Archives of environmental contamination and toxicology, 2017
The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including hist... more The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including historic and chronic contaminant inputs. These contaminants can adversely affect SFE fish populations, particularly white sturgeon, because they are a benthic dwelling, long-lived species. We measured a suite of metals and organic contaminants in liver and gonad tissues of 25 male and 32 female white sturgeon as well as several physiological indicators of sturgeon health. Most sturgeon (68% of males and 83% of females) were estimated to be between 13 and 17 years of age. Sturgeon tissues had elevated concentrations of several metals, including As, Ba, Cd, Cu, Cr, Pb, Hg, Ni, Se, and Zn. The most frequently detected organic contaminants in sturgeon livers and gonads were DDE, PCBs, PBDEs, and galaxolide. Selenium was detected at levels similar to those shown to cause impaired liver physiology and reproductive success in white sturgeon. Observed Hg levels were higher than those shown to result...
Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian... more Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian sturgeon Acipenser baerii swimming performance are unknown. Therefore, the effects of two fin ray biopsy methods on swimming performance of hatchery-reared, juvenile Siberian sturgeon were evaluated in this study. Treatment fish were subjected to one of two biopsy methods: removal of a 2- to 4-cm section from a marginal pectoral fin ray, or full removal of a marginal pectoral fin ray. Control fish were only subjected to a sham operation. A modified 2,936-l Brett-type swim tunnel was used to evaluate 10-min critical station-holding speeds (CSHS) and behavioral swimming characteristics of sturgeon immediately after fin ray biopsies were carried out. Fish sizes (range 65- to 84-cm fork length) were comparable among treatments. Mean 10-min CSHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and 111 ± 2.8 cm s−1 for the segment removal treatment, full removal treatment, and control treatment, respectively. ANOVA indicated that the two methods had no significant effect on the 10-min CSHS of Siberian sturgeon compared to the control treatment. Results indicate that fin ray removal has no effect on Siberian sturgeon swimming performance.
Transactions of the American Fisheries Society, 2017
AbstractThe objective of this study was to validate the use of fin ray strontium isotope ratios (... more AbstractThe objective of this study was to validate the use of fin ray strontium isotope ratios (87Sr:86Sr) via laser ablation (LA) to resolve fine-scale movement patterns in sturgeons (Acipenseridae) during freshwater rearing in early life stages. We conducted a laboratory experiment in which juvenile White Sturgeon Acipenser transmontanus were exposed to two water sources exhibiting distinctive 87Sr:86Sr isotope values (American River and Putah Creek, California) over weekly time periods to understand how water exposure histories are archived in pectoral fin rays. Using LA multicollector inductively coupled plasma mass spectrometry with a laser diameter of 65 µm, we detected distinct shifts in fin ray 87Sr:86Sr values to match a water source in fish that were exposed for 2, 4, 6, and 12 weeks. Fin ray 87Sr:86Sr values matched the new water source after 21.7 d (SD = 7.8; range = 11–36 d) of exposure. The lower limit of this estimate was constrained by the rate of fin ray growth as well as the LA spot siz...
Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Effo... more Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Efforts to understand and address the processes that regulate recruitment are of foremost importance for successful management and recovery. Fish biologists previously only knew San Francisco Estuary white sturgeon (Acipenser transmontanus) to spawn in the Sacramento River, California. We assessed potential white sturgeon spawning locations by deploying artificial substrate samplers during late winter and spring of 2011 and 2012 from river kilometers 115.2 to 145.3 of the San Joaquin River. Collections of fertilized eggs, coupled with hydrology data, confirm that white sturgeon spawned within one and four sites in the San Joaquin River during wet (2011; n = 23) and dry (2012; n = 65) water-year conditions. Small pulse flow augmentations intended to benefit juvenile salmonids appear to have triggered white sturgeon spawning within this system. Understanding the effects of water management on ...
Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluat... more Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluated for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to either a notch removal treatment in which a small section was removed from an anterior marginal pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed. Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified 3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH ) of A. transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and growth were evaluated over a 6 month period for a separate group of fish subjected to the same biopsy methods. Mean ± S.E. 10 min SCSH were 108·0 ± 2·3, 110·0 ± 2·6 and 115·0 ± 3·5 cm s(-1) for the notch removal group, full removal group and control group, respectively, and were not significantly different among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering were also not significantly different among treatment groups swimming at the same speeds. There were no mortalities and relative growth was similar among treatment groups. Average biopsy time for the notch removal method was lower and the wounds appeared to heal more quickly compared with the full removal method.
The goal of a day-long symposium on March 3, 2015, Sturgeon in the Sacramento-San Joaquin Watersh... more The goal of a day-long symposium on March 3, 2015, Sturgeon in the Sacramento-San Joaquin Watershed: New Insights to Support Conservation and Management, was to present new information about the physiology, behavior, and ecology of the green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) to help guide enhanced management and conservation efforts within the Sacramento-San Joaquin watershed. This symposium identified current unknowns and highlighted new electronic tracking technologies and physiological techniques to address these knowledge gaps. A number of presentations, each reviewing ongoing research on the two species, was followed by a round-table discussion, in which each of the participants was asked to share recommendations for future research on sturgeon in the watershed. This article presents an in-depth review of the scientific information presented at the symposium with a summary of recommendations for future research.
ABSTRACT We evaluated the influence of lake morphometry, water quality, and common carp Cyprinus ... more ABSTRACT We evaluated the influence of lake morphometry, water quality, and common carp Cyprinus carpio and largemouth bass Micropterus salmoides popu-lation structure on quality black crappie Pomoxis nigromaculatus and bluegill Lep-omis macrochirus populations for 20 Iowa impoundments. Growth of black crappie was positively related to growth of largemouth bass. Black crappie catch per unit effort (CPUE) was positively associated with watershed size and alkalin-ity and negatively related to largemouth bass growth. Size structure of bluegill populations was positively influenced by chlorophyll concentrations and large-mouth bass catch rates. Total phosphorus and CPUE of stock-to-quality length largemouth bass were also positively related to bluegill growth. Bluegill CPUE was inversely related to largemouth bass growth. Quality largemouth bass popu-lations were allied with turbid (high total suspended solids and low Secchi disk depth) impoundments that had a diverse shoreline and large watersheds. Large-mouth bass growth was inversely related to mean depth, and largemouth bass CPUE was inversely related to alkalinity and total suspended solids. Information from this study will be used to classify and rank impoundments in terms of their management priorities. Based on impoundment morphometry and water quality, managers can then target management practices toward species best suited to a particular impoundment.
