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Sturgeon
Kinds of Sturgeon Terms modified by Sturgeon Selected AbstractsManagement and Recovery Options for Ural River Beluga SturgeonCONSERVATION BIOLOGY, Issue 3 2010PHAEDRA DOUKAKIS caviar; CITES; criadero; Mar Caspio; puntos de referencia; sobrepesca Abstract:,Management of declining fisheries of anadromous species sometimes relies heavily on supplementation of populations with captive breeding, despite evidence that captive breeding can have negative consequences and may not address the root cause of decline. The beluga sturgeon (Huso huso), a species threatened by the market for black caviar and reductions in habitat quality, is managed through harvest control and hatchery supplementation, with an emphasis on the latter. We used yield per recruit and elasticity analyses to evaluate the population status and current levels of fishing and to identify the life-history stages that are the best targets for conservation of beluga of the Ural River. Harvest rates in recent years were four to five times higher than rates that would sustain population abundance. Sustainable rates of fishing mortality are similar to those for other long-lived marine species such as sharks and mammals. Yield per recruit, which is maximized if fish are first harvested at age 31 years, would be greatly enhanced by raising minimum size limits or reducing illegal take of subadults. Improving the survival of subadult and adult females would increase population productivity by 10 times that achieved by improving fecundity and survival from egg to age 1 year (i.e., hatchery supplementation). These results suggest that reducing mortality of subadults and adult wild fish is a more effective conservation strategy than hatchery supplementation. Because genetics is not factored into hatchery management practices, supplementation may even reduce the viability of the beluga sturgeon. Resumen:,El manejo de pesquerías de peces anádromos en declinación a veces depende estrechamente de la suplementación de poblaciones mediante la reproducción en cautiverio, no obstante la evidencia de que la reproducción en cautiverio puede tener consecuencias negativas y no abordar la causa principal de la declinación. El esturión beluga (Huso huso), una especie amenazada por el mercado de caviar negro y por reducciones en la calidad del hábitat, es manejado mediante el control de la cosecha y suplementación de poblaciones, con énfasis en esta. Utilizamos análisis de producción por recluta y de elasticidad para evaluar el estatus de la población y los niveles de pesca actuales y para identificar las etapas de la historia de vida que son los mejores blancos para la conservación del beluga en el Río Ural. Las tasas de cosecha en años recientes fueron cuatro a cinco veces mayores que las tasas que sustentarían la abundancia de la población. Las tasas sustentables de mortalidad por pesca son similares a las de otras especies marinas longevas como tiburones y mamíferos. La producción por recluta, que es maximizada si los peces son cosechados a la edad de 31 años, podría incrementar significativamente elevando los límites de talla mínima o reduciendo la captura ilegal de subadultos. La mejora de la supervivencia de hembras subadultas y adultas incrementaría la productividad de la población 10 veces más que la mejora obtenida incrementando la fecundidad y supervivencia de huevo a 1 año de edad (i. e., suplementación de poblaciones mediante reproducción en cautiverio). Estos resultados sugieren que la reducción de la mortalidad de peces silvestres subadultos y adultos es una mejor estrategia de conservación que la suplementación. Debido a que la genética no es considerada en las prácticas de manejo en los criaderos, la suplementación incluso puede reducir la viabilidad del esturión beluga. [source] The effect of some water parameters on the oxygen consumption rate of embryos and larvae of the Chinese Sturgeon (Acipenser sinensis)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 2006Jian-Yi. First page of article [source] Quality Attributes and Microbial Storage Stability of Caviar from Cultivated White Sturgeon (Acipenser transmontanus)JOURNAL OF FOOD SCIENCE, Issue 1 2010Joong-Han Shin ABSTRACT:, Caviar was prepared from white sturgeon (Acipenser transmontanus) roe by adjusting the water phase salt (WPS) to 4.0% to 6.3% by adding food grade NaCl. Fish were obtained from 2 different farms from the Inland Northwest (N,= 5). Salt was absorbed at a different rate and to a different extent by roe from different fish. The lipid content in the fish roe varied from 10.2% to 14.4% (w/w), with palmitic acid and oleic acid being the most abundant saturated and monounsaturated fatty acids present, respectively. The caviar contained high levels of