Welcome to the California Fisheries Blog

The California Sportfishing Protection Alliance is pleased to host the California Fisheries Blog. The focus will be on pelagic and anadromous fisheries. We will also cover environmental topics related to fisheries such as water supply, water quality, hatcheries, harvest, and habitats. Geographical coverage will be from the ocean to headwaters, including watersheds, streams, rivers, lakes, bays, ocean, and estuaries. Please note that posts on the blog represent the work and opinions of their authors, and do not necessarily reflect CSPA positions or policy.

Water Year 2016

Posted on November 22, 2016 by Tom Cannon

At an October 27, 2016 meeting of the Delta Stewardship Council, John Leahigh, Department of Water Resources chief operator for the State Water Project, briefed the council on Water Year 2016. Precipitation-runoff and reservoir storage were up considerable compared to 2014 and 2015. However exports were lower than expected, with reduced deliveries – only 5 to 75% – to south of Delta water contractors.

Mr. Leahigh attributed lower Delta exports to several factors:

A concerted effort to conserve Shasta storage (for winter-run salmon) at the expense of water deliveries, mainly to south-of-Delta contractors.
Higher summer Delta outflow that was needed to repel saltwater intrusion into the Delta caused by higher-than-normal tides associated with the warm-water “blob” along the coast. (This outflow served the dual purpose of reducing the salinity of Delta export water and allowing the water projects to meet salinity standards for Delta agriculture – see previous post.)
Lower San Joaquin River Delta inflow that “creates a dynamic in the Delta that makes it difficult to move stored water from the Sacramento basin to the south Delta”.
An inability to export Valley stormwater in winter-spring: “If we don’t pick it up, it ends up in the Bay and into the ocean.” (This is a not-too-subtle reference to winter-spring export restrictions for endangered fish and pitch for the proposed Delta tunnels.)

Mr. Leahigh concluded: “I think the key messages would be flexibility, nimbleness, and the fact that we have processes in place that would help us react to whatever we end up seeing in the coming year; there’s always a new challenge with respect to the hydrologic pattern and the regulatory environment, so just having those processes in place puts us one step forward.”

The important lesson here is that the state and federal water projects are flexible and nimble when it comes to water exports and deliveries. When it comes to the short-term needs of the fish and their habitat, not so much. The projects are ready with Temporary Urgent Change Petitions to benefit water deliveries, but not the environment.

Fundamental Needs of Central Valley Fishes – Part 1b: River Flows – Winter Flows

Posted on November 19, 2016 by Tom Cannon

In the coming months and years, regulatory processes involving water rights, water quality, and endangered species will determine the future of Central Valley fishes.

To protect and enhance these fish populations, these processes will need to address four fundamental needs:

River Flows
River Water Temperatures – holding, spawning incubation, juvenile rearing and migration.
Delta Outflow, Salinity, and Water Temperature
Valley Flood Bypasses

In the previous Part 1a post, I discussed river flows during fall. In this post, I discuss river flows during winter.

Winter Flows

Winter is the season of high river natural flows. Even in drought years, Sacramento River flows measurably spike during storms that provide stormwater runoff from numerous undammed tributaries and local sources (Figure 1). On the mainstem Sacramento River and those of its tributaries that also feature rim dams, most of the stormwater inflow is captured and stored for spring-fall water supply. On the San Joaquin River, all the major tributaries and mainstem have large storage reservoirs that capture Sierra and upper Valley runoff, so there is limited controlled winter runoff (Figure 2).

Winter flows are needed to attract adult winter-run and spring-run salmon, smelt, steelhead, and sturgeon to upriver spawning grounds. Winter flows also carry young salmon and steelhead to the Delta, Bay, and ocean by providing velocity, water temperature, and turbidity conditions that speed migration and deter predation by birds and fish. Winter flows stimulate food production and availability. Winter flows and associated high water levels provide access to off channel and floodplain rearing areas that provide refuge and food. Winter flows clean substrate and wash gravels, and thus improve spawning conditions. High winter flows wash sediment, nutrients, and organic material into the estuary that stimulate Bay-Delta productivity.

