Analyzing Fish Population Dynamics in the Bay-Delta

I have been analyzing the declines in Bay-Delta and Central Valley fish populations for over 40 years. Fish population dynamics were the focus of my college education and my 50-year career in environmental impact assessment. I have participated in all the major efforts to understand the Bay-Delta fish population declines. From all of these efforts, it is clear to me what has caused the major fish population crashes.

Pre-1970

First and foremost are the well known historic factors, the original sins pre-1970s of diverting water, building levees and dams, urban development, gold mining, cutting forests, polluting rivers, over-fishing, and introducing non-native species. These explain many of the major native fish population declines and extinctions such as the Sacramento perch and San Joaquin spring-run Chinook salmon, and the near extinctions of Delta smelt, green sturgeon, winter-run and spring-run salmon, and steelhead.

Post-1970

Since 1970, there have been dramatic declines in salmon, steelhead, smelt, sturgeon, splittail, and striped bass, often described as “recruitment failure” or failure to reproduce. While some of the blame most certainly is on continuing effects of the aforementioned original sins, the major post-1970 shifts were the consequence of a new array of stresses that hit the whole fish community, especially native fish populations. Most certainly the droughts of 76-77, 87-92, 01-02, 07-09, and 12-15 were a major underlying factor; however, it was the man-made responses to the droughts that caused most of the damage. Asian clam and other non-native aquatic invertebrate invasions to the Bay-Delta in the 80s were another stress, in part brought on by the aforementioned factors. Poor water management response to these new threats has caused further damage. The big culprits of change were the water management stresses described below.

1. State Water Project

The addition of the State Water Project (SWP) in the mid-1970s nearly tripled Delta export capacity (4400 to 11,400 cfs pumping rate1) and annual exports (2 million acre-feet to 6 million acre-feet annual exports). The additional Delta exports had huge fish population effects in the mid-70s from salvage mortality and entrainment of young fishes, as well as on fish habitat conditions in the rivers, Delta, and Bay. These stresses resulted in major population declines, which in turn resulted in the imposition of export restrictions in new water quality standards in 1978 (D-1485), and eventually to species listings under the Endangered Species Act in the 1990s.

2. Reservoir Operations

The increase in exports changed reservoir operations, including within-year reservoir release strategies and long-term multiyear reservoir storage patterns. Reservoir storage was depleted faster in droughts because of higher water supply demands. These effects continue today.

3. Water Supply Demands

Ever-increasing water supply demands from agricultural and municipal users have reduced river flows, Delta outflow, and reservoir storage. It’s not only the Delta’s 6 million acre-feet of exports, but the more than 20 million acre-feet from other Central Valley water diversions.

4. Invasive Species

Invasions of non-native clams, shrimp, fish, and zooplankton species since the 1970s have occurred in-part due to changes in Bay-Delta hydrology and water quality, as well as physical and biological habitat conditions. Delta pelagic (open water) habitat is now dominated by low-productivity reservoir water. The low salinity or mixing zone of the estuary became far less productive because of species invasions and reservoir water moving through to the south Delta export facilities, taking productive low-salinity habitat with it. The Delta is warmer from higher warm river inflows from spring through fall to feed water project exports, further favoring non-native warm-water fishes. Turbidity is lower, favoring non-natives. Invasive aquatic vegetation benefits from low turbidity, and the vegetation further favors non-native fishes over native fishes.

Post-1990

Since 1990, there have been steps backward that have undermined effective strategies and actions that had been undertaken beginning in the late 1970s to help depressed fish populations. Below are five examples in a long list of actions/changes.

1. Changes to D-1485

Beginning In 1978, Delta water quality standards in Decision 1485 placed restrictions on Delta exports, improved Delta outflows, and set salinity standards that had benefits for native fishes. Beginning in the 1990s, these post-1970 constraints on water diversions were changed, ignored, or eliminated. For example, new standards in D-1641 (1995 Accord) dropped the D-1485 June-July export restrictions.

2. Eliminating VAMP Export Restrictions and Higher Outflow Requirements in April and May

The Vernalis Adaptive Management Plan (VAMP) from 2000-2009, and its operational precursors under the CVPIA (1991) and the 1995 Accord, sought to protect Central Valley salmon and Delta native fishes by reducing April-May Delta exports and increasing spring Delta inflows and outflows. During the VAMP years, exports were restricted to less than 2000 cfs in April-May to protect fish (Figure 1). In the post-VAMP decade, restrictions were lifted and exports increased, especially in post-drought recovery wet years 2011 and 2017 (Figure 2).

