Electronic Theses and Dissertation

Rajungan (Portunus pelagicus) di perairan Lhokseumawe merupakan sumber daya perikanan yang memerlukan kajian aspek biologi dan morfometrik sebagai dasar pemahaman struktur populasi dan dinamika reproduksinya. Tujuan penelitian ini adalah untuk menganalisa aspek biologi dan morfometrik rajungan, meliputi karakter morfometrik, hubungan panjang–bobot, faktor kondisi, nisbah kelamin, kematangan gonad, dan ukuran pertama kali matang gonad. Penelitian dilakukan pada bulan Agustus–Desember 2025. Sebanyak 150 ekor contoh rajungan yang diambil secara acak dianalisis untuk mengetahui beberapa aspek biologi dan morfometriknya. Hasil penelitian menunjukkan bahwa karakter morfometrik rajungan memperlihatkan variasi ukuran tubuh yang luas dengan kisaran lebar karapas 71,7–148,4 mm, yang mencerminkan heterogenitas struktur populasi dari individu juvenil hingga dewasa. Pola pertumbuhan rajungan jantan dan betina bersifat alometrik positif. Faktor kondisi rajungan betina tertinggi pada Agustus lalu menurun hingga Oktober, sedangkan pada rajungan jantan meningkat hingga September sebelum kembali menurun. Nisbah kelamin rajungan berada dalam kondisi tidak seimbang. bahas tgk sedikit di bulan mana yang tkg tinggi (III,IV). Ukuran rajungan betina pertama kali matang gonad (L₅₀) sebesar 105 mmCW, sedangkan pada rajungan jantan sebesar 103 mmCW.

Kata kunci: hubungan panjang–bobot; faktor kondisi; nisbah kelamin; tingkat kematangan gonad

The blue swimming crab (Portunus pelagicus) in the waters of Lhokseumawe represents an important fishery resource that requires biological and morphometric studies to support the understanding of population structure and reproductive dynamics. This study aimed to analyze the biological and morphometric aspects of blue swimming crab, including morphometric characteristics, length–weight relationships, condition factor, sex ratio, gonadal maturity, and size at first sexual maturity. The study was conducted from August to December 2025. A total of 150 crab specimens were randomly collected and analyzed to evaluate their biological and morphometric characteristics. The results showed that the morphometric characteristics exhibited a wide range of body size variation, with carapace width ranging from 71.7 to 148.4 mm, reflecting population heterogeneity from juvenile to adult stages. The growth pattern of both male and female crabs was positively allometric. The condition factor of female crabs was highest in August and gradually decreased until October, whereas that of males increased until September before declining thereafter. The sex ratio was found to be unbalanced. High gonadal maturity levels, particularly stages III and IV, were predominantly observed in September and October. The size at first sexual maturity (L₅₀) was estimated at 105 mmCW for females and 103 mmCW for males. Keywords: length–weight relationship; condition factor; sex ratio; gonadal maturity; population structure