Habitat loss and degradation: The destruction and modification of natural habitats, particularly riparian zones, have impacted Chinook salmon populations. Urban development, agriculture, logging, and water diversion have altered river systems, reducing spawning grounds and rearing areas for juvenile salmon.
Overfishing: Commercial and recreational fishing practices have historically contributed to the overexploitation of Chinook salmon. Unsustainable fishing practices, including bycatch and lack of effective regulations, have led to population declines.
Hydroelectric dams: The construction of dams has blocked Chinook salmon migration routes, limiting their access to spawning grounds in upstream areas. Altered flow patterns, changes in water temperature, and disruption of natural sediment transport also affect salmon survival.
Climate change: Rising water temperatures due to climate change have made rivers less hospitable for Chinook salmon, which prefer cool, oxygen-rich waters. Changes in precipitation patterns and reduced snowpack have also impacted the availability of suitable habitats and the timing of salmon migrations.
Pollution: Water pollution from industrial and agricultural sources, including contaminants such as pesticides, heavy metals, and sewage, has degraded water quality and affected Chinook salmon health and survival.
Disease: Diseases and parasites, including those introduced through human activities, can cause outbreaks that affect Chinook salmon populations. Viral diseases like Infectious Hematopoietic Necrosis (IHN) and Bacterial Kidney Disease (BKD) have had significant impacts.
Predation: As top predators in the ecosystem, Chinook salmon face natural predators such as seals and sea lions. However, the overabundance of some predators, in part due to human activities that have reduced their natural predators, can contribute to increased salmon mortality.
Concerted conservation efforts, including habitat restoration, fishing regulations, and management strategies, are underway to prevent the extinction of Chinook salmon and support the recovery of their populations.