Pub Date : 2020-12-11DOI: 10.15447/sfews.2020v18iss4art1
S. Luoma
The year 2020 is one we are unlikely to forget. At a time when a global pandemic and an economic collapse drove changing technologies and social and economic inequalities, extreme weather events across the country reminded us, especially here in California, that the effects of a warming earth are undeniable. A tumultuous presidency ended, leaving behind a science establishment uncertain about what lies ahead. Such disruptions add to the concern about the disappearance of journals from the Internet, and so it is only natural that readers might be interested in the status of SFEWS. Even as formidable challenges lie ahead, the stability and resilience of SFEWS as one sign of optimism to carry into 2021.
{"title":"Signs of Optimism Beyond 2020","authors":"S. Luoma","doi":"10.15447/sfews.2020v18iss4art1","DOIUrl":"https://doi.org/10.15447/sfews.2020v18iss4art1","url":null,"abstract":"The year 2020 is one we are unlikely to forget. At a time when a global pandemic and an economic collapse drove changing technologies and social and economic inequalities, extreme weather events across the country reminded us, especially here in California, that the effects of a warming earth are undeniable. A tumultuous presidency ended, leaving behind a science establishment uncertain about what lies ahead. Such disruptions add to the concern about the disappearance of journals from the Internet, and so it is only natural that readers might be interested in the status of SFEWS. Even as formidable challenges lie ahead, the stability and resilience of SFEWS as one sign of optimism to carry into 2021.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47217769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-26DOI: 10.15447//SFEWS.2020V18ISS3ART1
Ted R. Sommer
Abstracts are not presented with Essays. -The SFEWS Editors
摘要不与随笔一起呈现-SFEWS编辑
{"title":"How to Respond? An Introduction to Current Bay–Delta Natural Resources Management Options","authors":"Ted R. Sommer","doi":"10.15447//SFEWS.2020V18ISS3ART1","DOIUrl":"https://doi.org/10.15447//SFEWS.2020V18ISS3ART1","url":null,"abstract":"Abstracts are not presented with Essays. -The SFEWS Editors","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49195379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-26DOI: 10.15447/SFEWS.2020V18ISS3ART6
Zoltan Matica
This review serves as a guide to improve multi-species fish passage. Human development along waterways in California during the last 160 years has adversely affected fish populations in many watersheds. Conflicts in water usage will only intensify with modern developments and population growth. Since most past fish-passage improvement efforts in California have focused on salmonids, I summarize the published studies and considerations that affect multi-species fish passage. To be effective, conditions in fishways need to meet the specific hydraulic requirements, as well as abilities, behavior, and size consideration for all fish species being considered. Turbulence, water depth, velocity, passage location, and design of a passage facility are essential elements to successful fish passage. Because of a lack of research on most of the native species, species-specific passage criteria are not fully defined, and it may be helpful to use data for physically similar, surrogate species found in similar habitats.
{"title":"Considerations for Multi-Species Fish Passage in California: A Literature Review","authors":"Zoltan Matica","doi":"10.15447/SFEWS.2020V18ISS3ART6","DOIUrl":"https://doi.org/10.15447/SFEWS.2020V18ISS3ART6","url":null,"abstract":"This review serves as a guide to improve multi-species fish passage. Human development along waterways in California during the last 160 years has adversely affected fish populations in many watersheds. Conflicts in water usage will only intensify with modern developments and population growth. Since most past fish-passage improvement efforts in California have focused on salmonids, I summarize the published studies and considerations that affect multi-species fish passage. To be effective, conditions in fishways need to meet the specific hydraulic requirements, as well as abilities, behavior, and size consideration for all fish species being considered. Turbulence, water depth, velocity, passage location, and design of a passage facility are essential elements to successful fish passage. Because of a lack of research on most of the native species, species-specific passage criteria are not fully defined, and it may be helpful to use data for physically similar, surrogate species found in similar habitats.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/SFEWS.2020V18ISS3ART6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46044049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-26DOI: 10.15447//SFEWS.2020V18ISS3ART2
Brendan Lehman, Rachel C. Johnson, M. Adkison, Oliver T. Burgess, R. Connon, N. Fangue, J. Foott, S. Hallett, Beatriz Martínez-López, Kristina M. Miller, Maureen K. Purcell, N. Som, P. Valdes-Donoso, Alison A. Collins
