THE POTENTIAL FOR COMBINED PRODUCTION OF SALINITY TOLERANT TILAPIA AND SHRIMP IN BRACKISH WATER PONDS IN INDONESIA

Introduction

The potential area for brackish water aquaculture in Indonesia is about 2.25 million ha of undeveloped and marginal land concentrated along the coast of Java Island, which contributed 614,518 ton in 2017 with the total value of around 1,59 billion USD. Total production is spread between traditional (216,791 ton), semi-intensive (360,617 ton) and intensive (37,109 ton) farming systems, and consists mostly of smallholder shrimp farmers operating low input traditional and semi-intensive systems.

Shrimp farming occupies around 53% of Indonesian aquaculture production in brackish water (1.15 million ton in 2017) second only to tilapia (1.27 million ton) (MMAF 2018). However, in recent years mass mortality and farm failures have made shrimp farming a high-risk industry, and resulted in the abandonment of land and ponds in many traditional shrimp farm areas. Consequently, many small-scale farmers are looking for alternative crops to secure their livelihoods. Promising alternatives are rotational cropping or co-culture of tilapia and shrimp.

Tilapia farming is predicted to become a key industry in Indonesia (Phillips et al. 2015). Fisheries extension officers in many areas in North Coast Java report that the number of tilapia farmers in brackish water ponds is rapidly increasing, and milkfish production declined from 747,445 tons in 2016 to 701,319 ton in 2017 (MMAF 2018). However, tilapia in high salinity ponds have lower growth rates, survival, and reproduction (Popma and Masser 1999, Cruz-Suarez et al. 2006, Bœuf and Payan 2001, Cnaani and Hulata 2011). The prevalence and economics of these systems have not been studied sufficiently to determine whether they are economically viable and sustainable.  economically viable and sustainable.

The objective of this study was to review the current status of combined tilapia and shrimp farming in Indonesia as a foundation for more in-depth economic analyses and to identify challenges, barriers, and opportunities that must be addressed in the near future.

Materials and methods

We conducted a survey of farmers in four provinces on Java Island (Banten, Central, East, and West) and to determine the current practices related to shrimp and tilapia farming in brackish water. 224 farmers were asked a series of questions about which species they farm, the systems they use, and the income they generate. To describe the patterns and trends, we summarized the number of farmers who earn low, medium and high incomes as percentages for each of provinces. We categorized the farming systems implemented in each province as monoculture, polyculture, mono-rotation, and poly-rotation and present these data as percentages. We also summarized the types of water aeration, pond lining systems, the use of commercial feed, the feeding rate and type of tilapia farmed as percentages.

Results

Our survey results show those farming practices vary between regions, and that polyculture and rotational farming systems are much less common in Banten than other regions of Java. We also found that the use of commercial feed and feeding rates varies between regions, with Banten farmers completely reliant on commercial feed, East Java farmers least reliant on commercial feed, and Central and West Java intermediate. More than half of farmers in Central Java, West Java and East Java applied commercial feed at less than 3% of fish biomass per day, while 56.3% of farmers in Banten applied a higher rate of 3-5% biomass per day.

Furthermore, the income levels of farmers vary between regions. Most farmers in Java Island (46.4-61.1%, depending on the province) are low-income earners. Medium income earners account for around a third, and less than a quarter of the farmers surveyed are high income earners. This regional variation could be affected by many factors that need to be analyzed in further study.

Discussion and conclusions

Recurrent shrimp farming failures caused by disease outbreaks have resulted in an important shift in farming systems in brackish water ponds in Indonesia. Shrimp monoculture is now only practiced in the most suitable areas, and a majority of shrimp farmers have shifted to tilapia or low-density shrimp production in polyculture systems. Farmers are implementing a variety of production rotational and polyculture systems in Central, East and West Java, but much less so in Banten. It seems that the lowest percentage of ponds in production driven their farming system.

However, despite the advantages, farming tilapia in abandoned brackish water shrimp ponds faces some challenges and obstacles. Currently available salinity tolerant tilapia strains show large variation in growth and survival, and further work is required to 1) develop an optimised breeding strategy to improve growth rate and survival of tilapia grown in shrimp ponds under fluctuating and unpredictable salinities, and 2) assess and compare the economic viability of various shrimp-tilapia farming systems.

Small scale shrimp tilapia farmers in all four provinces are dominated by low-income earners who practised low input production system which presumably ended up in a low productivity trap. Government support is needed to promote them to be more productive through providing a better financial access and supporting irrigation system, road, electricity, and other infrastructures in brackish water area.

References

MMAF (2018) Marine and Fisheries in Figures 2018. Ministry of Marine Affairs and Fisheries, Jakarta

Rimmer MA, Sugama K, Rakhmawati D, Rofiq R, Habgood RH (2013) A review and SWOT analysis of aquaculture development in Indonesia. Reviews in Aquaculture 5 (4):255-279. doi:10.1111/raq.12017.