Managing reservoirs and dams to increase fish stocks and benefits to fishers

Research by FISH and partners shows that adopting an integrated landscape approach to managing reservoirs and dams can mitigate their harmful impacts on fisheries and boost fish yields and benefits to communities living nearby.

Globally, there are 16.7 million humanmade reservoirs, providing vital services such as irrigation, flood control and drinking water. Nearly 60,000 reservoirs are behind large dams and contribute directly to 12–16 percent of the world’s irrigated food production.

But reservoirs, built to store water, adversely impact fisheries, by altering the flow of rivers, changing fish habitat and blocking fish migration routes. Likewise, in irrigation schemes, structures such as sluices, weirs, regulators and colverts create bottlenecks for fish when passing through the system.

There is huge potential for reservoirs and dams to create and enhance fisheries, both upstream and downstream. Research into integrated fish-crop systems shows that fish can be the most profitable component, and can improve the overall nutritional diversity and value compared to monocrop systems.

To harness this opportunity, dam operators and water managers should adopt an integrated landscape approach that gives more prominence to fisheries.

Specifically, management options to improve fisheries include:

  • considering fisheries in dam operation;
  • constructing or modifying water control structures for appropriate fish passage;
  • protecting existing fish habitat on rivers flowing into reservoirs;
  • increasing recruitment of fish and improving survival of juvenile fish;
  • improving reservoir habitat for fish;
  • regulation to prevent overexploitation of fisheries;
  • creating fisheries groups to empower local people as stewards.

These measures help mitigate the impacts of large dams on fish stocks while increasing fish yields and economic opportunities–a huge benefit for the farmers and smallholders living nearby.

This research is a key focus of FISH and the CGIAR Research Program on Water, Land and Ecosystems, which are collaborating to investigate how improved water and land management can sustain inland fisheries production in multifunctional landscapes and boost overall landscape productivity.

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