fish report header

Tough Choices in Dry Conditions

January 27, 2014


In times of extreme conditions, such as the current state of water scarcity in California, some sacrifices and tradeoffs inevitably have to be made. For example, the recent choice to reduce river flows in northern California is a necessary first step toward water conservation. However, the timing of the flow reductions resulted in sacrificing fall-run Chinook salmon, and an important fishing industry, in favor of winter-run Chinook salmon and steelhead, which are listed under the Endangered Species Act.


On the Sacramento River, endangered winter-run Chinook salmon, which typically spawn in May and June, arrived late last year and laid eggs in August instead. For the next three months, the U.S. Bureau of Reclamation was required to maintain water levels in the river for this endangered species to prevent their eggs from drying out before hatching. Unfortunately, when necessary cuts to flows from Shasta Dam were finally made in November, fall-run Chinook had already returned to the river and laid their own eggs. Waiting to decrease the flows left many fall-run Chinook salmon high and dry, and an estimated 20-40 percent of fall-run Chinook eggs may have been lost as water levels dropped.


Drought concerns at Folsom Lake have forced a similar situation on the American River, where flows are now at their lowest level since 1993. With no rain in sight, water cuts began this month, and fall-run Chinook salmon again took the hit in order to avoid jeopardizing protected steelhead. In this case, the U.S. Bureau of Reclamation wanted to reduce flows before the threatened steelhead returned to spawn, rather than risk dewatering their redds later. However, the timing meant an estimated 10 to 15 percent of unlucky fall-run Chinook redds dried out before the salmon emerged from the gravel. These and similar losses will surely have negative consequences for future fall-run populations, although their full extent remains to be seen.


It's not easy making the decision on what to sacrifice during a crisis, but in some cases the decision has already been made. The Endangered Species Act (ESA) is designed to protect and recover imperiled species in the hopes that one day they can become delisted. In some cases, delisting occurs when the protection of the species has allowed for the recovery of its populations. However, sometimes research can identify reasons why the species should not have been listed in the first place. In an article recently published in the California Waterblog, Peter Moyle posed the question, "Are Central Valley steelhead really 'threatened'?" In order to answer that question, it is important to determine if Central Valley steelhead genetics are still present in the Central Valley, and determine what factors produce anadromy in the species (Oncorhynchus mykiss).


Historically, some hatcheries spawned steelhead from the Eel and Klamath Rivers, and today, steelhead genetics in the Central Valley exhibit a closer resemblance to northern California coastal steelhead than their landlocked relatives behind dams in the Central Valley. It was also once thought that anadromy was strictly a genetic trait, but studies have shown otherwise: not all offspring from a steelhead necessarily display anadromous traits, while offspring from resident rainbow trout can exhibit anadromous behavior (Weigel et al. 2013). From a genetics standpoint, it can be argued that Central Valley steelhead have been extirpated from the Central Valley, although it could also be argued that they exist as O. mykiss exhibiting the life strategy of residency rather than anadromy. The nebulous status of steelhead complicates the decision of whether they ought to be prioritized over fall-run Chinook.


It is likely that even tougher decisions will need to be made as the drought persists. Agriculture is the largest consumer of water, and it is likely that land will be fallowed this year and farmers will be subsidized, leading to a loss of farming revenue. Water prices are sure to rise, as society is asked to cut back and find ways to conserve. During a crisis, environmental protections often take a back seat to social and economic concerns, and unfortunately this may continue until the skies open up again.

Follow Us! Like us on Facebook Follow us on Twitter View our photos on flickr View our videos on YouTube
email list
Recent Blog Posts

All in or not?   

Success for a Chinook salmon is defined as successfully spawning once, then dying - a reproduction strategy known as semelparity. Most do not meet this goal of ever reproducing, falling short in a variety of ways. Death can come early in life, as eggs or parr, or late, as smolts or adults. Seems like a risky proposition, right? Not surprisingly, this type of reproduction strategy is not a common strategy among vertebrates, likely due to the high risk of not being able to reproduce.

The most common reproductive strategy in fish is iteroparity, which is defined as multiple reproductive events over the course of a life time. Another salmonid species native to Central Valley streams, known both as rainbow trout (fish living only in freshwater) or steelhead (fish that migrate to the ocean), is iteroparous, meaning that its reproductive output can be spread out over several years if adults survive throughout that period.


On an evolutionary timescale, environmental conditions can favor one strategy over the other, with semelparity often favored when survival conditions are poor for adults and better for their offspring. Iteroparity is generally favored when survival conditions are poor for juveniles and generally better for adults, given that the adults can survive to reproduce multiple times.  

... Read more> 

IN THE NEWS: Recent stories you might have missed...
Drought imperils California salmon, steelhead
San Jose Mercury News  

The sensitive populations of fish that spawn in Northern California's creeks and rivers are starting to suffer from the brutal drought threatening the state's water supplies. In Sonoma and Santa Cruz counties, the National Marine Fisheries Service has heard reports of anglers catching endangered coho salmon trapped by low water flows. In the American River, water levels have dropped to a 20-year nadir, endangering the redds, or nests of eggs, laid by chinook... Read >
Drought prompts deep cuts in American River flows  
Sacramento Bee 
By the end of this week, water flows in the American River will be lower than anyone has seen in a generation. And soon, many residents of suburban Sacramento could be banned from watering their lawns. Unusual winter drought conditions are driving Sacramento-area water agencies to make difficult choices. Starting today, the effects will be visible to anyone who walks, fishes or boats along the American River, one of the largest in California.... Read more >
Glaciers, streamflow changes are focus of new Columbia River study 
University of Washington 

The Columbia River is perhaps the most intricate, complex river system in North America. Its diverse landscape crosses international borders and runs through subarctic, desert and sea-level ecosystems. Surrounding communities rely on the river for fishing, agriculture, transportation and electrical power. As the Earth warms, experts know the Columbia will change - they just don't know how much or when... Read more > 

What is killing the wild Atlantic salmon?

Toronto Star 

Like any good murder mystery, this one has a well-liked victim, many wily suspects and investigators committed to cracking the case.
They are getting closer. The victim is wild Atlantic salmon. And one of the investigators is Jon Carr, director of research and environment at the Atlantic Salmon Federation in St. Andrews, N.B. Carr would like nothing better than to get to the bottom of just why salmon numbers drop spectacularly once they leave... Read more >  

Strange ancient fish had front and back legs

Live Science

The closest known relative of the ancestors of limbed animals such as humans likely evolved the foundation for rear legs even before the move to land, researchers say. This ancestor may have even been able to walk underwater, they added. These findings reveal that a key step in the evolution of hind limbs happened in fish, challenging previous theories that such appendages evolved only after the move to land. Scientists investigated fossils of a 375-million-year-old fish known as Tiktaalik roseae, discovered in 2004 in northern Canada's Ellesmere Island... Read more >