hinook Salmon (Oncorhynchus tshawytscha) are increasingly vulnerable to anthropogenic activities and climate change, especially at their most southern range in California’s Central Valley. There is considerable interest in understanding stressors that contribute to population decline and in identifying management actions that reduce the effects of those stressors. Along the west coast of North America, disease has been linked to declining numbers of salmonids, and identified as a key stressor that results in mortality. In the Central Valley, targeted studies have revealed extremely high prevalence of infectious agents and disease. However, there has been insufficient monitoring to understand the effect that disease may have on salmon populations. To inform future research, monitoring, and management efforts, a two-day workshop on salmon disease was held at the University of California, Davis (UC Davis) on March 14-15, 2018. This paper summarizes the science presented at this workshop, including the current state of knowledge of salmonid disease in the Central Valley, and current and emerging tools to better understand its effects on salmon. We highlight case studies from other systems where successful monitoring programs have been implemented. First, in the Klamath River where the integration of several data-collection and modeling approaches led to the development of successful management actions, and second in British Columbia where investment in researching novel technologies led to breakthroughs in the understanding of salmon disease dynamics. Finally, we identify key information and knowledge gaps necessary to guide research and management of disease in Central Valley salmon populations.
{"title":"Disease in Central Valley Salmon: Status and Lessons from Other Systems","authors":"Brendan Lehman, Rachel C. Johnson, M. Adkison, Oliver T. Burgess, R. Connon, N. Fangue, J. Foott, S. Hallett, Beatriz Martínez-López, Kristina M. Miller, Maureen K. Purcell, N. Som, P. Valdes-Donoso, Alison A. Collins","doi":"10.15447//SFEWS.2020V18ISS3ART2","DOIUrl":"https://doi.org/10.15447//SFEWS.2020V18ISS3ART2","url":null,"abstract":"hinook Salmon (Oncorhynchus tshawytscha) are increasingly vulnerable to anthropogenic activities and climate change, especially at their most southern range in California’s Central Valley. There is considerable interest in understanding stressors that contribute to population decline and in identifying management actions that reduce the effects of those stressors. Along the west coast of North America, disease has been linked to declining numbers of salmonids, and identified as a key stressor that results in mortality. In the Central Valley, targeted studies have revealed extremely high prevalence of infectious agents and disease. However, there has been insufficient monitoring to understand the effect that disease may have on salmon populations. To inform future research, monitoring, and management efforts, a two-day workshop on salmon disease was held at the University of California, Davis (UC Davis) on March 14-15, 2018. This paper summarizes the science presented at this workshop, including the current state of knowledge of salmonid disease in the Central Valley, and current and emerging tools to better understand its effects on salmon. We highlight case studies from other systems where successful monitoring programs have been implemented. First, in the Klamath River where the integration of several data-collection and modeling approaches led to the development of successful management actions, and second in British Columbia where investment in researching novel technologies led to breakthroughs in the understanding of salmon disease dynamics. Finally, we identify key information and knowledge gaps necessary to guide research and management of disease in Central Valley salmon populations.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43621568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-26DOI: 10.15447/SFEWS.2020V18ISS3ART3
A. Jahn, E. KierWilliam
Combined water exports from Old River in the south end of California’s San Francisco Estuary (estuary) by state and federal pumping facilities entrain small fishes, including out-migrating juvenile salmon. Both export projects have fish salvage facilities that use behavioral barriers (louvers) in combination with screens to guide fish into collection areas from which they are trucked to release points in the western Delta. Sacramento River-origin Chinook Salmon are regularly taken in the projects’ fish salvage operations. Survival has been estimated within the boundaries of both intake structures, but not in Old River. Prevailing methods for estimating fish losses are based on studies of louver efficiency, near-field survival at the state facility, and assumed survival at the federal facility. The efficiency of the fish salvage operations is affected by several factors, including intake velocity, debris build-up on the louvers and trash racks, and by the omnipresence of predators in front of and within the fish guidance structures. Analysis of existing data suggests that under average conditions, juvenile salmon survive entrainment into the forebay of the state facility at a rate of less than 10%. There is no evidence for better survival at the federal facility. We found no data on predation outside of either the state’s forebay or the federal trash boom, structures which are separated by an approximately 2-km reach of Old River where predation on small fish is thought to be intense. We suggest an improvement to the existing loss estimation, and discuss some features of the studies needed to increase its accuracy and precision.
