Microanatomy of the antennal glands and their Na+/K+-ATPase activity in three true crab species (Brachyura), Portunus pelagicus (Linnaeus, 1758) (Portunidae), Macrophthalmus dentipes Lucas in Guérin, 1836 (Macrophthalmidae) and Eriocheir hepuensis Dai, 1991 (Varunidae)

There are differences between various crab species in the function and structure of organs involved in ionic and osmotic regulation processes. The antennal glands together constitute one of the most important organs involved in the osmoregulation in crabs. The present investigation aimed to study the tissue structure of the antennal glands and their Na+/K+-ATPase (NKA) pump activity in three true crab species from three different habitats, including the marine (Portunus pelagicus (Linnaeus, 1758)), the estuarine (Macrophthalmus dentipes Lucas in Guérin, 1836) and the freshwater habitat (Eriocheir hepuensis Dai, 1991). In this regard, the tissue structure of the antennal glands and the activity of the Na+/K+-ATPase (NKA) pump were assessed in these three selected species. The results showed that the antennal glands in all studied species consisted of two anterior parts and a posterior part. The anterior parts are composed of the proximal tubular region (PT) and the distal tubular region (DT). The PT and DT parts comprised the coelomosac and labyrinths in the anterior portion, and the bladder located in the posterior portion. However, despite the similarity in the general tissue structure of the antennal gland in marine, estuarine and freshwater crab species, some structural differences were observed between those species. Labyrinth cells, coelomosac podocytes, and bladder cells in the estuarine crab M. dentipes contained large vacuoles especially on the top (i.e., near the lumen) of the cells. The highest amount of NKA pump activity was measured in the antennal glands of M. dentipes (). The NKA pump plays a more important role in the estuary and seawater adaptation of crabs, but freshwater species are not highly dependent on the NKA enzyme for osmoregulation.

ACUTE TOXICITY OF Β-KITIN EXTRACTED FROM THE SHELL OF BLUE SWIMMING CRAB (PORTUNUS PELAGICUS LINN.)

Objective: This work aimed to study the acute toxicity of β-chitin extracted from crab shells in Bal b/c mice. Method: The acute toxicity test was performed by following the OECD guidelines. Female mice were given single or divided doses of β-chitin (maximum 24 h) with doses of 500, 1000, 2000, 4000, and 6000 mg/kg of BW. Observations were made for 14 d, including behaviour, body weight, organ weight, and histopathology of vital organs (stomach, heart, liver, kidney, and lung). Results: During 14 d, no deaths and no abnormalities in behaviour, bodyweight or organ weight were observed. Qualitative histopathological observations at the highest dose showed abnormalities of the liver and kidney compared to those of the control group. Nevertheless, the abnormalities did not affect the organ function. Conclusion: This acute toxicity study reveals that β-chitin up to a dose of 6000 mg/kg of BW is not toxic, as proved by the normal behaviour, body weight, and vital organ weight of the animals. Further chronic toxicities study is needed to confirm its safety.

Stock Assessment of the Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758) in Stock Enhancement Sites of Danajon Bank, Central Philippines

The stock status of Blue Swimming Crab (BSC), Portunus pelagicus, locally known as lambay, in Danajon Bank was assessed from June 2019 to September 2020 to monitor the impact of the BSC stock enhancement initiative by the Philippine Association of Crab Processors, Inc. (PACPI) in collaboration with BFAR 7. The stock was assessed based on the indicators, namely, catch per unit effort (CPUE), exploitation rate (E), average size, length at first maturity (Lm), and Spawning Potential Ratio (SPR). Data analysis was done using FAO-ICLARM Stock Assessment Tools (FiSAT) II software and the Barefoot Ecologist’s Toolbox for the Length-based Spawning Potential Ratio (SPR). Results show that BSC dominated the monitored landings accounting for 66% of the overall catch harvested mainly by crab pot and crab net. Higher CPUEs were obtained in the months of July, June, May and August with annual mean observed to be higher than the previous assessment conducted by ECOFISH in Danajon Bank particularly for crab pot. Population characteristics revealed that male crab grew slightly faster having higher asymptotic length (L∞ =21.65cm Carapace Width or CW) and growth constant (K=1.3yr-1) than female (L∞ =21.40cm CW, K=1.28yr-1). Sex ratio of male to female was at 1:1.28 indicating plenty of female crabs were captured than male. Gravid crabs were abundant in May, December, April and October. Recruitment pattern showed two pulses with primary peak occurred in April and May and secondary pulse happened in August and September. Encouraging performance indicator noted from this assessment was on the bigger probability of capture sizes and mean length of commonly caught BSC falling above the recommended catchable size of 10.2 cm CW pursuant to DA-DILG JAO No. 1 s. 2014. Maturity size (Lm) was estimated at 10.54 cm CW, though smaller than the previous reported Lm values in Danajon but still within the threshold. The estimated SPR was 26%, higher than 20% limit reference point but slightly lower than 27% recorded in the assessment done by ECOFISH Project in 2014 to 2015. The present SPR though lower than 30% precautionary threshold however higher than 21% generated in Visayan Sea Region 7 for the same period. The higher SPR in Danajon Bank compared to Visayan Sea maybe credited to the effect of stock enhancement activity implemented in the area, though observation is not yet conclusive. On the other hand, unfavorable indicators were seen on high exploitation rate (E), high exploitation at yield per recruit some of which already breached the optimum level, consequently subjecting Danajon Bank to high fishing pressure. It is recommended to continue the BSC stock enhancement program of PACPI and BFAR 7 taking consideration some strategies for improvement specified in the recommendations.

