Are Striped Bass about to make a comeback?

Unlike most of the Central Valley native fishes including salmon and smelt, striped bass have an inherent natural advantage or resilience: they are long-lived, have ten or more spawning year-classes in any spawning year, and produce a thousand times more eggs per female. This advantage has come into play after a decade of drought: in the spring of 2016, there are optimal spawning and early rearing conditions for striped bass.

The late April 20-mm Survey results indicate a possible strong year class for stripers compared to recent years. The distribution of larvae in late April 2016 (Figure 1) is the product of moderate normal year Delta outflow with low Delta exports. The 2016 distribution is a dramatic improvement over the critically dry year 2015 (Figure 2), the drought-year 2009 (Figure 3), and also the normal year 2010 (Figure 4).

Normal water year spring Delta outflows that place the Low-Salinity-Zone westward in Suisun Bay, combined with a strong spring plankton bloom, bode well for the growth and survival of young stripers. In contrast, conditions were poor in 2015, when young stripers were confined to the Delta under low Delta outflows and low productivity, and were subject to Delta exports and diversions (Figure 2). Chances of a comeback in the fall-index (Figure 5) remain to be seen, given the lack of summer Delta protections since 1995 under the existing Delta Water Quality Control Plan. Expected high summer exports and low Delta outflows, such as those in normal water year 2010 (the record low fall-index year), may yet preclude a comeback.

Figure 1. Striped bass larvae density distribution in 20-mm Survey #4, Apr 25-28, 2016.

Figure 1. Striped bass larvae density distribution in 20-mm Survey #4, Apr 25-28, 2016.

Figure 2. Striped bass larvae density distribution in 20-mm Survey #4, Apr 27-30, 2015.

Figure 2. Striped bass larvae density distribution in 20-mm Survey #4, Apr 27-30, 2015.

Figure 3. Striped bass larvae density distribution in 20-mm Survey #4, Apr 20-24, 2009.

Figure 3. Striped bass larvae density distribution in 20-mm Survey #4, Apr 20-24, 2009.

Figure 4. Striped bass larvae density distribution in 20-mm Survey #4, Apr 26-29, 2010.

Figure 4. Striped bass larvae density distribution in 20-mm Survey #4, Apr 26-29, 2010.

Figure 5. Striped bass fall index of young striped bass 1967-2013. Not shown are the near record low indices in 2014 and 2015 (59 and 52, respectively).

Figure 5. Striped bass fall index of young striped bass 1967-2013. Not shown are the near record low indices in 2014 and 2015 (59 and 52, respectively).

Hatcheries Release Salmon Smolts into Low Flows and Warm Water – April and early May, 2016

April 13. CBS San Francisco reports:

The federal government is funding the release of millions of Baby Chinook salmon into Battle Creek at the Coleman Federal Hatchery outside Red Bluff. Brett Galyean, deputy project leader at Coleman Federal Hatchery, said, “It’s a big day. It’s the first time in two years that we were able to release all the fish on station…. Because of the drought the last two years, the environmental conditions in the Sacramento River — warm water, low flow — caused us to truck fish.”… However, of the 12 million fish released, only one percent are expected to return to Battle Creek in three years to spawn.

April 29. Recent fishing report states:

This spring’s striper fishing on the Sacramento River has been going very well with daily limits of large Sacramento River striped bass. Most of the action has been from Colusa downriver through Verona as the Sacramento River is very low due to minimal releases from Keswick Dam and high volumes of irrigation pumping from the lower Sacramento River. Stripers mostly 18 to 24 inches are coming in daily with some very large female stripers 15 to 25 pounds coming in as well. Drifting live jumbo minnows has been working best in the daytime while black worms or white swim baits are working at night. The Coleman National Fish Hatchery has released the remaining 6 million fall-run juvenile salmon smolt into the Sacramento River. With low flows coupled with the massive irrigation pumping, the lower Sacramento River from Butte City downriver through Verona is extremely low, leaving exposed sand and gravel bars across the river. This is setting the stage for an incredible striper fishing as the smolts arrive in the lower Sacramento River. Striper fishing should be incredible as the stripers feed day and night on the hatchery salmon smolt just like last month when the first round of hatchery Sacramento River salmon smolt were released. Sacramento fishing.com fishing guide Dave Jacobs has witnessed countless striper boils as the spawning stripers have fed around the clock on the salmon smolts from Butte City downriver through Verona.