{"title":"Reconsidering the Estimation of Salmon Mortality Caused by the State and Federal Water Export Facilities in the Sacramento–San Joaquin Delta, San Francisco Estuary","authors":"A. Jahn, E. KierWilliam","doi":"10.15447/SFEWS.2020V18ISS3ART3","DOIUrl":"https://doi.org/10.15447/SFEWS.2020V18ISS3ART3","url":null,"abstract":"Combined water exports from Old River in the south end of California’s San Francisco Estuary (estuary) by state and federal pumping facilities entrain small fishes, including out-migrating juvenile salmon. Both export projects have fish salvage facilities that use behavioral barriers (louvers) in combination with screens to guide fish into collection areas from which they are trucked to release points in the western Delta. Sacramento River-origin Chinook Salmon are regularly taken in the projects’ fish salvage operations. Survival has been estimated within the boundaries of both intake structures, but not in Old River. Prevailing methods for estimating fish losses are based on studies of louver efficiency, near-field survival at the state facility, and assumed survival at the federal facility. The efficiency of the fish salvage operations is affected by several factors, including intake velocity, debris build-up on the louvers and trash racks, and by the omnipresence of predators in front of and within the fish guidance structures. Analysis of existing data suggests that under average conditions, juvenile salmon survive entrainment into the forebay of the state facility at a rate of less than 10%. There is no evidence for better survival at the federal facility. We found no data on predation outside of either the state’s forebay or the federal trash boom, structures which are separated by an approximately 2-km reach of Old River where predation on small fish is thought to be intense. We suggest an improvement to the existing loss estimation, and discuss some features of the studies needed to increase its accuracy and precision.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/SFEWS.2020V18ISS3ART3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42013118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-26DOI: 10.15447/SFEWS.2020V18ISS3ART5
L. Grimaldo, Jillian M. Burns, Robert E. Miller, A. Kalmbach, April Smith, Jason L. Hassrick, C. Brennan
Recruitment of estuarine organisms can vary dramatically from year to year with abiotic and biotic conditions. The San Francisco Estuary (California, USA) supports a dynamic ecosystem that receives freshwater flow from numerous tributaries that drain one of the largest watersheds in western North America. In this study, we examined distribution and habitat use of two forage fish larvae of management interest, Longfin Smelt Spirinchus thaleichthys and Pacific Herring Clupea pallasii, during a low-flow and a high-flow year to better understand how their rearing locations (region and habitat) may affect their annual recruitment variability. During the low-flow year, larval and post-larval Longfin Smelt were distributed landward, where suitable salinity overlapped with spawning habitats. During the high-flow year, larval Longfin Smelt were distributed seaward, with many collected in smaller tributaries and shallow habitats of San Francisco Bay. Local spawning and advection from seaward habitats were speculated to be the primary mechanisms that underlie larval Longfin Smelt distribution during the high-flow year. Larval Pacific Herring were more abundant seaward in both years, but a modest number of larvae were also found landward during the low-flow year. Larval Pacific Herring abundance was lower overall in the high-flow year, suggesting advection out of the area or poor recruitment. Future monitoring and conservation efforts for Longfin Smelt and Pacific Herring should recognize that potential mechanisms underlying their recruitment can vary broadly across the San Francisco Estuary in any given year, which suggests that monitoring and research of these two species expand accordingly with hydrologic conditions that are likely to affect their spawning and larval rearing distributions.
