How will dams hurt fish populations on the Mekong?

Although dams provide positive impacts on social economic developments, the negative impacts should not be neglected. The dams will block fish migration, disturb fish’ habitats and risk the critically endangered Irrawaddy and the Mekong Giant catfish extinction.

How do dams affect fish populations?

Dams can block or impede migration and have created deep pools of water that in some cases have inundated important spawning habitat or blocked access to it. … Low water velocities in large reservoirs also can delay salmon migration and expose fish to high water temperatures and disease.

How do dams affect the Mekong River?

Hydropower dams have had a dramatic effect on the Mekong river over the last two decades, resulting in unseasonable flooding and droughts, low water levels in the dry season, and drops in the amounts of sediment carried by the river, with drastic consequences for biodiversity and fisheries.

Do dams decrease fish populations?

The population of fish is dependent on the aquatic habitat, which supports all the biological functions. Dams block the passage of migration of fish, which disrupts the life cycle of many fishes.

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How does a dam kill fish?

Usually these mortalities or injuries are caused when the fish strike the spinning blades or the concrete walls. The intense water pressure also can kill the fish. Biologists estimate that if turbine passage is the only way past a dam, 10 to 15 percent of the fish that are drawn through the turbines will die.

Do dams hurt fish?

Dams harm fish ecology via river fragmentation, species migration prevention, reservoir and downstream deoxygenation, seasonal flow disruption, and blockage of nurturing sediments. Drastic sudden fish losses due to dams can also destroy the commercial and subsistence livelihoods of indigenous and traditional peoples.

What impacts would a dam have on the biodiversity of fish communities?

Dams create calm bodies of water, changing overall temperature regimes and sediment transport, leading to conditions which tend to favour generalist species. Loss of specialist species, particularly endemics, changes the community structure and leads to biotic homogenization.

How many dams does the Mekong River?

Eleven massive dams straddle the mighty Mekong River before it leaves China and flows into Myanmar, Laos, Thailand, Cambodia, and on into Vietnam.

How many dams does China have on the Mekong?

This disturbing situation has been exacerbated by the reduction in the flow of sediment down the river, sediment retained by China’s 11 Mekong dams.

Why do low head dams cause problems for fish?

Low-head dams may block fish pathway and cause the isolation of formerly panmictic populations (Porto et al., 1999), modify local habitat conditions and alter species composition of fish assemblages (Yan et al., 2013, Hitchman et al., 2018), and even affect the structure of food webs (Ruhí et al., 2016, Mor et al., …

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How are fish protected from dams?

These four primary passage routes (turbine, juvenile bypass, spillway, and surface passage) are the only ways, save for some passage through navigation locks, by which any downstream migrating fish can pass through one of these dams. Most upstream fish passage in the CSRB is via fishways (called “fish ladders” here).

What are negative effects of dams?

Dams store water, provide renewable energy and prevent floods. Unfortunately, they also worsen the impact of climate change. They release greenhouse gases, destroy carbon sinks in wetlands and oceans, deprive ecosystems of nutrients, destroy habitats, increase sea levels, waste water and displace poor communities.

Can fish swim up a dam?

All fish migrate to a degree, but dams have the biggest disrupting force on anadramous fish, like salmon or shad, which spawn in rivers but spend most of their lives in the ocean, and catadramous ones, like eel, which live in freshwater, but swim out into the ocean to do it.

What do you fish with a dam?

Top Dam Fishing Techniques

  1. Large Swimbaits. In the majority of the cases, dams feature currents. …
  2. Use Crankbaits. On top of being easy to throw, crankbaits cover a lot of ground and fish do love them. …
  3. Topwater Lures. …
  4. Jig Head and Soft Plastic. …
  5. Live Bait.