fish report header

The Status of Steelhead

February 24, 2014

 
Every juvenile rainbow trout (Oncorhynchus mykiss) living in California's Central Valley has in its genetic makeup the ability to out-migrate to the Pacific Ocean and become a steelhead trout. Historically, this ability has allowed
O. mykiss to survive catastrophic events, such as drought. However, these days there is little incentive for

O. mykiss to develop into steelhead: the path these fish must navigate to the ocean now teems with introduced predators and offers little good habitat for rearing along the way. Federal and state management practices have also created an environment that favors O. mykiss to stay in their natal streams, maturing into adult rainbow trout instead of steelhead. 

 

Before dams were built, rivers along the West Coast of the United States were entirely influenced by local climate conditions. As snow packs melted in the spring, rivers and streams would swell quickly and provide an ideal opportunity for out-migration. As spring turned into summer, river levels would taper off, eventually leading to just trickling streams in early fall. These natural conditions caused fish to leave their natal rivers and migrate to the ocean to survive. Fish that could adapt to an adult life at sea were heavily favored and could grow much larger in the ocean where food sources were abundant (Wilson 1997). However, predation in the ocean was also much greater, so fish adapted by returning to reproduce in their natal streams, where predation was historically less intensive. In addition to the development of an anadromous life history, O. mykiss retained the ability to live entirely in freshwater. This dual life history pattern of steelhead and rainbow trout makes the species more adaptable to changing environmental conditions (McEwan 2001). In fact, it is typical to have both life history patterns occurring in the same stream, and resident and anadromous parents can produce offspring of both varieties (Courter et al. 2013).

Steelhead populations are now beset by numerous challenges: impassible dams block access to 80-95% of historically available steelhead habitat, alteration of downstream river channels has greatly reduced the rearing habitat of out-migrating juveniles, and many intentionally introduced predator species, like large and smallmouth bass, make the environment even more inhospitable (Lindley et al. 2006). Furthermore, unlike the historically dry conditions in most Central Valley streams during early fall that would prompt O. mykiss to migrate to the ocean, current water management practices include water releases from dams throughout the year, creating an environment that favors juvenile O. mykiss
staying in their local streams year round.

 

California Central Valley steelhead are currently categorized as a Distinct Population Segment (DPS)
that is listed as "threatened" under the Endangered Species Act. This DPS includes all anadromous

O. mykiss that spawn naturally below dams in Central Valley streams, as well as fish produced by the Feather River Hatchery and Coleman National Fish Hatchery. But the health of the population has seen little improvement since the listing, leading scientists to call for policies and management that better reflect the reality of the steelhead's genetic and ecological situation. For example, most of the steelhead in the Central Valley now come from hatcheries, and the genetics of the hatchery fish bear the signature of stock from the Eel River, making these fish more closely related to coastal steelhead than to their rainbow trout counterparts in the Central Valley above the dams (Nielsen et al. 2005). It might make more sense to include populations of above-dam rainbow trout in the steelhead DPS, since these fish possess perhaps the truest remaining Central Valley steelhead genetics. Despite modifications to the environment that favor a resident life history, Central Valley steelhead have still managed to survive - but it is important to recognize the current steelhead population is simply not the same as it was historically.

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
The lay of the land
Characterizing habitat types is an important component of environmental science, and many of our projects require understanding a study site's geography (see On Point, It's a Wrap!). To collect this information, we  often conduct stream cross sections. We first divide the river into a number of sections that represent the length of the study site, then take depth and velocity measurements at equal distances across the width of the stream in each section. Cross sections allow us to piece together a habitat map based on data collected at different points that represent the habitat as a whole.

The technician seen here is taking velocity measurements while out on a redd survey (see
Hunt for Redds in October). We take cross sections during redd surveys to get a more detailed look at the environment in which salmon prefer to make their nests. For example, eggs may be less successful at hatching in areas where water velocity is too slow because of poor oxygen exchange and the accumulation of metabolic waste around the eggs (Chapman 1988). On the other hand, adult Chinook salmon are not expected to spawn where the water velocity is too high because the effort needed to fight the current may sap their available energy reserves (Brett 1965).  The data collected from a cross section can then be applied to activities like habitat restoration and help create more suitable habitat to meet the needs of both spawning and rearing salmon... Read more > 
IN THE NEWS: Recent stories you might have missed...
Mekong Delta to suffer fresh water shortage next month
VietNamNet Bridge

The intrusion will cause a shortage of fresh water for households to use during the dry season, said the institute. The delta's provinces have begun implementing measures to control saline water intrusion, including closing sluice gates at river mouths. Soc Trang Province has closed sluice gates in Long Phu and Tran De districts to prevent saline water entering rice fields. The salt content of the water of the Hau River in Long Phu's Dai Ngai Commune now exceeds 0.15 percent,... Read more > 

Saving California's salmon for the long run will be an uphill battle 
KCET  
California can do a lot to keep its native salmon and other fish species going through this record drought, and through the inevitable worse ones to come, according to a leading fisheries biologist. But it's going to take hard work and hard choices, and Californians will need to rethink the way the state manages water, he says. In a post published Monday on UC Davis's California Water Blog, Peter Moyle, a biologist who's widely regarded as the dean of California fisheries science, details both short-term and long-term measures he thinks will be needed to keep California's native fish... Read more >
Court could change salmon hatchery programs in Ore, Wash, Calif
The Oregonian   

People on the West Coast have counted on fish hatcheries for more than a century to help rebuild populations of salmon and steelhead decimated by overfishing, logging, mining, agriculture and hydroelectric dams, and bring them to a level where government would no longer need to regulate fisheries. But hatcheries have thus far failed to resurrect wild fish runs. Evidence showing artificial breeding makes for weaker fish has mounted... Read more > 

Protecting fish from California's extreme drought    

NOAA Fisheries

It seems intuitive that fish need water, but with California facing its driest two-year period on record, water is becoming harder and harder to come by. To ensure California's threatened and endangered fish populations survive the drought, NOAA is working hand-in-hand with the state and other federal agencies on water, fisheries and wildlife strategies. Historically, salmon and steelhead populations were geographically widespread throughout the central and northern California coast... Read more > 

Halibut bycatch limits reduced for Alaskan groundfish fisheries

FIS

NOAA Fisheries is implementing a plan to tighten limits on the amount of halibut bycatch that could be caught in the commercial groundfish fisheries in the Gulf of Alaska (GOA). The fishery management plan amendment, "Amendment 95," is intended to minimize halibut bycatch in the GOA groundfish fisheries to the extent practicable while preserving the potential for the full harvest of groundfish in the GOA.... Read more > 

fishbio.com     [email protected]