{"title":"Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary","authors":"L. Grimaldo, Jillian M. Burns, Robert E. Miller, A. Kalmbach, April Smith, Jason L. Hassrick, C. Brennan","doi":"10.15447/SFEWS.2020V18ISS3ART5","DOIUrl":"https://doi.org/10.15447/SFEWS.2020V18ISS3ART5","url":null,"abstract":"Recruitment of estuarine organisms can vary dramatically from year to year with abiotic and biotic conditions. The San Francisco Estuary (California, USA) supports a dynamic ecosystem that receives freshwater flow from numerous tributaries that drain one of the largest watersheds in western North America. In this study, we examined distribution and habitat use of two forage fish larvae of management interest, Longfin Smelt Spirinchus thaleichthys and Pacific Herring Clupea pallasii, during a low-flow and a high-flow year to better understand how their rearing locations (region and habitat) may affect their annual recruitment variability. During the low-flow year, larval and post-larval Longfin Smelt were distributed landward, where suitable salinity overlapped with spawning habitats. During the high-flow year, larval Longfin Smelt were distributed seaward, with many collected in smaller tributaries and shallow habitats of San Francisco Bay. Local spawning and advection from seaward habitats were speculated to be the primary mechanisms that underlie larval Longfin Smelt distribution during the high-flow year. Larval Pacific Herring were more abundant seaward in both years, but a modest number of larvae were also found landward during the low-flow year. Larval Pacific Herring abundance was lower overall in the high-flow year, suggesting advection out of the area or poor recruitment. Future monitoring and conservation efforts for Longfin Smelt and Pacific Herring should recognize that potential mechanisms underlying their recruitment can vary broadly across the San Francisco Estuary in any given year, which suggests that monitoring and research of these two species expand accordingly with hydrologic conditions that are likely to affect their spawning and larval rearing distributions.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/SFEWS.2020V18ISS3ART5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49009439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-26DOI: 10.15447/SFEWS.2020V18ISS3ART4
Ted R. Sommer, B. Schreier, J. Louise Conrad, L. Takata, Bjarni Serup, R. Titus, C. Jeffres, E. Holmes, Jacob V. E. Katz
Large areas of California’s historic floodplain have been separated from adjacent river channels by levee construction, allowing the development of an extensive agricultural industry. Based on successful partnerships between agriculture and conservation groups to support migrating waterfowl, we examined whether seasonally flooded rice fields could be modified to provide off-channel rearing habitat for juvenile Chinook Salmon Oncorhynchus tshawytscha. During winter and spring of 2012-2017, we conducted a series of experiments in Yolo Bypass and other regions of California’s Central Valley using hatchery Chinook Salmon as a surrogate for wild Chinook Salmon, the management target for our project. Overall, we found that seasonally flooded fields are highly productive, resulting in significantly higher levels of zooplankton and high Chinook Salmon growth rates as compared to the adjacent Sacramento River. We found similar results for multiple geographical areas in the Central Valley, and in different cover types, such as non-rice crops and fallow areas. Although field substrate type did not detectably affect fish growth and survival, connectivity with upstream and downstream areas appeared to drive fish occupancy, because rearing young salmon were generally attracted to inflow in the fields, and not all of the fish successfully emigrated off the fields without efficient drainage. In general, we faced numerous logistic and environmental challenges to complete our research. For example, periodic unmanaged floods in the Yolo Bypass made it difficult to schedule and complete experiments. During severe drought conditions, we found that managed agricultural habitats produced low and variable salmon survival results, likely because of periodically high temperatures and concentrated avian predation. In addition, our project required substantial landowner time and effort to install and maintain experimental fields. Recent and future infrastructure improvements in Yolo Bypass could substantially improve options for experimental work and broaden efforts to enhance salmon habitat.
