Will your fish make it to sea?
Your salmon are currently swimming towards the ocean. Odds of survival are currently quite low. Last year less than 20% of coho salmon we tracked made it from the stream they were born in to the ocean. Why are the odds so low?
Salmon in the Eel River watershed have long faced many threats including overfishing, mechanized logging, dams, water diversion, and drought. Today they have another threat to contend with: the invasive Sacramento pikeminnow! Pikeminnow compete with, prey on, and alter behavior of juvenile salmon – all of which impacts salmon recovery.
The Pikeminnow Problem
Since their introduction in 1979, pikeminnow have spread throughout the Eel River basin. While pikeminnow are native to other waters in California including the Sacramento River, these fish are not native to the Eel River watershed or other coastal waters, and they pose a mortal threat to young salmon. Pikeminnow are voracious predators with a diverse appetite that includes salmon and steelhead. And they don’t just prey on the small ones — large pikeminnows are capable of eating fish up to 20 inches! They are also well adapted for life in the Eel River and for a warming climate.
Pikeminnow
In addition to predation, pikeminnow directly compete with young salmon for limited food sources (insects) in the watershed. The presence of pikeminnow can also reduce and simplify salmon life history diversity – which is the way salmon have survived for millions of years across the dynamic and explosive Pacific Rim! Pikeminnow presence can determine which sections of river or even which specific pools young salmon can occupy or which areas they must avoid. They may also affect the timing of juvenile salmon migration. In the past several decades that means much of the mainstem Eel River and South Fork Eel River have been a dangerous place for salmon during most of the spring, summer, and fall, even when water temperatures are suitable for salmon to grow! Because of these impacts to salmon, pikeminnow suppression has become a key priority for Eel River salmonid recovery. The Wiyot Tribe has been leading pikeminnow monitoring and suppression efforts in the Eel River for years and CalTrout, UC Berkeley, CDFW, and Stillwater Science have been working with the Tribe to understand how pikeminnow suppression affects salmon recovery.
"If we can decrease pikeminnow predation and interaction with the native fish, we are hopeful it can help to facilitate salmon recovery."
– Dr. Gabe Rossi, UC Berkeley & CalTrout Research Scientist
How can we solve the pikeminnow problem?
Before we can address the problem, we must understand how, where, and when pikeminnow are affecting salmon. The tags embedded in your fish give us crucial information about where to target pikeminnow suppression efforts. When we tag fish we can identify mortality hot spots, or places where salmon are most vulnerable to pikeminnow predation. Once we identify those hot spots, we can figure out how to address them.
On the Eel River, a collaborative team including the Wiyot Tribe, CalTrout, UC Berkeley, the California Department of Fish and Wildlife, Stillwater Sciences, Cal Poly Humboldt, and others works to collect and analyze fish tracking data and implement solutions to improve survival odds. These solutions include:
1. Pikeminnow Weir: We install and monitor a pikeminnow weir to prevent migration upstream by pikeminnow and protect rearing habitat for young salmon.
2. Active Suppression: Together, we actively suppress pikeminnow using nets, snorkels, and spears to remove them from the watershed. We are also hosting a Pikeminnow Fishing Derby from July 20 - August 31 where you too can get involved in our suppression efforts!
3. Research for Long-Term Eradication: We research methods for long-term eradication of pikeminnow including altering sex chromosomes.
4. Estuary Habitat Restoration: We restore habitat in the Eel River estuary to ensure fish that successfully migrate down the river have quality habitat waiting for them before life at sea begins.
Dams block access to historical spawning and rearing habitats. Downstream, dams alter the timing, frequency, duration, magnitude, and rate of change of flows decreasing habitat quality and survival.