May 1. Yet another fishing report notes:

The striper action has been incredible for the past several weeks. While many of the stripers are post spawn they are hanging out and destroying recent salmon plants coming out of the hatcheries…. Before the past weekend, he found great action on the Feather River, but heavy boat traffic over the weekend slowed down the Feather since an armada showed up. Salmon smolts were released in the Feather this past week, and the combination of low flows and clear water made for a killing zone for the smolts…. The bite lasted until most of the baby salmon made it to the Sacramento River, and I was able to follow them down the Sacramento a couple of miles until the fishing got tough…. The California Department Fish and Wildlife hatchery on the Feather river is planning on releasing their final stock of 1 million into the Feather river instead of trucking them around the river and Delta pumps to the Suisun Bay. The Federal hatchery on Battle creek released 4 plus million salmon fry this past week and will dumping an additional 1.9 million fall run fish into Battle Creek this coming Friday. The is [sic] opposed to these releases due to the current lower flows and clear water. With high numbers of spawning stripers and low / clear flows most of these fish will never make it as far as Sacramento. Past studies have shown that 94% of hatchery salmon released on the upper Sac never make it to San Pablo bay in these conditions.

May 2. SacBee Fishing continues the theme:

SACRAMENTO RIVER, Red Bluff to Colusa – Salmon smolts have been released from Coleman National Fish Hatchery, and are expected to fuel a hot striper bite from Butte City to Verona. The river is dropping, which caused many of the stripers to drop downstream last week. Anglers now expect stripers to move upriver to feed on the salmon smolts.

Sacramento River Conditions

The Sacramento River water quality Basin Plan objective requires no water temperature greater than 56°F upstream of Hamilton City and no temperature greater than 68°F upstream of Sacramento. Water temperature Red Bluff (upstream of Hamilton City) has already reached a daily average of 62°F, well above the required limit (and this with Shasta full of cold water). Water temperatures below Hamilton City have reached 69°F (at Wilkins Slough). Downstream-migrating smolts are stressed and more vulnerable to predation as water temperatures approach 60°F, yet managers continue to release hatchery smolts from the Battle Creek and Feather River hatcheries. Adult winter-run and spring-run Chinook salmon, now migrating upstream in the Sacramento River, are also being stressed by water temperatures greater than 65°F. The 60-65°F range is optimal for striped bass feeding and metabolism. ARE THE HATCHERY SMOLTS SIMPLY CHUM FOR STRIPERS???

Sac at Red Bluff

FISHBIO Strikes Again – Predation Is the Problem, Not Water Diversions – Right or Wrong?

On Wednesday, February 10, 2016, the Water, Power and Oceans Subcommittee held a one-panel oversight hearing on “The Costly Impacts of Predation and Conflicting Federal Statutes on Native and Endangered Fish Species.” FISHBIO President Doug Demko was invited to provide testimony on the issue in reference to California’s Central Valley.

FishBio photo

FishBio photo

FishBio’s testimony begins: “California resource agencies sink tens of millions of dollars every year into a failing effort to protect native and endangered fish species, while also bolstering introduced top-level predators that are decimating the very fish they are required to maintain.”

  1. Failure to protect native and endangered fish species in the Central Valley has far more to do with water management within the federal Central Valley Project and State Water Project and lack of protections from water quality standards and biological opinions, especially during four multi-year droughts beginning in the late-1970’s. Over a billion dollars have been spent by federal and state agencies on fish recovery, with strongly positive results between droughts.
  2. In no way have the recovery efforts bolstered introduced top-level predators such as the striped bass. As noted in the testimony, stocking of striped bass ceased nearly two decades ago. Striped bass production had declined dramatically over the past three decades along with the native fish. Summer water quality standards that once protected striped bass were removed twenty years ago.
  3. The increases in stocking of hatchery salmon smolts to over 30 million annually in the Central Valley have encouraged and sustained the remaining striped bass, which now focus more on young salmon. Adult striped bass now concentrate in spring below all the Central Valley salmon hatcheries and dams. Remnants of the once prolific striped bass population await the fat hatchery smolts in all 300 miles to the Golden Gate. A shift in prey and location of prey has forced more Striped Bass into the rivers and tributaries for prey.
  4. Yearly Hatchery Steelhead Photo

    Photo: yearling hatchery steelhead smolt fed on wild salmon fry in American River. (Photo by author)

    The stocking of millions of large yearling salmon and steelhead smolts also contributes directly to predation on wild salmon and steelhead fry. (see photo at right)

  5. Research has shown that habitat changes have had more to do with increased predator populations like largemouth bass in the Delta. Controlling habitat change is the proven way to limit predators, rather than direct control of predators, which does not work (logistically impossible and very costly and inefficient).

