ECOSYSTEM MODEL OF SEABASS CULTIVATION IN KERAMBA FLOATING NET AT INNER AMBON BAY

• Main Author: Lelly Sabrina, Purwanti
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39413
• Institution: Institut Teknologi Bandung

Nowadays, seabass cultivation in floating net cages is being developed by the government. Seabass as the object of cultivation is chosen because it has high economic value and high resistance to the environment. Balai Perikanan Budidaya Laut (BPBL) Ambon has executed seabass cultivation by using floating net cages at Inner Ambon Bay. Ecosystem model simulation is performed in order to know about the growth rate of seabass at Inner Ambon Bay. According to the survey performed in the project of “Ocean Current System of Indonesia Waters and Its Effect on Marine Fisheries Production” on May 2017, it is obtained several data regarding to the condition of water at Inner Ambon Bay. Its temperature is 29,8 – 30,9 °C, the value of surface salinity is 26,1 – 31,4‰, and it has chlorophyll concentration as much as 0,88 – 3,61 mg/m3. The simulation of ecosystem model is used to calculate two-way interaction between nutrients, phytoplankton, zooplankton, and detritus (NPZD) with zooplanktontivor. Zooplantontivor is fishes that consume zooplankton. Seabass which spread has mass class 2 and has weight approximately 10 grams while harvested seabass has weight 300 – 400 grams. Model simulation is carried out for 4 years (2015 - 2018) with a time step of 6 minutes. The input model uses data on temperature and average nitrate concentration from the BPBL Ambon in 2015 - 2018. Simulation of Inner Ambon Bay aquatic ecosystem model is executed to determine the natural NPZD concentrations regardless the existence of fishes. The model simulation results show that the average nutrient concentration in Inner Ambon Bay is 3,52 mmolC / m3 in the west season, 3,84 mmolC / m3 in the east season, and 3,61 mmolC / m3 in the transitional season 1, and 3,56 mmolC / m3 in the transitional season 2. While the concentration of nutrients in the form of nitrate in Ambon Bay (based on measurements carried out by LIPI in 2009), in the east season the average nitrate concentration on the surface is 0,09 mmolC / m3 while in the west season is 0,014 mmolC / m3. The average nitrate concentration at the bottom of Inner Ambon Bay in the east season is 0,485 mmolC / m3 and in the west season is 0,047 mmolC / m3. The concentration of nutrients, zooplankton, and detritus is higher when the condition of fishes are not present, the differences for each of them is reaching 0,189 mmolC / m3, 2,08 mmolC / m3, and 1,126 mmolC / m3. While the concentration of phytoplankton is higher when the fishes are present, with the difference for both of them are 0,28 mmolC / m3. The fastest growth rate of seabass with natural feed scenario is 257 days when seeds spread in January with the growth rate is 1,52 grams / day. Meanwhile, the fastest growth rate of seabass with added non-natural feed scenario is 175 days when seeds spread in February with the growth rate is 2,23 grams / day.