Important fish migrations take place in the Lower Mekong River of Southern Lao PDR during the dry and wet season months. The riparian communities are aware of these movements and target a large number of species using a wide range of fishing gear. The objectives of the research were to identify the main migratory species, the timing, fish production, direction, purpose, main influencing factors and the change in magnitude of migration between years. Research into the wet-season movements has been carried out from 2007 to 2013 in one rocky channel (Hoo Som Yai) at the Great Fault Line (Khong district) with supported by Fisheries Program of Mekong River Commision (MRC). The Catch Per Unit Effort (CPUE) data were recorded directly from fishers operating the Lee traps and measured water flow in Hoo Som Yai from late May to the end of September each year. The data were collected in wet season from 2007 to 2013 showed the main wet season migrants come from the families, Pangasidae, Siluridae catfish and Cyprinidae. The white fish were the dominant species that passed to this channel and follow by grey fish. A few black fish were also captured.

1. By: Douangkham Singhanouvong
Deputy Director of LARReC
Living Aquatic Resources Research Center (LARReC)))
American Fisheries society Conference
16-20 August 2015, Portland USA

3. 1. Background
2. Methodology
3. Result
4. Conclusion

4.  Important fish migration take place in the Lower Mekong
River of southern Lao PDR during both the dry and wet
season.
 There are several fish species that migrate in both up and
downstream directions from the South to North all both
seasons.
 Lack of information about fish migration, fish abundant
and almost no quantitative data has been available for
future baseline monitoring.
 So, the Lee trap research has been started since 1993 - 98,
supported by IDRC, Canada.
 From 2007 to 2013 the study was supported by Fisheries
Programme of Mekong River Commission ( MRC)

5. Khong district
(Or Khong Island)
1.1 Location of study

6. Water Fall

10. 1.2 Hoosom Yai channel (Con’t)

11. Lee traps or Bamboo -wing traps are one of
the most popular fishing gears in Laos
especially in Southern part. They are
made from Bamboo with the length of 8
to 10 meter and wide around 1.5 meter.
These gears are mainly used in the wet
season, set in appropriate channels and
placed in position to intercept the
nocturnal fish movement.
Lee trap are also placed directly in the
current with half of the bamboo matting
structure in the water, and half out
the water. These traps are caught
mainly fish that move up stream, when
they could not pass to the strength
current then they flow down into the
Lee trap (Singhanouvong. D, 1994).

12. An overall objectives
 To provide a time series of relative abundance
estimate for migratory white fish in the lower
Mekong River in order to monitor the effects of
fisheries management and basin development
activities.

13. 1) To monitor and determine status and trends
in fisheries resources in terms of diversity and
relative abundance in the Khone Falls through
temporal and spatial variation.
2) To support valuable information on fisheries
resources for fisheries management and impacts
assessment purposes.

14. 2.1. Data collection:
-Started from the end of May to the
September every year
-Count the number of fishing gear (lee
trap) that are working.
- Count the number and weigh of each
species caught for important species.
- Measurements of the mean flow
volume (m3/s) passing down HSY
- CPUE data recorded as
kg/trap/nightMeasured and weighted a fish

15. Year May June July August Sept
2007 17 17 0 0 0
2008 0 10 9 5 4
2009 17 18 10 7 7
2010 17 18 10 7 7
2011 21 22 10 2 3
2012 22 20 16 10 9
2013 21 21 16 7 6

16. 3.1. Catch Per Unit Effort and trend ( 2007 to 2013)

17. 3.2. CPUE top five species and trend (2007-2013)

18. Labeo chrysophekadion Pangasius larnaudiei
Hemisilurus mekongensis.
Bagarius yarrelli
Hemisilurus mekongensis

19. 3.3. Fish biodiversity

20. 3.4. Total fish landing by year (kg)

21. 3.5. Total catch by month and year (kg)
Year May June July August Sep
2007 100,7 557 0 0 0
2008 0 682 1,176 887 69
2009 1,013 2,219 660 365 339
2010 80 594 2,214 974 501
2011 202 654 468 167 76
2012 544 1,000 429 449 284
2013 73 1,091 543 309 124

22. 3.6. total catch by feeding type (%)

23. Carnivorous
Herbivorous
Omnivorous
Osteochilus microcephalus
Labeo chrysophekadion
Botia modesta
Pangasius conchophilus
Micronema sp

24. 3.7. total catch by ecological characteristic

25. White Fish

26. Gray Fish Black Fish
Estuary Fish

27. • The daily catches in 2012 and
2013 were increased especially
during the high flow late May
and Early June.
• The number of fish species and
quantities of fish catch changes
from May to September.
• The main species reported in
the catch were :
Pangasius larnaudiei, Bagarius
yarrelli, Labeo chrysophekadion,
Pangasius conchophilus and
Hemisilurus mekongensis.

28. • The white fish were the dominant
species and follow by grey fish,
black fish and estuary fish
• The total catch from 2007 to 2013
varied depending on water flows.
• The highest catches were in 2009
and 2010 and the lower catches
were 2007 and 2011.
• The rainfall and water level were
perhaps the main factors affecting
fish catches.
• The Length frequencies of the main
five species shows not much
changed in term of length during
2008 to 2013.

29. • The results that we
have gathered can
now be applied to the
fisheries resources
management.
• This management is
important for the
Lower Mekong Basin
development planning
purposes.