“However, only recently has the existing body of science on predation been recognized among fisheries managers as a major source of juvenile salmon mortality.” This statement is simply not true. Hatchery salmon smolts have been trucked to the Bay for three decades to avoid the hundreds of miles of predator gauntlet. Predation studies at specific locations such as the Red Bluff Diversion Dam have long indicated predation problems. The dam was removed because it was a recognized predator “hot spot”.

There is no doubt that predation by non-native fish like Striped Bass and Largemouth Bass is a major factor in Chinook Salmon and Steelhead mortality in the Central Valley. However singling them out as the primary cause of native fish declines misses the key factor: water management. Salmon, smelt, and bass got along well until the State Water Project came on line in the 1970s and increased Delta exports from 2 million to 6 million acre-feet per year. There is no doubt that droughts and climate change have added to or sped up changes; however the underlying problem remains water diversions.

“It has now become clear that predation may significantly limit the success of salmon recovery efforts (NMFS 2009b; Dauble et al., 2010).” While this statement may be true under existing conditions where salmon production is limited by water management and habitat degradation (with predation exacerbated by these factors), the solution should be a broader range of risk factor management, not just a focus on predation. For example, spring reservoir releases can reduce predation risk by speeding emigration, increasing turbidity, and reducing water temperature.

“The survival estimate of 7% in 2012 was much lower than the 40-60% previously estimated by mark-recapture studies conducted by CDFW.” In drought years like 2012, reservoirs capture and retain nearly all winter-spring flows. No doubt this creates better conditions for Striped Bass (and resident Rainbow Trout and Pikeminnow) predation on young salmon that are programmed to emigrate when Mother Nature provides appropriate freshets. So is the problem predation or lack of natural flows? (This problem could be partly mitigated through a more comprehensive approach in the worst case drought years by capturing young salmon in migrants traps and transporting them to the Bay, thus avoiding the predators in the river (and Delta). In such dry years adult Striped Bass could also be effectively captured in upstream migrant traps and transported to the Bay where other types of prey are far more abundant.)

“[N]o changes in sportfishing regulations, and, to date, no meaningful actions of any kind have been taken to accept or address the problem.” Changing sport fishing regulations would be a drop in the bucket and alienate most sport fishermen. Why doesn’t CDFW take the hundreds of thousands of young striped bass salvaged each summer at the Delta export pumps (and returned to the west Delta) and stock them in a southern California reservoir? Because that would cripple the Bay-Delta striper fishery – an angler’s Catch-22. Why doesn’t CDFW take the catch from hundreds of bass tournaments each year in the Delta somewhere other than nice spots in the Delta? Because that would cripple the world-renowned bass fishery – another Catch-22. FishBio describes the bounty fishery on Columbia River predators that are less desired as gamefish. It is altogether different to put a bounty on Striped Bass and Largemouth Bass.

FishBio noted that harvest restrictions on non-native sport fish have recently been removed on the Columbia River to protect native salmonids. “A similar policy change in California, coupled with focused removal and suppression efforts, could lead to improved survival conditions for native species as has been demonstrated on the Columbia River.” Columbia River salmonid fisheries are far more valuable and popular than bass and walleye fisheries. Furthermore, there is little else managers can do on the Columbia to benefit salmon. Water diversions in the Columbia are far less of a problem, and managers on the Columbia have already severely limited hydropower production to provide spring spills for salmon. These actions have brought record or near record salmon and steelhead runs.

In conclusion, Striped Bass and Largemouth Bass are two of the top sportfish in the Central Valley. Destroying their populations and sport fisheries, and associated socio-economic benefits, without addressing water management, the real culprit, will not solve or defuse the problem.