polyunsaturated fatty acids (PUFA) (35% to 37%) with docosahexanoic acid being the most abundant ,-3 long chain fatty acid. There were no significant differences in microbial storage stability for caviars from different fish stored at 3 °C. However, for caviar stored at 7 °C, there was less growth of,Listeria monocytogenes,(using a cocktail of ATCC 19114, 7644, 19113 strains) in 2 samples (2B46 and 0F05) until day 20. In 2 other samples (453F and 2519), which had lower initial microbial loads, less overall microbial growth was observed, indicating that culture and harvest practices result in compositional differences between fish, which may impact both product composition and storage stability. [source] Border Landscapes: The Politics of Akha Land Use in China and Thailand by Janet C. SturgeonTHE CANADIAN GEOGRAPHER/LE GEOGRAPHE CANADIEN, Issue 1 2008PETER VANDERGEEST No abstract is available for this article. [source] SOME GOOD AND BAD NEWS FOR ETHICAL INTUITIONISMTHE PHILOSOPHICAL QUARTERLY, Issue 232 2008Pekka Väyrynen The core doctrine of ethical intuitionism is that some of our ethical knowledge is non-inferential. Against this, Sturgeon has recently objected that if ethical intuitionists accept a certain plausible rationale for the autonomy of ethics, then their foundationalism commits them to an implausible epistemology outside ethics. I show that irrespective of whether ethical intuitionists take non-inferential ethical knowledge to be a priori or a posteriori, their commitment to the autonomy of ethics and foundationalism does not entail any implausible non-inferential knowledge in areas outside ethics (such as the past, the future, or the unobservable). However, each form of intuitionism does require a controversial stand on certain unresolved issues outside ethics. [source] Study of Epidermis Development in Sturgeon (Acipenser persicus) LarvaeANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2010Z. Saadatfar With 10 figures Summary Fish skin is essential for survival, maintenance of body shape, and protection against the shock and infection. During week 1 of sturgeon larval development, the epidermis is thin and not differentiated in various layers yet, but by week 4,6 the thickness increases and various layers appear, depending upon the region of the body. Mucous cells differentiate early in development on the surface of epithelium and contain acid and neutral mucopolysaccharides. Primordial sensory buds are visible within the epithelia of the skin of the head in week 1 larvae, and become numerous during later larval development. Club cells are specialized epidermal cells that have an immune function and appear in the middle layer of the head and trunk epidermis on week 4. [source] A New Look on the Origin of the Gonad and the Müllerian Duct: the Sturgeon (Acipencer) as a Model for Vertebrate Urogenital DevelopmentANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005K. -H. The origin of the vertebrate gonad and the Müllerian duct are still a matter of debate. According to the majority of recent textbooks, the gonad is a product of the proliferating coelothelium and therefore derived from the mesoderm of the lateral plate region. The Müllerian duct grows parallel to the Wolffian duct, but it is not clear to what extent the latter contributes actively to the development of the former. In the last decade, we reinvestigated early gonadogenesis and Müllerian duct development in a number of vertebrate model species using various morphological techniques (TEM, SEM, immunohistochemistry). The conclusion of our studies is that rudimentary or regressing nephrostomial tubules, particularly cells of their nephrostomes, must be regarded as the immediate precursors of the somatic cells of the gonadal crest and the Müllerian infundibular field. According to this concept, both structures are derivatives of the intermediate mesoderm. Nephrostomial tubules are regular components of the primitive pro- and mesonephros. They connect the nephric tubule or the nephric corpuscle to the coelomic cavity and open into the latter by means of a funnel-like mouth, the nephrostome (coelomostome). In the larval sterlet, Acipenser ruthenus, short, segmentally arranged nephrostomial tubules with well-developed nephrostomes are present in the region of the cranial opisthonephros. Cells of the medial nephrostomial lips proliferate, surround the germ cells that have accumulated in this location and form a continuous gonadal crest. Cells of the lateral nephrostomial lips proliferate also, spread out on the coelomic surface, replace the original flat mesothelial cells over the Wolffian duct and the cranial opisthonephros and form the Müllerian infundibular field. At about 28 days, a flat pocket begins to invaginate the infundibular field. This pocket is the