Noaa fisheries, Government agency

A study has found that sea lions have the largest negative effect on early-arriving endangered Chinook salmon in the lower Columbia River.The results of this study, conducted by the University of Washington and NOAA Fisheries, were published in the Journal of Applied Ecology.The Columbia River is home to one of the West Coast's most important Chinook salmon runs. Through late spring and early summer, mature fish return from the sea and begin their arduous journey upriver to spawn. In recent years, these fish have faced an additional challenge due to hungry California sea lions.Opportunistic sea lions have learned that by swimming as far as 145 miles upriver, they can easily feast on migrating salmon, including those hindered by the Bonneville Dam."We investigated whether mortality rates varied depending on the specific threatened Chinook salmon population, determined by when they arrive in the river," said lead author Mark Sorel, a doctoral student at the UW School of Aquatic and Fishery Sciences. "We found that, based on their individual return timing and the abundance of sea lions in the river when they return, individual populations experience different levels of sea lion-associated mortality."Researchers learned that the earliest arriving populations of Chinook salmon experienced an additional 20 per cent mortality over previous years, and the later arriving populations experienced an additional 10 per cent. This increase in mortality was associated with increased sea lion abundance at those times of the year in the period of 2013 to 2015 compared to the period of 2010 to 2012.The numbers of California sea lions are highest at the mouth of the Columbia in early spring before they depart for their breeding grounds in southern California. The researchers also discovered that the earliest arriving salmon migrate through the lower Columbia River more slowly than those arriving later in the season, thereby increasing their exposure to predation."This information on how different populations are affected by sea-lion associated mortality is key because recovery of endangered Chinook salmon requires multiple of the individual populations to be healthy," said Sorel.California sea lions have seen their numbers rebound along much of the US West Coast since the passage of the Marine Mammal Protection Act of 1972, which protects them from being killed, captured and harassed. The increased presence of sea lions is now at odds with the endangered salmon populations on which they feed, putting managers in a difficult position.Researchers are concerned that something must be done quickly as these hunting behaviors are learned, and the problem could continue to grow exponentially. In August, the National Marine Fisheries Service granted approval for Washington, Idaho, Oregon and several Pacific Northwest tribes to capture and euthze both problematic California and Steller sea lions within a larger area of the lower Columbia and Willamette Rivers. Previously, only California sea lions could be killed in these rivers if managers deemed them a threat to salmon.This complicated decision was enacted after non-lethal methods, such relocation and hazing, to limit the impact sea lions have on salmon -- plus some targeted lethal removal -- were met with limited success."This is often a challenging management problem as both sea lions and salmon are of strong interest to the public, and both are protected under federal statutes," said Sorel. "Management must consider multiple social values and operate within existing legal frameworks."Continued monitoring will help to reduce the remaining uncertainty about the effects of sea lions on salmon and the expected outcomes of alternative management actions.( With inputs from ANI )Disclaimer: This post has been auto-published from an agency feed without any modifications to the text and has not been reviewed by an editor

Home

City

Latest News

Cricket

LT Premium

National

International

Maharashtra

Opinions

Chhatrapati Sambhajinagar

Nagpur

Entertainment

Photos

Business

Technology

Sports

Lifestyle

Social Viral

Lokmat Games

Health

Lok Sabha Election 2024

Heatwave In India

Mumbai Water Cut

Maharashtra Lok Sabha Election

IPL 2024

Salman Khan

Noaa FisheriesFOLLOW

Noaa fisheries, Latest News

International :US households heated with natural gas face 30pc increase in winter bills: Energy Dept

Americans that rely on natural gas for home heating can expect to pay nearly one-third more this winter, with steeper increases for those using oil and propane, the Energy Information Administration said in a report. ...

International :Biden administration launches new initiative to counter climate crisis

The Biden administration is launching a new government initiative to deliver accessible and actionable information to individuals and communities that are being hit by flooding, drought, wildfires, extreme heat, coastal erosion, and other intensifyin ...

International :Earth's energy imbalance doubled in 14 years: NASA

Washington, June 19 Raising an alarm over human-caused climate change, NASA-led research has revealed that the amount of ... ...

International :CO2 emissions at record high despite Covid-19 pandemic

Washington, June 8 The Carbon dioxide (CO2) in the Earth's atmosphere has again peaked last month, reaching historic ... ...

Technology :Early-arriving endangered Chinook salmon take brunt of sea lion predation

A study has found that sea lions have the largest negative effect on early-arriving endangered Chinook salmon in the lower Columbia River. ...