RAP PUBLICATION 2005/12
ASIA-PACIFIC FISHERY COMMISSION
A review of stock enhancement practices
Sena S. De Silva and Simon Funge-Smith
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De Silva, S.S. and Funge-Smith, S.J. 2005. A review of stock enhancement practices in the inland water fisheries of Asia. Asia-Pacific Fishery Commission, Bangkok, Thailand. RAP Publication No. 2005/12, 93 p.
Inland fisheries contribute only about ten percent to global fish production. Asia is the leading producer of inland fish, accounting for over 80 percent of the total production. Until recently, the inland fisheries sector had taken back stage in fisheries development plans, particularly so, given the emphasis being placed on aquaculture development throughout the world, including Asia. This report evaluates the inland fishery practices in a number of Asian countries according to habitat type, role in overall food fish supplies and development trends. Special emphasis is laid on stock enhancement in inland fisheries in Asia, and only those fisheries in which some form of stock enhancement is practised are considered in this report.
In Asia, inland fisheries are mostly rural, artisanal activities catering to rural populations and providing an affordable source of animal protein, employment and household income. Stock enhancement is an integral component of many inland fisheries. With recent developments in artificial propagation techniques for fast-growing and desirable fish species and the consequent increased availability of seed stock, such activities are beginning to affect inland fishery production in most Asian countries. Indeed, new avenues of production such as culture-based fisheries are increasingly adopted and seen as a way forward in most countries. Inland fishery activities also have a distinct advantage in that their development is usually less resource intensive than is aquaculture.
The economic viability of stock enhancement of large lacustrine waterbodies and rivers has not been demonstrated in any of the Asian countries, the fisheries of such waterbodies being dependent on naturally recruited stocks. The most successful stock enhancements in Asia are in floodplain beels and oxbow lakes in Bangladesh where the use of small waterbodies that are not capable of supporting natural fisheries has led to culture-based fisheries having stock and recapture rates that are very high. Culture-based fisheries are not resource intensive and are community-based activities. However, their success requires major institutional changes, and these are affected by national and local governments. In general, they can be considered to have the greatest potential for further development.
A major concern related to stock enhancements in inland waters is their possible effects on biodiversity. This is for two reasons: firstly, most countries depend wholly or partially on exotic species for stock enhancement and secondly, freshwater fishes are known to be among the most threatened of vertebrates. Major studies should be undertaken to evaluate the current situation so that remedial steps can be taken, if needed, without causing serious harm to some of the stock enhancement practices that are gaining momentum.
Table of Contents
1.1 Contribution of fish to food security and human nutrition
1.2 Sourcing foodfish requirements
1.3 Purpose of this review
2. Inland water resources of Asia
2.1 Riverine resources
2.2 Natural lakes
3. Inland fisheries of selected countries in the region
3.1 Inland fishing gear
3.2 Catch composition
4. Stock enhancement: general considerations
4.1 Stock enhancement of inland waters in Asia
4.1.1 Rivers and floodplains
4.1.2 Lakes and reservoirs
5. Stock enhancement of floodplain fisheries
5.1.1 Stock enhancement of floodplains and beels
5.1.2 Species used and production
5.1.3 Fingerling/seed supplies
5.1.4 Economic analysis
5.1.5 Administrative arrangements/management of stock-enhanced fisheries
5.1.6 Socio-economic impacts
5.2.1 Stock enhancement of floodplain fisheries
5.2.2 Fingerling supplies
5.2.3 General observations
6. Stock enhancement practices in large lakes and reservoirs
6.2.1 Inland fisheries
6.2.2 Stock enhancement strategies
6.5 PR China
6.6 Sri Lanka
6.6.1 The inland fishery
6.6.2 Stock enhancement
6.7.1 Inland fisheries
6.7.2 Stock enhancement
6.8 Viet Nam
6.8.1 Stock enhancement strategies
7. Recommendations for stock enhancement in large lacustrine waterbodies
7.1 Summary evaluation of current stock enhancement practices
7.2 Developing a stock enhancement strategy for large inland waterbodies
7.2.1 Does the waterbody require a stock enhancement strategy?
7.2.2 What form should the enhancement take?
7.2.3 How to decide what to stock?
7.3 Constraints to developing and sustaining stock enhancement strategies for large waterbodies
8. Stock-enhancement in small and medium-sized inland waterbodies
8.1 Stock enhancement and/or culture-based fisheries in Asia
8.2 Constraints to culture-based fishery development
8.2.1 Species combinations and stocking ratios
8.2.2 Seed supplies
8.2.3 Management structures/institutions
8.2.4 Harvesting and marketing
8.3 Fingerling production for stock enhancement
9. Biodiversity issues in relation to stock enhancement in inland waters
9.1 Biodiversity issues associated with floodplain fisheries stock enhancement
9.2 Biodiversity issues related to stock enhancement in large lacustrine waters
9.3 Biodiversity issues in culture-based fisheries
10. Socio-economic issues related to stock enhancement in inland waters