3. Temporary Urgency Change Petitions (TUCPs) and Orders

Temporary urgency change orders during the recent drought allowed April-May Delta outflow to fall to around 5000 cfs in 2014 and 2015, from the normal near-10,000 cfs lower limit (Figure 3). Such low outflows in combination with Delta exports are devastating to Delta native fishes and Central Valley salmon and steelhead.

4. Delta Channel Barriers

The operation of the Delta Cross Channel, Head of Old River, South Delta, and False River barriers helps to keep export salinity down by funneling the fresher Sacramento River water to the south Delta export pumps. This increases the efficiency of exports in taking reservoir water in drier years and seasons. With the exception of the Head of Old River, barrier operation also funnels Delta native fish production (pelagic eggs and juveniles) and migrating young salmon (and their low salinity habitat and food sources) directly to the export pumps instead of to the Bay.

5. Suisun Marsh Salinity Control Gates

Since the installation of the Suisun Marsh Salinity Control Gates (SMSCG) in Montezuma Slough in 1989, the Slough and Marsh no longer function as critical low salinity habitat in drier years and seasons. Without high freshwater inflow, the Slough and Marsh no longer maintain the high biological production the once contributed to the Bay. The following excerpt from a DWR 2019 blog post inadvertently describes how limited the benefits of Suisun Marsh have become in the absence of flow:

DWR launched a pilot project last year that directed more fresh water flow into Suisun Marsh. The action involved opening salinity control gates in the summer months instead of during fall and winter, as is customarily done to reduce salinity in the marsh for migrating ducks and other waterfowl. The Delta smelt relies on low-salinity water – opening the salinity control gates allowed the smelt to enter the marsh from the Sacramento River, where it can access greater amounts of food and shelter.

Extinction looms so closely over the Delta smelt population that the project could have been considered a success even if it didn’t lure any countable Delta smelt to the marsh, said DWR Lead Scientist Ted Sommer. Just creating the conditions that allow smelt to thrive – that is, low salinity levels, lots of food, and high turbidity or muddy water that magnetizes smelt – would have been a cause for celebration.

Conclusion

There are many, many other examples of adverse changes that have put fish population dynamics in the Delta in a perpetual downward spiral. Since 1970, almost of all them involve reduction of Delta inflow and outflow, elimination of measures to mitigate the effects of reduced Delta inflow and outflow, and/or the biological response to reduced Delta inflow and outflow.

Figure 1. State south Delta exports (Harvey Banks pumping plant) in spring 1997-2010.

Figure 2. State south Delta exports (Harvey Banks pumping plant) in spring 2011-2019.

Figure 3. Delta outflow April-May 2007-2009 and 2013-2015 droughts.

 

 

 

  1. Initially exports were even higher with the new 11,000 cfs export capacity of the State Water Project. Total exports reached 12,000-14,000 cfs

Delta June 2019

Water year 2019 has been a very wet year.  Yet salmon and sturgeon survival was compromised by low flows and high water temperatures in the Sacramento River this spring.1 Young salmon survival has been further compromised by low flows, high exports, and high water temperatures in the Delta this past June.

Many of the wild smolts produced in Central Valley rivers this year entered the Delta in May and left (or died) by the end of June, as observed in Delta export salvage collections (Figure 1).  Many of the wild smolts captured in the south Delta likely originated from San Joaquin tributaries.  South Delta exports were near maximum at 10,000 cfs, about 70-80% of San Joaquin inflow to the Delta and 20% of total Delta inflow.  The high exports caused lower flows and associated high water temperatures (>20oC) in the Delta channel of the lower San Joaquin River (Figure 2), and contributed to similarly high temperatures in the lower Sacramento River channel (Figure 3).

The high Delta water temperatures (>20oC) compromised the survival of the salmon smolts in June.  Reducing the export limit to 5000-6000 cfs in June of this wet year would have kept the water temperature near a 20oC limit.  The water quality standards in the 1980’s and 1990’s under D-1485 had a 6,000 cfs June export limit.  In the past two decades under D-1641, the June export limit changed to 65% of total inflow.

New Delta water quality standards should provide export limits and inflow/outflow minimums that protect salmon through the spring months.

Figure 1. Chinook salmon salvage at south Delta export facilities in 2019. Note the prevalence of wild (non-hatchery) smolts in May-June.

Figure 2. Water temperature and tidally-filtered flow at Jersey Point in the lower San Joaquin River channel of the Delta in June 2019.

