Sturgeon Culture Research Articles

A New Sturgeon Herpesvirus from Juvenile Lake Sturgeon Acipenser fulvescens Displaying Epithelial Skin Lesions.

Herpesvirus infections of sturgeon pose a potential threat to sturgeon culture efforts worldwide. A new epitheliotropic herpesvirus named Acipenser herpesvirus 3 (AciHV-3) was detected in hatchery-reared Lake Sturgeon Acipenser fulvescens displaying skin lesions in central Canada. The growths were discovered in the fall, reached average prevalence levels of 0.2-40% and eventually regressed. No unusual mortality was observed. The cellular changes within the lesions included epithelial hyperplasia and were reminiscent of other herpesvirus infections. The virus was not evident in lesions examined by electron microscopy. Skin tissue homogenates from symptomatic sturgeon produced atypical cytopathic effects on a primary Lake Sturgeon cell line, and next-generation sequence analysis of the DNA samples revealed the presence of an alloherpesvirus. A new genotyping PCR assay targeting the major capsid protein sequence detected AciHV-3 in symptomatic Lake Sturgeon as well as other apparently healthy sturgeon species. Bayesian inference of phylogeny reconstructed with a concatenation of five alloherpesvirus core proteins revealed a new Alloherpesviridae lineage isomorphic with a new genus. The presence of AciHV-3 homologs in cell lines and sturgeon sequence datasets, low sequence divergence among these homologs and branching patterns within the genotyping phylogeny provide preliminary evidence of an endogenous virus lifestyle established in an ancestral sturgeon.

Isolation, identification of an Aeromonas veronii strain, and the immune response of hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂) to the bacteria

Hybrid sturgeon (Acipenser baerii ♀ × Acipenser schrenckii ♂) holds significant importance in the aquaculture industry in China. However, the recurring disease outbreaks caused by Aeromonas veronii have led to substantial economic losses in hybrid sturgeon culture. Further, the immune response of hybrid sturgeon to A. veronii infection remains poorly understood. Therefore, this study isolated and characterized a bacterial strain from affected fish, which was subsequently identified as A. veronii based on various characteristics. Moreover, severe histopathological changes, including degeneration and necrosis of the gill cells and intestinal villi, were observed in the diseased fish. Transcriptome data analysis using GO and KEGG enrichment revealed dynamic changes and enrichment of classical immune-and hematopoietic-related pathways following A. veronii infection. Additionally, significant changes were observed in the proportion of blood lymphocytes and antioxidative enzyme levels during A. veronii infection. Further investigations showed that the infected fish serum inhibited A. veronii replication. These findings provide valuable insights into the immune response of hybrid sturgeon against A. veronii infection.

Staphylococcus sciuri causes disease and pathological changes in hybrid sturgeon acipenser baerii × acipenser schrencki.

Hybrid sturgeon is the main species of sturgeon cultured in China, with the advantages of a fast growth rate, early sexual maturity, fertile offspring, and more stable genetic traits. In May 2021, a large number of deaths characterized by superficial hemorrhage and liver damage occurred in a sturgeon farm in Yichang, Hubei Province, which posed a significant risk to hybrid sturgeon captive breeding. We isolated a pathogenic bacterium named D-59 from the diseased sturgeon with apparent symptoms. The pathogen was identified as Staphylococcus sciuri using 16S rRNA gene phylogenetic analysis combined with biochemical identification. Regression experiments showed that D-59 exhibited clinical signs similar to those of diseased sturgeon in the farm after intraperitoneal injection into hybrid sturgeon. High-throughput sequencing of gut microbes in D-59-infected sturgeon showed that the number of gut microbial species decreased in infected sturgeon, the number of some intestinal commensal bacteria decreased, and the balance of the intestinal microorganisms was disrupted. Histopathological sections indicated many inflammatory cells, congestion, and even necrosis in the tissue of diseased sturgeon. Analysis of blood indexes revealed an increase in the proportion of mononuclear cells and a decrease in the proportion of lymphocytes in the peripheral blood of diseased sturgeon. Significantly elevated serum levels of aspartate aminotransferase and alanine aminotransferase, whereas alkaline phosphatase, total protein, albumin, and globulin were decreased in diseased sturgeon. Antimicrobial susceptibility tests demonstrated that D-59 is susceptible to florfenicol, enrofloxacin, and neomycin sulfate. This study aimed to highlight the dangers of Staphylococcus sciuri infection during hybrid sturgeon culture and to provide recommendations for diagnosis and treatment.

