1. Page 1 Challenges for Fish Pass Solutions in the Mekong
River Stefan Schmutz Carina Mielach Institute of Hydrobiology and
Aquatic Ecosystem Management Department of Water, Atmosphere and
Environment BOKU - University of Natural Resources and Life
Sciences, Vienna, AUSTRIA AFS Annual Meeting Portland Tuesday,
August 18, 2015: 1:20 PM, B-118 (Oregon Convention Center)
2. Page 2 Fish fauna of the Mekong River
3. Page 3 Worlds 10th longest river (4,909 km) 6 countries
>800 fish species (biodiversity hotspot) exact number is unknown
2nd highest species richness in the world (after Amazon) Diversity
increases from headwaters to lower sections Highest inland fish
productivity Fish fauna
5. Page 5 Fish fauna 0 50 100 150 200 250 300 Henicorhynchus
ornatipinnis Labiobarbus lineatus Henicorhynchus cryptopogon
Henicorhynchus lineatus Henicorhynchus lobatus Lobocheilos
cryptopogon Paralaubuca barroni Paralaubuca typus
Amblyrhynchichthys micracanthus Henicorhynchus siamensis
Yasuhikotakia modesta Labiobarbus leptocheilus Lycothrissa
crocodilus Pangasius macronema Puntioplites proctozystron Tenualosa
thibaudeaui Osteochilus hasseltii Osteochilus vittatus Hampala
dispar Pangasius pleurotaenia Puntioplites falcifer Mekongina
erythrospila Poropuntius malcolmi Bangana behri Hemibagrus
filamentus Notopterus notopterus Phalacronotus bleekeri Cirrhinus
microlepis Hemibagrus nemurus Hampala macrolepidota
Cyclocheilichthys enoplus Helicophagus waandersii Hemisilurus
mekongensis Labeo chrysophekadion Boesemania microlepis Chitala
ornata Cosmochilus harmandi Pangasius elongatus Pangasius bocourti
Pangasius conchophilus Pangasius krempfi Micronema apogon Pangasius
larnaudii Phalacronotus apogon Pangasianodon hypophthalmus
Probarbus labeamajor Probarbus jullieni Bagarius yarrelli Wallago
attu Catlocarpio siamensis Pangasianodon gigas Pangasius
sanitwongsei < 25 cm 25 to < 50 cm 50 to < 100 cm 100 cm
< 25 cm 25 to < 50 cm 50 to < 100 cm 100 cm not conisdered
in this report 100 200 300 cm Maximum length of commercially
important species Data sources: Poulsen et al. (2004), Baran et al.
(2005), Halls et al. (2013) and fishbase.org Halls et al. (2013):
16 species comprise 50% of the total catch Halls et al. (2013)
6. Page 6 Fish fauna migration triggers Flora & fauna
evolved in accordance to distinct hydrological cycle and highly
depend on timing (seasonality), duration and magnitude of flows 4
distinct seasons limited habitat availability, water quality
alteration determines productivity Transition seasons trigger
migrations (e.g. spawning)
7. Page 7 Fish fauna migration guilds Migratory (white) and
non-migratory (black) species with intermediate (grey) guild (Baran
2006, 2010, Welcomme 2001, Poulsen et al. 2002, Ferguson et al.
2011) More detailed classification (MRC 2009) (1) Rithron resident;
(2) Migratory main channel (& tributaries) resident guild; (3)
Migratory main channel (& tributaries) spawner guild; (4)
Migratory channel refuge seeker guild; (5) Generalist guild; (6)
Floodplain resident guild; (7) Estuarine resident guild; (8)
Semi-anadromous guild; (9) Catadromous guild; (10) Marine guild
(enters estuaries opportunistically)
8. Page 8 Fish fauna migration systems (Poulsen et al. 2002,
Baran 2006)
9. Page 9 Facilities for upstream migration Facilities for
downstream migration
10. Page 10 Fish pass types Large scale bypass systems Bypass
channels & rock ramps Nature-like Technical Upstream Downstream
Vertical slot fish passes Fish protection Fish passage Screens
Bypasses Spill flowFish-friendly turbines
11. Page 11 2. Facilities for upstream migration
12. Page 12 Upstream fish pass functionality
Attraction/perceptibility where migrating fish search for a way up-
/downstream close to the - barrier - migration corridor - main
current Passage (for all species) hydraulic conditions (swimming
capabilities) spatial conditions (large species, high biomass)
Post-passage effects reservoir (no orientation or suitable habitat)
At least during spawning periods but preferably all year long
13. Page 13 Upstream fish pass perceptibility several entries
Wide barriers (at least two, one at each side) Variable water
levels Multiple entrances required close to banks and mid-stream
bottom, mid-water, surface high flow, low flow
14. Page 14 Upstream fish pass perceptibility Attraction flow
Has to be actively recognised and tracked by fish (0.7-1.5 m/s) Low
turbulence (in large rivers, depending on the location) Additional
flow can be introduced at downstream part Attraction flow turbines
Water coming from the tailrace
15. Page 15 Upstream fish pass passability spatial dimensions H
= 66 L = 300 slot depth (ds) 2 to 2.5 * H = 132 to 165 cm pool
width (Wp) 2 * L = 600 cm slot width (ws) 3 * W = 123 cm (for
nature-like FP by a factor of 1.25-1.5 larger) Estimation for
Mekong giant catfish pool length (Lp) 3 * L = 900 cm hydr. depth
(Dmin) 2.5 * H = 165 cm
16. Page 16 Vertical slot fish pass Example: Geesthacht, Elbe
River, Germany FP length 550 m Weir head 4 m 45 pools 9 x 16 m 2
slots/ pool 1.6 m Max. discharge 15 m/s (2% of MQ) Passage of 43
species 300.000 ind./year Also large individuals of Atlantic
salmon, sander, European catfish and 3 m long sturgeon
17. Page 17 3. Facilities for downstream migration
18. Page 18 Downstream fish pass Fish protection (to prevent
migration through turbines) Behavioural barriers Physical barriers
Construction of suitable downstream fish pass systems
Fish-compatible turbines Bypass systems Spillway passage Trap &
truck Widely lacking for large, multi-species rivers Solutions for
passive downstream drift of fish larvae through reservoirs?
19. Page 19 6. Conclusion and future research priorities
21. Page 21 Integrative fish pass solutions Jungwith et al.2005
Fish ladder Integrated mitigation solutions
22. Page 22 Mekong fish passes Remaining challenges and
research Most fish passes for small-medium sized-dams (15m height)
Mainly for upstream migration Large migrating species Migration
peaks with high biomass High diversity of species (with different
requirements) Limited knowledge of all migratory species (e.g.
Mekong) High discharge variations Fish passage efficiencies
(multiple dams!) Worldwatch Institute 292 m high Xiaowan Dam.
Mekong, China
23. Page 23 Thank you for your attention! Stefan Schmutz
University of Natural Resources and Life Sciences Vienna Institute
of Hydrobiology and Aquatic Ecosystem Management Max Emanuel-Strae
17, A-1180 Wien Tel.: +43 1 47654-5202, Fax: +43 1 47654-5217
[email protected] www.boku.ac.at For more information see
Mekong River Commission report