekayaan jenis rendah dengan nilai 1,86 dan 1,69, serta dominasi yang rendah dengan nilai 0,34 dan 0,19. Berdasarkan hasil uji t-Hutcheson diperoleh perbedaan yang signifikan pada indeks keanekaragaman antara lokasi mengalir dan menggenang. Hasil analisis variasi genetik menggunakan gen COI pada jenis ikan berkelimpahan rendah diperoleh perbedaan genetik pada sekuen Mystacoleucus marginatus di lokasi menggenang yang ditandai dengan adanya substitusi pada tiga basa nukleotida yaitu pada basa ke 363, 381, dan 601. Sampel Macrognathus aculeatus dan penelitian ini memiliki persentase kesamaan 99% dengan sampel Macrognathus aculeatus pada GenBank.

Ichthyofauna from southwest coast of Bali

Nyoman Dati Pertami — 2022-06-29

The southwest coast of Bali is part of the waters of the Bali Strait. Information regarding ichthyofauna diversity around southwest coast of Bali is not yet done. This study aims to reveal the Ichthyofauna of fish in the waters of the southwest coast of Bali. The study was conducted from April 2017 to May 2018 at three sampling stations including the waters of Pengambengan and Pekutatan (Jembrana Regency), with waters of Yeh Leh (Tabanan Regency). Fish are caught using gill nets and ring trawls. This study succeeded in identifying 43 species of fish representing 24 families. Most types of fish caught are Goldstripe sardinella (Sardinella gibbosa) (36%), Shortfin scad (Decapterus macrosoma) (20%), Bali sardinella (Sardinella lemuru) (16%), and Bullet tuna (Auxis rochei) (7%).

Abstrak

Pantai barat daya Bali merupakan bagian dari kawasan perairan Selat Bali. Informasi terkait iktiofauna di pantai barat daya Bali belum pernah dilakukan. Penelitian ini bertujuan untuk mengungkap keberagamana ikan di perairan pantai barat daya Bali. Penelitian dilakukan pada bulan April 2017 hingga Mei 2018 di tiga stasiun pengambilan sampel meliputi perairan Pengambengan dan Pekutatan (Kabupaten Jembrana), serta perairan Yeh Leh (Kabupaten Tabanan). Ikan ditangkap dengan menggunakan jaring insang dan pukat cincin. Penelitian ini berhasil mengidentifikasi 43 jenis ikan yang mewakili 24 famili. Jenis ikan yang paling banyak tertangkap adalah tamban (Sardinella gibbosa) (36%), layang (Decapterus macrosoma) (20%), lemuru (Sardinella lemuru) (16%), dan tongkol (Auxis rochei) (7%).

Growth pattern and condition factor of the common silver-biddy Gerres oyena (Forsskål, 1775) juveniles from seagrass ecosystem of Karang Congkak Island, Kepulauan Seribu

Adinda Kurnia Putri — 2022-06-29

A seagrass bed of Karang Congkak Island has been known as the nursery habitat for many marine fishes. The common silver-biddy (Gerres oyena) is one of the temporary resident fishes that inhabits seagrass beds of Karang Congkak Island before they migrate to their adult habitat to join the adult population. The aims of this research are to analyze the growth pattern, condition factor and food preferences of the common silver-biddy while they utilized the seagrass beds of Karang Congkak Island as their nursery ground. Sampling was conducted from March 2018 to March 2019 with 10 times frequency of sampling in total. Sample was towed using a beach seine net with 10x1 m in dimension and 3 mm mesh size. Parameters that were analyzed in this research were a length-weight relationship, condition factor, and food preferences. A total of 2762 juveniles of the common silver-biddy were collected and were classified into 10 length classes. The results showed that in general, the growth pattern of the common silver-biddy was positive allometric (b>3), although some months were isometric (b=3). The overall condition factor ranged from 0.87 – 2,05 and it fluctuated throughout the months. The diet which has the main role in determining the fish growth of the common silver-biddy was dominated by the group of copepods. The positive allometric growth pattern of the common silver-biddy and the high value of condition factor describe that seagrass ecosystem of Karang Congkak Island is a suitable nursery ground for the juveniles of the common silver-biddy.