Figure 3. Water temperature and tidally-filtered flow at Rio Vista in the lower Sacramento River channel of the Delta in June 2019.

 

 

Selective Chinook Salmon Sport Fisheries in Puget Sound With notes on variants for Coho salmon and Steelhead.

Introduction

The Endangered Species Act (ESA) imposed complex challenges to the management of the sport fishery for Chinook salmon in Puget Sound, Washington State. In order to protect limited stocks of “native or wild” Chinook (i.e., those that are not from hatchery origin and naturally spawn in streams), total closures to sport fishing were strongly considered.

Wild and “hatchery” Chinook (i.e., those that are reared in a hatchery) co-mingle in the same Puget Sound habitat. The hatchery fish are often sufficiently abundant in many areas to allow some level of sport fishing. Total closure of the sport fishery for all Chinook was therefore a major issue for sport fishermen because of the high economic value of the sport, the potential overabundance of adult hatchery fish, and the sport of catching this prized species.

To differentiate hatchery from wild salmon, the adipose fin is removed from hatchery-reared smolts before release. Thus, when an angler brings a Chinook to shore or a boat, the angler can visually determine if it is from hatchery origin, based on the absence of this fin. This allows a mark-selective fishery targeting hatchery fish.

Mark-selective Chinook salmon fisheries are sometimes further constrained by “encounter” quotas. In Puget Sound, quotas for angler “encounters” (a combination of legal-size Chinook, wild Chinook, sublegal hatchery fish, and sublegal wild fish) are established annually for 9 specific marine management areas. For selective river fisheries in the Puget Sound area, the encounter approach is not used.

Current management using quotas on catch and encounters allows sport fisheries on hatchery Chinook salmon. Co-managers Washington Department of Fisheries (WDFW) and Native American Tribes use three major methods to manage the Chinook sport fisheries in Puget Sound:

  1. review of angler punch card data,
  2. creel census surveys supplemented with test boat fishing and aerial surveys, and
  3. quotas on encounters in areas of Puget Sound where sublegal and legal sized Chinook salmon co-mingle.

Punch Cards

In addition to a fishing license, anglers fishing for salmon (all species) and certain other species (e.g., steelhead and halibut) must also purchase a punch card. When one of these species is caught and kept, the angler records the date, location, species, and other information on the card. The punch card must be returned to the WDFW at the end of the recording season. If the cards are not returned, there is a penalty charge made on the next license purchased. The card is used to determine annual harvest and historical trends for the various management areas.

Creel Census

To supplement the punch card information, additional “real time” data are monitored through angler “creel” surveys at various sites. These face-to-face surveys collect information on species caught and kept, number of fish released (including any wild salmon, sublegal fish, others species), hours and management area fished.

Encounters

Recording encounters involves the reporting during creel surveys of all Chinook kept and released, including whether fish caught were legal-sized and adipose clipped, legal-adipose intact, sublegal-adipose clipped, or sublegal-adipose intact. Information collected during the creel surveys also records Chinook retained and an estimate from the angler of those that have been hooked and released (legal, sublegal, or native). This information is supplemented by test boat fishing and aerial surveys.

During the pre-season, each of the 9 management areas in Puget Sound is assigned specific seasonal encounter quota numbers. If any of the quotas are reached in an area, that area is closed to further fishing for Chinook.

Discussion

Mark-selective sport fisheries on hatchery salmon in the Puget Sound have been allowed through the use of quotas on angler catch and encounters for specific management areas. The quotas are determined during the pre-season by the fisheries co-managers WDFW and the Tribes. Quotas are derived from a model that includes historical punch card data, spawning surveys from earlier years, and other population and catch data.

The sport fishery for Chinook has severely declined in recent decades. There is a wide array of potential reasons for this decline. These include massive increases in predators (e.g., seals and sea lions), ocean conditions, loss of freshwater habitat, and others. In past decades, fishing for Chinook salmon was open the entire year, with much higher daily limits (up to 3 fish). The fishery has been severely reduced to only a few weeks in summer and limited months in the winter, often with only a 1 fish daily limit. The addition of the encounters approach in recent years has also contributed to large crowds that are condensed into the shortened periods. This, for some, has catching a prized Chinook salmon a lot less enjoyable.

In general, the encounters approach has been useful for allowing Chinook salmon sport fishing to continue on a limited basis while maintaining protections for wild Chinook. There are some drawbacks, however. For example, if the pre-season estimate of Chinook abundance for a particular management area is underestimated, the encounters quota may be reached early and the season closed, even though there may be substantially high survival rates that might have allowed a higher quota value.