{"title":"Farm to Fish: Lessons from a Multi-Year Study on Agricultural Floodplain Habitat","authors":"Ted R. Sommer, B. Schreier, J. Louise Conrad, L. Takata, Bjarni Serup, R. Titus, C. Jeffres, E. Holmes, Jacob V. E. Katz","doi":"10.15447/SFEWS.2020V18ISS3ART4","DOIUrl":"https://doi.org/10.15447/SFEWS.2020V18ISS3ART4","url":null,"abstract":"Large areas of California’s historic floodplain have been separated from adjacent river channels by levee construction, allowing the development of an extensive agricultural industry. Based on successful partnerships between agriculture and conservation groups to support migrating waterfowl, we examined whether seasonally flooded rice fields could be modified to provide off-channel rearing habitat for juvenile Chinook Salmon Oncorhynchus tshawytscha. During winter and spring of 2012-2017, we conducted a series of experiments in Yolo Bypass and other regions of California’s Central Valley using hatchery Chinook Salmon as a surrogate for wild Chinook Salmon, the management target for our project. Overall, we found that seasonally flooded fields are highly productive, resulting in significantly higher levels of zooplankton and high Chinook Salmon growth rates as compared to the adjacent Sacramento River. We found similar results for multiple geographical areas in the Central Valley, and in different cover types, such as non-rice crops and fallow areas. Although field substrate type did not detectably affect fish growth and survival, connectivity with upstream and downstream areas appeared to drive fish occupancy, because rearing young salmon were generally attracted to inflow in the fields, and not all of the fish successfully emigrated off the fields without efficient drainage. In general, we faced numerous logistic and environmental challenges to complete our research. For example, periodic unmanaged floods in the Yolo Bypass made it difficult to schedule and complete experiments. During severe drought conditions, we found that managed agricultural habitats produced low and variable salmon survival results, likely because of periodically high temperatures and concentrated avian predation. In addition, our project required substantial landowner time and effort to install and maintain experimental fields. Recent and future infrastructure improvements in Yolo Bypass could substantially improve options for experimental work and broaden efforts to enhance salmon habitat.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/SFEWS.2020V18ISS3ART4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44911683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-07DOI: 10.15447/SFEWS.2021V19ISS2ART3
C. Ghalambor, Edwin Grosholtz, E. Gross, K. Jeffries, J. Largier, S. McCormick, Ted R. Sommer, Johnathan Velotta, A. Whitehead
Climate change-driven sea level rise and altered precipitation regimes are predicted to alter patterns of salt intrusion within the San Francisco Estuary. A central question is: Can we use existing knowledge and future projections to predict and manage the anticipated ecological impacts? This was the subject of a 2018 symposium entitled “Ecological and Physiological Impacts of Salinization of Aquatic Systems from Human Activities.” The symposium brought together an inter-disciplinary group of scientists and researchers, resource managers, and policy-makers. Here, we summarize and review the presentations and discussions that arose during the symposium. From a historical perspective, salt intrusion has changed substantially over the past 10,000 years as a result of changing climate patterns, with additional shifts from recent anthropogenic effects. Current salinity patterns in the San Francisco Estuary are driven by a suite of hydrodynamic processes within the given contexts of water management and geography. Based on climate projections for the coming century, significant changes are expected in the processes that determine the spatial and temporal patterns of salinity. Given that native species—including fishes such as the Delta Smelt and Sacramento Splittail—track favorable habitats, exhibit physiological acclimation, and can adaptively evolve, we present a framework for assessing their vulnerability to altered salinity in the San Francisco Estuary. We then present a range of regulatory and structural management tools that are available to control patterns of salinity within the San Francisco Estuary. Finally, we identify major research priorities that can help fill critical gaps in our knowledge about future salinity patterns and the consequences of climate change and sea level rise. These research projects will be most effective with strong linkages and communication between scientists and researchers, resource managers, and policy-makers.