primordium of the Müllerian ostium abdominale. The findings in Acipenser can be generalized and transferred to other vertebrates. [source] Identification of Acipenseriformes species in tradeJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2008A. Ludwig Summary Sturgeons and paddlefishes (Acipenseridae) are highly endangered freshwater fishes. Their eggs (sold as caviar) are one of the most valuable wildlife products in international trade. Concerns of overharvesting and the conservation status of many of the 27 extant species of Acipenseriformes led to all species being included on the CITES Appendices in 1998. Since then international trade in all products and parts from sturgeon and paddlefish has been regulated. However, despite the controls on trade, unsustainable harvesting continues to threaten many populations. Illegal fishing and trade continues to be a threat to the management of these fish. To enforce the regulation of legal trade and prevention of illegal trade, the development of a uniform identification system for parts and derivates of Acipenseriformes has been identified as an urgent requirement. Ideally this system should be suitable for (i) identification at the species-level of caviar and other products from Acipenseriformes; (ii) population identification; (iii) source identification (wild vs aquaculture); and (iv) determining the age of caviar because strict timeframes govern its international trade. This paper reviews the techniques currently available and their potential to be used in an identification system for Acipenseriformes species and their products in trade. A review of all available identification techniques has shown that there is not a single method that can meet all requirements (see i,iv), and it does not appear to be feasible to develop such a method in the near future therefore the most appropriate methods need to be developed for each. Considering the advantages and disadvantages of all techniques reviewed in this document, the following conclusions can be drawn: (i) for the identification of species, approaches are recommended that target mitochondrial cytochrome b sequences (RFLP, nested PCR or direct sequencing). However, they show limitations for the detection of hybrids (although natural hybrids are rare, the number of artificially produced hybrids in aquaculture is increasing) and for the differentiation of the following closely related species complexes: Acipenser gueldenstaedti,Acipenser baerii,Acipenser persicus,Acipenser naccarii; Acipenser medirostris,Acipenser mikadoi; and Scaphirhynchus albus,Scaphirhynchus plathorhynchus,Scaphirhynchus suttkusi; (ii) the identification of different populations of the same species is currently not feasible because genetic data are incomplete for most populations, and stocking and release programmes, which have become more and more common, often result in a mixture of phenotypes and genotypes, thereby impeding the creation and application of such a population identification system; (iii) source identification based on genetic approaches can be excluded at present because there are no genetic differences between wild and hatchery-raised fish. This is the result of the continuing restocking of natural populations with captive fish and vice versa. However, because rearing (i.e. environmental) conditions are different, methods focusing on differences in water quality or food seem to be more appropriate (for example differences in fatty acid composition). So far, very few studies have been conducted and therefore, source identification methods merit further exploration; and (iv) the age of a product in trade cannot be detected by DNA-based methods and protein profiling is undoubtedly impractical due to hard-to-perform, labour-and cost-intensive methods, which are highly susceptible to protein degradation. Arising from the limits discussed above, the next steps in the development of a uniform sturgeon identification system are proposed to be the following: (i) designation of qualified reference laboratories at national levels in (re-) exporting and importing countries. These should be approved through a standardized testing procedure, for instance a ring test on blind samples. Registered laboratories should be published and disseminated and their accreditations should be subject to certain guarantees regarding quality, economic independence and scientific rigour. Operational procedures have to be determined and standardized among reference laboratories; (ii) establishment of reference collections that are accessible to the reference laboratories containing DNA analyses results and information on the location and availability of tissue samples. This is highly recommended as an important step towards a population identification system and indispensable for a