Coho salmon and steelhead are also adipose clipped at the hatchery. This allows selective sport fisheries for these species to continue as well, while allowing release of wild spawning adults. However, the encounters methodology is not currently used for these species (capture of sublegal fish is low). In areas where adult Coho populations are low, a selective fishery may occur, in which only hatchery fish are allowed to be retained. However, in areas where populations of “native” Coho are abundant, both wild and hatchery Coho may be kept.

In general, nearly all steelhead management areas in Washington require release of native steelhead, which, in most cases, have a high survival rate when released.

In sum, these mark-selective sport fisheries in Puget Sound allow sport fisheries that otherwise might be banned altogether. Harvest of hatchery fish may also help reduce competition with wild fish for spawning habitat and food resources.

 

Shasta River Update – April 2019

A February 20, 2019 article in the Eureka Times-Standard reported continuing improvement of Klamath River fall-run Chinook.

“The number of natural area spawners was 53,624 adults, which exceeded the preseason expectation of 40,700. However, the stock is still in “overfished” status as escapement was not met the previous three seasons. The estimated hatchery return was 18,564 adults for the basin.

Spawning escapement to the upper Klamath River tributaries (Salmon, Scott, and Shasta Rivers), where spawning was only minimally affected by hatchery strays, totaled 21,109 adults. The Shasta River has historically been the most important Chinook salmon spawning stream in the upper Klamath River, supporting a spawning escapement of 27,600 adults as recently as 2012 and 63,700 in 1935. The escapement in 2018 to the Shasta River was 18,673 adults. Escapement to the Salmon and Scott Rivers was 1,228 and 1,208 adults, respectively.”

In a May 2017 post, I discussed an increasing contribution to the Klamath run from the Shasta River.  In Figure 1 below, I have updated my original spawner-recruit analysis from the prior post with 2017 and 2018 escapement numbers for the Shasta River.  The Shasta run in fall 2018 was third highest on record for the Shasta River.  The river’s fall-run population continues to benefit from improved water management.  Coho salmon and steelhead have yet to show significant improvements (Figure 2).

An February 26, 2019 article from the publication Grist (posted in 2/26/19 Maven’s Digest) describes changes to water management in the Shasta River.  The Nature Conservancy, using public grant funds, purchased the nearly 5000-acre Shasta Big Springs Ranch for $14 million in 2009.  More recently, the California Department of Fish and Wildlife purchased the water rights of the Shasta Big Springs Ranch.  Now, more water is left in the Shasta River, and only a third (1500 acres) of the ranch remains irrigated.  The article in Grist states that the new allocation of water has negatively affected the ranch’s ability to support wildlife and threatened its ability to support ranching.  In addition, the article questions the benefits of the new management regime to fish: “[T]he fish don’t seem to be doing much better either.”

While some will argue the relative values of ranching and fish protection,  I see no grounds to argue that changes in water management have not been positive to the Shasta River and Klamath River salmon.  Summer flows in the river below the ranch appear to have improved over the long term average (Figure 3).  Many of the Shasta River’s Chinook and Coho salmon spawn in the Big Springs area and in the river below Big Springs, and depend on flow and cold water input from the springs.  Even with the contribution of this flow, water temperatures are marginal (>65oF) for young salmon from May to September (Figure 4).

From my perspective, the loss of several thousand acres of irrigated pasture out of roughly 25,000 acres in the Shasta Valley seems a small price to pay for a large step towards the recovery of Shasta and Klamath River salmon.

Figure 1. Spawner-recruit relationship for Shasta River. Escapement estimates (log10X – 2 transformed) are plotted for recruits by escapement (spawners) three years earlier. Year shown is recruit (escapement) year. The number is the year that fish returned to the Shasta River to spawn. The color of the number depicts the water-year type in the Shasta River during the year the recruits reared. The color of the circle depicts the water-year type in the Klamath River during the year the recruits reared. Blue is for Wet water-year types. Green is for Normal water-year types. Red is for Dry water-year types. Example: 90 depicts fish that returned to the Shasta River as adult spawners in 1990. These fish were spawned in 1987 and reared in winter-spring 1988. The red number shows that the 1988 rearing year was a Dry water year in the Shasta River; the red circle shows that the 1988 rearing year was a Dry water year in the Klamath River. Note very poor recruits per spawner in 1990-1993 drought period, compared with relatively high recruits per spawner from 2011-2018, even though the latter period included the 2012-2016 drought.

