ABSTRAK: Rajungan (P. pelagicus, Linnaeus, 1758) adalah salah satu hasil perikanan utama di Betahwalang, Demak. Penangkapan rajungan diduga dilakukan secara intensif oleh nelayan di Des Betahwalang, maka diperlukan langkah pengelolaan yang tepat untuk menjaga kelestarian dan konservasi rajungan. Informasi aspek morfometri rajungan bias digunakan sebagai salah satu acuan dalam pengelolaan rajungan berkelanjutan. Tujuan penelitian adalah untuk mengkaji tingkat kematangan gonad dan morfometri rajungan yang dilaksanakan pada bulan Juli – September 2019 di Desa Betahwalang, Demak. Penelitian menggunakan metode survey dengan analisis yang bersifat deskriptif yang dilakukan secara “time-series”. Pengamatan sampel rajungan sebesar 10% dari hasil tangkapan yang didaratkan oleh setiap nelayan di pengepul rajungan. Total rajungan yang diamati 5.480 ekor terdiri dari betina 2.960 ekor dan jantan 2.388 ekor. Hasil penelitian menunjukkan pertumbuhan rajungan jantan bersifat allometrik positif, sedangkan rajungan betina cenderung bersifat allometrik negatif dengan seks rasio relatif seimbang. Rajungan betina diduga mengalami pertama kali matang gonad pada selang kelas lebar karapas 70 – 79 mm. Sampel pengamatan fekunditas dan kematangan telur pada 126 ekor rajungan betina bertelur. Kematangan telur dilihat dari pigmen warnanya secara berurutan mulai pigmen warna kuning, orange, coklat dan hitam, serta berdasarkan ukuran diameter telur. Fekunditas telur memiliki korelasi yang sangat kuat terhadap lebar karapas yang berarti semakin besar ukuran rajungan, maka jumlah telur semakin banyak. Selama penelitian masih ditemukan rajungan “undersize” sebesar 18% (981 ekor) dan rajungan betina bertelur sebesar 24% (716 ekor), yang berarti nelayan di Desa Betahwalang belum menerapkan kriteria dan ukuran layak tangkap sesuai dengan peraturan yang berlaku.ABSTRACT: Blue swimming crab (P. pelagicus, Linnaeus, 1758) is one of main fisheries products in Betahwalang, Demak. High-intensity levels of catching the blue swimmer crab by fisherman may need sustainable management to protect and conserve the population. The purpose of this study was to determine about gonad maturity level and morphometrical aspect of blue swimming crab started from July – September 2019. There’s a descriptive survey method used in this study with time-series observations. The sample size is about 10% of the total number landed crab from each fisherman. The total sample are 5.348 that consist of 2.960 female crabs and 2.388 male crabs. The results showed the male crabs has a positive allometric on growth parameters, but the females have an allometric positive and negative growth parameters, and balanced sex-ratio. Female crabs may reach the first matured gonad level between 70 – 79 mm of carapace width. Fecundity and egg’s maturity observation used 126 berried female crabs. The egg’s maturity based on the pigment color started from yellow, became orange, brown and black also by egg diameter increase. The analysis showed that female crab fecundity has a strong correlation to the increase of carapace width, which means carapace width increase followed by egg’s amount increasing. During the study, it was found about 18% (981 crabs) the undersize crabs (<100 mm) and 24% (716 crabs) the berried female crabs, which means the Betahwalang fisherman hasn’t applied the rule yet.

Mangrove degradation is one of the most common issues in the coastal areas of Java, which can cause ecological impacts and even disadvantage for local community. The mangrove forest degradation can be identified based on the vegetation analysis results, which could potentially contribute to the mangrove ecosystem management and rehabilitation programs in the coastal areas. Mangroves in Keboromo Village was the rehabilitation and cultivation area, but often get damaged by ocean waves. This study aims to determine the ecological and vegetation conditions of mangrove ecosystems consist of species composition, density, canopy cover, tree height, and environmental parameters were held in February 2023. The method used was direct observation using transect quadrants of 10x10 m2. The average mangrove density of all observation stations was 3.425 individuals/ha for the tree category, 575 individuals/ha for the sapling category, and 250 individuals/ha for the seedling category. The average percentage of canopy cover was 78.41%. The average height of mangrove trees at all stations is 4.15 m. The environmental parameters were still compatible with the water quality standard for biota and mangrove life. The mangrove forest degradation level based on standard criteria and guidelines for determining mangrove degradation is categorized as low, indicated by mangrove density >1500 individuals/ha and canopy cover >75%. Poor conditions were measured for sapling and seedling densities, which may be caused by environmental factors unsupportive for mangrove regeneration. Based on the results of mangrove vegetation analysis in Keboromo Village, it can state the mangrove ecosystem condition is good. However, management programs are needed to keep the mangroves sustainable.