On the Sacramento River, winter flows carry juvenile winter-run, spring-run, late-fall-run, and fall-run salmon through up to 200 miles of rivers and the Delta to the Bay and ocean. Much of the route is leveed and channelized, with little cover/refuge and abundant predators. Higher flows provide turbidity and lower water temperatures that deter predation.

In the San Joaquin River watershed downstream of the rim dams, flows are minimal in the absence of flood flows and dam spills. Thus, de facto drought conditions persist downstream of San Joaquin watershed dams in all but the wettest years. Recruitment into the salmon populations is confined to San Joaquin offspring produced in wet years, augmented by hatcher strays, since there is minimal juvenile survival to the ocean in other years because of low flows.

In the non-flood years where reservoirs capture most reservoir inflow during the winter, supplemental releases from Central Valley reservoirs should be considered to piggy-back on and enhance natural flow pulses to benefit salmon and other native fish. Such action would most benefit salmon populations below rim dams. Such releases can be prescribed as a portion of the natural or unimpaired inflow to the reservoirs.

Figure 1. Daily average Delta inflow from the Sacramento River 2012-2016 as measured at Freeport. Red circles denote winter-spring flow pulses that support important ecological processes such as salmon migration. Water years 2012-2015 were drought years; 2016 was a below-normal water year.

Figure 2. Delta inflow from the San Joaquin River 2012-2016 as measured at Vernalis. Prescribed fall and spring flow releases from reservoirs for salmon migrations dominate the hydrograph in these drought years. Winter flow pulses were lacking with the exception of 2016. Water years 2012-2016 were drought years in the San Joaquin watershed.

Fundamental Needs of Central Valley Fishes – Part 1a: River Flows – First Pulse of Fall Rains

Posted on November 16, 2016 by Tom Cannon

In the coming months and years, regulatory processes involving water rights, water quality, and endangered species will determine the future of Central Valley fishes.

To protect and enhance these fish populations, these processes will need to address four fundamental needs:

River Flows
River Water Temperatures
Delta Outflow, Salinity, and Water Temperature
Valley Flood Bypasses

In this post, I summarize a portion of the issues relating to River Flows: Fall Rains. Part 1b will cover winter river flows.

River Flows – Fall Rains

In most years, the first substantial fall rainfall stimulates many important ecological processes such as salmon and smelt spawning runs and salmon and steelhead smolt migrations to the ocean. Figure 1 below shows the effects of 2016’s late October rains, and Figure 2 below shows the effects of 2015’s December rains, in the lower Sacramento River flows at Wilkins Slough near Yuba City below Colusa. Most of these flow pulses came from storm runoff from un-dammed upper Sacramento Valley tributaries such as Cow, Cottonwood, and Battle Creeks. Such flow pulses stimulate the migrations of young salmon toward the ocean. Figure 3 below documents these migrations in the form of rotary screw trap collections at Knights Landing in the lower Sacramento River.

Under current operations, flows from the major reservoirs are generally held to the minimum requirement in the fall season in order to increase reservoir storage (Figure 4).¹ What is needed are flow pulses (spills) from the major Valley reservoirs to the major rivers below dams, to stimulate the migration of the juvenile salmon spawned immediately downstream of these dams. Just downstream of Whiskeytown Reservoir on Clear Creek, Shasta and Keswick reservoirs on the upper Sacramento River, Oroville Reservoir on the Feather River, and Folsom and Nimbus reservoirs on the American River are vitally important salmon-producing reaches whose flow is completely controlled by the operation of the dams. Water releases timed to the natural flow pulses would stimulate migration from these important salmon-producing reaches, providing even more flow and stimulus for young salmon from all the Valley rivers to pass successfully through the Delta and Bay to the ocean.

Meanwhile, downstream in the Delta, the CVP and SWP export facilities generally ramp up exports during the initial storm pulse (Figure 5 below shows an example from 2016). Because of the importance of the initial storm pulse, the CVP and SWP should limit exports during the initial pulse, not only to help salmon get through the Delta and Bay, but also to minimize the diversion of young salmon to the south Delta.

Figure 1. Lower Sacramento River flow at Wilkins Slough in fall 2016.

