fish report header

Winners and Losers in Warm, Dry Times  

August 25, 2014

This third, continuous dry year in California highlights that droughts are not only stressful for people, they are also concerning for fish and wildlife - at least, for the native species. However, one group poised to benefit from the current tough times is the nonindigenous species that have been introduced to California's waterways, which are often hardier and more tolerant of adverse conditions.  Recent news stories reveal the drought is taking its toll on native fishes, particularly salmonids. Steelhead in the Napa River have reportedly experienced a sharp drop in the number of out-migrating juveniles because of warm temperatures and fish passage barriers. Salmon River spring-run Chinook are dying before spawning due to low flow and increasing temperatures. And salmon deaths have been reported in the Klamath Basin, a grim reminder of the 60,000 Chinook that died in the basin in 2002 when warming water temperatures perpetuated gill rot disease. Other wildlife are also at risk: this fall, when millions of waterfowl make their way down the Pacific Flyway, they will encounter dramatically reduced wetland habitat and food supply, conditions that breed competition and disease. 


Salmonids and other freshwater fishes depend on the cold-water releases of Central Valley reservoirs, but hard times are coming if our current reservoir storage continues to decline. Shasta Reservoir, Lake Oroville and Don Pedro Reservoir are all below 50% capacity. California's fourth largest reservoir, New Melones, sits at 25% capacity and is predicted to reach a mere 14% of capacity by the end of September. As a result, deep, cold-water pools in the reservoirs are diminishing, leaving only the warmer surface water to release for downstream fisheries. The future of salmon returning to spawn in future years may be in jeopardy if the drought continues. Some are proposing to collect salmon entering their natal rivers and strip them of their eggs and milt, then fertilize and incubate the eggs in a hatchery until river temperatures are low enough to return the eggs back to gravel beds to continue their life cycle. While this extreme intervention might only be considered because salmon are economically valuable, the effort wouldn't help other native fishes present in the rivers year-round that must also contend with the warmer water.


These drought conditions may offer a window into the future, as the effects of climate change come to fruition. The California Environmental Protection Agency released a report last year chronicling evidence of climate change that can already be seen all around us: less spring run-off from diminished Sierra snowpack, rising reservoir water temperatures, and glacial melt. Researchers have been franticly churning out models to predict the effects of such changing hydrological patterns on our streams and rivers. A recent report by the National Wildlife Federation reveals that of 40 major U.S. rivers, half experienced significant warming over the past century, and 70 percent of rivers in the Southwest witnessed increased temperatures during the past 55 years.


Diminished run-off and warming water temperatures do not bode well for native Western fishes that are adapted to cold-water habitats, but they do provide opportunities for non-native fish species to thrive, as many are well suited for warm-water environments. Many of the species introduced to California can tolerate a wide range of environmental conditions, and a multi-year drought and changing climate may allow these species to further impact and out-compete native species not adapted to the new temperature regime. A recent publication by U.C. Davis researchers indicates that the vast majority (82%) of native California fishes are highly vulnerable to climate change, whereas only 19% of introduced species are highly vulnerable (Figure 1, Moyle et al. 2013). The study predicts that most native fish populations will decline and some, mostly cold-water species, will go extinct - but most introduced fish will increase in abundance and range. It appears that it's a good time to be a catfish, or other introduced fish, in California.

Figure 1. The relative vulnerability to climate change of native and introduced fishes in California. Data from Moyle et al. (2013).
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
Foreign fact finding


At FISHBIO, we place a great value on thinking and working internationally, so when a group of Chinese researchers contacted us seeking some information on the Vaki Riverwatcher, we were happy to host their visiting delegation for a consultation.  


The visiting researchers were searching for solutions to monitor multiple target species of concern that may pass through fish ladders being constructed at new dams. After providing an overview of the capabilities of the Riverwatcher at our Oakdale office, we sat down for a discussion with the group about the advantages of the unit over traditional video monitoring, such as reduced labor needs and more reliable fish identification in turbid conditions thanks to the infrared recording of fish silhouettes.  


We pointed to several other facilities, such as Daguerre Point Dam on the Yuba River and the Robles Fish Passage Facility on the Ventura River, that have had success using the Riverwatcher to monitor fish passage through their own ladders. In addition, we described our use of portable resistance board weirs in combination with the Riverwatcher to identify and easily differentiate between multiple target species (see Fish Counting Weirs).  



After a tour of our Oakdale office and further discussions about the other monitoring services we provide, the research team continued on with their American tour, heading to additional sites along the coast to investigate other monitoring installations along the way.


The team came stateside looking for a solution for monitoring fish passage at structures being constructed in the country's push for increased hydroelectric power. According to China's development plan for 2011-2015, the country plans to increase its renewable energy consumption to 11.4% of total consumption by the end of 2015.  


In fact, half of the hydropower installed in 2012 was in China, which has more installed renewable energy capacity than anywhere else in the world (both including and excluding hydroelectric power). With more than 85,000 dams estimated to exist in China and hundreds more in the works, monitoring migrating fish populations at these structures is becoming more important than ever.


IN THE NEWS: Recent stories you might have missed...
Tribes rally to demand water for Klamath salmon 


Members of three Northern California Indian tribes rallied outside a federal water agency office in Sacramento to demand more water be released from reservoirs to prevent the spread of a parasite among salmon returning to the Klamath River to spawn. The U.S. Bureau of Reclamation says Regional Director David Murillo met for an hour Tuesday with members of the Hoopa Valley, Yurok and Karuk tribes. There was no indication the bureau was changing its plans to hold off any water releases... Read more > 
GPS is tracking West's vanishing water, scientists surprised to learn
National Geographic

Throughout the western United States, a network of Global Positioning System (GPS) stations has been monitoring tiny movements in the Earth's crust, collecting data that can warn of developing earthquakes.To their surprise, researchers have discovered that the GPS network has also been recording an entirely different phenomenon: the massive drying of the landscape caused by the drought that has intensified over much of the region since last year... Read more > 

Columbia River record-breaking fall Chinook return 1.5 million strong  
Indian Country Today

The number of Chinook salmon returning to spawn up the Columbia River is set to bust last year's record of nearly a million, with a whopping 1.5 million fish returning this fall. The commercial fishing season has already opened, with fishers from the Nez Perce, Umatilla, Warm Springs, and Yakama tribes taking to the Columbia River with the first of five tribal commercial gillnet openings beginning on August 18, the Columbia River Inter-Tribal Fish Commission (CRITFC) announced in a media release. They could get as much as 3.5 million pounds of salmon... Read more > 

Rights to California surface water far greater than average runoff      
Los Angeles Times  

California over the last century has issued water rights that amount to roughly five times the state's average annual runoff, according to new research that underscores a chronic imbalance between supply and demand.
That there are more rights than water in most years is not news. But UC researchers say their study is the most comprehensive review to date of the enormous gap between natural surface flows and allocations... Read more > 

New fishing nets reduce bycatch, sparing sea life  


Six years ago, the Norwegian coast guard filmed a Scottish fishing vessel riding gray swells, dumping 5 metric tons of dead fish back into the North Sea. Over the European Union catch quota, and so unable to keep all the fish they'd caught, the fishermen had to ditch some. To the Norwegians, who aren't part of the EU and hold a strict discards ban, the waste was shocking. When this news reached Dan Watson, a young British designer, it became the inspiration for SafetyNet, an ocean fishing net that allows certain fish to escape via lighted rings, offering more catch selectivity... Read more >