Hydro Power and Fish Migration – Protecting Endangered Species
Every year, millions of fish migrate thousands of miles across oceans and rivers to reproduce. When barriers such as hydropower dams prevent this movement, populations decline and become endangered.
Fortunately, dam operators can take several measures to assist migrating fish in reaching their destinations. However, these efforts must be tailored specifically for each power plant and region.
Hydroacoustic Sonar Surveys
Hydroacoustic sonar surveys are a non-invasive way of assessing fish populations. They use either fixed or boat-based imaging equipment to collect data such as depth (bathymetry), fish density and abundance, size distribution and behavior.
They can also be employed to study fish migration patterns. For instance, fixed hydro-acoustic stations are placed at stream “pinch points” and fish ladders to assess migratory fish populations.
Hydro-acoustic surveys involve placing a high-resolution hydroacoustic camera in the water at predetermined transects to sample fish and bottom characteristics. Specialized software processes individual fish’s characteristic acoustic signals to produce estimates of density, abundance, size and behavior.
In addition to assessing fish migratory movements, mobile horizontal echosounding with high-resolution hydroacoustic cameras is an efficient method for sampling fish densities in large rivers. It provides georeferenced real-time information about individual fish that cannot be replicated using traditional sampling techniques like electrofishing.
Acoustic telemetry is a technique used to monitor marine animals by broadcasting sound pulses called ‘pings’ into the water. These pings can be detected by receivers placed at critical locations and habitats.
Acoustic telemetry allows researchers to track animal movement over long periods of time and on scales from 100 metres up to several kilometers. This provides valuable information regarding habitat use, home range size, marine protected areas effectiveness, stock assessment methods and migratory patterns.
Acoustic telemetry is a straightforward technology that requires two pieces of equipment: transmitters and receivers. The transmitter sends out an acoustic signal to a tag attached to a fish of interest, which the receiver detects by its unique ID number.
Salmon and other migratory fish have been severely restricted in their migration paths by dams in many regions around the world. To help reopen these fishways, NOAA has collaborated with numerous partners to remove obstacles, improve water quality, and build community support for wildlife conservation initiatives.
Some species that were once extinct have been rediscovered, such as sockeye salmon in Washington State’s Baker River basin and shortnose sturgeon on Maine’s Penobscot River. Unfortunately, many more have gone extinct since 1973 with the passage of the Endangered Species Act (ESA).
Passage assessments are essential to assess how well a crossing will facilitate passage and preserve river/stream continuity for wildlife in these areas. The assessment should also incorporate an evaluation of the channel type and long profile, taking into account any likely changes that may take place along its lifespan.
Passage Monitoring is the process of assessing the success of fish passage improvement projects. This helps guarantee that migratory fish have access to various waterways for transit.
OWEB’s Stream Restoration program has conducted numerous successful monitoring studies throughout the Pacific Northwest to assess how well fish passage improvements are functioning. These efforts help safeguard endangered species and guarantee they can flourish.
A passage plan for a voyage must be created and used by the ship’s bridge team to decide the safest route, avoiding obstacles and hazards along the way. This involves four stages: Appraisal, Planning, Execution and Monitoring.
The passage plan should cover the entire voyage and take into account weather, traffic density, oceanographic conditions and fuel, water and food rations available on board. Once approved by the master, it should be executed and monitored by the bridge team with adjusted speed based on ETA as well as weather & sea conditions.