Hydrology and chemistry of floodwaters in the Yolo Bypass, Sacramento River system, California, during 2000

2002 ◽  
Keyword(s):  
River System ◽  
Sacramento River ◽  
Yolo Bypass

Early Life History of Fishes in the San Francisco Estuary and Watershed

2004 ◽  
Keyword(s):  
Life History ◽  
San Francisco ◽  
Early Life ◽  
Oncorhynchus Tshawytscha ◽  
San Francisco Estuary ◽  
Sacramento River ◽  
Yolo Bypass ◽  
Species Abundances ◽  
Native Fishes ◽  
Rotary Screw

<em>Abstract.</em>—We examined assemblage patterns of early life stages of fishes for two major tributaries of the upper San Francisco Estuary: (1) Sacramento River channel, and (2) Yolo Bypass, the river’s seasonal floodplain. Over four hydrologically diverse years (1999–2002), we collected 15 species in Yolo Bypass egg and larval samples, 18 species in Yolo Bypass rotary screw trap samples, and 10 species in Sacramento River egg and larval samples. Fishes captured included federally listed species (delta smelt <em>Hypomesus transpacificus </em>and splittail <em>Pogonichthys macrolepidotus</em>) and several game species (American shad <em>Alosa sapidissima</em>, striped bass <em>Morone saxatilis</em>, crappie <em>Pomoxis </em>spp., and Chinook salmon <em>Oncorhynchus tshawytscha</em>). As in other regions of the estuary, alien fish comprised a large portion of the individuals collected in Yolo Bypass (40–93% for egg and larval net samples; 84–98% for rotary screw trap samples) and Sacramento River (80–99% for egg and larval net samples). Overall ranks of species abundances were significantly correlated for Yolo Bypass and Sacramento River, suggesting that each assemblage was controlled by similar major environmental factors. However, species diversity and richness were higher in Yolo Bypass, likely because of a wider variety of habitat types and greater hydrologic variation in the floodplain. In both landscapes, we found evidence that timing of occurrence of native fishes was earlier than aliens, consistent with their life history and our data on adult migration patterns. We hypothesize that Yolo Bypass favors native fishes because the inundation of seasonal floodplain typically occurs early in the calendar year, providing access to vast areas of spawning and rearing habitat with an enhanced food web. Conclusions from this analysis have implications for the management of aquatic biodiversity of tributaries to the San Francisco Estuary and perhaps to other lowland rivers.

scholarly journals Use of a Managed Flow Pulse as Food Web Support for Estuarine Habitat

2021 ◽  
Vol 19 (3) ◽  
Author(s):  
Jared Frantzich ◽  
◽  
Brittany Davis ◽  
Michael MacWilliams ◽  
Aaron Bever ◽  
...  
Keyword(s):  
Resource Management ◽  
San Francisco ◽  
Essential Fatty Acids ◽  
Specific Conductivity ◽  
Sacramento River ◽  
Flow Pulse ◽  
Study Region ◽  
Yolo Bypass ◽  
Estuarine Habitat ◽  
Net Flows

While freshwater inflow has been a major focus of resource management in estuaries, including the upper San Francisco Estuary, there is a growing interest in using focused flow actions to maximize benefits for specific regions, habitats, and species. As a test of this concept, in summer 2016, we used a managed flow pulse to target an ecologically important region: a freshwater tidal slough complex (Cache Slough Complex–CSC). Our goal was to improve estuarine habitat by increasing net flows through CSC to enhance downstream transport of lower trophic-level resources, an important driver for fishes such as the endangered Delta Smelt Hypomesus transpacificus. We used regional water infrastructure to direct 18.5 million m³ of Sacramento River flow into its adjacent Yolo Bypass floodplain, where the pulse continued through CSC. Simulations using a 3-D hydrodynamic model (UnTRIM) indicated that the managed flow pulse had a large effect on the net flow of water through Yolo Bypass, and between CSC and further downstream. Multiple water quality constituents (specific conductivity, dissolved oxygen, nutrients [NO₃ + NO₂, NH₄, PO₄]) varied across the study region, and showed a strong response to the flow pulse. In addition, the lower Sacramento River had increased phytoplankton biomass and improved food quality indices (estimated from long-chain essential fatty acids) after the flow pulse. The managed flow pulse resulted in increased densities of zooplankton (copepods, cladocerans) demonstrating potential advection from upper floodplain channels into the target CSC and Sacramento River regions. This study was conducted during a single year, which may have had unique characteristics; however, we believe that our study is an instructive example of how a relatively modest change in net flows can generate measurable changes in ecologically relevant metrics, and how an adaptive management action can help inform resource management.

scholarly journals Major Histocompatibility Complex Differentiation in Sacramento River Chinook Salmon

Genetics ◽  
1999 ◽  
Vol 151 (3) ◽  
pp. 1115-1122
Author(s):  
Timothy J Kim ◽  
Karen M Parker ◽  
Philip W Hedrick
Keyword(s):  
Major Histocompatibility Complex ◽  
Chinook Salmon ◽  
Binding Sites ◽  
River System ◽  
Amino Acid Replacement ◽  
Sacramento River ◽  
Antigen Binding ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Selection For

Abstract The chinook salmon of the Sacramento River, California, have been reduced to a fraction of their former abundance because of human impact and use of the river system. Here we examine the genetic variation at a major histocompatibility complex class II exon in the four Sacramento chinook salmon runs. Examination of the alleles found in these and other chinook salmon revealed nucleotide patterns consistent with selection for amino acid replacement at the putative antigen-binding sites. We found a significant amount of variation in each of the runs, including the federally endangered winter run. All of the samples were in Hardy-Weinberg proportions. A significant amount of genetic differentiation between runs was revealed by several measures of differentiation. Winter run was the most genetically divergent, while the spring, late-fall, and fall runs were less differentiated.

scholarly journals Intraspecific variation in migration timing of green sturgeon in the Sacramento River system

2021 ◽  
Author(s):  
Scott F. Colborne ◽  
Lawrence W. Sheppard ◽  
Daniel R. O’Donnell ◽  
Daniel C. Reuman ◽  
Jonathan A. Walter ◽  
...  
Keyword(s):  
Life History ◽  
Movement Patterns ◽  
River System ◽  
Bimodal Distribution ◽  
Sacramento River ◽  
Green Sturgeon ◽  
Life History Variation ◽  
Acipenser Medirostris ◽  
Migration Timing ◽  
Timing Of Migration

AbstractBackgroundUnderstanding movement patterns of anadromous fishes is critical to conservation management of declining wild populations and preservation of habitats. Yet, infrequent observations of individual animals fundamentally constrain accurate descriptions of movement dynamics.MethodsIn this study, we synthesized over a decade (2006–2018) of acoustic telemetry tracking observations of green sturgeon (Acipenser medirostris) in the Sacramento River system to describe major anadromous movement patterns.ResultsWe observed that green sturgeon exhibited a unimodal in-migration during the spring months but had a bimodal distribution of out-migration timing, split between an ‘early’ out-migration (32%) group during May - June, or alternatively, holding in the river until a ‘late’ out-migration (68%), November - January. Focusing on these out-migration groups, we found that river discharge, but not water temperature, may cue the timing of migration, and that fish showed a tendency to maintain out-migration timing between subsequent spawning migration events.ConclusionsWe recommend that life history descriptions of green sturgeon in this region reflect the distinct out-migration periods described here. Furthermore, we encourage the continued use of biotelemetry to describe migration timing and life history variation, not only this population but other green sturgeon populations and other species.

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