Figure 2. Lower Sacramento River flow at Wilkins Slough in late fall 2015.

Figure 3. Catch of juvenile salmon in Knights Landing rotary screw traps 2001-2004 vs. flow in lower Sacramento River at Wilkins Slough.

Figure 4. Release of water from Shasta/Keswick to upper Sacramento River near Redding, fall 2016.

Figure 5. Export of water from south Delta by State Water Project, fall 2016.

For additional discussion of the negative effects of this practice, see previous post. ↩

American River Salmon Hatchery Begins Taking Salmon

Posted on November 14, 2016 by Tom Cannon

California Department of Fish and Wildlife has announced that it opened the American River Nimbus Hatchery ladder on Nov 2. At the same time, the feds have managed to cool down the river to allow salmon in the river to also begin spawning (Figure 1). The Bureau of Reclamation cooled the river by opening lower level outlets of Folsom Dam for a portion of the day beginning in late October (Figures 2 and 3). This allowed the release of colder water from deep in the reservoir into the Nimbus regulating reservoir directly downstream of Folsom Reservoir. There, the cold water mixed with warmer reservoir waters before discharge to the lower American River.

The real story here is that the feds had to wait until November to cool water both in the river, and in the Nimbus Fish Hatchery just downstream of Nimbus Dam. The supply of cold water in Folsom Reservoir is limited this fall because of excessive releases of stored water to the Delta this past summer (see prior post). The summer shrinkage of Folsom’s cold-water pool subjected the salmon that entered the lower American River in September and October to a month or more of stress from warm water. That stress will likely reduce survival of pre-spawn and spawning salmon, diminish their success in spawning, and make many of eggs and embryos spawned in the river unviable.

Figure 1. Water temperature below Nimbus Dam on the lower American River near the Nimbus Hatchery Oct 4 – Nov 2, 2016. Red line denotes safe water temperature for holding and spawning salmon, and salmon egg survival.

Figure 2. Temperature of the water released from Folsom Dam Oct 21 – Nov 2, 2016. Red circles show the release of water from Folsom’s cold-water pool.

Figure 3. Flow releases from Folsom Dam. Red circles depict flow releases of cold water from lower level outlet of dam Oct 21 – Nov 2, 2016.

Does the Central Valley Need a Predator Removal Program?

Posted on November 11, 2016 by Tom Cannon

The Columbia River Pikeminnow Sport Reward Program just finished another year. A near-record 200,000 adult pikeminnow were harvested and $1.7 million rewards paid. The goal of the program is to harvest 10-20% of the population each year to reduce the population about 50%. Harvest rates in recent years reached as high as 17% as compared to this year’s 11%.

So why after 25 years is the program still harvesting near-record numbers of pikeminnow? The likely reason is that the program is not based on sound science. The Columbia pikeminnow population dynamics likely are best described with a standard Ricker-Type Population Model (see chart below), with reduced recruitment of young at high adult population levels because of competition and cannibalism. The introduction of a light harvest can actual increase recruitment of young by reducing competition and cannibalism, with the increased recruitment replacing the harvest, even providing a constant harvest or yield. This is how fishery quotas may be sustained year after year, such as in Alaska’s Bristol Bay Sockeye salmon fishery.

This same dynamic likely applies to pikeminnow and some other predators in the Central Valley. Pikeminnow are likely near their saturation level in the Central Valley. Any light harvest such as from a sport-reward or removal program would likely have little or no effect. Increasing harvest on non-native predators like largemouth bass by reducing sport-fishing harvest regulations would likely also have a limited benefit. However, striped bass, the most popular sport fish in the Delta, has a population that is already seriously depressed by long-term loss of juveniles to water diversions. Striped bass may respond more directly to increased harvest, further reducing recruitment and further depressing the population.

Thus the species composition of fish that eat other fish could change, satisfying those who vilify stripers and infuriating those who fish for them. But the potential for reduced overall loss of juvenile salmon or other native species that might follow from “predator removal” is far more complex and questionable than its proponents maintain.

Ricker-type stock-recruitment population dynamics model that likely applies to Columbia River and Sacramento River pikeminnow populations