North American Journal of Fisheries Management, 2007
The mountain whitefish (Prosopium williamsoni) is native to western North America and occupies a ... more The mountain whitefish (Prosopium williamsoni) is native to western North America and occupies a diversity of lentic and lotic systems from the McKenzie River in British Columbia, Canada, to the Colorado River in the United States (Behnke 2002). Compared to other salmonid species, mountain whitefish are not a popular game fish, thereby resulting in low interest in mountain whitefish populations by management agencies (Northcote and Ennis 1994). Historically, anglers have speculated that interspecific competition existed between mountain whitefish and other, more desirable, salmonid species (Overton et al. 1978). Although this speculation has been unsubstantiated, the negative perception of mountain whitefish has led some management agencies to deplete mountain whitefish populations to reduce perceived competitive interactions with trout (Corsi 1956, Erickson 1971). Overall, little research has focused on mountain whitefish populations (Northcote and Ennis 1994, Meyer
We examined fish populations, limnological conditions, lake basin morphology and watershed charac... more We examined fish populations, limnological conditions, lake basin morphology and watershed characteristics to evaluate patterns in population characteristics of ecologically important fish species in relation to environmental conditions in agriculturally eutrophic lake systems. Fish populations and environmental characteristics were sampled from 129 Iowa lakes using standard techniques from 2001-2006. Lakes with high catch rates of common carp (Cyprinus carpio) had high nutrient concentrations, high phytoplankton biomass and low water transparency. In addition, lakes with high catch rates of common carp had low catch rates of important sport fishes including bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis). The relationship between common carp and sport fishes appeared to function as an ecological threshold. Specifically, when common carp catch rates were >2 kilograms per fyke net night, catch rates of sport fish were always low and water quality in the study lakes was poor. Shallow systems (natural lakes, oxbows) had higher densities of common carp compared to deeper systems (impoundments, surface mines), thereby suggesting that shallow lakes are most sensitive to the effects of common carp and that restoration efforts incorporating biomanipulation of common carp will likely be most successful in shallow systems.
Precision of Scales and Dorsal Spines for Estimating Age of Common Carp Zachary J. Jackson and Mi... more Precision of Scales and Dorsal Spines for Estimating Age of Common Carp Zachary J. Jackson and Michael C. Quist Department of ... several studies have reported that scales tend to underestimate fish age (eg, Marwitz and Hubert 1995, Kocovsky and Carline 2000, lsermann ...
Standard methods for comparing population characteristics within and among fish populations great... more Standard methods for comparing population characteristics within and among fish populations greatly enhance communications among fisheries scientists, improve the efficiency of data analysis, and provide insight that helps guide management actions. Although standard methods are available for comparing some fish population characteristics (e.g. length structure, body condition), similar methods are lacking for comparing growth. The purpose of this study was to provide standards (i.e. percentiles and a standard growth model) for nine ecologically and recreationally important fish species. Percentile distributions of mean back-calculated length at age were estimated using data obtained from the published literature and from data solicited from state and federal agencies throughout North America. Percentiles of growth were estimated for bluegill, Lepomis macrochirus Rafinesque, common carp, Cyprinus carpio Linnaeus, flathead catfish, Pylodictis olivaris (Rafinesque), largemouth bass, Micropterus salmoides (Lacepe`de), sauger, Sander canadensis (Griffith & Smith), smallmouth bass, Micropterus dolomieu Lacepe`de, white bass, Morone chrysops (Rafinesque) and yellow perch, Perca flavescens (Mitchill). Standard growth models (i.e. von Bertalanffy models) were developed for these species and for channel catfish, Ictalurus punctatus (Rafinesque). These results provide tools that will help scientists compare growth of fishes across North America.
Common carp Cyprinus carpio occurs in several non-native areas worldwide, where it is generally r... more Common carp Cyprinus carpio occurs in several non-native areas worldwide, where it is generally regarded as either naturalised or invasive. Anatolia (Turkey) represents a unique region for evaluating common carp growth, due both to its location at the southernmost range of expansion of the species' wild form and to most of its water bodies having been stocked with domesticated strains. Based on a review of length-at-age data for common carp stocks from 45 water bodies sampled between 1953 and 2007, regional patterns in growth across climates, water body types, scalation variants and sexes, along with altitudinal gradients in growth performance and mortality, were investigated. Growth rates were lower in cold and arid relative to temperate climates, and also under hot or dry summers; this was true also of the mirror relative to the scale variant, males to females, but not of water body types (i.e., man-made reservoirs, natural lakes, water courses). Growth performance and mortality decreased with increasing altitude and decreasing temperature, likely due to optimisation of resource allocation between growth and reproduction. Growth rate of common carp from Anatolia was consistently lower compared to its native (Eurasian) and, especially, invasive (North American) counterparts, which reflected an opportunistic life-history strategy. Lower growth rates in Anatolia were ascribed to lower resilience of the widespread mirror variant together with limited habitat for spawning in man-made reservoirs. Better knowledge of common carp growth in Anatolia will improve stock management and conservation efforts. Further studies will help clarify the mechanisms responsible for evolutionary genotype–phenotype inter-relationships.
Fin ray biopsies are commonly used to age sturgeon,
but the effects of fin ray biopsy on Siberian... more Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian sturgeon Acipenser baerii swimming performance are unknown. Therefore, the effects of two fin ray biopsy methods on swimming performance of hatchery-reared, juvenile Siberian sturgeon were evaluated in this study. Treatment fish were subjected to one of two biopsy methods: removal of a 2- to 4-cm section from a marginal pectoral fin ray, or full removal of a marginal pectoral fin ray. Control fish were only subjected to a sham operation. A modified 2,936-l Brett-type swim tunnel was used to evaluate 10-min critical station-holding speeds (CSHS) and behavioral swimming characteristics of sturgeon immediately after fin ray biopsies were carried out. Fish sizes (range 65- to 84-cm fork length) were comparable among treatments. Mean 10-min CSHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and 111 ± 2.8 cm s−1 for the segment removal treatment, full removal treatment, and control treatment, respectively. ANOVA indicated that the two methods had no significant effect on the 10-min CSHS of Siberian sturgeon compared to the control treatment. Results indicate that fin ray removal has no effect on Siberian sturgeon swimming performance.