Comparative analysis of sturgeon- and catfish-derived Yersinia ruckeri reveals the genetic variation and the risk of heavy antibiotic resistance

Sturgeon (Acipenseriformes) and catfish (Siluriformes) are two of the most famous special economic animals, accounting for 1.3 million tons of production in China. Enteric redmouth disease caused by Yersinia ruckeri is common in these two fishes. This study carried out a surveillance of ERM from April 2016 to August 2018 in the Sichuan province. The genotyping and the distribution of antibiotic resistance profiles (ARPs) and genes (ARGs) of Y. ruckeri were established in this study. The results showed that Y. ruckeri was a common pathogen in catfish and sturgeon, accounting for 25.56 % and 17.65 %, respectively. Sixteen strains were obtained and were clustered into 5 genotypes which has a fish-specific characteristic. Y. ruckeri had appeared resistance to 14 of the 20 antibiotics, and 39 antibiotic resistance genes were detected positively from 95 specific primers. Also, there were significant differences in antibiotic resistance profiles among different strains. The sturgeon-derived Y. ruckeri had higher detection rates of aac(6)-Ib(aka aacA4)-1, aac(6)-Ib(aka aacA4)-2, aac(6)-Ib(aka aacA4)-3, fox5 and acrF, and higher resistance rates to ampicillin, ciprofloxacin, levofloxacin, kanamycin, and neomycin compared with the catfish-derived strains. Our results indicated that Y. ruckeri might become an important pathogen in catfish and sturgeon culture in Sichuan, and there were different subspecies of variation. Besides, Y. ruckeri has enriched many antibiotic resistances that may help evolve into super bacteria.

A hydroponic plants and biofilm combined treatment system efficiently purified wastewater from cold flowing water aquaculture

Recently, more and more cold flowing water aquaculture has been adopted, but its wastewater treatment is always ignored, which causes great pressure on the environment. In this study, a compound in-situ treatment system that applied hydroponic plants and biofilm was constructed to treat the wastewater produced by cold flowing water culture of sturgeon. The removal efficiency of the nutrients from culture and the microbial composition in water and biofilm were tested, the correlation between the water quality indexes and bacterium was analyzed, and the abundance of nitrogen and phosphorus cycling genes was quantified. The results show that the system respectively achieved 90%, 100%, 100%, 100% and 48% removal efficiency of NH4+-N, NO3−-N, TN, TP and COD which were produced by experimental sturgeon culture. Chinese cabbage (Brassica rapa var. chinensis) and water dropwort (Oenanthe javanica) showed obvious growth in the four plants, which contributed to the removal of nutrients from wastewater. Besides, in the biofilm, Proteobacteria, Bacteroidetes and Verrucomicrobia became the top three dominant flora at the phylum level, and Flavobacterium, Rhodoferax, Sphaerotilus and Chitinimonas became the top four dominant flora at the genus level, which promoted the removal of nitrogen in the wastewater. The FAPROTAX analysis result shows that the highest functions within the carbon and nitrogen metabolisms were significantly identified in the biofilm, such as chemoheterotrophy, aerobic chemoheterotrophy and nitrate reduction. Further, the abundance of denitrifying genes (narG and napA) was higher than the nitrifying related genes (nxrB and amoA), indicating the more active denitrifying process. In summary, the compound in-situ treatment system efficiently removed nutrients from cold flowing water aquaculture. And the combined purification of hydroponic plants and biofilm which is rich in denitrifying bacterium plays an essential role in this process.

Physiological responses of Siberian sturgeon (Acipenser baerii) juveniles fed on full-fat insect-based diet in an aquaponic system