Figure 2. Shasta River salmonid runs from 1930 to 2017. Source: https://www.casalmon.org/salmon-snapshots/history/shasta-river

Figure 3. Shasta River flows in the Shasta River below Big Springs 2016-2018 with 30 year average. Note summer base flow appears to have improved by approximately 10-30 cfs.

Figure 4. Water temperature in the Shasta River below Big Springs including summers of 2017 and 2018. Source: DWR CDEC.

 

 

No Funding Help for Central Valley Salmon Hatcheries: Sacramento Valley Salmon Recovery Program and Proposition 3 Strike Out

California’s salmon hatchery programs badly need major projects and upgrades.  The future of wild and hatchery salmon runs, as well as commercial and sport fisheries in California, depends on these programs.  However, hatchery programs are operated and funded under antiquated water project mitigation programs that lack a progressive approach (and funding) for hatcheries in salmon ecosystems in California.  And neither the Sacramento Valley Salmon Recovery Program (SVSRP) nor Proposition 3 includes investments in hatcheries.

California Salmon Hatcheries:

  • Iron Gate Hatchery: Coho, Fall Chinook and Steelhead (Klamath River)
  • Trinity River Hatchery: Coho, Fall Chinook, Spring Chinook and Steelhead (Trinity River)
  • Nimbus Hatchery: Fall Chinook and Steelhead (American River)
  • Mokelumne Hatchery: Fall Chinook and Steelhead (Mokelumne River)
  • Merced Hatchery: Fall Chinook (Merced River)
  • Feather River Hatchery: Fall Chinook, Spring Chinook and Steelhead (Feather River)
  • Coleman National Fish Hatchery: Fall Chinook, Late-fall Chinook and Steelhead (Battle Creek)
  • Livingston Stone National Fish Hatchery: Winter Chinook (Sacramento River)

The California Hatchery Review Project and Hatchery Science Review Group (HSRG)1 identified major problems/issues, goals, and expectations related to California salmon hatcheries:

  • Serious loss and degradation of habitat limits natural production of salmon and steelhead in California.
  • Hatchery program goals have been consistently expressed in terms of juvenile production rather than adult production.
  • Program purposes have not been clearly defined.
  • Hatchery monitoring and evaluation programs and Hatchery Coordination Teams are needed.
  • Program size has been set independent of any consideration of potential impacts of hatchery fish on affected natural populations.
  • Off-site releases promote unacceptable levels of straying among populations.
  • Marking/tagging programs are needed for real-time identification of all hatchery-origin Chinook salmon returning to hatchery facilities.
  • Standards for fish culture, fish health management and associated reporting are inadequate and need to be improved.
  • Populations and population boundaries have not been established for non-listed species and are needed for effective development of integrated hatchery programs.
  • Harvest management of Sacramento River Fall Chinook should account for the productivity of naturally-spawning adults.

Program goals:

  • Improving the efficiency of hatchery operations
  • Reducing the impact of hatcheries on natural populations
  • Supporting commercial, tribal, and recreational fisheries

Expectations from hatchery programs:

  • Reduction in the domestication of hatchery fish
  • Reduction in the negative impacts of hatchery fish on natural spawning populations
  • Improved prospects for the long-term successful coexistence of hatchery and natural fish

NMFS’s Salmon Recovery Plan, in addition to supporting the recommendations of the HSRG, also promotes the following action:  “Develop and implement an ecosystem based management approach that integrates harvest, hatchery, habitat, and water management, in consideration of ocean conditions and climate change (Lindley et al. 2009).”

Because scientific studies have shown that hatcheries reduce the long-term fitness and survival of salmon species, and California’s listed salmon and steelhead cannot be sustained without hatcheries, it is imperative that hatchery programs be upgraded to safeguard the future of salmon in California.  One way to accomplish this goal and the others described above is to adopt the goals and objectives of a Conservation Hatchery Strategy.

First, there needs to be a shift away from hatcheries as mitigation for long-ago-built dams and water diversions, and a shift toward hatcheries contributing directly to salmon recovery and conservation.  Dumping tens of million salmon and steelhead hatchery smolts at the eight hatcheries or trucking some to the Bay may sustain a minimal coastal fishery, but it will not bring recovery or delisting of endangered populations.  Conservation hatcheries are a necessary tool for salmon recovery.

The eight hatchery programs need funding to convert them to conservation hatcheries.  That funding could come from the SVSRP and resource agency programs, and future ballot initiatives, as well as mitigation programs.  At a minimum, the SVSRP should be integrated into an ecosystem-based management approach that includes conservation hatcheries.