The objective of this study was to validate the use of fin ray strontium isotope ratios (87Sr:86S... more The objective of this study was to validate the use of fin ray strontium isotope ratios (87Sr:86Sr) via laser ablation (LA) to resolve fine-scale movement patterns in sturgeons (Acipenseridae) during freshwater rearing in early life stages. We conducted a laboratory experiment in which juvenile White Sturgeon Acipenser transmontanus were exposed to two water sources exhibiting distinctive 87Sr:86Sr isotope values (American River and Putah Creek, California) over weekly time periods to understand how water exposure histories are archived in pectoral fin rays. Using LA multicollector inductively coupled plasma mass spectrometry with a laser diameter of 65 μm, we detected distinct shifts in fin ray 87Sr:86Sr values to match a water source in fish that were exposed for 2, 4, 6, and 12 weeks. Fin ray 87Sr:86Sr values matched the new water source after 21.7 d (SD = 7.8; range = 11–36 d) of exposure. The lower limit of this estimate was constrained by the rate of fin ray growth as well as the LA spot size. Additionally, we assessed how diet affected fin ray 87Sr:86Sr values by feeding a marine-derived pellet feed commonly used in aquaculture to a subset of White Sturgeon, while others were fed a diet consisting of fish with 87Sr:86Sr values that matched their respective water source. Generally, we observed only a minor influence of diet, but there was some variability across individual fish in the effect of diet on the resulting fin ray 87Sr:86Sr value. As with any geochemical analytical technique, fin ray microchemistry has some limitations related to individual variability in fin ray growth and development; however, it is a promising approach to reconstructing sturgeon migratory history by using a nonlethal sampling method.
The goal for using genetic information derived from embryo samples is to gain insight into the re... more The goal for using genetic information derived from embryo samples is to gain insight into the reproductive biology of adult white sturgeon, Acipenser transmontanus Richardson. The relationship between egg development stages on the extraction of quality DNA was determined, and subsequent genotype data were used to infer contributing spawner numbers. White sturgeon DNA was present in extractions from all stages; however, pre-gastrulation stage embryos generally failed to amplify sufficient genetic loci for analysis. Using experimentally created families, multivariate ANOVA and maximum-likelihood sibship methods estimated the presence of 10 contributing parents from 11 actual adult spawners. It was observed that unidentified half-sibling relationships (offspring sharing one parent) caused error for inferring parent numbers. Genetic methods estimated 13–40 parents potentially contributed to a collection of wild-caught embryos, with variable numbers of parents inferred from separate spawning events (varying from 8 to 24). Egg source material provides a means to enhance the accuracy of annual spawning population size estimates, which is important for informing habitat restoration, harvest and water management decisions and recovery planning.
The San Francisco Estuary (SFE) is heavily
influenced by anthropogenic activities, including hist... more The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including historic and chronic contaminant inputs. These contaminants can adversely affect SFE fish populations, particularly white sturgeon, because they are a benthic dwelling, long-lived species. We measured a suite of metals and organic contaminants in liver and gonad tissues of 25 male and 32 female white sturgeon as well as several physiological indicators of sturgeon health. Most sturgeon (68% of males and 83% of females) were estimated to be between 13 and 17 years of age. Sturgeon tissues had elevated concentrations of several metals, including As, Ba, Cd, Cu, Cr, Pb, Hg, Ni, Se, and Zn. The most frequently detected organic contaminants in sturgeon livers and gonads were DDE, PCBs, PBDEs, and galaxolide. Selenium was detected at levels similar to those shown to cause impaired liver physiology and reproductive success in white sturgeon. Observed Hg levels were higher than those shown to result in lower condition factor and gonadosomatic indices in white sturgeon. Liver galaxolide levels correlated with decreased plasma estradiol levels in female sturgeon. The Cd, As, and Cu warrant further investigation, because they were detected at levels known to impair fish health. Our results suggest contaminants are negatively affecting SFE white sturgeon health and fitness. Future SFE white sturgeon contaminant research is suggested.
Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Effo... more Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Efforts to understand and address the processes that regulate recruitment are of foremost importance for successful management and recovery. Fish biologists previously only knew San Francisco Estuary white sturgeon (Acipenser transmontanus) to spawn in the Sacramento River, California. We assessed potential white sturgeon spawning locations by deploying artificial substrate samplers during late winter and spring of 2011 and 2012 from river kilometers 115.2 to 145.3 of the San Joaquin River. Collections of fertilized eggs, coupled with hydrology data, confirm that white sturgeon spawned within one and four sites in the San Joaquin River during wet (2011; n ¼ 23) and dry (2012; n ¼ 65) water-year conditions. Small pulse flow augmentations intended to benefit juvenile salmonids appear to have triggered white sturgeon spawning within this system. Understanding the effects of water management on spawning and subsequent recruitment is necessary to increase white sturgeon recruitment to the San Francisco Estuary.
Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluat... more Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluated for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to either a notch removal treatment in which a small section was removed from an anterior marginal pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed. Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified 3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH) of A. transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and growth were evaluated over a 6month period for a separate group of fish subjected to the same biopsy methods. Mean±s.e. 10 min SCSH were 108⋅0±2⋅3, 110⋅0±2⋅6 and 115⋅0±3⋅5 cms−1 for the notch removal group, full removal group and control group, respectively, and were not significantly different among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering were also not significantly different among treatment groups swimming at the same speeds. There were no mortalities and relative growth was similar among treatment groups. Average biopsy time for the notch removal method was lower and the wounds appeared to heal more quickly compared with the full removal method.
The goal of a day-long symposium on March 3,
2015, Sturgeon in the Sacramento–San Joaquin
Watersh... more The goal of a day-long symposium on March 3, 2015, Sturgeon in the Sacramento–San Joaquin Watershed: New Insights to Support Conservation and Management, was to present new information about the physiology, behavior, and ecology of the green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) to help guide enhanced management and conservation efforts within the Sacramento–San Joaquin watershed. This symposium identified current unknowns and highlighted new electronic tracking technologies and physiological techniques to address these knowledge gaps. A number of presentations, each reviewing ongoing research on the two species, was followed by a round-table discussion, in which each of the participants was asked to share recommendations for future research on sturgeon in the watershed. This article presents an in-depth review of the scientific information presented at the symposium with a summary of recommendations for future research.