Over the last years, the potential use of Black Soldier Fly meal (BSF) as a new and sustainable aquafeed ingredient has been largely explored in several fish species. However, only fragmentary information is available about the use of BSF meal-based diets in sturgeon nutrition. In consideration of a circular economy concept and a more sustainable aquaculture development, the present research represents the first comprehensive multidisciplinary study on the physiological effects of a BSF diet during sturgeon culture in an aquaponic system. Siberian sturgeon (Acipenser baerii) juveniles were fed over a 60-days feeding trial on a control diet (Hi0) and a diet containing 50% of full-fat BSF meal respect to fish meal (Hi50). Physiological responses of fish were investigated using several analytical approaches, such as gas chromatography-mass spectrometry, histology, Fourier Transformed Infrared Spectroscopy (FTIR), microbiome sequencing and Real-time PCR. While aquaponic systems performed optimally during the trial, Hi50 group fish showed lower diet acceptance that resulted in growth and survival reduction, a decrease in hepatic lipids and glycogen content (FTIR), a higher hepatic hsp70.1 gene expression and a worsening in gut histological morphometric parameters. The low feed acceptance showed by Hi50 group sturgeon highlighted the necessity to improve the palatability of BSF-based diet designed for sturgeon culture.

The aquaculture of Acipenseriformes. Part 6. Northern and South America

The history and contemporary state of global aquaculture of sturgeons and paddlefish are reviewed. The paddlefish Polyodon spathula became first object of cultivation of Acipenseriformes in USA. The paddlefish has high rate of growth in ponds using natural feeds, mature females can produce about 15% of their body weight in roe similar to eggs of star sturgeon Acipenser stellatus. Some liabilities include juveniles vulnerable to bird predation, poor tolerance to high densities, low oxygen and handling stress, waiting period of at least 7 years before females produce eggs. The paddlefish farming is carried out mainly in Kentucky, Indiana, Missouri and Alabama in polyculture with canal catfish Ictalurus punctatus or freshwater shrimp Macrobrachium rosenbergii. The most important object of North-American sturgeon breeding is white sturgeon Acipenser transmontanus, the biggest and fast-growing species of Acipenser genera. The largest commercial sturgeon farms are located in California, Idaho and Florida. A research program on biotechnology of white sturgeon farming has been initiated by the University of California at Davis in December 1979. The first successful artificial propagation of white sturgeon from Sacramento River was carried out in 1980, the first hatchery females matured in 1994. The hatchery progeny of Snake River white sturgeon was received in 1988, the first females matured in 2000. The first caviar was processed only after maturation of second generation. In Florida and North Carolina farmers used for cultivation small number of Russian sturgeon A. gueldenstaedti, Siberian sturgeon A. baeri, sterlet A. ruthenus, beluga Huso huso and star sturgeon A. stellatus. The total annual volume of sturgeon farming in USA was equal to 1285 tons (1166 MT). In Canada the only object of sturgeon farming is white sturgeon with annual production near 2 tons of caviar. In South America Uruguay has developed sturgeon culture with one large farm created in 1994 using help of Russian specialists.

Effect of concrete pond and net-cage culture systems on growth performance and haematological parameters of Siberian sturgeon (Acipenser baerii)

The effect of concrete pond and net-cage culture systems on growth and haematological indices of the Siberian sturgeon (Acipenser baerii) were studied in a 90-day experiment. A total of 300 fish with a stocking density of 12.6 ± 0.37 kg/m2 (initial average weight 1140 ± 53.8 g) were stocked in floating net-cages. Also, 276 fish with a stocking density of 12.6 ± 0.29 kg/m2 and an initial average weight of 1097 ± 72.6 g were stocked in concrete ponds. Throughout the study, the average weight, mean length, and haematological parameters of the fish in each environment were recorded every 30 days. The fish in net-cages displayed higher growth rate (GR), specific growth rate (SGR), and body weight increase (BWI) as well as a lower food conversion rate (FCR) when compared to the fish in concrete ponds. No differences in the condition factor (CF) or survival rate (SR) were found in the trial. In terms of haematological parameters, there was no difference between the ponds and net-cages for the values of red (RBC) and white (WBC) blood cells, haematocrit (Hct), haemoglobin (Hb), MCV, MCH, MCHC, lymphocyte, monocyte, neutrophil, and eosinophil in the initial 30-day and 60-day sampling periods. In the 90-day sampling period, a statistical difference was found in the RBC, MCV, MCH, and WBC values between the ponds and net-cages. Furthermore, in the 90-day sampling period, no statistical difference was found in the Hct, Hb, MCHC, lymphocyte, monocyte, neutrophil, and eosinophil values. Consequently, the Siberian sturgeon culture in net-cages is advantageous to concrete ponds in regards to the growth parameters.

