Why are there so few salmon left?
There are many reasons for the decline in salmon populations. Logging an area around a stream reduces the shade and nutrients available to the stream and increases the amount of silt or dirt in the water, which can choke out developing eggs. Dams cause fish to die from the shock of going through the turbines and from predators that eat the disoriented fish as they emerge from the dam. Overfishing is another source of death that can contribute to the decline of salmon. The weather affects the amount of food that is available to salmon in the ocean. Pollution and disease have also contributed to population declines.
Learn more: Questions and Answers about Salmon
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In Hot Water: Climate Change is Affecting North American Fish
Climate change is already affecting inland fish across North America -- including some fish that are popular with anglers. Scientists are seeing a variety of changes in how inland fish reproduce, grow and where they can live.
Community flood protection may also help endangered salmon to thrive
Building a river setback levee to reduce the risk of flood for a community may also help endangered fish species to thrive, according to the results of a novel computer model reported by the U.S. Geological Survey.
Endangered Salmon Population Monitored with eDNA for First Time
CORVALLIS, Ore. — Scientists from the U.S. Geological Survey and Washington State University have discovered that endangered Chinook salmon can be detected accurately from DNA they release into the environment. The results are part of a special issue of the journal Biological Conservation on use of environmental DNA to inform conservation and management of aquatic species.
New Method Monitors Riverbed and Flows to Protect Spawning Salmon
USGS scientists took high-tech sensors typically found in devices such as smart phones and embedded them into a new method to monitor riverbed movements that can help protect spawning habitat for endangered salmon. Developed in cooperation with Seattle Public Utilities for the Cedar River, the new method is published in the Journal of Hydrology.
Wild Atlantic Salmon Found in New York's Salmon River
Scientists recently discovered wild young Atlantic salmon in New York's Salmon River. This is the first time in more than a century that salmon produced naturally in the wild have been found in what was once New York's premier salmon stream. Forty-one wild Atlantic salmon were collected in June and July. All of the salmon were under one year old and ranged in length from about 2 – 2.5 inches.
Removal of Obsolete Forest Roads Can Reduce Erosion and Sediment That Impair Salmon-bearing Streams
Removing abandoned forest roads and restoring the natural characteristics of slopes and stream channels in the Redwood National and State Parks in northern California have substantially reduced the delivery of sediment to salmon-bearing streams, according to a research geologist with the U.S. Geological Survey.
Acoustic-tagged juvenile Chinook salmon being released
Acoustic-tagged juvenile Chinook salmon being released.
An Alaskan Sockeye Salmon. USGS photo gallery. BLM photo.
Bacterial Kidney Disease in a spring Chinook salmon
A Spawning Coho Salmon
Coho salmon fins just above water surface. Female coho select breeding sties based on specific characteristics that offer protection and desired habitat for juveniles. Photo courtesy of Steven Clark, BLM
PubTalk 2/2015 — Undamming Washington's Elwha River
by Amy East USGS Research Geologist
- Hear about river response to the largest dam removal in history.
- Causing disturbance as a means of restoration: how well does it work?
- Will legendary salmon runs return?
Atlantic Salmon (Salmo salar)
Zoe Zyollewski handles an adult Atlantic salmon caught in the Connecticut River.