general species identification system; (iii) creation of a website access to the reference collections containing the reference database information about genetic samples, comparable to NCBI, which provides background data: sample location; population information; citation; available genetic data; location of archival storage; currently treated and distributed caviar and status of analysis. This website should also be a forum for the exchange of knowledge on and experiences with identification systems, species and population status information, relevant scientific research, etc.; and (iv) the outcome of the trade identification tests should be made available to the reference laboratories for future reference. The universal caviar labelling system could incorporate an indication of the verification of the consignment. In view of the lack of knowledge and the great need to develop a uniform identification system for Acipenseriformes with regard to the importance of the international caviar trade, further scientific guidance and appropriate research is strongly recommended. Progress should be assessed and exchanged on a regular basis. [source] Sturgeons in Greece: a reviewJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2008I. Paschos Summary In the past, sturgeons were practically unknown in Greece, both to the public and to scientists, the latter not having had the opportunity to study wild populations of the four native species. Populations of stellate sturgeon (,cipenser stellatus Pallas, 1771), Adriatic sturgeon (Acipenser naccarii Bonaparte, 1836), and beluga sturgeon (Huso huso L., 1758) gradually collapsed by the end of the 1970s. Only the River Evros (Thrace, N.W. Greece) sustained a small fishery and caviar canning operation with European sturgeon (A.,sturio L., 1758) until 1975. Collapse of stocks was mainly attributed to overfishing, pollution and damming. Sturgeons became widely known after initial farming efforts by the Municipal Hatchery at Lake Ioannina in 1992. Broodstock or fertilized eggs of species with high aquaculture potential, such as sterlet (Acipenser ruthenus L., 1758), Russian sturgeon (Acipenser gueldenstaedtii Brandt, 1833), bester hybrid (A.,ruthenus ×H. huso), paddlefish (Polyodon spathula Walbaum, 1792), Siberian sturgeon (Acipenser baerii Brandt, 1869) and white sturgeon (Acipenser transmontanus Richardson, 1836) were imported into Greece between 1992 and 2004. Hatchery technology, larval rearing and production systems are reviewed in this paper and, despite problems, past and present efforts appear to meet a particular interest of the aquaculture sector as well as of those interested in the restoration of wild stocks. [source] Growth performance and body composition of sub-yearling Persian sturgeon, (Acipenser persicus, Borodin, 1897), fed different dietary protein and lipid levelsJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2007M. Mohseni Summary In order to evaluate the protein and energy requirement of Persian sturgeon (Acipenser persicus) sub-yearlings, eight experimental diets containing two protein levels (40% and 45%) and four lipid levels (10%, 15%, 20% and 25%) were tested. Sturgeons (W0 = 136.8 g) were fed the experimental diets to satiation four times daily for 150 days, resulting in a final mean weight of 375.8 g. Growth was significantly affected by lipid content of the diets. At 40% protein level, weight gain and specific growth rate (% per day) were significantly improved (P < 0.05) by increasing the dietary lipid (energy) content. Protein efficiency ratio (PER) was significantly affected by different dietary treatments for each dietary protein level tested, reaching a mean value of 3.58 in fish fed high lipid diets and a PER of 2.77 in low lipid diets. Results obtained in the present study suggest that the optimum dietary protein content for Persian sturgeon is 40%, with an estimated optimum protein-to-energy ratio of 18,20 mg kJ,1. [source] The 5th International Symposium on Sturgeons: a conference with major emphasis on conservation, environmental mitigation and sustainable use of the sturgeon resourcesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2006Article first published online: 10 JUL 200 First page of article [source] The 5th International Symposium on Sturgeons: a conference with major emphasis on conservation, environmental mitigation and sustainable use of the sturgeon resourcesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2006Harald Rosenthal First page of article [source] Management and Recovery Options for Ural River Beluga SturgeonCONSERVATION BIOLOGY, Issue 3 2010PHAEDRA DOUKAKIS caviar; CITES; criadero; Mar Caspio; puntos de referencia; sobrepesca Abstract:,Management of declining fisheries of anadromous species sometimes relies heavily on