Growth, survival and fatty acids profile of Polychaete, Nereis diversicolor (Müller, 1776) cultured using waste water of great sturgeon, Huso huso (Linnaeus, 1758), culture at different densities in an integrated farming system

Growth and survival of Polychaete, Nereis diversicolor fed on waste water of great sturgeon, Huso huso at different densities were studied. The study aimed to assess the efficacy of feeding of N. diversicolor with waste water derived from different densities of great sturgeon culture as well as to find a balance between fish density and growth of the worm. The worms (0.2-0.3 kg m-2) with an initial mean weight of 0.05 g were fed for 55 days with waste water of great sturgeon at densities of 2-3, 3-4 and 4-5 kg m-2 fish. A group of worms fed with fish feed was considered as the control. The obtained results showed that the biomass and average weight of the harvested worms were significantly higher at the density of 3-4 kg m-2 fish than in the other two treatments (p<0.05). Also, worms fed with fish feed (control group) showed higher survival rate and biomass production than the treatments. Some fatty acids were abundant in worms from the treatments, specifically 14:0, 16:0, C18:1n9c, 20:1, 22:1n-9, 18:3n-3, 20:2, 20:5n-3 (EPA) and 22:6n-3 (DHA), but were significantly lower than the control worms. The results demonstrate that production of N. diversicolor using fish waste water was highly efficient and can offer a sustainable solution to remove organic load in the aquaculture waste waters. Also, production of N. diversicolor via this method as an alternative source of fatty acids and protein for H. huso production could achieve multiple aims such as retention of valuable lipids from the H. huso waste water.

我国鲟鱼养殖产业现状及发展趋势

我国鲟鱼养殖产业现状及发展趋势

Mechanical shock during egg de-adhesion and post-ovulatory ageing contribute to spontaneous autopolyploidy in white sturgeon culture (Acipenser transmontanus)

Spontaneous autopolyploidy, a 1.5x increase in genome size resulting from second polar body retention after fertilization, has been documented in cultured sturgeons, with the proportion of spontaneous autopolyploid progeny ranging widely among maternal families. Sturgeon farms wish to reduce the number of spontaneous autopolyploids because their progeny, when crossed with a normal ploidy parent, exhibit intermediate ploidies, resulting in reproductive abnormalities. However, there is limited knowledge of the causes of the second polar body retention in sturgeon culture. In this study, we report the results of experiments performed from 2015 to 2019 aimed at identifying the sources of spontaneous autopolyploidy in white sturgeon (Acipenser transmontanus) culture. In collaboration with several sturgeon farms, we tested whether post-ovulatory ageing, mechanical shock during egg de-adhesion, and the combined effects of both factors increased spontaneous autopolyploidy. To test the effect of post-ovulatory ageing, eggs were collected from females and either fertilized at the industry normative time (2–5 h post-oviposition) or stored in ovarian fluid at 15 °C for 6–8 h before fertilization. To test the effect of mechanical shock, eggs were collected, fertilized 2–5 h post-oviposition and exposed to either gentle or vigorous mixing during the 60 min de-adhesion treatment. Results from this work reveal that post-ovulatory ageing does increase the incidence of spontaneous autopolyploidy in some females, but overall the proportions produced were low (range 0–15%). Proportions of spontaneous autopolyploids in eggs exposed to vigorous mixing were also variable (1–92%) but significantly higher in 75% of the females when compared to their respective controls or gentle mixing treatments, indicating that mechanical shock during egg de-adhesion is likely the primary cause of spontaneous autopolyploidy. To our knowledge this is the first study to document mechanical shock to eggs during de-adhesion as a cause of abnormal ploidy in cultured fishes. We observed high variability in egg quality among females and a significant relationship between embryo mortality and the incidence of spontaneous autopolyploidy when eggs were exposed to mechanical shock. Repeated spawning of a female that produced a high proportion of spontaneous autopolyploids provided preliminary evidence that genetic background may influence the likelihood that a female's eggs will be prone to second polar body retention when subjected to mechanical shock. Although spontaneous autopolyploidy in sturgeon culture will likely never be eliminated entirely, we provide practical recommendations to sturgeon producers to reduce its incidence in a production setting.

