Habitat Trouble for Pacific Chinook Salmon and Coho Salmon in Pacific Coast States
from the National Fish Habitat Partnership's 2015 Through a Fish's Eye Report
Summary
The Sacramento River represents by far the largest population of returning Chinook Salmon (Oncorhynchus tshawytscha). There are four distinct spawning runs of Chinook Salmon; fall, late fall, winter, and spring. Historically, maximum spawning runs in the Central Valley approached 2 million salmon including: 100,000 late-fall fish; 200,000 winter fish; 700,000 spring fish; and 900,000 early fall fish. Current spawning sizes are a fragment of historic numbers and some of the spawning runs are listed stocks under the Federal Endangered Species Act. In 2009, total Chinook Salmon spawning populations were fewer than 69,000 salmon including: 50,000 fall fish; 10,000 late-fall fish; 3,800 spring fish; and 4,700 winter fish. In 2015, Sacramento [...]
Summary
The Sacramento River represents by far the largest population of returning
Chinook Salmon (
Oncorhynchus tshawytscha). There are four distinct spawning runs of Chinook Salmon; fall, late fall, winter, and spring. Historically, maximum spawning runs in the Central Valley approached 2 million salmon including: 100,000 late-fall fish; 200,000 winter fish; 700,000 spring fish; and 900,000 early fall fish. Current spawning sizes are a fragment of historic numbers and some of the spawning runs are listed stocks under the Federal Endangered Species Act. In 2009, total Chinook Salmon spawning populations were fewer than 69,000 salmon including: 50,000 fall fish; 10,000 late-fall fish; 3,800 spring fish; and 4,700 winter fish. In 2015, Sacramento River winter-run Chinook Salmon were named as a
Species in the Spotlight, a NOAA program that seeks to draw focus to key endangered species. Winter-run Chinook salmon spawn during the warmer summer months but are blocked from their historic coldwater spawning grounds by the Shasta and Keswick dams. Managed releases of cold water from the Shasta reservoir, among other conservation measures including habitat restoration, are critical to the survival of the species.
The Chinook Salmon population abundance in the Puget Sound is also decreasing according to the Puget Sound Partnership’s 2015 State of the Sound report, which determined that the mean total abundance of naturally spawning Chinook salmon was lower in the recent 3-year period of 2011-2013 than in the baseline 5-year period of 2006-2010. Although 10 indicators that measure the health of the Puget Sound are improving, many of which are measures of the habitat restoration work in which a significant investment has been made, a positive biological response has not been seen from Chinook Salmon. One reason for this could be that it takes a while to detect salmon response to habitat work because their life cycles cause them to return to spawn between the ages of 2-6 years and trends over a number of years are needed to detect changes in populations. In addition, ocean conditions impact returning adults; gains seen in the juveniles' survival resulting from habitat gains may, in some cases, be lost to unfavorable ocean conditions.
Central California Coast (CCC) coho salmon are an evolutionarily significant unit of salmon and was first listed as threatened under the Endangered Species Act in 1996. It was relisted as endangered in 2005, where it has remained since, showing an overall downward trend. CCC coho salmon spend the first portion of their lives feeding on plankton and insects in freshwater, before migrating into estuarine and marine environments to feed on small fish. After two-three years in the Pacific Ocean, these salmon return to the stream in which they hatched (or in other cases the stream in which they were released) to spawn, thus ending their life cycle. There are numerous factors threatening CCC coho salmon including but not limited to surface water extraction, climate change, drought, estuary impairment, loss of wetlands, and legacy effects of timber harvest. Bright spots do exist however, where populations are showing signs of improvements due to conservation hatchery work and habitat improvement projects. Included as a
NOAA Species in the Spotlight, the priority recovery actions for CCC coho salmon include expanding hatchery programs to prevent extinction, expanding restoration and funding partnerships in target locations, and improving freshwater survival.
The U.S Geological Survey (USGS) is partnering with the National Fish Habitat Partnership (NFHP) to produce the 2015 report entitled, "Through a Fish's Eye: The Status of Fish Habitats in the United States 2015". The information contained within this item is a product of NFHP. The Bureau is neither responsible nor liable for the accuracy or the use of the scientific content within this item. This content is considered preliminary pending subsequent review and approval.