supplementation of populations with captive breeding, despite evidence that captive breeding can have negative consequences and may not address the root cause of decline. The beluga sturgeon (Huso huso), a species threatened by the market for black caviar and reductions in habitat quality, is managed through harvest control and hatchery supplementation, with an emphasis on the latter. We used yield per recruit and elasticity analyses to evaluate the population status and current levels of fishing and to identify the life-history stages that are the best targets for conservation of beluga of the Ural River. Harvest rates in recent years were four to five times higher than rates that would sustain population abundance. Sustainable rates of fishing mortality are similar to those for other long-lived marine species such as sharks and mammals. Yield per recruit, which is maximized if fish are first harvested at age 31 years, would be greatly enhanced by raising minimum size limits or reducing illegal take of subadults. Improving the survival of subadult and adult females would increase population productivity by 10 times that achieved by improving fecundity and survival from egg to age 1 year (i.e., hatchery supplementation). These results suggest that reducing mortality of subadults and adult wild fish is a more effective conservation strategy than hatchery supplementation. Because genetics is not factored into hatchery management practices, supplementation may even reduce the viability of the beluga sturgeon. Resumen:,El manejo de pesquerías de peces anádromos en declinación a veces depende estrechamente de la suplementación de poblaciones mediante la reproducción en cautiverio, no obstante la evidencia de que la reproducción en cautiverio puede tener consecuencias negativas y no abordar la causa principal de la declinación. El esturión beluga (Huso huso), una especie amenazada por el mercado de caviar negro y por reducciones en la calidad del hábitat, es manejado mediante el control de la cosecha y suplementación de poblaciones, con énfasis en esta. Utilizamos análisis de producción por recluta y de elasticidad para evaluar el estatus de la población y los niveles de pesca actuales y para identificar las etapas de la historia de vida que son los mejores blancos para la conservación del beluga en el Río Ural. Las tasas de cosecha en años recientes fueron cuatro a cinco veces mayores que las tasas que sustentarían la abundancia de la población. Las tasas sustentables de mortalidad por pesca son similares a las de otras especies marinas longevas como tiburones y mamíferos. La producción por recluta, que es maximizada si los peces son cosechados a la edad de 31 años, podría incrementar significativamente elevando los límites de talla mínima o reduciendo la captura ilegal de subadultos. La mejora de la supervivencia de hembras subadultas y adultas incrementaría la productividad de la población 10 veces más que la mejora obtenida incrementando la fecundidad y supervivencia de huevo a 1 año de edad (i. e., suplementación de poblaciones mediante reproducción en cautiverio). Estos resultados sugieren que la reducción de la mortalidad de peces silvestres subadultos y adultos es una mejor estrategia de conservación que la suplementación. Debido a que la genética no es considerada en las prácticas de manejo en los criaderos, la suplementación incluso puede reducir la viabilidad del esturión beluga. [source] Elevated organochlorines in the brain,hypothalamic,pituitary complex of intersexual shovelnose sturgeonENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2006Brian T. Koch Abstract Organochlorine compounds (OCs), including polychlorinated biphenyls and organochlorine pesticides, were used on lands adjacent to the Middle Mississippi River (MMR; USA) from 1930 through 1988, and they continue to occur in MMR fish. These compounds are estrogenic and/or antiandrogenic, and they alter hormone production and reception within the brain and gonads of male fish, resulting in intersexuality and/or suppressed gonadal development. To assess how OCs affect reproduction of MMR fish, we quantified OC accumulation, intersexuality, and gonadal development in male shovelnose sturgeon (Scaphirhynchus platorynchus) throughout the MMR during the spring of 2003. Gonads were observed for intersexual characteristics, weighed to calculate the gonadosomatic index (GSI), and examined histologically. Tissue accumulation of OCs was quantified in gonads, brain,hypothalamic,pituitary (BHP) complex, and fillets. Four of 48 mature males were identified macroscopically as intersexuals, and a fifth was found through histology (a 10.4% incidence). Intersexuals accumulated higher concentrations of OCs in the BHP complex compared with those of mature males. In addition, GSI and OC