PARAMETER POPULASI DAN RASIO POTENSI PEMIJAHAN IKAN TONGKOL KOMO (Euthynnus affinis, Cantor 1849) DI LAUT JAWA SEBELAH UTARA JAWA TIMUR

Ikan tongkol komo (Euthynnus affinis) merupakan salah satu komoditas ekonomis penting yang tertangkap di perairan Laut Jawa sebelah utara Jawa Timur. Tingkat pemanfaatan ikan tongkol komo terus meningkat sehingga perlu dikelola dengan baik untuk keberlanjutannya agar tidak mengalami penurunan stok. Tujuan penelitian ini untuk mengevaluasi status sumberdaya ikan tongkol komo dengan mengestimasi parameter populasi dan rasio potensi pemijahan dengan pendekatan ukuran panjang ikan, digunakan sebagai titik acuan biologis dalam menentukan kondisi stok ikan. Sebanyak 1995 data ukuran panjang ikan yang dikumpulkan secara acak selama bulan Februari hingga Juni 2021 di Pasongsongan, Jawa Timur. Metode ELEFAN digunakan untuk menentukan parameter populasi yaitu pertumbuhan, kematian, dan laju pemanfaatan. Analisis rasio potensi pemijahan dilakukan dengan menggunakan parameter populasi, dan parameter biologi yang didapatkan dari hasil penelitian sebelummnya dengan paket LB-SPR. Hasil analisis pertumbuhan von Bertalanffy ikan tongkol komo dari penelitian ini diperoleh persamaan Lt= 60,9 (1-e-0,41(t-0,19)). Rata-rata tongkol komo yang tertangkap belum matang gonad (Lc<Lm), tekanan penangkapan dalam kategori tinggi dan rekrutmen dalam stok terganggu. Hal ini terlihat bahwa rasio mortalitas penangkapan relatif (F/M) = 2,51, laju eksploitasi (E) = 0,71, dan SPR = 20%. Oleh sebab itu diperlukan penyusunan pengelolaan yang efektif untuk keberlanjutan stok ikan tongkol komo.Kawakawa (Euthynnus affinis) is one of the important economic commodities caught in the sea waters north of East Java. The utilization rate of kawakawa is quite high, so it is necessary to regulate the sustainability of kawakawa stock to maintain it. This study aimed to evaluate the status of kawakawa fish resources by estimating population parameters and spawning potential ratio (SPR) with a fish length approach, used as a biological reference point in determining fish stock conditions. 1995 data on the length of fish were collected randomly from February to June 2021 in Pasongsongan, East Java. The ELEFFAN method was used to determine population parameters: growth, mortality, and utilization rate. SPR analysis was carried out using population and biological parameters obtained from previous studies with the LB-SPR package. The results of von Bertalanffy's growth analysis for kawakawa from this study were written with the equation Lt= 60.9 (1-e-0.41(t-0.19)). The average kawakawa caught was immature gonads (Lc<Lm), fishing pressure was also still high, and recruitment in stock was disrupted. It can be seen that the relative fishing mortality ratio (F/M) = 2.51, exploitation rate (E) = 0.71, and SPR = 20%. Therefore, it is necessary to develop effective management for the sustainability of kawakawa stocks

Status dan sebaran mangrove di kawasan konservasi Taman Pulau Kecil, Kabupaten Tapanuli Tengah, Provinsi Sumatera Utara