Transcriptome profile of Amur sturgeon (Acipenser schrenckii) liver provides insights into immune modulation in response to Yersinia ruckeri infection

Amur sturgeon Acipenser schrenckii, an economically important freshwater fish cultured in China, is now facing numerous bacterial diseases during aquaculture. Infection by Yersina ruckeri causes high mortality and great economic loss in sturgeon culture. To better understand the immune response of Amur sturgeon to Y. ruckeri infection, we performed the transcriptome analysis using livers from Y. ruckeri-infected fish and a control group through RNA-Seq technology. Totally 119 300 unigenes with high quality were obtained. Moreover, 1112 differently expressed genes (DEGs) including 468 up-regulated genes and 644 down-regulated genes were identified based on the expression patterns. 63 immune-related DEGs, such as TLR5, IL-8, NALP3, CCL19/21, C1qC, Hsp70/90 and MHCI, were identified and further divided into 15 KEGG pathways via enrichment analysis using KEGG database. The expression patterns of DEGs were validated by qRT-PCR. In addition, 55 990 potential SSRs were identified from 34 580 transcripts, and 1 696 286 candidate SNPs were identified in the A. schrenckii liver transcriptome. This study will provide the first and crucial information on the immune mechanism of Amur sturgeon against bacterial infection.

Trancriptome profiles of Amur sturgeon spleen in response to Yersinia ruckeri infection

Yersinia ruckeri (YR) is the causative agent of yersiniosis which has caused significant economic losses in fish culture worldwide, including in Amur sturgeon (Acipenser schrenckii) culture. To better understand the mechanism of the immune responses to YR in Amur sturgeon, the transcriptomic profiles of the spleens from YR-infected and non-infected groups were obtained using RNA-seq techniques. The de novo assemblies yielded totally 145 670 unigenes from the two libraries. The total numbers of transcripts in YR-infected and non-infected groups were from 110 893 to 147 336, with the mean length varying from 560 to 631 (N50: from 882 to 1083). GO analysis revealed that 10 038 unigenes were categorized into 26 biological processes subcategories, 17 cellular components subcategories and 19 molecular functions subcategories. A total of 59 487 unigenes were annotated in the KEGG pathway and 20 pathways were related to the immune system. 1465 differently expressed genes (DEGs) were identified, including 377 up-regulated genes and 1088 down-regulated genes. 125 DEGs were found to be related to immune responses of Amur sturgeon and further divided into 16 immune-related KEGG pathways, including antigen processing and presentation, complement and coagulation cascades, T cell receptor signaling pathway, B cell receptor signaling pathway, NOD-like receptor signaling pathway, chemokine signaling pathway, etc. Eight of the DEGs were further validated by qRT-PCR. Altogether, the results obtained in this study will provide insight into the immune response of Amur sturgeon against Y. ruckeri infection.

Nuclear DNA markers for identification of Beluga and Sterlet sturgeons and their interspecific Bester hybrid

Sturgeons (Acipenseriformes) are among the most endangered species in the world due to fragmentation and destruction of their natural habitats and to overexploitation, mainly for highly priced caviar. This has led to the development of sturgeon culture, originally for reintroduction, but more recently for caviar production. In both cases, accurate species identification is essential. We report a new tool for accurate identification of Huso huso and Acipenser ruthenus based on nuclear DNA markers. We employed ddRAD sequencing to identify species-specific nucleotide variants, which served as specific binding sites for diagnostic primers. The primers allowed identification of Huso huso and Acipenser ruthenus as well as their discrimination from A. baerii, A. schrenckii, A. gueldenstaedtii, A. stellatus, A. persicus, A. mikadoi, A. transmontanus, and H. dauricus and identification of A. ruthenus and H. huso hybrids with these species, except hybrid between A. ruthenus and A. stellatus. The species-specific primers also allowed identification of bester (H. huso × A. ruthenus), the most commercially exploited sturgeon hybrid. The tool, based on simple PCR and gel electrophoresis, is rapid, inexpensive, and reproducible. It will contribute to conservation of remaining wild populations of A. ruthenus and H. huso, as well as to traceability of their products.