Spesifikasi dan Identifikasi Hasil Tangkapan Garok Rajungan di Pelabuhan Perikanan Pantai (PPP) Bondet Kabupaten Cirebon, Jawa Barat

Crayfish (Portunus pelagicus) is the leading export commodity of Indonesian fishermen. The increasing demand for exports and high selling prices have made fishermen at the Bondet Beach Fishing Port, Cirebon Regency, use garok crabs to maximize their catch. The purpose of this study was to identify tool specifications, catch yields, selectivity and productivity of garok crab fishing gear operated at the Bondet Coastal Fishery Port, Cirebon Regency, West Java. The research was carried out in April – June 2021. The method used was a case study method with quantitative descriptive analysis to determine the specifications of the tools and catches taken by interviewing fishermen. The results showed that the crab claws were included in the dredge gear category. Its components consist of body mouth, garok, frame, nets, and ropes of various sizes. The main catch of garok crab in Cirebon Regency consists of small crab (Portunus pelagicus), and by-catch in the form of shellfish, shrimp, cuttlefish, and demersal fish, with a total of 14 species. This tool is classified as non-selective because of the small size of the bag mesh construction (30 mm) so that this tool catches many species with large and small size fish caught. The average catch obtained from 5 trips was 23.8 kg, with the lowest catch on the 2nd trip, which was 19.7 kg and the highest on the 5th trip, which was 31.3 kg, while the average sweep area was 0.0040 km2 with an average productivity of 3.97 kg/hour and the highest catch rate value was obtained on the 5th trip, which was 5.21 kg/hour, while the lowest catch rate was found on the second trip, which was 3.28 kg/hour.

Penggunaan Alat Tangkap Bubu Lipat Terhadap Potensi Hasil Tangkapan Rajungan Portunus pelagicus di Teluk Hurun, Kabupaten Pesawaran

Pemanfaatan sumberdaya perairan di teluk Hurun saat ini masih sangat potensial. Salah satu pemanfaatan sumberdaya perairan yaitu optimalisasi alat tangkap bubu lipat yang ekonomis dan ramah lingkungan. Penerapan alat tangkap ini diharapkan dapat memberikan gambaran potensi rajungan yang ada di teluk Hurun. Materi yang digunakan yaitu bubu lipat dan perlengkapan penangkapan lainnya. Penggunanaan alat tangkap bubu lipat menghasilkan tangkapan rajungan sebesar 88,98 kg (market size) dan 16,82 kg (under size) dengan jumlah yang diperolah masing-masing yaitu 916 ekor (market size) dan 358 ekor (under size).

KEPADATAN DAN POLA SEBARAN RAJUNGAN Portunus pelagicus (Linnaeus, 1758) DI PERAIRAN PESISIR KECAMATAN BATU AMPAR, KABUPATEN KUBU RAYA

Rajungan (Portunus pelagicus) merupakan biota akuatik yang memiliki komoditas ekonomi dan dimanfaatkan oleh masyarakat pesisir mangrove Kecamatan Batu Ampar, sehingga perlu mendapat pengawasan keberadaannya di alam. Tujuan kegiatan pengabdian ini adalah mengetahui kepadatan, pola sebaran, dan mengetahui korelasi karakteristik habitat rajungan dengan kepadatan. Penelitian ini dilaksanakan selama bulan Desember 2019-Februari 2020. Pengambilan sampel dilakukan pada 3 stasiun penelitian menggunakan gill net berukuran 4 inchi. Data yang diperoleh kemudian dianalisis meliputi kepadatan dan pola sebaran. Korelasi karakteristik habitat dianalisis menggunakan Principal Component Analysis (PCA). Pengaruh stasiun dan waktu penangkapan dianalisis menggunakan Anova dua jalur. Kepadatan rajungan berkisar 222-2581 ind/km2 dan berbeda selama bulan Desember-Februari. Pola Sebaran pada bulan Desember dan Januari termasuk seragam dan mengelompok, bulan Februari memiliki sebaran seragam dan acak. Stasiun penelitian tidak berpengaruh terhadap kepadatan rajungan, sedangkan waktu penelitian di Pesisir Batu Ampar memberikan pengaruh. Kepadatan populasi rajungan dan pola sebaran rajungan berkorelasi positif terhadap kedalaman, kecerahan, salinitas, pH air, kecepatan arus air, kecepatan angin, suhu air, DO, dan CO2 bebas.