accumulation within the BHP complex, gonads, and fillets of mature males were negatively related. Exposure to OCs before or during sexual differentiation likely induces intersexuality in MMR shovelnose sturgeon, and exposure throughout gonadal maturation inhibits gonadal development. [source] Restoration of sturgeons: lessons from the Caspian Sea Sturgeon Ranching ProgrammeFISH AND FISHERIES, Issue 3 2000D.H. Secor Depletion of sturgeon stocks world-wide has increased interest in aquaculture-based restoration programmes. The Caspian Sea Sturgeon Ranching Programme (SRP) of the former Soviet Union represents a unique opportunity to evaluate expense, benefits and potential ecological and genetic effects of such restoration programmes. The SRP was initiated in the 1950s to compensate for lost spawning habitat in the Volga River and elsewhere. After its completion in 1962, the Volgograd Dam reduced spawning grounds in the Volga River system, the principal spawning tributary of the Caspian Sea, by ,80%. For two of the three commercial sturgeon species (Russian sturgeon, Acipenser güldenstädti, and stellate sturgeon, A. stellatus), yields improved after the imposition of the 1962 moratorium on sturgeon harvests in the Caspian Sea. Volga River fisheries were managed for spawning escapement. Although imprecisely known, the contribution of the millions of stocked Russian and stellate juveniles during 1962,91 was most likely important to sustaining fisheries, although less so (contributing to <30% of the adult stock) than natural recruitment. Apparently, reduced spawning grounds, supplemented with artificial spawning reefs were sufficient to support reproduction and large fishery yields of Russian and stellate sturgeons. For beluga sturgeon, Huso huso, harvests in the Volga River were nearly all dependent upon hatchery stocking. Beluga sturgeon spawning grounds were mostly eliminated with the construction of the Volgograd Dam. Without the hatchery programme, beluga sturgeon in the Volga River and Caspian Sea would in all likelihood have been extirpated. Currently, sturgeons are severely depleted in the Volga River and Caspian Sea due to poaching and lack of co-operation between countries exploiting the species. Aquaculture-based restoration in Russia is now viewed a chief means of rebuilding stocks of Caspian Sea sturgeons. [source] Physico-biochemical parameters and protein profiles of sperm from beluga Huso husoJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2010P. Li Summary Basic physico-biochemical parameters and protein profiles of sperm from beluga (Huso huso), have been evaluated. The results show a stable spermatozoan velocity (ranging from 136.23 ± 5.63 to 105.78 ± 5.27 ,ms,1) and motility during 2 min post activation, as well as a long duration of the overall spermatozoa motility period (up to 5 min). Mean values were determined for seminal plasma protein concentration (0.29 ± 0.16 mg ml,1), spermatozoa concentration (0.28 ± 0.27 × 109 spz ml,1), seminal plasma osmolality (51.33 ± 4.91 mOsmol kg,1), the pH (8.49 ± 0.01) and Na+ (18.97 ± 3.65 mm), K+ (2.83 ± 1.36 mm), Ca2+ (0.19 ± 0.06 mm), Mg2+ (0.49 ± 0.23 mm) and Cl, (6.33 ± 0.58 mm) concentrations. Moreover, in seminal plasma, five protein bands with molecular weights (MW) of 71, 49, 46, 34, 29 kDa were identified. In spermatozoa, about 100 spots with molecular weights varying from 26.5 to 107 kDa and iso-electric points ranging from 5 to 9.5 were found. The observed physiological and biochemical properties, together with protein patterns, should be considered for the development of methods for controlled reproduction and sperm cryopreservation for the highly endangered beluga sturgeon. [source] Vulnerability of age-0 pallid sturgeon Scaphirhynchus albus to fish predationJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2010By W. E. French Summary Stocking is a commonly employed conservation strategy for endangered species such as the pallid sturgeon, Scaphirhynchus albus. However, decisions about when, where and at what size pallid sturgeon should be stocked are hindered because vulnerability of pallid sturgeon to fish predation is not known. The objective of this study was to evaluate the vulnerability of age-0 pallid sturgeon to predation by two Missouri River predators under different flow regimes, and in combination with alternative prey. To document vulnerability, age-0 pallid sturgeon (<100 mm) were offered to channel catfish Ictalurus punctatus and smallmouth bass Micropterus dolomieu in laboratory experiments. Selection of pallid sturgeon by both predators was measured by offering pallid sturgeon and an alternative prey, fathead minnows Pimephales promelas, in varying prey densities. Smallmouth bass consumed more age-0 pallid sturgeon (0.95 h,1) than did channel catfish (0.13 h,1), and predation rates did not differ between water velocities supporting sustained (0 m s,1) or prolonged swimming speeds (0.15 m s,1). Neither predator positively selected pallid sturgeon when alternative prey was available. Both predator species consumed more fathead minnows than pallid sturgeon across all prey density combinations. Results indicate that the vulnerability of age-0 pallid sturgeon to predation by channel catfish and smallmouth bass is low, especially in the presence of an alternative fish prey. [source] Kootenai River velocities, depth, and white sturgeon spawning site selection , a mystery unraveled?JOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2009V. L. Paragamian Summary The Kootenai River white sturgeon Acipenser transmontanus population in Idaho, US and British Columbia (BC), Canada became recruitment limited shortly after Libby Dam became fully operational on the Kootenai River, Montana, USA in 1974. In the USA the species was listed under the Endangered Species Act in September of 1994. Kootenai River white sturgeon spawn within an 18-km reach in Idaho, river kilometer (rkm) 228.0,246.0. Each autumn and spring Kootenai River white sturgeon follow a ,short two-step' migration from the lower river and Kootenay Lake, BC, to staging reaches downstream of Bonners Ferry, Idaho. Initially, augmented spring flows for white sturgeon spawning were thought to be sufficient to recover the population. Spring discharge mitigation enhanced white sturgeon spawning but a series of research investigations determined that the white sturgeon were spawning over unsuitable incubation and rearing habitat (sand) and that survival of eggs and larvae was negligible. It was not known whether post-Libby Dam management had changed the habitat or if the white sturgeon were not returning to more suitable spawning substrates farther upstream. Fisheries and hydrology researchers made a team effort to determine if the spawning habitat had been changed by Libby Dam operations. Researchers modeled and compared velocities, sediment transport, and bathymetry with post-Libby Dam white sturgeon egg collection locations. Substrate coring studies confirmed cobbles and gravel substrates in most of the spawning locations but that they were buried under a meter or more of post-Libby Dam sediment. Analysis suggested that Kootenai River white sturgeon spawn in areas of highest available velocity and depths over a range of flows. Regardless of the discharge, the locations of accelerating velocities and maximum depth do not change and spawning locations remain consistent. Kootenai River white sturgeon are likely spawning in the same locations as pre-dam, but post-Libby Dam water management has reduced velocities and shear stress, thus sediment is now covering the cobbles and gravels. Although higher discharges will likely provide more suitable spawning and rearing conditions, this would be socially and politically unacceptable because it would bring the river elevation to or in excess of 537.66 m, which is flood stage. Thus, support should be given to habitat modifications incorporated into a management plan to restore suitable habitat and ensure better survival of eggs and larvae. [source] Overwinter survival of stocked age-0 lake sturgeonJOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2009J. A. Crossman Summary Knowledge of age-specific survivorship is critical when developing management prescriptions for imperiled species such as the lake sturgeon (Acipenser fulvescens). Management has focused on population restoration through hatchery supplementation, largely in the absence of data about relationships between hatchery rearing conditions, size/age at release, and estimates of overwinter survival for stocked age-0 lake sturgeon. Young of the year lake sturgeon were reared from egg to age 3 months in two separate hatchery environments: a streamside hatchery on the natal Upper Black River, Michigan, and a traditional hatchery environment. From age 3 to 6 months all fish were reared in the traditional hatchery. Fish (n = 20) originating from each rearing environment were surgically implanted with ultrasonic transmitters at 6 months of age (mean total length: 31.4 cm; mean weight: 106.4 g) and released into Black Lake in December 2005. Tracking using manual and automated hydrophones was conducted during April and May 2006 to estimate overwinter survival and to test for differences in survival of fish reared in different hatchery environments. Eighteen fish (45%) were detected, 16 (40%) of which survived the winter (range of distance traveled between observations of surviving fish was 0.09,0.55 km). The remaining fish were not detected. No significant differences in survival were documented due to rearing environment or size at