Archives of environmental contamination and toxicology, 2017
The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including hist... more The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including historic and chronic contaminant inputs. These contaminants can adversely affect SFE fish populations, particularly white sturgeon, because they are a benthic dwelling, long-lived species. We measured a suite of metals and organic contaminants in liver and gonad tissues of 25 male and 32 female white sturgeon as well as several physiological indicators of sturgeon health. Most sturgeon (68% of males and 83% of females) were estimated to be between 13 and 17 years of age. Sturgeon tissues had elevated concentrations of several metals, including As, Ba, Cd, Cu, Cr, Pb, Hg, Ni, Se, and Zn. The most frequently detected organic contaminants in sturgeon livers and gonads were DDE, PCBs, PBDEs, and galaxolide. Selenium was detected at levels similar to those shown to cause impaired liver physiology and reproductive success in white sturgeon. Observed Hg levels were higher than those shown to result...
Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian... more Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian sturgeon Acipenser baerii swimming performance are unknown. Therefore, the effects of two fin ray biopsy methods on swimming performance of hatchery-reared, juvenile Siberian sturgeon were evaluated in this study. Treatment fish were subjected to one of two biopsy methods: removal of a 2- to 4-cm section from a marginal pectoral fin ray, or full removal of a marginal pectoral fin ray. Control fish were only subjected to a sham operation. A modified 2,936-l Brett-type swim tunnel was used to evaluate 10-min critical station-holding speeds (CSHS) and behavioral swimming characteristics of sturgeon immediately after fin ray biopsies were carried out. Fish sizes (range 65- to 84-cm fork length) were comparable among treatments. Mean 10-min CSHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and 111 ± 2.8 cm s−1 for the segment removal treatment, full removal treatment, and control treatment, respectively. ANOVA indicated that the two methods had no significant effect on the 10-min CSHS of Siberian sturgeon compared to the control treatment. Results indicate that fin ray removal has no effect on Siberian sturgeon swimming performance.
Transactions of the American Fisheries Society, 2017
AbstractThe objective of this study was to validate the use of fin ray strontium isotope ratios (... more AbstractThe objective of this study was to validate the use of fin ray strontium isotope ratios (87Sr:86Sr) via laser ablation (LA) to resolve fine-scale movement patterns in sturgeons (Acipenseridae) during freshwater rearing in early life stages. We conducted a laboratory experiment in which juvenile White Sturgeon Acipenser transmontanus were exposed to two water sources exhibiting distinctive 87Sr:86Sr isotope values (American River and Putah Creek, California) over weekly time periods to understand how water exposure histories are archived in pectoral fin rays. Using LA multicollector inductively coupled plasma mass spectrometry with a laser diameter of 65 µm, we detected distinct shifts in fin ray 87Sr:86Sr values to match a water source in fish that were exposed for 2, 4, 6, and 12 weeks. Fin ray 87Sr:86Sr values matched the new water source after 21.7 d (SD = 7.8; range = 11–36 d) of exposure. The lower limit of this estimate was constrained by the rate of fin ray growth as well as the LA spot siz...
Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Effo... more Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Efforts to understand and address the processes that regulate recruitment are of foremost importance for successful management and recovery. Fish biologists previously only knew San Francisco Estuary white sturgeon (Acipenser transmontanus) to spawn in the Sacramento River, California. We assessed potential white sturgeon spawning locations by deploying artificial substrate samplers during late winter and spring of 2011 and 2012 from river kilometers 115.2 to 145.3 of the San Joaquin River. Collections of fertilized eggs, coupled with hydrology data, confirm that white sturgeon spawned within one and four sites in the San Joaquin River during wet (2011; n = 23) and dry (2012; n = 65) water-year conditions. Small pulse flow augmentations intended to benefit juvenile salmonids appear to have triggered white sturgeon spawning within this system. Understanding the effects of water management on ...
Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluat... more Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluated for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to either a notch removal treatment in which a small section was removed from an anterior marginal pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed. Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified 3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH ) of A. transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and growth were evaluated over a 6 month period for a separate group of fish subjected to the same biopsy methods. Mean ± S.E. 10 min SCSH were 108·0 ± 2·3, 110·0 ± 2·6 and 115·0 ± 3·5 cm s(-1) for the notch removal group, full removal group and control group, respectively, and were not significantly different among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering were also not significantly different among treatment groups swimming at the same speeds. There were no mortalities and relative growth was similar among treatment groups. Average biopsy time for the notch removal method was lower and the wounds appeared to heal more quickly compared with the full removal method.
The goal of a day-long symposium on March 3, 2015, Sturgeon in the Sacramento-San Joaquin Watersh... more The goal of a day-long symposium on March 3, 2015, Sturgeon in the Sacramento-San Joaquin Watershed: New Insights to Support Conservation and Management, was to present new information about the physiology, behavior, and ecology of the green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) to help guide enhanced management and conservation efforts within the Sacramento-San Joaquin watershed. This symposium identified current unknowns and highlighted new electronic tracking technologies and physiological techniques to address these knowledge gaps. A number of presentations, each reviewing ongoing research on the two species, was followed by a round-table discussion, in which each of the participants was asked to share recommendations for future research on sturgeon in the watershed. This article presents an in-depth review of the scientific information presented at the symposium with a summary of recommendations for future research.
ABSTRACT We evaluated the influence of lake morphometry, water quality, and common carp Cyprinus ... more ABSTRACT We evaluated the influence of lake morphometry, water quality, and common carp Cyprinus carpio and largemouth bass Micropterus salmoides popu-lation structure on quality black crappie Pomoxis nigromaculatus and bluegill Lep-omis macrochirus populations for 20 Iowa impoundments. Growth of black crappie was positively related to growth of largemouth bass. Black crappie catch per unit effort (CPUE) was positively associated with watershed size and alkalin-ity and negatively related to largemouth bass growth. Size structure of bluegill populations was positively influenced by chlorophyll concentrations and large-mouth bass catch rates. Total phosphorus and CPUE of stock-to-quality length largemouth bass were also positively related to bluegill growth. Bluegill CPUE was inversely related to largemouth bass growth. Quality largemouth bass popu-lations were allied with turbid (high total suspended solids and low Secchi disk depth) impoundments that had a diverse shoreline and large watersheds. Large-mouth bass growth was inversely related to mean depth, and largemouth bass CPUE was inversely related to alkalinity and total suspended solids. Information from this study will be used to classify and rank impoundments in terms of their management priorities. Based on impoundment morphometry and water quality, managers can then target management practices toward species best suited to a particular impoundment.