FISHBIO takes on Stripers – again

In a recent blog post1, FISHBIO again discuss the role they allege that Striped Bass are playing in limiting salmon production in the Central Valley. They bring up the 5-year-old proposal to reduce regulations on the Striped Bass fishery that was soundly rejected by fishermen, resource managers, environmentalists, and scientists alike. They state that despite the fact that anglers spend more than ten times the hours spent fishing for stripers than for salmon, the economic benefit of striper fishing is far below that of salmon fishing.

Well, assuming the raw economic numbers are true:

  1. The State closed the Striped Bass commercial fishery a century ago.
  2. The Striped Bass fishery is year-round and throughout most of the Central Valley, whereas the salmon fishery is seasonal and more localized. There must be some social value in diversity.
  3. The economic status of Striped Bass fishermen is far more diverse than salmon fishermen. There must be some social value in supporting a broader range of citizens.
  4. Many California residents are from the East, where stripers are king and there are no salmon.
  5. Much of the salmon fishery value derives from the ocean fisheries, whereas the striper fishery is focused on Bay-Delta and inland waters. The relative cost of fishing in these regions is very different.
  6. Most of the salmon fishery value (over 90%) is derived from hatchery fish. The Striped Bass supplemental rearing program was closed over a decade ago. The striper effort was ten times higher then, the number of stripers was up to ten times higher in the past, and the economic value was also likely ten times higher.

The other portion of FISBIO’s argument concerns the role of Striped Bass predation in salmon declines.

  • “ During the early 1900s, striped bass thrived alongside salmon, but as salmon declined over the latter part of the century, the impact of these introduced predators took a proportionally greater toll on the salmon population.” There is no evidence to support this statement. Stripers have declined more than salmon. There are still 30-million hatchery smolts for a much smaller striper population to feed on.
  • “Controlling predators to help their prey species is not a new idea; other states have been controlling non-native and native predators with measured success for decades.” No doubt the greatest “predator control” success (over 90%) has been on the Striped Bass population by the federal and state export pumps over the past two decades.
  • “While California has failed to act, some political support for predator control has recently developed at the federal level. Multiple bills currently proposed in Congress include provisions for advancing predator control in the Delta.” These bills were sponsored by San Joaquin Valley congressmen and have little chance of passing.
  • “While these federal actions alone may not be sufficient to produce population increases in some threatened or endangered species, there is evidence that predation is a major barrier to salmon recovery, and the proposed legislation demonstrates a changing mindset toward controlling predation of declining species.” There is no evidence that predation by Striped Bass on wild threatened salmon runs is even in the top ten reasons for their declines. The “mindset change” is to divert attention away from the real reasons for threatened salmon declines, or from having to pay for their recovery.

Finally FISHBIO speaks to “changing mindsets” of anglers: “Perhaps the biggest hurdle to controlling non-native species like striped bass will be changing the mindset of the fishing community that cares deeply about these popular predators.” They mean that anglers should accept the false premise that Striped Bass are the problem and should allow them to be exterminated.

Striped Bass Status

Striped Bass (stripers) came from New Jersey by train in milk cans 135 years ago to provide a vibrant commercial fishery and regional food supply. Today, stripers remain a prized gamefish in Central Valley rivers, the Delta, and the Bay. Like the native smelts, salmon, steelhead, herring, and sturgeon, stripers have undergone a dramatic decline over the past several decades (Figure 1). Many have blamed the stripers for these declines, when in fact the entire fish community and food-chain of the Bay-Delta has suffered from the man-made spring-summer droughts in the Central Valley. Stripers may prey on listed salmon, steelhead, and smelt, but are far more likely to prey upon native and non-native competitors and predators of these listed species.

Despite their strong inherent ability to recover (high reproductive capacity and long life 1 ), stripers have declined in abundance from 3-5 million adult fish in the 60s and 70s to less than a half million adults in recent years (CDFW unpublished data). A hatchery and pen-rearing program in the late 1990s and early 2000s released millions of young stripers, which led to some recovery in young production (Figure 1) and adult catch (Figure 2). Today, all indications are that stripers are now at record low levels. Stripers are one of the species identified as suffering in the Bay-Delta’s Pelagic Organism Decline2. Their decline can be directly related to Delta water exports, especially in summers of dry years since 1995, when summer protections for stripers were removed from Bay-Delta water quality standards.

