Alaska Science Center

Pilgrim River Watershed (Nome)--Temperature and Spawning Success of Salmon

The Pilgrim River near Nome, Alaska, offers an opportunity to evaluate effects of increased water temperatures on spawning success of salmon near the current northern extent of their range.


Temperature is an important determinant of fish production and aquatic food web dynamics. Changes in freshwater lakes and rivers due to climate change have the potential to alter fish populations and this is especially true in arctic and subarctic systems. Particularly susceptible to changes in river conditions are anadromous salmon due to the physiological challenge of migrating upriver to spawn and complete their life cycle. Recently, low numbers of sockeye salmon (Oncorhynchus nerka) have returned to the Pilgrim River (Nome, AK) coinciding with warm river temperatures. We hypothesize that higher river temperatures have increased the energetic demands on sockeye salmon causing more en route and pre-spawn mortality. This mortality reduces spawning escapement and eventually contributes to the low number of returning adults. We will deploy temperature sensors throughout the Pilgrim River and capture sockeye salmon at multiple points throughout their upriver migration to measure their energy density. A non-lethal microwave meter will be used to measure the lipid content of the fish, an estimate of their energetic condition. We will also measure the amount of pre-spawn mortality from carcasses on the spawning grounds. Determining if the higher temperatures are an energetic cost to migrating salmon will help identify a mechanism influencing spawning escapement and population dynamics. Exploring the influence of temperature on sockeye salmon in the Pilgrim River will be insightful as we are likely to see a large effect of temperature at the northern end of the distribution of salmon.
Title Type
Sockeye Salmon (Oncorhynchus nerka) Body Condition and Water Temperature Along the Pilgrim River, Northwestern Alaska, 2013-2016Data
Count of Sockeye Salmon (Oncorhynchus nerka), River Temperature, and River Height in the Pilgrim River, Nome, Alaska, 2003-2014Data


Carey, Michael , 907-786-7197

Status: onGoing
Start Year: 2013
End Year: 2018

Project Sites

BLM - Anchorage District Office

USGS Mission Area and Program
EcosystemsFisheries Program

Major Initiatives
USGS - Marine and Freshwater Ecology

Biosphere > Aquatic Ecosystems > Rivers/Stream Habitat