Kelimpahan, Pola Distribusi dan Pola Pertumbuhan Lobster Air Tawar (Cherax quadricarinatus) Di Perairan Sungai Aek Jambu, Desa Batang Bulu Jae, Kabupaten Padang Lawas, Sumatera Utara

Abstract

The Aek Jambu River is a body of water that has a river length of 2210 meters and a river width of 4 to 7 meters. This river is used by the local community as a source of irrigation water for the needs of rice fields, washing places and so on. One of the biota that is often found in the waters of the Aek Jambu River is the freshwater lobster (C. quadricarinatus) which is a member of the crustaceae group. This freshwater crayfish is widely used by the local community as a source of livelihood because it has high economic value. Collecting freshwater lobsters from the Aek Jambu River is carried out by the community continuously without regard to the size of the lobsters, so that it can interfere with the growth and size of these lobsters. This study aims to determine the abundance, distribution patterns, and growth patterns of freshwater lobsters in the Aek Jambu River. Retrieval of lobsters is carried out by going along the river for 60 meters which is divided into 3 stations with each station being 20 meters long. Station 1 is a plantation area, station 2 is an area near the settlement of the surrounding community, and station 3 is an activity free area where community activity is rarely found. Freshwater crayfish (C. quadricarinatus) were obtained, analyzed for abundance by counting the number of individual lobsters at each station, for analysis of distribution patterns using the Morisita Index formula, and for analysis of growth patterns by calculating the length and total fresh weight of the lobsters. The results of the study, the highest abundance value was obtained at station 3, namely 0.06 m2 and the lowest at station 2, namely 0.02 m2. The distribution pattern of crayfish (C. quadricarinatus) at stations 1 and 3 is clumped, while station 2 is uniform. The growth pattern of lobsters (C. quadricarinatus) from each station is negative allometric or b < 3, meaning that the increase in length is more dominant than the increase in weight.