Economic development in the Mekong region has brought with it considerable environmental change, with more to follow. The river has already been highly modified by a plethora or perturbations including damming for hydropower and irrigation, disconnection of the flood plains for agriculture and growing urbanization. These have all impacted on the fish and fisheries and delivery of aquatic food products from the system, but the system has to date remained largely resilient, or has it? This paper explores the widespread degradation of the system and how fisheries have responded, looks at future prospects of the river and how the fisheries may be impacts and final examines opportunities which may help to mitigate future development scenarios, especially with respect to hydropower development.

1. Fisheries of the Mekong:
Death by a 1000 Cuts or
Just Another Day at the Office
Vu Vi An, Ian G. Cowx,
With support from
Kaviphone Phouthavong, Martin Mallen Cooper, Bun Peng,
So Nam, Apiradee Hanpongkittikul

2. Content:
1.Introduction
2.Trend of fisheries in the Mekong Delta
3.Pressures on the fisheries
4.Opportunities and mitigation

3. 1. Introduction:
− Total yield in the LMB: over 2.5 million tons (19% of OAAs):
Thailand: 36%; Viet Nam: 33%; Cambodia: 23%; and Laos:
8%. Total value: about US$6.5 billion/year.
− Per capita consumption average: about 33.7kg/person/year
(VN: 39kg; Cam: 36.8kg; Thailand: 29kg; Laos: 28.6kg).
− Fish diversity: 800 – 1200 species
with 30+ of high commercial
importance.
− At least 7 giant fish: Mekong giant
catfish (P. gigas), giant pangasius (P.
sanitwongsei), giant barb (C.
siamensis), striped barb (P. jullieni) +
Mekong dolphin (O. brevirostris)…
(Hortle, 2007; Hogan, 2011)

4. 1. Introduction:
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
1-Jan-13
15-Jan-13
29-Jan-13
12-Feb-13
26-Feb-13
12-Mar-13
26-Mar-13
9-Apr-13
23-Apr-13
7-May-13
21-May-13
4-Jun-13
18-Jun-13
2-Jul-13
16-Jul-13
30-Jul-13
13-Aug-13
27-Aug-13
10-Sep-13
24-Sep-13
8-Oct-13
22-Oct-13
5-Nov-13
19-Nov-13
3-Dec-13
17-Dec-13
31-Dec-13
Waterlevel(masl)
Vietnamese Mekong Delta: Tan Chau station
Up to
50%
Concentration
of fish in
permanent
water bodies
Adults
movement +
Drift of larvae
to feeding
areas on the
flooded areas
Movement to
dry season
refuges, and
dispersal
DRY Season:
FLOOD Season:

5. - White fish (undertaking
long distance
migrations): 36% of
capture;
- Black fish (floodplain
resident fish, limited
lateral migrations): 50%
of capture;
- Grey fish: 14 % of
capture.
− Fish migtate all
seasons of year.
1. Introduction:

6. 2. Trend of fisheries in the Mekong Delta:
Fishing habitats (gillnetting) vs Flooding scheme:
− Mainstream : 52%
− Tribitary : 24%
− Flooded rice field : 24%
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0%
20%
40%
60%
80%
100%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Waterlevel(m)
Fishingfrequency
Mainstream Tributary Rice field Water Level

7. 2. Trend of fisheries in the Mekong Delta:
- Statistics (capture only):
Total yield: 1,040,759 t
Marine:
Fish: 653,600 t
Others: 263,184 t
Inland : 124,626 t
- 67% of households
in An Giang province
participate in fishing,
only 7% are full time
fishers.
0
20
40
60
80
100
120
140
160
180
200
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
InlandYield(thousandtons)
Year
0
100
200
300
400
500
600
700 2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
MarineFishYield(thousandtons)
(Sjorslev et al., 2001)
Inland: decline 34%
or 2.83%/year.

8. 2. Trend of fisheries in the Mekong Delta:
- Fishers' catch monitoring program (FP/MRC): 2007 – 2014
Average daily catch: 5.45kg/day/fisher gillnet.
0
5
10
15
20
25
Jun-07
Nov-07
Apr-08
Sep-08
Feb-09
Jul-09
Dec-09
May-10
Oct-10
Mar-11
Aug-11
Jan-12
Jun-12
Nov-12
Apr-13
Sep-13
Feb-14
Jul-14
Averagecatchrate(kg/day)
2009

9. 2. Trend of fisheries in the Mekong Delta:
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
5
10
15
20
25
Waterlevel(m)
Catchrate(kg/day)
Catch rate
Water Level
- Fishers' catch monitoring program (FP/MRC): 2007 – 2014
Average daily catch: 5.45kg/day/fisher gill net.
2009

10. 2. Trend of fisheries in the Mekong Delta:2. Trend of fisheries in the Mekong Delta:
- Fishers’ catch monitoring program (FP/MRC): 2007 – 2014
Decline: 8.5kg/day (2007) to 6.4kg/day (2014).
0
2
4
6
8
10
12
14
16
18
2007 2008 2009 2010 2011 2012 2013 2014
Averagecatchrate(kg/day)

11. 3. Pressures on the fisheries:
Major threats to inland fisheries include:
• Over-fishing + destructive
fishing methods
• In-channel barriers (Blocking
of fish migration routes)
• Land use changes
(habitat loss)
• Industrial and urban pollution
• Urbanisation • Agricultural pollution:
pesticides
• Run-of-river abstractions • Mining pollution
• Irrigation • Sediment mining
• Impoundments • Climate change
• Aquaculture linked to
invasive species
• Hydrological changes (e.g.
timing and extent of flooding)
• Flood mitigation measure • Hydropower

