Green mussel culture using longlines and traditional stake methods in Indonesia
November 03,2020
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GAA
The green mussel (Perna viridis) is an excellent source of protein, fat and carbohydrates and a popular source of food for local communities throughout Southeast Asia, including Indonesia.
Because the mussel reproduces throughout the year, requires no supplemental food input, grows to harvestable size in about six months and requires no mangrove removal for pond construction, it is particularly promising as a sustainable aquaculture product for culture in erosion‐sensitive mangrove coasts. Additionally, mussel culture does not require highly sophisticated techniques, knowledge or equipment, which makes it particularly suitable for use in small‐scale artisanal settings.
Indonesia lags far behind in the culture of molluscs and little recent work has been done on mussel culture in Indonesia. Green mussel culture in the country takes place in sheltered marine mangrove waters and traditionally only involves the use of bamboo stakes. In the Demak Regency, northeast of Semarang on the northern coast of central Java, negative impacts from shrimp farming have promoted interest in mangrove‐friendly alternatives.
This article – adapted and summarized from the original publication [Rejeki, S. et al. 2020. Increased production of green mussels (Perna viridis) using longline culture and an economic comparison with stake culture on the north coast of Java, Indonesia. Aquaculture Research, 2020; 00:1-8.] – reports on feasibility trials to develop green mussel culture as an alternative livelihood for the impoverished coastal fishing communities of Demak, Java. The green mussel is already being harvested from man‐made structures in the surrounding areas and, as is the case with several other bivalves, is a well‐established local food.
The study was carried out in Morosari Village, on the northern coast of Central Java, Indonesia, just 2 km northeast of Semarang in the coastal zone of the Demak Regency. The area was selected based on its physical suitability for aquaculture and the absence of potential interference from other fishing activities.
The experimental site had an average depth of 0.77 meters, temperature of 29.8 to 30.2 degrees-C, salinity 27.7 to 38.4 ppt and current speed of 8.0 to 15.0 cm per second. Dissolved oxygen was 5.4 to 6.2 mg/L and pH was 7.1 to 7.8, while average ammonia and phosphate concentrations were 0.105 ppm and 0.590 ppm, respectively. The site was connected to the open sea through several canals of about 20 meters in width.
Our results show that mussel culture using longlines for both spat collection and grow‐out at densities of 50 mussel seeds per stocking is a simple, low‐cost and easily adopted source of income for households in areas where other means of income generation have been lost or are limited. Culture of the species in other countries in the region has proven profitable and has developed into important sources of income and food for coastal communities
As an aquaculture practice, longlines are a mangrove‐friendly alternative livelihood as it does not require mangroves to be removed for pond construction. They can be placed alongside mangrove channels, in lagoons, inside abandoned ponds and in shallow marine areas seawards from the mangrove forests without any need to cut mangroves or excavate ponds. In fact, longline culture is even considered ideal for unprotected open‐sea culture conditions. Thus, mussel culture can serve as an economic incentive to preserve mangroves so the latter can be left intact to fulfil their many other important ecosystem functions.
Environmental contamination is known to be a problem for shellfish in heavily populated areas along the north coast of Java. For Semarang and the area of concern, the situation is less clear, but at least two studies suggest that contamination levels are low enough for safe consumption. However, even though the coastal area of Demak is still largely rural and probably less contaminated, the issue of contamination deserves close attention.
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Theme(s): Fisheries Development and Aquaculture.