Mangroves are an important part of determining conservation areas as well as determining zoning within conservation areas. Therefore, information on the status and distribution of mangroves is essential in managing conservation areas. This study was conducted in Taman Pulau Kecil, Central Tapanuli District. The data was collected in June 2019. The sampling sites consisted 26 points (1-15 at the Mursala Island and its surroundings and 16-27 in the Tapian nauli Bay (maindland)). The study revealed 17 mangrove species from 9 families consisted of 14 true mangroves and 3 associated mangroves namely pandan (Pandanus tectorius), waru (Thespesia populnea), and ketapang (Terminalia catappa). Analysis of the importance of mangrove species in Taman Pulau Kecil, Central Tapanuli district showed that Rizophora, Xilocarpus, and Bruguiera have a large influence and role in the mangrove vegetation community. Mangroves in conservation area at Taman Pulau Kecil were in the good category. However, the condition and status of mangroves in Tapian Nauli Bay had better condition with the density of 3.120 ind/ha while in Mursala  Island and its surroundings with density of 2.356 ind/ha.Keywords: Mangrove, Marine Protected area, Mursala Island, Tapian Nauli BayABSTRAKMangrove merupakan salah satu ekosistem penting dalam penentuan kawasan konservasi serta dalam penentuan zonasi di dalam kawasan konservasi. Oleh karena itu, informasi status dan sebaran mangrove penting dalam upaya pengelolaan kawasan konservasi. Lokasi pengambilan data mangrove di kawasan konservasi daerah Taman Pulau Kecil Kabupaten Tapanuli Tengah. Pengambilan data dilakukan pada bulan Juni 2019. Lokasi pengambilan data pada 26 titik pengamatan yang terdiri dari titik 1-15 di Pulau Mursala dan sekitarnya dan titik 16-27 di Teluk Tapaian Nauli (pulau sumatera). Hasil penelitian ditemukan 17 spesies mangrove dari 9 famili. Jenis mangrove tersebut terdiri dari 14 mangrove sejati dan 3 mangrove ikutan yaitu pandan (P. tectorius), waru laut (Thespesia populnea), dan ketapang (Terminalia catappa). Analisis nilai penting jenis mangrove di KKPD Taman Pulau Kecil Tapanuli Tengah menunjukkan bahwa Rizophora, Xilocarpus, dan Bruguiera memiliki pengaruh dan peran yang besar dalam komunitas vegetasi mangrove. Mangrove di KKPD Taman Pulau Kecil Tapanuli Tengah termasuk kategori baik. Namun kondisi dan status mangrove di Teluk Tapian Nauli lebih baik dengan kerapatan rata-rata 3,120 ind/ha dibanding di Pulau Mursala dan sekitarnya dengan kerapatan rata-rata 2,356 ind/ha.Kata kunci: Mangrove, Kawasan konservasi perairan, Pulau Mursala, Teluk Tapian Naul

Secondary Productivity of Crambidae Family in Cigambreng River, Tapos Village, Bogor: Produktivitas Sekunder Famili Crambidae di Sungai Cigambreng, Desa Tapos, Bogor

Secondary productivity is the formation of biomass of heterotrophic organisms in units of time including biomass that is lost in a certain time unit. The Crambidae family is an insect that has aquatic larvae and will become an air insect after the larval phase. This species has the potential to become a pest for agriculture. The study was conducted in October 2019 for one month. The Crambidae family species found consists of two species, Petrophila sp. and Elophila sp. The abundance of Crambidae during the study ranged from 100 ind/m2 to 422 ind/m2. Secondary productivity was analyzed by the size frequency method. The secondary productivity of the Crambidae family in Cigambreng river waters for one month was 47.7915 g/m2/month, the biomass formed was 14.9669 g/m2 and the P/B ratio was 3.1931.Produktivitas sekunder adalah pembentukan biomasa organisme heterotrof dalam satu satuan waktu termasuk biomassa yang hilang dalam satuan waktu tertentu. Famili Crambidae adalah serangga yang memiliki fase larva akuatik. Jenis ini berpotensi menjadi hama bagi kegiatan pertanian. Penelitian ini dilakukan di bulan Oktober 2019 selama satu bulan. Famili Crambidae yang ditemukan terdiri dari dua genus yaitu Petrophila sp. dan Elophila sp. Kelimpahan Famili Crambidae selama penelitian berkisar antara 100 ind/m2 hingga 422 ind/m2. Produktivitas sekunder famili Crambidae di sungai Cigambreng, Desa Tapos, Bogor selama satu bulan adalah 47.7915 g/m2/bulan, biomassa yang terbentuk adalah 14.9669 g/m2 dan P/B ratio sebesar 3,1931

Produktivitas Sekunder Organisme Bentik (Ordo Diptera) di Sungai Cigambreng, Desa Tapos, Kecamatan Tenjolaya, Kabupaten Bogor, Jawa Barat

Insekta memiliki biodiversitas dengan  penyebaran yang luas diseluruh dunia. Sampling dilakukan sekali dalam seminggu selama bulan Oktober 2019. Ditemukan total  717 spesimen Ordo Diptera yang melingkupi dua famili di Sungai Cigambreng. Tiap famili yang diperoleh melingkupi satu jenis yakni Antocha sp. (Famili Tipulidae.) dan Krenopelopia sp. (Chironomidae). Kehadiran jenis chironomid mengindikasikan adanya beban masukan berlebihan (Polutan) ke dalam perairan sungai Cigambreng. Secara umum, kelimpahan tertinggi diperoleh pada pengamatan ke empat yakni 284 ind/m2, sedangkan kelimpahan terendah diperoleh pada pengamatan ke dua yakni 60 ind/m2. Produktivitas sekunder melingkupi P/B Rasio sebesar 3.034/bulan dengan kecepatan produksi 14.2458 (g/m2/bln) dan biomassa (4.6954 g/m2).Insekta has biodiversity with a wide distribution throughout the world. Sampling was carried out once a week during October 2019. A total of 717 specimens of  Order Diptera were found which covered two families in the Cigambreng River. Each family obtained includes one type, Antocha sp. (Family Tipulidae.) and Krenopelopia sp. (Chironomidae). The presence of a chironomid has indicates an excessive input load (pollutant) into the waters of the Cigambreng River. In general, the highest abundance was obtained at the fourth observation, 284 ind/m2, while the lowest abundance was obtained at the second observation, which was 60 ind/m2. Secondary productivity covers P/B ratio of 3.034 /month with a production speed of 14.2458 (g/m2/month) and biomass (4.6954 g/m2)

