Breeding for salinity tolerant tilapia

Abstract

Indonesia is an archipelago state that consists of thousand islands, and around 70% of the area is covered with water. With this advantage, Indonesia has become the third major world aquaculture producer (FAO, 2022). Shrimp, tilapia and seaweeds are the main products contributing to the increase of gross domestic product (GDP), gross regional domestic product (GRDP) and the volume of national aquaculture production from 2010 to 2018 (Oktopura et al., 2020). The Coastal environment offers a huge potential area for aquaculture, nationally involving more than 800.000 brackish water farmers. Total shrimp production was 0.88 million ton in 2022 of which 27.1% was exported, only second to tilapia (1.17 million ton), representing an export value of around 2.04 billion US dollars (MMAF, 2022). With strong demand and high prices, shrimp farming has become the most valuable aquaculture sector, and this encouraged shrimp farmers to increase their production.However, a combination of poor water management, increasing density and high levels of commercial feed during intensification has caused serious land and environmental degradation. Disease outbreaks have caused repeated farming failures resulting in many shrimp farmers suffering from financial problems and quitting shrimp farming altogether. Alternative species for shrimp farmingShifting to other species has been a commonly used strategy to minimize economic losses since shrimp farming has become a high-risk industry. Shrimp and milkfish have traditionally dominated brackish water pond production . Grouper and seabass are also produced in brackish water, but in intensive, tank based, systems because these species need specific requirements to grow normally. Smallholder farmers cannot access the financial and technical resources required to farm these two species.Farming tilapia in brackish water is becoming more preferred in the coastal areas. To date, the majority of tilapia are produced in fresh water, and brackish water farming contributes only 3.3% of total production. Fisheries extension services in Central Java have recently reported that the number of tilapia farmers in brackish water ponds is increasing. The rapid growth of tilapia in brackish water has also encouraged many milkfish farmers to shift to tilapia farming, particularly in East and Central Java. The selling price for tilapia in many