{"title":"Ecological Effects of Climate-Driven Salinity Variation in the San Francisco Estuary: Can We Anticipate and Manage the Coming Changes?","authors":"C. Ghalambor, Edwin Grosholtz, E. Gross, K. Jeffries, J. Largier, S. McCormick, Ted R. Sommer, Johnathan Velotta, A. Whitehead","doi":"10.15447/SFEWS.2021V19ISS2ART3","DOIUrl":"https://doi.org/10.15447/SFEWS.2021V19ISS2ART3","url":null,"abstract":"Climate change-driven sea level rise and altered precipitation regimes are predicted to alter patterns of salt intrusion within the San Francisco Estuary. A central question is: Can we use existing knowledge and future projections to predict and manage the anticipated ecological impacts? This was the subject of a 2018 symposium entitled “Ecological and Physiological Impacts of Salinization of Aquatic Systems from Human Activities.” The symposium brought together an inter-disciplinary group of scientists and researchers, resource managers, and policy-makers. Here, we summarize and review the presentations and discussions that arose during the symposium. From a historical perspective, salt intrusion has changed substantially over the past 10,000 years as a result of changing climate patterns, with additional shifts from recent anthropogenic effects. Current salinity patterns in the San Francisco Estuary are driven by a suite of hydrodynamic processes within the given contexts of water management and geography. Based on climate projections for the coming century, significant changes are expected in the processes that determine the spatial and temporal patterns of salinity. Given that native species—including fishes such as the Delta Smelt and Sacramento Splittail—track favorable habitats, exhibit physiological acclimation, and can adaptively evolve, we present a framework for assessing their vulnerability to altered salinity in the San Francisco Estuary. We then present a range of regulatory and structural management tools that are available to control patterns of salinity within the San Francisco Estuary. Finally, we identify major research priorities that can help fill critical gaps in our knowledge about future salinity patterns and the consequences of climate change and sea level rise. These research projects will be most effective with strong linkages and communication between scientists and researchers, resource managers, and policy-makers.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43279217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-07DOI: 10.15447/SFEWS.2021V19ISS2ART5
L. Mitchell, U. Fish, Randall D. Baxter
The Fall Midwater Trawl Survey has provided data on aquatic organisms in the San Francisco Estuary for over five decades. In 2014–2015, a study was conducted to investigate and quantify the efficiency of this trawl for catching the endangered fish species Delta Smelt (Hypomesus transpacificus). In an analysis based on that study, we calculated retention probability—the probability that a Delta Smelt is retained in the cod end of the trawl—as a function of fish length and fit a selectivity curve reflecting the relationship between size and retention. Here we return to the same gear efficiency study and further utilize the data set by (1) fitting selectivity curves for three additional pelagic fish species: Threadfin Shad (Dorosoma petenense), American Shad (Alosa sapidissima), and Mississippi Silverside (Menidia beryllina), (2) refitting the selectivity curve for Delta Smelt to incorporate between-haul variability, and (3) calculating the lengths of 50% and 95% retention in order to characterize and compare the resulting selectivity curves. We also present retention data on age-0 Striped Bass (Morone saxatilis), all of which were retained in the cod end. We found that Threadfin Shad, American Shad, and Delta Smelt are 95% retained at 45, 49, and 61 mm fork length, respectively. Because data were limited for Mississippi Silverside, American Shad, and age-0 Striped Bass, we used body shape, in conjunction with retention data, to develop hypotheses about selectivity based on whether each species’ body shape resembles that of Threadfin Shad, which are more deep-bodied and laterally compressed, or Delta Smelt, which are more fusiform. We also found that retention-at-length was more variable for Delta Smelt than for Threadfin Shad, potentially because length is a good predictor of retention in deep-bodied, laterally compressed fish whereas maximum girth is a better predictor of retention in fusiform fish.