Community Structure on Seagrass Fish Resources at Pandaratan Beach, North Sumatra

Seagrass beds are potential marine resources to be utilized, and ecologically, seagrass beds are some of the important functions of the coastal area. Many organisms are ecologically and biologically very dependent on the presence of seagrasses. The ecosystem is an important food source for the organism by many sea organisms that use it as a spawning place. This study aims to determine the diversity of fish in seagrass beds in Padaratan Beach, Sarudik Subdistrict, Central Tapanuli Regency. A gillnet is used to obtain fish samples at three observation stations during the period from mid-March to April 2018. Fish diversity can be agreed by looking at the composition of fish species and diversity index. The results of this study show the total number of fish obtained, 196 individuals, consisting of 12 families and 14 species. The highest number of fish catches is at Station II with a total catch of 70 individuals. The highest relative abundance of stations I, II, and III with values ​​of 22.96%, 20.01%, and 23.07% are found in fish species from the family Hemaramphidae with Zenarchopterus gilli species. The diversity index value (H') of all observation stations shows that species richness is in a moderate condition with values ​​of the station I (2,339), station II (2,439) and station III (2,367). While the uniformity value (e), shows the value of station I (0.866) station II (0.924) and station III (0.897) observations are in a stable condition (0.75 <e d ”1.00). Such conditions indicate that the distribution at each observation station is equitable.Padang lamun berfungsi sebagai daerah asuhan (nursery ground), sebagai tempat mencari makan (feeding ground), dan daerah untuk perlindungan. Penelitian ini bertujuan untuk mengetahui Struktur Komunitas Sumberdaya ikan di ekosistem lamun yang dilakukan di pantai Pandaratan, Kecamatan Sarudik, Kabupaten Tapanuli Tengah dari Maret hingga April 2018. Gill net adalah alat untuk menangkap ikan di tiga stasiun yang ditentukan. Keragaman ikan dapat dinilai dengan melihat komposisi spesies ikan dan indeks keanekaragaman. Hasil penelitian ini menunjukkan 196 individu, terdiri dari 12 famili dan 14 spesies. Jumlah spesies ikan tertinggi di stasiun II dengan total tangkapan 70 individu. Spesies ikan yang paling mendominasi di semua stasiun adalah Zenarchopterus gilli dengan nilai kelimpahan relatif di stasiun pertama 22,96%, stasiun kedua 20,01% dan stasiun terakhir 23,07%. Nilai indeks keanekaragaman (H’) dari semua stasiun dapat dikategorikan dalam kelas menengah yang nilainya antara 2.367-2.439. Nilai indeks kesetaraan semua stasiun dapat dikategorikan dalam kelas stabil dengan skor antara 0,897-0,903, sedangkan untuk nilai indeks dominasi semua stasiun dapat dikategorikan dalam kelas rendah yang skornya antara 0,102-0,127

Distribution and ecological status of mangroves in the Nias Islands-North Sumatra Province: Distribution and ecological status of mangroves in the Nias Islands

The Nias Islands are a group of islands located on the west coast of Sumatra. Nias Island is the main and largest island on the West Coast of Sumatra. Information on the distribution and potential status of mangroves in the Nias Islands has been reported, but it is limited to a narrow area and not yet comprehensive throughout the Nias Islands. This study aims to determine the distribution and ecological status of mangroves in the Nias Islands. The research location was divided into two observation areas, namely 15 points on Nias Island and 23 points on the southern part of Nias. The research was carried out in June 2019 and June 2021. Mangrove sampling was carried out using the "spot check" method which refers to Bengen (2004). The results showed that the mangroves found in the Nias Islands consisted of 22 primary mangrove species and 9 secondary mangrove species. Rhizophora apiculata, Rhizophora mucronata, and Xylocarpus granatum are the most abundant mangrove species and are commonly found in the Nias Islands. The thickness of mangroves in the Nias Islands ranges from 15 – 880 m. The density of mangroves found reached 350-4,360 ind/ha. Mangrove cover reaches 0.08-31.62 m2/ha. The results of the analysis of the significant value of mangrove species show that Rhizophora mucronata and Rhizophora apiculata have a large influence and role in the mangrove vegetation community on Nias Island. Mangroves in the Nias Islands are categorized as damaged–good. The good category was found in South Nias, Belukar Bay, and Bengkuang Bay, while the damaged category was found in Lahewa Bay and Dalam Ba