12. 3. Pressures on the fisheries:
0 50 100 150 200 250 300 350
Alien species
Catching spawners
Climate change
Weak enforcement
Population growth
Fishing pressure in upstream
Pollution
Habitat loss
Pesticide
Hydrology
Catching small fishes
Dyke construction
More fishers
Illegal gears
Frequency (# fishers)
34.5%
31.7%
11.4%
6.6%
4.8%
4.0%
3.4%
1.0%
0.9%
0.5%
0.4%
0.3%
0.3%
0.1%
Fishers’ perception:

13. 3. Pressures on the fisheries:
Illegal gears in the MD:
- Fishing gears: >120
gear types: small and
simple: Traps;
Gillnetting; Hook and
lines, Towing/
dragging; Castnet,
Scooping, Collection
by hand, Liftnet;
Bagnet …
- Illegal gears: Fishing with
electricity and chemicals; Gears
with small mesh-size.
Motobyke
taxi
0.09%
Aquaculture
1.42% Small
business
2.46%
Fishing
only
22.44%
Labor
28.03%
Agricultural
activities
45.55%
Fishers’ likelihoods:

14. 3. Pressures on the fisheries:
% Catch of Exotic Species:
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
2007 2008 2009 2010 2011 2012 2013
%CatchofExoticspecies
Year
Including 9 exotic species: Pterygoplichthys disjunctivus, Colossoma
macropomum, Oreochromis sp., Hypophthalmichthys molitrix, Clarias gariepinus,
Labeo rohita, Cyprinus carpio, Ctenopharyngodon idella, Hypophthalmichthys nobilis.
Exotic species: Fishers’s cacth monitoring program FP/MRC

15. 3. Pressures on the fisheries:
Habitat Loss in the MD: Rice…
Vo Tong Xuan (1975) Wyatt et al. (2012)
Rice farming: Change from Floating rice (6 months/crop , ~2tons/ha/
crop, 1 crop/year only, planting during flooding season) to TN rice –
“God of agriculture rice” - (3 months/crop, 5-7 tons/ha/crop, up to 3
crops/year, planting in any season).
1975: Floating rice dominated
2012: High yield rice +
Intensive

16. 3. Pressures on the fisheries:
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
1-Jan 1-Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec
3rd rice crop:
Habitat Loss in the MD: Rice…
1st rice crop: plant earlier by pumping water out…

17. 3. Pressures on the fisheries:
Inland fish yield & Rice farming areas:
0
250
500
750
1,000
1,250
1,500
1,750
2,000
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
Ricefarmingarea(thou.Ha)
Inlandfishyield(thou.tons)
Inland capture yield
Rice farming area
Negative relationship: p<0.005
Habitat Loss in the MD: Rice…

18. 3. Pressures on the fisheries:
Water control structure:
• Every dot is a registered
water control structure.
• Loss of connectivity = loss
of productivity in
floodplain/riverine
fisheries.
The MRC water
structures map
JICA/MARD’s project: in 7
coastal provinces. Structural:
Saline intrusion prevention
sluice gate contruction;
Seashore protection and
improvement. Non-Structural:
Cropping calendar
adjustment and
improvement….

19. 3. Pressures on the fisheries:
Hydropower dams:
9 planned dams on LMB
(mainstream) – two under
construction.
23 existed dams (> 20
MW) on tributaries.
 Many more tributary
dams are projected or
under construction.
- Cambodia: 20 projects (1 Ope; 1 Und;
0 Lic; 18 Plan).
- Laos: 100 projects (21 Ope; 25Und; 16
Lic; 38Plan).
- Thailand: 7 Ope prjects.
- Viet Nam: 15 projects (13 Ope; 1 Und;
0 Lic; 1 Plan). Niel et al. (2014)

20. 3. Pressures on the fisheries:
Linkage Between Drivers and Impacts:
Hydropower Projects Other exogenous factors
Changes in River Flows,
Sediment Transport, and
Water Quality
Obstructions in Fish
Migration Routes &
Habitat Connectivity
Changes in Fish Habitat
Quality, Quantity, &
Productivity
Fisheries Impacts

21. 4. Opportunities and mitigation:
Fisheries’ characteristics:
Inland Fisheries Marine Fisheries
Small-scale gears Large commercial gears
Informal Formal (e.g. licenced)
Dispersed, often hidden by
geography/vegetation
Visible, large gears at open sea
Landings dispersed and
informal
Landing centralized and visible
Part-time fishing dominates
(e.g. mixed farming/fishing
lifestyles on river floodplains)
Professional fishing dominates,
i.e. very few part-time fishers
Most catch consumed
domestically
Most is exported out of the
community of capture
Many people participate Few people participate
Modified from: FAO RAP Publication 2002/11

22. 4. Opportunities and mitigation:
Mitigation measures:
Mitigation measures to ameliorate likely impacts focus on:
• in-take and outfall locations;
• fish passage facilities – upstream and downstream,
• ‘Friendly’ turbine design;
• measures to ameliorate the potential impact of depleted
reaches – allocation of flows;
• replacement of lost fisheries – aquaculture and stocking;
• need habitat connectivity to complete fish life cycle;
• fish friendly irrigation scheme.

23. Thank you
Especially to AFS
and SEAFDEC