Sida BDP2 FISHERIES ASSESSMENT BDP2: FISHERIES ASSESSMENT METHODOLOGY Ashley S. Halls Basin Development Plan 2nd Regional Stakeholder Forum Stakeholder Forum Chiang Rai Thailand 15 ‐ 16 October 2009 Chiang Rai, Thailand, 15 ‐ 16 October, 2009
Purpose • Overview of proposed methodology to assess likely outcomes of the likely outcomes of the development scenarios on future yields of fish and OAA in the LMB.
Resource Scope • Wild capture fish and… • OAA (e.g. frogs, crabs, small shrimp). • Excludes potential national development plans for the • Excludes potential national development plans for the aquaculture sector (not included in development scenarios). • But autonomous aquaculture development in reservoirs assumed. • Excludes unplanned or unspecified mitigation measures (e.g. fish pass facilities in flood control embankments) fish pass facilities in flood control embankments).
Spatial Scope • “All aquatic fish habitats where changes to yield would be expected as a result of the diminished access to these habitats or arising from changes to hydrological conditions within them due to development activities”.
Development Scope • • Three major development themes are Three major development themes are included: 1. Hydropower 2 2. Irrigation (& other abstractions) Irrigation (& other abstractions) 3. Flood Control (overlaps irrigation)
Development Pressures • How do dams, flood control embankments and irrigation projects affect fish yields? and irrigation projects affect fish yields?
Dams, flood control embankments, irrigation Barrier and passage effects Modified flow effects First Order: First Order: • Changes to flow volume, timing and duration • Obstruction of fish migrations Obstruction of fish migrations • Changes to water quality: • Dam passage mortality Temperature, dissolved gas and nutrient • Trapping or scouring of sediments concentrations, and sediment load. Second Order: • Changes to primary production in fish habitats. • Changes to habitat availability and quality . g y q y Third Order (Fish Impacts): • Temporal and spatial changes to fish fauna abundance, biomass and diversity
Mainstream and Tributary Dam Impacts ‐ Quantified impacts Dams 1 st and 2 nd Order Impacts Obstruction of fish migrations and passage mortality (if applicable). Barrier and passage Interruption of downstream sediment transport. effects Formation of reservoirs in tributaries upstream of dams. Formation of reservoirs in tributaries upstream of dams. Increased flooded area. Increased dry season water levels Decreased flow velocity. I Increased sediment deposition due to low flow conditions. ea ed edi e t de o itio due to lo flo o ditio M difi d Modified flow effects: Rapid (short ‐ term) fluctuations in water levels (hydropeaking) Upstream / Stabilized water levels (no flood pulse). reservoirs Vertical stratification of the water column. Increased water depth. Changes to water temperature. Increased water transparency. Diminished and delayed floodplain inundation y p Increased dry season water levels Diminished and delayed flows (discharge) in channel. Modified Reduced sediment transport downstream. flow effects: Rapid (short ‐ term) fluctuations in water levels (hydropeaking) Rapid (short term) fluctuations in water levels (hydropeaking). Downstream Changes to salinity in delta regions. Release of deep cold, nutrient ‐ rich but often anoxic waters. Release of gas super ‐ saturated water.
Flood Control Project Impacts ‐ Quantified impacts Q ifi d i Flood control control schemes 1st and 2nd Order Impacts (FCDI) Inside flood zone) Obstruction of fish migrations between floodplain and main channel. Barrier and passage passage Interruption of sediment transport to floodplains Interruption of sediment transport to floodplains. effects Passage mortality via pumps for irrigation and flood control. Diminished and delayed flooding inside poldered areas Diminished and delayed flooding inside poldered areas M difi d Modified flow effects: Increases to river discharge as flow is constrained to main channel. Increased use of pesticides and fertilizers for HYV’s of crops.
Irrigation Project Impacts ‐ Quantified impacts ‐ Quantified impacts Irrigation Projects 1st and 2nd Order Impacts (Outside of flood zone) Barrier and Barrier and Obstruction of fish migrations between project and river system Obstruction of fish migrations between project and river system. passage Passage mortality via pumps for irrigation. effects Increased area of ‘ricefield landscape’ i.e. small ponds, reservoirs, and surrounding ricefields forming the irrigation project. Modified Downstream reductions to flow by irrigation abstractions or flow effects: diversions from channels WITHIN the floodzone or connected to the river system. Increased use of pesticides and fertilizers
Quantifiable Impacts LOSSES: 1. Barrier impacts of dams and flood control embankments embankments. 2. Flood modification impacts in the flood zone arising from water storage above dams and abstractions for from water storage above dams and abstractions for irrigation (& water supply). GAINS / COMPENSATION: 3. Reservoir fisheries above tributary dams. 4. Irrigation projects.
