Moving forward with the tides in Myanmar
For several generations, residents of the coastal areas of Yangon region, Myanmar, living within the mangrove forest area or in its vicinity have been depending on the mangrove forests as a source for livelihood. A focus of their activities was on fishing operation of sorts, including the collection of all kinds of crustaceans, e.g. penaeid shrimps and mangrove crabs [mud crabs] belonging to the Scylla genus.
As a move to increase the yield in hard-to-access areas, enclosures (ponds) – fitted with ‘water gates’ (monks) to manage the water exchange of the enclosed areas according to the tidal water exchange – were established. These natural depressions, enclosed with often improvised dikes are following an integrated management system, known as ‘trap and hold aquaculture system’. Small scale shrimp farmers (SSF) nowadays manage farms of about 50 acres (most) up to several hundred acres (a few).
Based on low/ zero input -with focus on the ingress of post-larval shrimp (PL) and other crustaceans – yet with substantial effort in terms of enclosure maintenance- it was and still is possible to attain a reasonable income. Regular and systematic maintenance of the animals in the enclosure -from post-larval stage up to market size- leads to annual yields of up to 20-150kg/ha. Following a polyculture system of shrimp in combination with high value fin fish species (e.g. seabass, Lates calcarifer), the total yield can reach 250 kg ha-1 y-1. In general, the stocking density in the enclosures is low to very low (1-2 PL sqm-1), compared to semi-intensive/ intensive production systems, the latter with the wide array of negative impact factors for the mangrove ecosystems, as discussed elsewhere.
Due to illegal collection of shrimp PL and deteriorating habitat conditions of in the coastal region (mangrove destruction, industrial and community effluents, infrastructure development, encroachment), sufficient influx of PL shrimps through tidal water exchange is rare nowadays, resulting in the need for additional stocking of hatchery produced PL (with often questionable health status). Aside from sufficient PL for grow-out up to market size, a regular water exchange in the enclosures is required, as metabolites and -depending on the season- soil leaching compounds that are accumulating in the enclosure, have to be washed out. Though we do not have water chemistry analyses to support this assumption for the Mayanzwebar area (Kyauktan T/S), it is well known that compounds associated with organic decomposition have a negative impact on the growth performance. Also, at a usually low water depth, regular water exchange is required to keep the water temperature in a range, that favors good growth performance of the shrimps. Thus, tidal creeks, connecting the enclosures with the river’s/ bay’s open water body, are the life-line for facilitating the regular tidal water exchange. These tidal creeks in conjunction with well-maintained water gates (mostly executed as wooden structures) are the basis for providing favorable growth conditions to shrimps and other organisms reared in the enclosures.
One concern – often raised by resource users – that there’s need for mechanically clearing of the tidal creeks with ‘heavy equipment’ seems disputable and needs further clarification. Through diligent and (tidal-) timely water exchange, the scouring force of the water, subsiding from the enclosures, and reaching peak amplitudes during the period of full moon/ new moon will keep the creeks open and thus will support a reliable water exchange as needed.
However, it’s a fact that these maintenance works take time and effort, probably money to cover wages for employing laborers, which is brought forward more often than once only by the shrimp farmers and is often used as an argument for relative inactivity. Oftentimes, it appears that the farmers miss out on the consideration that all the efforts, activities and inputs, in the end, are justified by the returns at the end of the grow-out period (As mentioned, efforts are mostly required in terms of human labor force, accompanied by minimal operation budget for maintenance and hardware).
An intervention from the Myanmar Union government, assisted by the MYSAP project (jointly implemented by the Myanmar Department of Fisheries (DOF) and Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH and funded by the European Union and the German Ministry for Economic Cooperation and Development (BMZ)), is aiming (i.a.) at the improvement of the productivity of those tidal enclosures (often covered to a sizable extent with mangroves). A substantially improved income of SSFs and the entire community can be expected once the smooth function of the enclosures’ water gates through input of able and qualified engineering personnel for advisory and on-site support is assured.
However, for having a continuous improvement of the income level in the area through the sustainable aquaculture sector, the need for improvement doesn’t stop at the production side of the ‘aquaculture value-chain’. Capacity development has to go beyond the level of local farmers, it equally has to address other elements, subsumed as ancillary services, e.g. harvest / post-harvest operations, transport logistics). Altogether, these aspects are milestones for improving mangrove friendly aquaculture productivity in the area without compromising the urgent need for subsequent mangrove conservation.
However, it can’t be overrated, that technical expertise, competence and the resulting input of DOF personnel on township level (as standing force) are quintessential in order to critically validate and improve the production conditions of the mangrove friendly ‘trap-and-hold’ system. This will be an essential contribution on the way forward to qualify ‘simple’ resource users to responsible and sustainably acting stewards of the mangrove forest in coastal Myanmar.
Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH
Practical Background in aquaculture & years of experience in CB-coastal zone management/ MPA-Management for resilience