秋季中水拖网调查提供了旧金山河口50多年来水生生物的数据。2014-2015年，研究人员对这种拖网捕捞濒危鱼类三角洲胡瓜鱼的效率进行了调查和量化。在基于该研究的分析中，我们计算了保留概率——三角洲甜瓜在拖网的鳕鱼末端被保留的概率——作为鱼长度的函数，并拟合了一条反映大小和保留之间关系的选择性曲线。在这里，我们回到相同的渔具效率研究，并进一步利用数据集:(1)拟合另外三种中游鱼类的选择性曲线:Threadfin Shad (Dorosoma petenense)， American Shad (Alosa sapidissima)和Mississippi Silverside (Menidia beryllina);(2)重新调整Delta Smelt的选择性曲线，以纳入运输之间的变化;(3)计算50%和95%保留的长度，以表征和比较所得的选择性曲线。我们还提供了0岁条纹鲈鱼(Morone saxatilis)的保留数据，所有这些数据都保留在鳕鱼端。我们发现Threadfin Shad, American Shad和Delta Smelt分别在45,49和61 mm叉长时保留了95%。由于密西西比银鱼、美国鲥鱼和0岁条纹鲈鱼的数据有限，我们使用身体形状，结合保留数据，根据每个物种的身体形状是否与Threadfin Shad(身体更深，横向压缩)或Delta Smelt(身体更梭状)相似，来提出关于选择性的假设。我们还发现，与长尾鱼相比，长尾鱼的保留率变化更大，这可能是因为长度是深身、侧向压缩鱼类保留率的良好预测指标，而最大周长是梭状鱼保留率的更好预测指标。
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Pub Date : 2020-06-07DOI: 10.15447/SFEWS.2021V19ISS2ART6
Brock M. Huntsman, Fredrick Feyrer, M. Young
Resource managers often rely on long-term monitoring surveys to detect trends in biological data. However, no survey gear is 100% efficient, and many sources of bias can be responsible for detecting or not detecting biological trends. The SmeltCam is an imaging apparatus developed as a potential sampling alternative to long-term trawling gear surveys within the San Francisco Estuary, California, to reduce handling stress on sensitive species like the Delta Smelt (Hypomesus transpacificus). Although believed to be a reliable alternative to closed cod-end trawling surveys, no formal test of sampling efficiency has been implemented using the SmeltCam. We used a paired deployment of the SmeltCam and a conventional closed cod-end trawl within the Napa River and San Pablo Bay, a Bayesian binomial N-mixture model, and data simulations to determine the sampling efficiency of both deployed gear types to capture a Delta Smelt surrogate (Northern Anchovy, Engraulis mordax) and to test potential bias in our modeling framework. We found that retention efficiency—a component of detection efficiency that estimates the probability a fish is retained by the gear, conditional on gear contact—was slightly higher using the SmeltCam (mean = 0.58) than the conventional trawl (mean = 0.47, Probability SmeltCam retention efficiency > trawl retention efficiency = 94%). We also found turbidity did not affect the SmeltCam’s retention efficiency, although total fish density during an individual tow improved the trawl’s retention efficiency. Simulations also showed the binomial model was accurate when model assumptions were met. Collectively, our results suggest the SmeltCam to be a reliable alternative to sampling with conventional trawling gear, but future tests are needed to confirm whether the SmeltCam is as reliable when applied to taxa other than Northern Anchovy over a greater range of conditions.
{"title":"Use of the SmeltCam as an Efficient Fish Sampling Alternative Within the San Francisco Estuary","authors":"Brock M. Huntsman, Fredrick Feyrer, M. Young","doi":"10.15447/SFEWS.2021V19ISS2ART6","DOIUrl":"https://doi.org/10.15447/SFEWS.2021V19ISS2ART6","url":null,"abstract":"Resource managers often rely on long-term monitoring surveys to detect trends in biological data. However, no survey gear is 100% efficient, and many sources of bias can be responsible for detecting or not detecting biological trends. The SmeltCam is an imaging apparatus developed as a potential sampling alternative to long-term trawling gear surveys within the San Francisco Estuary, California, to reduce handling stress on sensitive species like the Delta Smelt (Hypomesus transpacificus). Although believed to be a reliable alternative to closed cod-end trawling surveys, no formal test of sampling efficiency has been implemented using the SmeltCam. We used a paired deployment of the SmeltCam and a conventional closed cod-end trawl within the Napa River and San Pablo Bay, a Bayesian binomial N-mixture model, and data simulations to determine the sampling efficiency of both deployed gear types to capture a Delta Smelt surrogate (Northern Anchovy, Engraulis mordax) and to test potential bias in our modeling framework. We found that retention efficiency—a component of detection efficiency that estimates the probability a fish is retained by the gear, conditional on gear contact—was slightly higher using the SmeltCam (mean = 0.58) than the conventional trawl (mean = 0.47, Probability SmeltCam retention efficiency > trawl retention efficiency = 94%). We also found turbidity did not affect the SmeltCam’s retention efficiency, although total fish density during an individual tow improved the trawl’s retention efficiency. Simulations also showed the binomial model was accurate when model assumptions were met. Collectively, our results suggest the SmeltCam to be a reliable alternative to sampling with conventional trawling gear, but future tests are needed to confirm whether the SmeltCam is as reliable when applied to taxa other than Northern Anchovy over a greater range of conditions.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45853538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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