North American Journal of Fisheries Management, 2007
The mountain whitefish (Prosopium williamsoni) is native to western North America and occupies a ... more The mountain whitefish (Prosopium williamsoni) is native to western North America and occupies a diversity of lentic and lotic systems from the McKenzie River in British Columbia, Canada, to the Colorado River in the United States (Behnke 2002). Compared to other salmonid species, mountain whitefish are not a popular game fish, thereby resulting in low interest in mountain whitefish populations by management agencies (Northcote and Ennis 1994). Historically, anglers have speculated that interspecific competition existed between mountain whitefish and other, more desirable, salmonid species (Overton et al. 1978). Although this speculation has been unsubstantiated, the negative perception of mountain whitefish has led some management agencies to deplete mountain whitefish populations to reduce perceived competitive interactions with trout (Corsi 1956, Erickson 1971). Overall, little research has focused on mountain whitefish populations (Northcote and Ennis 1994, Meyer
We examined fish populations, limnological conditions, lake basin morphology and watershed charac... more We examined fish populations, limnological conditions, lake basin morphology and watershed characteristics to evaluate patterns in population characteristics of ecologically important fish species in relation to environmental conditions in agriculturally eutrophic lake systems. Fish populations and environmental characteristics were sampled from 129 Iowa lakes using standard techniques from 2001-2006. Lakes with high catch rates of common carp (Cyprinus carpio) had high nutrient concentrations, high phytoplankton biomass and low water transparency. In addition, lakes with high catch rates of common carp had low catch rates of important sport fishes including bluegill (Lepomis macrochirus), largemouth bass (Micropterus salmoides), black crappie (Pomoxis nigromaculatus) and white crappie (P. annularis). The relationship between common carp and sport fishes appeared to function as an ecological threshold. Specifically, when common carp catch rates were >2 kilograms per fyke net night, catch rates of sport fish were always low and water quality in the study lakes was poor. Shallow systems (natural lakes, oxbows) had higher densities of common carp compared to deeper systems (impoundments, surface mines), thereby suggesting that shallow lakes are most sensitive to the effects of common carp and that restoration efforts incorporating biomanipulation of common carp will likely be most successful in shallow systems.
Precision of Scales and Dorsal Spines for Estimating Age of Common Carp Zachary J. Jackson and Mi... more Precision of Scales and Dorsal Spines for Estimating Age of Common Carp Zachary J. Jackson and Michael C. Quist Department of ... several studies have reported that scales tend to underestimate fish age (eg, Marwitz and Hubert 1995, Kocovsky and Carline 2000, lsermann ...
Standard methods for comparing population characteristics within and among fish populations great... more Standard methods for comparing population characteristics within and among fish populations greatly enhance communications among fisheries scientists, improve the efficiency of data analysis, and provide insight that helps guide management actions. Although standard methods are available for comparing some fish population characteristics (e.g. length structure, body condition), similar methods are lacking for comparing growth. The purpose of this study was to provide standards (i.e. percentiles and a standard growth model) for nine ecologically and recreationally important fish species. Percentile distributions of mean back-calculated length at age were estimated using data obtained from the published literature and from data solicited from state and federal agencies throughout North America. Percentiles of growth were estimated for bluegill, Lepomis macrochirus Rafinesque, common carp, Cyprinus carpio Linnaeus, flathead catfish, Pylodictis olivaris (Rafinesque), largemouth bass, Micropterus salmoides (Lacepe`de), sauger, Sander canadensis (Griffith & Smith), smallmouth bass, Micropterus dolomieu Lacepe`de, white bass, Morone chrysops (Rafinesque) and yellow perch, Perca flavescens (Mitchill). Standard growth models (i.e. von Bertalanffy models) were developed for these species and for channel catfish, Ictalurus punctatus (Rafinesque). These results provide tools that will help scientists compare growth of fishes across North America.
Common carp Cyprinus carpio occurs in several non-native areas worldwide, where it is generally r... more Common carp Cyprinus carpio occurs in several non-native areas worldwide, where it is generally regarded as either naturalised or invasive. Anatolia (Turkey) represents a unique region for evaluating common carp growth, due both to its location at the southernmost range of expansion of the species' wild form and to most of its water bodies having been stocked with domesticated strains. Based on a review of length-at-age data for common carp stocks from 45 water bodies sampled between 1953 and 2007, regional patterns in growth across climates, water body types, scalation variants and sexes, along with altitudinal gradients in growth performance and mortality, were investigated. Growth rates were lower in cold and arid relative to temperate climates, and also under hot or dry summers; this was true also of the mirror relative to the scale variant, males to females, but not of water body types (i.e., man-made reservoirs, natural lakes, water courses). Growth performance and mortality decreased with increasing altitude and decreasing temperature, likely due to optimisation of resource allocation between growth and reproduction. Growth rate of common carp from Anatolia was consistently lower compared to its native (Eurasian) and, especially, invasive (North American) counterparts, which reflected an opportunistic life-history strategy. Lower growth rates in Anatolia were ascribed to lower resilience of the widespread mirror variant together with limited habitat for spawning in man-made reservoirs. Better knowledge of common carp growth in Anatolia will improve stock management and conservation efforts. Further studies will help clarify the mechanisms responsible for evolutionary genotype–phenotype inter-relationships.
Fin ray biopsies are commonly used to age sturgeon,
but the effects of fin ray biopsy on Siberian... more Fin ray biopsies are commonly used to age sturgeon, but the effects of fin ray biopsy on Siberian sturgeon Acipenser baerii swimming performance are unknown. Therefore, the effects of two fin ray biopsy methods on swimming performance of hatchery-reared, juvenile Siberian sturgeon were evaluated in this study. Treatment fish were subjected to one of two biopsy methods: removal of a 2- to 4-cm section from a marginal pectoral fin ray, or full removal of a marginal pectoral fin ray. Control fish were only subjected to a sham operation. A modified 2,936-l Brett-type swim tunnel was used to evaluate 10-min critical station-holding speeds (CSHS) and behavioral swimming characteristics of sturgeon immediately after fin ray biopsies were carried out. Fish sizes (range 65- to 84-cm fork length) were comparable among treatments. Mean 10-min CSHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and 111 ± 2.8 cm s−1 for the segment removal treatment, full removal treatment, and control treatment, respectively. ANOVA indicated that the two methods had no significant effect on the 10-min CSHS of Siberian sturgeon compared to the control treatment. Results indicate that fin ray removal has no effect on Siberian sturgeon swimming performance.