Abstrak

Ekosistem lamun Pulau Karang Congkak merupakan habitat pengasuhan yuwana berbagai spesies ikan laut. Ikan kapas-kapas (Gerres oyena) merupakan salah satu ikan penghuni sementara lamun Pulau Karang Congkak sebelum akhirnya beruaya ke habitat induknya untuk bergabung dengan populasi ikan dewasa. Penelitian ini bertujuan untuk menganalisis pola pertumbuhan dan faktor kondisi yuwana ikan kapas-kapas selama menghuni perairan ekosistem lamun Pulau Karang Congkak. Penelitian dilakukan dari Maret 2018 sampai Maret 2019 dengan total frekuensi pengambilan sampel selama 10 bulan. Contoh ikan diambil dengan menarik pukat tarik pantai berdimensi 10 m x1 m dan mata jaring 3 mm. Parameter yang diamati pada penelitian ini adalah hubungan panjang-bobot ikan, faktor kondisi, dan preferensi makanan ikan. Selama penelitian terkumpul sebanyak 2765 yuwana ikan yang dapat dikelompokkan menjadi 10 kelompok kelas ukuran panjang. Pola pertumbuhan panjang ikan kapas-kapassecara keseluruhan bertipe alometrik positif (b > 3), namun pada beberapa bulan tertentu ditemukan pola pertumbuhan isometrik (b=3). Faktor kondisi selama penelitian berkisar antara 0,87-2,05 dan berfluktuasi setiap bulan. Makanan ikan yang merupakan faktor penentu pertumbuhan ikan kapas-kapas didominasi oleh kelompok kopepoda. Pola pertumbuhan ikan kapas-kapas yang alometrik positif dengan faktor kondisi yang tinggi memberikan gambaran bahwa padang lamun Pulau Karang Congkak merupakan daerah asuhan yang baik bagi yuwana ikan kapas-kapas.

Feeding preferences and diet overlap of sciaenids fishes in Pabean Bay, Indramayu

Charles P. H. Simanjuntak — 2022-06-29

The trophic ecology of Sciaenid fishes, one group of the demersal fishes in Pabean Bay, Indramayu is described in our study. A total of 14 types of prey were identified belonging to three groups (Decapod Crustacean, Mollusca, and Bony fishes) to analyze the feeding preferences and diet breadth overlap. The preferred prey items of Johnius belangerii (Belanger's croaker) were Calappidae (Ii = 16.12), followed by Squilla sp. (15.5), and Penaeus sp. (14.6); while Johnius borneensis (Sharpnose hammer croaker) were Penaeus sp. (Ii = 86.5), followed by Calappidae (3.45), and Acetes sp. (1.38); Johnius macropterus (Largefin croaker) were Penaeus sp. (Ii = 35), followed by Callapidae (5); Nibea soldado (Soldier croaker) were Penaeus sp. (Ii = 25.63) followed by Squilla sp. (23.98), and Charybdis sp. (16.42); Otolithes ruber (Tigertooth croaker) was Penaeus sp. (Ii = 25.63). The diet breadth (BA) values indicate that Sharpnose hammer croaker (BA = 0.06) and Tigertooth croaker (BA = 0.07) are high specialist consumers, while Belanger's croaker (BA = 0.36) and Soldier croaker (BA =0.34) are considered as non-specialized feeders. Our study showed that sciaenid fishes have overlapping trophic niches intra and inter-specific due to their common feeding on decapod crustaceans. The high trophic overlap between predators suggests that Sciaenid fishes in Pabean Bay are competing with each other when food resources are limited.

Abstrak

Ekologi trofik famili Sciaenidae, salah satu kelompok ikan demersal di perairan Teluk Pabean, Indramayu dideskripsikan melalui studi ini. Sebanyak 14 jenis makanan dari tiga kelompok utama (Krustasea Decapoda, Moluska, dan ikan bertulang sejati) berhasil diidentifikasi untuk analisis preferensi dan tumpang tindih relung makanan ikan Sciaenidae. Mangsa yang diminati oleh ikan Johnius belangerii (Belanger's croaker) adalah Calappidae (Ii = 16,12), diikuti oleh Squilla sp. (15,5), dan Penaeus sp. (14,6); sementara ikan Johnius borneensis (Sharpnose hammer croaker) menyukai Penaeus sp. (Ii = 86,5), disusul oleh Calappidae (3,45), dan Acetes sp. (1,38); ikan Johnius macropterus (Largefin croaker) menyenangi Penaeus sp. (Ii = 35), diikuti oleh Callapidae (5); sedangkan ikan Nibea soldado (Soldier croaker) cenderung memilikih Penaeus sp. (Ii = 25,63), Squilla sp. (23,98), dan Charybdis sp. (16,42); sedangkan Otolithes ruber (Tigertooth croaker) lebih banyak mengonsumsi Penaeus sp. (Ii = 25,63). Nilai relung makanan (BA) mengindikasikan bahwa ikan Sharpnose hammer croaker (BA = 0,06) dan Tigertooth croaker (BA = 0,07) adalah termasuk pemangsa yang spesialis, sedangkan Belanger's croaker (BA = 0,36) dan Soldier croaker (BA = 0,34) lebih cenderung sebagai pemangsa yang bukan spesialis. Tumpang tindih relung makanan khususnya jenis krustasea decapoda terjadi baik antarspesies maupun antar individu dari spesies yang sama, termasuk antar kelompok ukuran. Tumpang tindih relung makanan yang tinggi antar ikan predator menunjukkan bahwa kelompok ikan Sciaenidae di Teluk Paben berkompetisi memperebutkan makanan saat terjadi kelangkaan sumberdaya makanan.

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. . — 2022-06-29