Keragaman morfometrik rajungan Portunus pelagicus (Linnaeus, 1758) di Selat Sunda dan Selatan Jawa untuk pengelolaan perikanan

Abstract

Rajungan hidup di perairan pesisir dengan substrat berpasir atau berlumpur. Perbedaan lingkungan perairan dan intensitas penangkapan mempengaruhi keragaman karakter morfometrik sebagai bentuk adaptasi dan mencirikan unit stok. Tujuan penelitian ini adalah untuk menganalisis keragaman morfometrik rajungan di Selat Sunda (mewakili WPP NRI 572) dan Selatan Jawa (mewakili WPP NRI 573). Pengambilan sampel rajungan di tiga lokasi yang berbeda yaitu Labuan (hasil tangkapan di Selat Sunda), Cilacap dan Banyuwangi (hasil tangkapan di Selatan Jawa). Pengukuran karakter morfometrik dengan metode konvensional dan Truss Network Analysis (TNA). Analisis hubungan lebar karapas dengan bobot menunjukkan bahwa rajungan di ketiga lokasi memiliki pola pertumbuhan masing-masing adalah isometrik, alometrik negatif, dan alometrik positif. Hasil uji kruskal wallis menunjukkan bahwa terdapat beberapa karakter morfometrik yang berbeda nyata pada rajungan jantan dan betina. Analisis kluster menunjukkan bahwa rajungan di Cilacap dan Banyuwangi memiliki kemiripan yang lebih tinggi dibandingkan dengan rajungan Labuan. Hasil analisis diskriminan menunjukkan bahwa populasi rajungan di Labuan berbeda dengan populasi rajungan di Cilacap dan Banyuwangi. Perbedaan karakter morfometrik menunjukkan bahwa potensi rajungan di ketiga lokasi memiliki lebih dari satu unit stok, sehingga diperlukan pengelolaan yang berbeda antara rajungan di Selat Sunda dengan rajungan di Selatan Jawa.

Blue swimming crabs (BSC) inhabit sandy or muddy substrates of coastal waters. Variations of the aquatic environment and fishing intensity might affect on morphological characters of spesies to facilitate adaptation and both might characterize stock unit as well. This study was aimed at analyzing morphometric diversity of blue swimming crab in water of Sunda Strait (representative of Fisheries Management Area (FMA) 572 of Indonesia) and South of Java (representative of FMA 573 of Indonesia). The crab samples were taken from three different locations, Labuan (catches in the Sunda Strait), Cilacap, and Banyuwangi (catches in the South of Java). Convensional method and Truss Network Analysis (TNA) were applied on morphometric character measurement. Analysis of the relationship between carapace width with weight showed that blue swimming crab in those three locations showed isometric, negative allometric, and positive allometric growth patterns. Result of the kruskal wallis test showed that morphometric characters were significantly different between male and female individuals. Cluster analysis showed that crabs of Cilacap and Banyuwangi showed high similarities which tended to be close population, while Labuan’s crabs were seemed to be dissimilar. Result of the discriminant analysis showed that the blue swimming crab population in Labuan was different from the populations blue swimming crab in Cilacap and Banyuwangi. Therefore, differences in morphometric characters indicate that the potential of the blue swimming crab in those three locations were originated from more than one stock unit, so that different management is needed between BSC in the Sunda Strait and South of Java.