The objective of this study was to validate the use of fin ray strontium isotope ratios (87Sr:86S... more The objective of this study was to validate the use of fin ray strontium isotope ratios (87Sr:86Sr) via laser ablation (LA) to resolve fine-scale movement patterns in sturgeons (Acipenseridae) during freshwater rearing in early life stages. We conducted a laboratory experiment in which juvenile White Sturgeon Acipenser transmontanus were exposed to two water sources exhibiting distinctive 87Sr:86Sr isotope values (American River and Putah Creek, California) over weekly time periods to understand how water exposure histories are archived in pectoral fin rays. Using LA multicollector inductively coupled plasma mass spectrometry with a laser diameter of 65 μm, we detected distinct shifts in fin ray 87Sr:86Sr values to match a water source in fish that were exposed for 2, 4, 6, and 12 weeks. Fin ray 87Sr:86Sr values matched the new water source after 21.7 d (SD = 7.8; range = 11–36 d) of exposure. The lower limit of this estimate was constrained by the rate of fin ray growth as well as the LA spot size. Additionally, we assessed how diet affected fin ray 87Sr:86Sr values by feeding a marine-derived pellet feed commonly used in aquaculture to a subset of White Sturgeon, while others were fed a diet consisting of fish with 87Sr:86Sr values that matched their respective water source. Generally, we observed only a minor influence of diet, but there was some variability across individual fish in the effect of diet on the resulting fin ray 87Sr:86Sr value. As with any geochemical analytical technique, fin ray microchemistry has some limitations related to individual variability in fin ray growth and development; however, it is a promising approach to reconstructing sturgeon migratory history by using a nonlethal sampling method.
The goal for using genetic information derived from embryo samples is to gain insight into the re... more The goal for using genetic information derived from embryo samples is to gain insight into the reproductive biology of adult white sturgeon, Acipenser transmontanus Richardson. The relationship between egg development stages on the extraction of quality DNA was determined, and subsequent genotype data were used to infer contributing spawner numbers. White sturgeon DNA was present in extractions from all stages; however, pre-gastrulation stage embryos generally failed to amplify sufficient genetic loci for analysis. Using experimentally created families, multivariate ANOVA and maximum-likelihood sibship methods estimated the presence of 10 contributing parents from 11 actual adult spawners. It was observed that unidentified half-sibling relationships (offspring sharing one parent) caused error for inferring parent numbers. Genetic methods estimated 13–40 parents potentially contributed to a collection of wild-caught embryos, with variable numbers of parents inferred from separate spawning events (varying from 8 to 24). Egg source material provides a means to enhance the accuracy of annual spawning population size estimates, which is important for informing habitat restoration, harvest and water management decisions and recovery planning.
The San Francisco Estuary (SFE) is heavily
influenced by anthropogenic activities, including hist... more The San Francisco Estuary (SFE) is heavily influenced by anthropogenic activities, including historic and chronic contaminant inputs. These contaminants can adversely affect SFE fish populations, particularly white sturgeon, because they are a benthic dwelling, long-lived species. We measured a suite of metals and organic contaminants in liver and gonad tissues of 25 male and 32 female white sturgeon as well as several physiological indicators of sturgeon health. Most sturgeon (68% of males and 83% of females) were estimated to be between 13 and 17 years of age. Sturgeon tissues had elevated concentrations of several metals, including As, Ba, Cd, Cu, Cr, Pb, Hg, Ni, Se, and Zn. The most frequently detected organic contaminants in sturgeon livers and gonads were DDE, PCBs, PBDEs, and galaxolide. Selenium was detected at levels similar to those shown to cause impaired liver physiology and reproductive success in white sturgeon. Observed Hg levels were higher than those shown to result in lower condition factor and gonadosomatic indices in white sturgeon. Liver galaxolide levels correlated with decreased plasma estradiol levels in female sturgeon. The Cd, As, and Cu warrant further investigation, because they were detected at levels known to impair fish health. Our results suggest contaminants are negatively affecting SFE white sturgeon health and fitness. Future SFE white sturgeon contaminant research is suggested.
Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Effo... more Inadequate recruitment is a hallmark of declining sturgeon populations throughout the world. Efforts to understand and address the processes that regulate recruitment are of foremost importance for successful management and recovery. Fish biologists previously only knew San Francisco Estuary white sturgeon (Acipenser transmontanus) to spawn in the Sacramento River, California. We assessed potential white sturgeon spawning locations by deploying artificial substrate samplers during late winter and spring of 2011 and 2012 from river kilometers 115.2 to 145.3 of the San Joaquin River. Collections of fertilized eggs, coupled with hydrology data, confirm that white sturgeon spawned within one and four sites in the San Joaquin River during wet (2011; n ¼ 23) and dry (2012; n ¼ 65) water-year conditions. Small pulse flow augmentations intended to benefit juvenile salmonids appear to have triggered white sturgeon spawning within this system. Understanding the effects of water management on spawning and subsequent recruitment is necessary to increase white sturgeon recruitment to the San Francisco Estuary.
Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluat... more Effects of two fin-ray sampling methods on swimming performance, growth and survival were evaluated for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to either a notch removal treatment in which a small section was removed from an anterior marginal pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed. Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified 3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH) of A. transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and growth were evaluated over a 6month period for a separate group of fish subjected to the same biopsy methods. Mean±s.e. 10 min SCSH were 108⋅0±2⋅3, 110⋅0±2⋅6 and 115⋅0±3⋅5 cms−1 for the notch removal group, full removal group and control group, respectively, and were not significantly different among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering were also not significantly different among treatment groups swimming at the same speeds. There were no mortalities and relative growth was similar among treatment groups. Average biopsy time for the notch removal method was lower and the wounds appeared to heal more quickly compared with the full removal method.