Despite low adult numbers and poor summer Delta habitat conditions, recent production of young stripers in wet years is consistent with recent historical levels (Figures 3 and 4). However, production of young is very low in dry years (Figure 5). The reason for the difference between wet and dry year survival is the location of low-salinity nursery habitat in the estuary (Figures 6, 7, and 8). Young stripers are more vulnerable to Delta exports in dry years when Delta inflows are low and their Low Salinity Zone3 nursery area is located in the Delta (Figure 9).

What can be done to help stripers and the striper fishery?

  1. The Low Salinity Zone of the estuary must be kept out of the central Delta by providing sufficient Delta outflow. This would help to keep Delta pelagic fishes and their planktonic food-chain (as well as salt) out of the export pumps.
  2. Stripers should be relocated from below Central Valley river diversion dams where stripers concentrate in summer and become a localized predatory nuisance. (Such locations are generally closed to fishing.) Stripers should be relocated to Central San Francisco Bay where they support a valuable sport fishery and there are other sources of prey.
Figure 1. Young Striped Bass summer (A) and fall (B) abundance indices.  (Source: CDFW)

Figure 1. Young Striped Bass summer (A) and fall (B) abundance indices. (Source: CDFW)

Figure 2.  Striped Bass adult catch pattern in Bay-Delta sport fishery. ( Source:  CDFW)

Figure 2. Striped Bass adult catch pattern in Bay-Delta sport fishery. ( Source: CDFW)

Figure 3.  Young Striped Bass density distribution in July 1995 20-mm Survey.

Figure 3. Young Striped Bass density distribution in July 1995 20-mm Survey.

Figure 4.  Young Striped Bass density distribution in July 2011 20-mm Survey.

Figure 4. Young Striped Bass density distribution in July 2011 20-mm Survey.

Figure 5.  Young Striped Bass density distribution in July 2014 20-mm Survey.

Figure 5. Young Striped Bass density distribution in July 2014 20-mm Survey.

Figure 6.  Young Striped Bass density distribution in June 2015 20-mm Survey.

Figure 6. Young Striped Bass density distribution in June 2015 20-mm Survey.

Figure 7. Catch distribution of young Striped Bass in Summer Townet Survey July 2011, a wet year.  Magenta line is 2640 EC salinity (commonly referred to as X2).  Green line in 500 EC salinity

Figure 7. Catch distribution of young Striped Bass in Summer Townet Survey July 2011, a wet year. Magenta line is 2640 EC salinity (commonly referred to as X2). Green line in 500 EC salinity

Figure 8.  Catch distribution of young Striped Bass in Summer Townet Survey July 2014, a drought year.  Magenta line is 2640 EC salinity (commonly referred to as X2).  Green line in 500 EC salinity.

Figure 8. Catch distribution of young Striped Bass in Summer Townet Survey July 2014, a drought year. Magenta line is 2640 EC salinity (commonly referred to as X2). Green line in 500 EC salinity.

Figure 9.  The mechanism for poor Striped Bass survival in summers of dry years is larval and juveniles being drawn from north to south across the Delta to the south Delta export pumps (blue box).  The Low Salinity Zone is in Delta and is continually degraded by loss to pumps.  Magenta line is the approximate location of 2640 EC salinity (about 2 ppt salinity, commonly referred to as X2).  Green line is the approximate location of 500 EC salinity, generally considered the upper extent of the Low Salinity Zone.

Figure 9. The mechanism for poor Striped Bass survival in summers of dry years is larval and juveniles being drawn from north to south across the Delta to the south Delta export pumps (blue box). The Low Salinity Zone is in Delta and is continually degraded by loss to pumps. Magenta line is the approximate location of 2640 EC salinity (about 2 ppt salinity, commonly referred to as X2). Green line is the approximate location of 500 EC salinity, generally considered the upper extent of the Low Salinity Zone.

  1. http://www.dfg.ca.gov/fish/Resources/Striped_Bass/Biology.asp
  2. http://www.science.calwater.ca.gov/pod/pod_index.html
  3.  The Low Salinity Zone is defined as the location of brackish water with salinity of 1-6 parts salt per thousand in water as compared to 32 ppt in seawater.