Challenges for Fish Pass Solutions in the Mekong River

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

4. Page 4 Fish fauna Giant pangasius (Pangasius sanitwongsei CR) Mekong giant catfish (Pangasianodon gigas CR) Giant barb (Catlocarpio siamensis CR) Giant Sheatfish (Wallago attu NT) Goonch (Bagarius yarrelli NT) Seven-striped barb (Probarbus jullieni EN) Thicklip barb (Probarbus labeamajor EN) Striped catfish (Pangasianodon hypophthalmus EN) Highest number of giant freshwater fish FAO

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

20. Page 20 Innovation: Hydroconnect Up- & downstream fish pass Downstream passage Upstream passage 28/08/2015

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