The passage of fish is an issue that needs to be considered during the design and planning stage of proposed developments (dam site selection), and adequate consideration should be given to appropriate mechanisms for their transfer.  It is essential that adequate research is dedicated to understanding the aquatic ecosystem that will be affected, as each is unique, and solutions for one scheme can rarely be directly applied to other schemes.

Fish ladders or mechanical fish elevators are often focussed on as a management measure to assist fish with their upstream migration, although these can be of mixed success.  Catch and release programs are commonly undertaken for both the upstream and the downstream migration, and hatcheries and re-stocking programs are employed where necessary.  Fish hatcheries can help maintain populations of native species that thrive within the reservoir but cannot successfully reproduce.

To address downstream migration issues, many measures have been employed to divert fish away from the turbine intake to safer passageways, such as purpose built channels or pipes going around or through a dam wall.  Diversion methods can include fish screens, strobe lights, sound or air bubbles, and electrical fields.  Assisted cues, such as changes in water chemistry or operational conditions, can be utilised, as can controlled releases or additional spill at appropriate times of year.  Improvements in turbine, spillway and/or overflow design can minimise fish injury or mortality on the downstream migration.

Ultimately, the mitigation solutions to address fish passage risks needs to be considered within the context of an over-arching cost-benefit analysis for a hydropower scheme.