Dietary copper requirement of juvenile Russian sturgeon Acipenser gueldenstaedtii

To quantify the dietary copper (Cu) requirement of Russian sturgeon Acipenser gueldenstaedtii, copper sulfate (CuSO4·5H2O) was added into the basal semi-purified diet at seven levels 0, 1, 2, 4, 6, 8 and 16mgCukg−1 diet yielding the actual dietary values of 0.3, 1.5, 2.4, 4.4, 6.2, 8.3 and 16.1mgCukg−1 diet, respectively. Each diet was fed to sturgeon (11.84±0.07g) in triplicate in a flow-through system for 8weeks. The Cu concentration in the rearing water was 0.8–1.2μgL−1 during the trial period. The weight gain rate (WGR) and feed efficiency were significantly higher in fish fed 2.4 to 8.3mgCukg−1 than those fed 0.3, 1.5 or 16.1mgCukg−1. The highest WGR was found in fish fed 6.2mgCukg−1. The whole-body Cu concentrations were highest in fish fed 6.2 to 16.1mgCukg−1. The liver Cu concentration was highest in fish fed 16.1mgCukg−1 diet and lowest in fish fed diets Cu levels range from 0.3 to 4.4mgCukg−1. Hepatic copper–zinc superoxide dismutase (Cu–Zn SOD) activities, total antioxidant capacity and serum ceruloplasmin activity were significantly higher in fish fed 6.2 and 8.3mgCukg−1 diet than those in other treatments. The lowest hepatic malondialdehyde values were observed in fish fed 6.2 and 8.3mgCukg−1. No significant differences were in survival, hepatosomatic index, viscerosomatic index and condition factor among all the treatments. There were also no significant differences in whole body moisture, crude protein, crude lipid and ash between all the treatments. Analysis of broken-line regression based on the WGR, whole-body Cu concentration, hepatic Cu–Zn SOD and serum ceruloplasmin activity of the fish fed different diets indicates that the minimum Cu concentration in the semi-purified diet for juvenile Russian sturgeon (12–70g) is at 7–8mgkg−1. Statement of relevanceThe dietary copper (Cu) requirement of juvenile Russian sturgeon was investigated. Dietary Cu deficiency and over-loading significantly reduced growth, feed utilization and antioxidant capacity. The results suggest that the appropriate dietary Cu content is considerable in Russian sturgeon farming. Minimum dietary Cu level for this species is recommend as 7–8mgCukg−1 in this study. These information will be useful in developing a practical diet for Russian sturgeon culture.

Early Development and Allometric Growth in Laboratory-Reared European Chub Leuciscus cephalus (Linnaeus, 1758)

Sturgeon production involves unavoidable handling procedures inducing stress response. Clove oil is the anaesthetic commonly used in sturgeon culture to minimise stress and pain. Propofol is one of the most frequently used anaesthetic in humans. Propofol is a promising candidate anaesthetic for fish. The aim of the study was to compare the effect of propofol and eugenol on haematological and biochemical blood profile of Russian sturgeon. Determined indices covered: PCV, RBC, Hb, MCV, MCHC, MCH, leucogram, and concentration of calcium cations, inorganic phosphates, total proteins, albumins, globulins, ammonia, triacylglycerols, glucose, and the activity of creatine kinase, alkaline phosphatase and aspartate aminotransferase. Exposure to both anaesthetics caused a stress response in Russian sturgeon expressed as changes in WBC system and increased values of PCV, Hb, glucose, triacylglycerols, inorganic phosphates, calcium and ammonia. The impact of eugenol was more sever and longer being. No damage of internal organs was stated. According to our results, propofol is safe anaesthetic for Russian sturgeon.

Preliminary Investigation of Dietary Soy Sensitivity in Shovelnose Sturgeon

Sturgeon culture has developed greatly since the 1980s. Cultured sturgeon are often fed a commercial salmonid feed high in fish meal (FM). However, economic and sustainability concerns have put pressure on aquafeed manufactures to incorporate alternative proteins such as soybean meal (SBM). This experiment investigates dietary SBM sensitivity in shovelnose sturgeon (Scaphirhynchus platorhynchus). Diets were formulated to contain 0%, 17%, 34%, and 51% SBM and fed for 8 weeks. Weight gain, specific growth rate (SGR), feed efficiency (FE), body and liver composition, and intestinal histology were determined. Although sturgeon growth rates were low for all diets, weight gain in fish fed the diet with 17% SBM averaged 55.6% of sturgeon fed the fish meal-based control diets. Statistically lower negative growth and FE (P < 0.05) were observed when SBM was included at 51% of the diet. However, whole-body proximate composition and hepatic lipid and glycogen content were not altered by dietary SBM inclusion level, and histological evaluation of the distal intestine was inconclusive. These results provide preliminary insight into the effect of diets containing high levels of SBM on growth and health of Scaphirhynchus sturgeon.