The goal of a day-long symposium on March 3,
2015, Sturgeon in the Sacramento–San Joaquin
Watersh... more The goal of a day-long symposium on March 3, 2015, Sturgeon in the Sacramento–San Joaquin Watershed: New Insights to Support Conservation and Management, was to present new information about the physiology, behavior, and ecology of the green (Acipenser medirostris) and white sturgeon (Acipenser transmontanus) to help guide enhanced management and conservation efforts within the Sacramento–San Joaquin watershed. This symposium identified current unknowns and highlighted new electronic tracking technologies and physiological techniques to address these knowledge gaps. A number of presentations, each reviewing ongoing research on the two species, was followed by a round-table discussion, in which each of the participants was asked to share recommendations for future research on sturgeon in the watershed. This article presents an in-depth review of the scientific information presented at the symposium with a summary of recommendations for future research.
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Papers by Zac Jackson
but the effects of fin ray biopsy on Siberian sturgeon
Acipenser baerii swimming performance are unknown.
Therefore, the effects of two fin ray biopsy methods on
swimming performance of hatchery-reared, juvenile Siberian
sturgeon were evaluated in this study. Treatment fish
were subjected to one of two biopsy methods: removal of a
2- to 4-cm section from a marginal pectoral fin ray, or full
removal of a marginal pectoral fin ray. Control fish were
only subjected to a sham operation. A modified 2,936-l
Brett-type swim tunnel was used to evaluate 10-min critical
station-holding speeds (CSHS) and behavioral swimming
characteristics of sturgeon immediately after fin ray
biopsies were carried out. Fish sizes (range 65- to 84-cm
fork length) were comparable among treatments. Mean
10-min CSHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and
111 ± 2.8 cm s−1 for the segment removal treatment, full
removal treatment, and control treatment, respectively.
ANOVA indicated that the two methods had no significant
effect on the 10-min CSHS of Siberian sturgeon compared to
the control treatment. Results indicate that fin ray removal
has no effect on Siberian sturgeon swimming performance.
(LA) to resolve fine-scale movement patterns in sturgeons (Acipenseridae) during freshwater rearing in early life
stages. We conducted a laboratory experiment in which juvenile White Sturgeon Acipenser transmontanus were
exposed to two water sources exhibiting distinctive 87Sr:86Sr isotope values (American River and Putah Creek,
California) over weekly time periods to understand how water exposure histories are archived in pectoral fin rays.
Using LA multicollector inductively coupled plasma mass spectrometry with a laser diameter of 65 μm, we detected
distinct shifts in fin ray 87Sr:86Sr values to match a water source in fish that were exposed for 2, 4, 6, and 12 weeks.
Fin ray 87Sr:86Sr values matched the new water source after 21.7 d (SD = 7.8; range = 11–36 d) of exposure. The
lower limit of this estimate was constrained by the rate of fin ray growth as well as the LA spot size. Additionally,
we assessed how diet affected fin ray 87Sr:86Sr values by feeding a marine-derived pellet feed commonly used in
aquaculture to a subset of White Sturgeon, while others were fed a diet consisting of fish with 87Sr:86Sr values that
matched their respective water source. Generally, we observed only a minor influence of diet, but there was some
variability across individual fish in the effect of diet on the resulting fin ray 87Sr:86Sr value. As with any
geochemical analytical technique, fin ray microchemistry has some limitations related to individual variability in
fin ray growth and development; however, it is a promising approach to reconstructing sturgeon migratory history
by using a nonlethal sampling method.
(offspring sharing one parent) caused error for inferring parent numbers.
Genetic methods estimated 13–40 parents potentially contributed to a collection of wild-caught embryos, with variable numbers of parents inferred from separate spawning events (varying from 8 to 24). Egg source material provides a means to enhance the accuracy of annual spawning population size estimates, which is important for informing
habitat restoration, harvest and water management decisions and recovery planning.
influenced by anthropogenic activities, including historic
and chronic contaminant inputs. These contaminants can
adversely affect SFE fish populations, particularly white
sturgeon, because they are a benthic dwelling, long-lived
species. We measured a suite of metals and organic contaminants
in liver and gonad tissues of 25 male and 32
female white sturgeon as well as several physiological
indicators of sturgeon health. Most sturgeon (68% of males
and 83% of females) were estimated to be between 13 and
17 years of age. Sturgeon tissues had elevated concentrations
of several metals, including As, Ba, Cd, Cu, Cr, Pb,
Hg, Ni, Se, and Zn. The most frequently detected organic
contaminants in sturgeon livers and gonads were DDE,
PCBs, PBDEs, and galaxolide. Selenium was detected at
levels similar to those shown to cause impaired liver
physiology and reproductive success in white sturgeon.
Observed Hg levels were higher than those shown to result
in lower condition factor and gonadosomatic indices in
white sturgeon. Liver galaxolide levels correlated with
decreased plasma estradiol levels in female sturgeon. The
Cd, As, and Cu warrant further investigation, because they
were detected at levels known to impair fish health. Our
results suggest contaminants are negatively affecting SFE
white sturgeon health and fitness. Future SFE white sturgeon
contaminant research is suggested.
for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to
either a notch removal treatment in which a small section was removed from an anterior marginal
pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed.
Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified
3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH) of A.
transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and
growth were evaluated over a 6month period for a separate group of fish subjected to the same biopsy
methods. Mean±s.e. 10 min SCSH were 108⋅0±2⋅3, 110⋅0±2⋅6 and 115⋅0±3⋅5 cms−1 for the notch
removal group, full removal group and control group, respectively, and were not significantly different
among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering
were also not significantly different among treatment groups swimming at the same speeds. There were
no mortalities and relative growth was similar among treatment groups. Average biopsy time for the
notch removal method was lower and the wounds appeared to heal more quickly compared with the
full removal method.
2015, Sturgeon in the Sacramento–San Joaquin
Watershed: New Insights to Support Conservation and
Management, was to present new information about
the physiology, behavior, and ecology of the green
(Acipenser medirostris) and white sturgeon (Acipenser
transmontanus) to help guide enhanced management
and conservation efforts within the Sacramento–San
Joaquin watershed. This symposium identified current
unknowns and highlighted new electronic tracking
technologies and physiological techniques to address
these knowledge gaps. A number of presentations,
each reviewing ongoing research on the two species,
was followed by a round-table discussion, in which
each of the participants was asked to share recommendations
for future research on sturgeon in the
watershed. This article presents an in-depth review
of the scientific information presented at the symposium
with a summary of recommendations for future
research.
but the effects of fin ray biopsy on Siberian sturgeon
Acipenser baerii swimming performance are unknown.