Other Impacts: qualitative assessment assessment • Qualitative assessments will be undertaken to highlight the likely scale and direction of the remaining 1 st and 2 nd the likely scale and direction of the remaining 1 and 2 order impacts of fish yields.
Assessment Methodology • OUTLINE OF QUANTITATIVE ASSESSMENT METHODOLOGY: 1. Barrier impacts of dams & flood control projects 2. 2 Reservoir fisheries Reservoir fisheries 3. Modified (flow) flood impacts 4. Irrigation project impacts g p j p
1. Barrier Impacts: Dams and Flood Control Embankments Control Embankments Impacts will vary among species depending upon: • Scale of their migrations • Scale of their migrations. • Type of migrations (longitudinal / lateral). • Tolerance to environmental conditions and behavioural flexibility (adaptability). • We can approximately group species into 9 ‘guilds’ according W i l i i 9 ‘ ild ’ di to these characteristics as follows…
GUILD 1 GUILD 1 GUILDS 1, 6, 7 GUILDS 1, 6, 7 Spawning areas Spawning areas GUILDS 2, 3, 8, 9 GUILDS 2, 3, 8, 9 Guilds 4 & 5 Guilds 4 & 5 Rithron Tributary GUILD 6 GUILD 6 GUILD 6 GUILD 6 Tributary Floodplain Guild Guild Name Name Examples Examples Species resident in the rithron, Species resident in the rithron, Raiamas guttatus Hypsibarbus malcolmi Migrate long distances upstream Migrate long distances upstream Guild 5: Guild 5: Short distance migrations in Short distance migrations in Guild 4: Guild 4: Irrigated and rain-fed 2 1 Channel Resident Rithron resident Tor laterivittatus Probarbus jullieni estuary and floodplains. estuary and floodplains. y y p p to spawn (or feed). to spawn (or feed) to spawn (or feed). to spawn (or feed) main channel. main channel main channel main channel. Non N Non ‐ obligatory obligatory bli bli t t Obligatory lateral Obli Obligatory lateral Obli l l l l Tor sinensis Pangasius conchophilus T P i i i h hil wetlands e.g. rice fields Channa micropeltes Cosmochilus harmandi; lateral lateral migration migration Adults and drifting eggs/ larvae/ Adults and drifting eggs/ larvae/ Lateral migrations between Lateral migrations between Outside flood zone 6 3 Channel Spawner Blackfish Henicorhynchus siamensis; Clarias batrachus No significant longitudinal or lateral No significant longitudinal or lateral juveniles return to downstream juveniles return to downstream migration migration Paralaubuca typus Anabas testudineus channel & floodplain. channel & floodplain. migrations. migrations. Tenualosa thibaudeaui Arius maculates feeding habitat. feeding habitat. GUILD 6 GUILD 6 GUILD 6 GUILD 6 Guild Name Glossogobius giuris Glossogobius giuris Examples p 7 8 8 7 Delta Resident (Semi) Anadromous Tenualosa toil Delta Resident (Semi) Anadromous Tenualosa toil GUILD 3 GUILD 3 GUILD 3 GUILD 3 Polynemus longipectoralis Lycothrissa crocodilus Catlocarpio siamensis Includes anadromous and Includes anadromous and Guild 4: Obligatory lateral Guild 4: Obligatory lateral Guild 5: Highly adaptable. Guild 5: Highly adaptable. Macrobrachium Barrier impacts low. Barrier impacts low. 4 Floodplain Spawner Puntioplites falcifer catadromous species. catadromous species. migrations for spawning/ migrations for spawning/ Non Non ‐ obligatory lateral 9 Catadromous obligatory lateral Hemibagrus spilopterus rosenbergii Barbonymus gonionotus Anguilla marmorata feeding & refuge. Vulnerable feeding & refuge. Vulnerable migrations. Persists in migrations. Persists in Vulnerable to damming. Vulnerable to damming. 5 Generalist Labeo chrysophekadion Mainstream to flood control to flood control. to flood control to flood control. i impoundments. impoundments. i d d t t GUILD 7 GUILD 7 GUILD 7 GUILD 7 Wallago attu W ll tt Floodplain GUILD 7
Assessment Methodology ESTIMATING IMPACTS OF DAMS ON YIELDS OF HIGHLY MIGRATORY SPECIES: GUILDS 2,3,8,9.
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