Survival and Growth of Lake Sturgeon during Early Life Stages as a Function of Rearing Environment

AbstractThe need for hatchery programs to reflect the latest scientific knowledge is critical for understudied groups with unique ecologies such as Acipenseriform species, including Lake Sturgeon Acipenser fulvescens. In order to address uncertainties regarding the efficacy of Lake Sturgeon culture techniques, we quantified and compared growth and survival at the egg, larval, and juvenile life history stages as a function of hatchery rearing environment over 2 years (two cohorts). Furthermore, we evaluated growth and survival of juveniles produced from three methods of progeny collection including direct gamete takes, collection of naturally spawned eggs from the stream substrate, and collection of larvae dispersing downstream from the spawning grounds. Progeny from each collection method were evenly divided between a streamside hatchery on the natal river and a traditional hatchery. Progeny reared at the streamside hatchery experienced a natural temperature regime and were exposed to natal water only filtered to remove larger sediments. We found that daily survival at the egg stage varied as a function of hatchery environment, duration of incubation, and maternal sources. Microbial infection during incubation contributed significantly to mortality, was higher, and occurred earlier in the incubation period at the streamside hatchery than at the traditional hatchery. Hatching rate was significantly higher at the streamside hatchery in 2006 than at the traditional hatchery. Daily survival at the larval stage was high at both hatcheries but was significantly higher at the streamside hatchery in 2006. Importantly, survival of progeny collected as dispersing larvae was significantly lower during the first week of rearing in both hatchery environments and years. Growth rates at the juvenile stage were comparable between hatcheries and inter‐individual variation in growth increased through the rearing period in both years. Natural temperature regimes resulted in variable egg incubation time and concomitant variation in larval size at hatch that extended into the juvenile stage. Results indicate conservation hatchery programs that incorporate rearing environments reflective of natural conditions can increase phenotypic variation in stocked progeny without compromising survival in the hatchery.

Effect of Altering Dietary Protein: Energy Ratios on Juvenile Pallid Sturgeon Growth Performance

AbstractPallid Sturgeon Scaphirhynchus albus are endemic to the large, freshwater, river systems of North America and have long been prized for caviar production. Declining wild populations and fishing prohibitions have created interest in the culture of these fish. Protein and energy are often the first nutrients examined when attempting to identify diets appropriate for a novel culture species. Therefore, the present study evaluated the effects of different dietary protein: energy ratios on Pallid Sturgeon growth and body composition. Twelve semipurified diets composed of four crude protein (CP) levels (32, 39, 46, and 53%) and three gross energy (GE) levels (3,600, 4,200, and 4,800 kcal/kg) were fed to 180 juvenile Pallid Sturgeon for 18 weeks. Diets were offered to triplicate groups of five fish each in separate tanks. Fish were fed 2% body weight daily and sampled every 3 weeks. Mean weight gain and body composition were significantly affected by GE content of the dietary treatment (P ≤ 0.05), but not by dietary CP or protein and energy interactions (P &gt; 0.05). The most energetically dense diets yielded significantly larger fish than the least energetically dense diets and the intermediate diets were not significantly different from either extreme. These results suggest that Pallid Sturgeon are able to perform similarly across a wide range of protein: energy ratios (79–147 mg protein/kcal), as long as adequate dietary energy (≥3,800 kcal GE/kg) is provided and essential amino acids are not limiting. This research is the first to evaluate dietary protein: energy ratios for Scaphirhynchus sturgeon culture.

Optimizing the co-feeding strategy of Persian sturgeon (Acipenser persicus) larvae using Artemia nauplii and formulated diet

High mortality and labor costs are associated with first-feeding sturgeon culture, particularly during the period of dietary transition from live to formulated feed. Therefore we investigated the effects of various feeding treatments on the survival and growth of the Persian sturgeon ( Acipenser persicus ) larvae during a 20-day culture period. Three replicate groups (250 fish/replicate) of first-feeding larvae were fed according to four main feeding regimes: (1) live food (live nauplii of brine shrimp Artemia urmiana ); (2) indirect transition (5 days live food followed by gradual transition to formulated diet); (3) direct transition (using different combinations of live and formulated diet from the start feeding onwards); (4) formulated feed (FD) from the start feeding. Results indicated that growth and survival were higher in the indirect transition feeding regime than in other regimes. Based on our study, co-feeding of A. persicus should start five days after prior feeding with live food.