Therefore, the effects of two fin ray biopsy methods on
swimming performance of hatchery-reared, juvenile Siberian
sturgeon were evaluated in this study. Treatment fish
were subjected to one of two biopsy methods: removal of a
2- to 4-cm section from a marginal pectoral fin ray, or full
removal of a marginal pectoral fin ray. Control fish were
only subjected to a sham operation. A modified 2,936-l
Brett-type swim tunnel was used to evaluate 10-min critical
station-holding speeds (CSHS) and behavioral swimming
characteristics of sturgeon immediately after fin ray
biopsies were carried out. Fish sizes (range 65- to 84-cm
fork length) were comparable among treatments. Mean
10-min CSHS (mean ± SE) were 113 ± 3.4, 109 ± 2.5, and
111 ± 2.8 cm s−1 for the segment removal treatment, full
removal treatment, and control treatment, respectively.
ANOVA indicated that the two methods had no significant
effect on the 10-min CSHS of Siberian sturgeon compared to
the control treatment. Results indicate that fin ray removal
has no effect on Siberian sturgeon swimming performance.
(LA) to resolve fine-scale movement patterns in sturgeons (Acipenseridae) during freshwater rearing in early life
stages. We conducted a laboratory experiment in which juvenile White Sturgeon Acipenser transmontanus were
exposed to two water sources exhibiting distinctive 87Sr:86Sr isotope values (American River and Putah Creek,
California) over weekly time periods to understand how water exposure histories are archived in pectoral fin rays.
Using LA multicollector inductively coupled plasma mass spectrometry with a laser diameter of 65 μm, we detected
distinct shifts in fin ray 87Sr:86Sr values to match a water source in fish that were exposed for 2, 4, 6, and 12 weeks.
Fin ray 87Sr:86Sr values matched the new water source after 21.7 d (SD = 7.8; range = 11–36 d) of exposure. The
lower limit of this estimate was constrained by the rate of fin ray growth as well as the LA spot size. Additionally,
we assessed how diet affected fin ray 87Sr:86Sr values by feeding a marine-derived pellet feed commonly used in
aquaculture to a subset of White Sturgeon, while others were fed a diet consisting of fish with 87Sr:86Sr values that
matched their respective water source. Generally, we observed only a minor influence of diet, but there was some
variability across individual fish in the effect of diet on the resulting fin ray 87Sr:86Sr value. As with any
geochemical analytical technique, fin ray microchemistry has some limitations related to individual variability in
fin ray growth and development; however, it is a promising approach to reconstructing sturgeon migratory history
by using a nonlethal sampling method.
(offspring sharing one parent) caused error for inferring parent numbers.
Genetic methods estimated 13–40 parents potentially contributed to a collection of wild-caught embryos, with variable numbers of parents inferred from separate spawning events (varying from 8 to 24). Egg source material provides a means to enhance the accuracy of annual spawning population size estimates, which is important for informing
habitat restoration, harvest and water management decisions and recovery planning.
influenced by anthropogenic activities, including historic
and chronic contaminant inputs. These contaminants can
adversely affect SFE fish populations, particularly white
sturgeon, because they are a benthic dwelling, long-lived
species. We measured a suite of metals and organic contaminants
in liver and gonad tissues of 25 male and 32
female white sturgeon as well as several physiological
indicators of sturgeon health. Most sturgeon (68% of males
and 83% of females) were estimated to be between 13 and
17 years of age. Sturgeon tissues had elevated concentrations
of several metals, including As, Ba, Cd, Cu, Cr, Pb,
Hg, Ni, Se, and Zn. The most frequently detected organic
contaminants in sturgeon livers and gonads were DDE,
PCBs, PBDEs, and galaxolide. Selenium was detected at
levels similar to those shown to cause impaired liver
physiology and reproductive success in white sturgeon.
Observed Hg levels were higher than those shown to result
in lower condition factor and gonadosomatic indices in
white sturgeon. Liver galaxolide levels correlated with
decreased plasma estradiol levels in female sturgeon. The
Cd, As, and Cu warrant further investigation, because they
were detected at levels known to impair fish health. Our
results suggest contaminants are negatively affecting SFE
white sturgeon health and fitness. Future SFE white sturgeon
contaminant research is suggested.
for hatchery-reared sub-adult white sturgeon Acipenser transmontanus. Fish were subjected to
either a notch removal treatment in which a small section was removed from an anterior marginal
pectoral-fin ray, or a full removal treatment in which an entire marginal pectoral-fin ray was removed.
Control fish did not have fin rays removed, but they were subjected to a sham operation. A modified
3230 l Brett-type swim tunnel was used to evaluate 10 min critical station-holding speeds (SCSH) of A.
transmontanus, immediately after the fin ray biopsies were obtained with each method. Survival and
growth were evaluated over a 6month period for a separate group of fish subjected to the same biopsy
methods. Mean±s.e. 10 min SCSH were 108⋅0±2⋅3, 110⋅0±2⋅6 and 115⋅0±3⋅5 cms−1 for the notch
removal group, full removal group and control group, respectively, and were not significantly different
among treatments. Behavioural characteristics including tail-beat frequency and time spent hunkering
were also not significantly different among treatment groups swimming at the same speeds. There were
no mortalities and relative growth was similar among treatment groups. Average biopsy time for the
notch removal method was lower and the wounds appeared to heal more quickly compared with the
full removal method.
2015, Sturgeon in the Sacramento–San Joaquin
Watershed: New Insights to Support Conservation and
Management, was to present new information about
the physiology, behavior, and ecology of the green
(Acipenser medirostris) and white sturgeon (Acipenser
transmontanus) to help guide enhanced management
and conservation efforts within the Sacramento–San
Joaquin watershed. This symposium identified current
unknowns and highlighted new electronic tracking
technologies and physiological techniques to address
these knowledge gaps. A number of presentations,
each reviewing ongoing research on the two species,
was followed by a round-table discussion, in which
each of the participants was asked to share recommendations
for future research on sturgeon in the
watershed. This article presents an in-depth review
of the scientific information presented at the symposium
with a summary of recommendations for future
research.