release. This study represents the first quantified estimate of overwinter survival for stocked age-0 lake sturgeon. The minimum estimate of 40% survival through the first winter is encouraging for hatchery programs, and will aid in the development of management prescriptions for this species. [source] Ancient mitochondrial DNA analyses of Iberian sturgeonsJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2009A. Ludwig Summary Today's European sturgeons are relics of erstwhile widely distributed populations, diminished mainly by overfishing and habitat changes over the centuries. While extinct European populations in the Baltic and North seas have been identified as Acipenser oxyrhinchus or A. sturio, a clear species determination on the Iberian Peninsula is still lacking. Plans to conserve existing populations and to re-introduce extinct wild populations in European rivers will benefit from information of historic population/genotype composition. In this study, we used techniques involving ancient DNA as well as morphological comparisons based on bony scutes to identify twelve samples from five archaeological sites (650bc,1500ad, one sample dated 10.1,11.8 ky) on the Iberian Peninsula. All amplified PCR products of bony scutes (n = 5) had the mitochondrial DNA haplotypes of European sturgeon. Neither mitochondrial haplotypes of A. naccarii nor mitochondrial haplotypes of A. oxyrinchus were found. [source] Multiple molecular approaches yield no evidence for sex-determining genes in lake sturgeon (Acipenser fulvescens)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2008C. R. McCormick Summary Common DNA-based sexing assays have been widely used for the conservation and management of mammals and birds. However, many fishes do not have genetic sex determination and in those that do, the plasticity of the genes involved means that species-specific assays are normally required. Such DNA-sexing markers would be especially valuable in lake sturgeon (Acipenser fulvescens) because of their sexual monomorphism, delayed sexual maturity, and conservation status. We tried to identify genetic differences between male and female lake sturgeon using several different molecular genetic methods, including randomly amplified polymorphic DNA, representational difference analyses, subtractive hybridization, and a candidate gene approach. Ultimately, a number of genes were identified but none was sex-specific. Although the ultimate mechanism of sex determination is yet unknown, it is possible that sex determination is environmental in lake sturgeon, especially since recent studies have also failed to identify sex determination genes in other sturgeon species. [source] Effects of dietary l -carnitine supplements on growth and body composition in beluga sturgeon (Huso huso) juvenilesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2008M. Mohseni Summary The effects of dietary l -carnitine on growth performance, whole body composition and feed utilization were studied in beluga, Huso huso. Fish were randomly allocated in 15 tanks (30 fish per tank) and triplicate groups were fed to satiety during 84 days one of five isonitrogenous (41% CP) and isoenergetic (20 MJ kg,1) diets, each differing in l -carnitine content [0 (control), 300, 600, 900 and 1200 mg kg,1 diet]. At the end of the trial, fish grew from 19- to 23-fold in weight, from 8.4 g to a maximum of 191 g. Fish fed 300,600 mg l -carnitine had the highest specific growth rate (SGR, 3.69 and 3.72% day,1) and protein efficiency ratio (PER, 0.95 and 0.99), and the lowest feed conversion ratio (FCR, 1.4 and 1.3) than the other groups (P < 0.0001). SGR, PER and FCR were the poorest for fish fed 1200 mg l -carnitine, while fish fed the unsupplemented and 900 mg l -carnitine supplemented diet showed intermediate performance. Body lipid concentration decreased significantly from 5.8 to 5.1% (P < 0.0001) with dietary l -carnitine supplementation increasing from 0 to 300 mg. Energy content was significantly lower in fish fed the 900 and 1200 mg l -carnitine diet (5.8 MJ kg,1), when compared with the other treatment groups (6.4,6.6 MJ kg,1). The results indicated that feeding sturgeon on diets supplemented with 300 mg l -carnitine kg,1 diet improved growth performance, and stimulated protein-sparing effects from lipids. [source] Dietary vitamin A requirement of juvenile Amur sturgeon (Acipenser schrenckii)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2008H. Wen Summary The present experiment was conducted to determine the dietary vitamin A requirement of juvenile Amur sturgeon (Acipenser schrenckii) by formulating seven semipurified diets containing 10, 258, 510, 1050, 2020, 4100 and 8300 IU vitamin A (as retinol acetate) kg,1 diet, respectively. Each experimental diet was fed to triplicate groups of 20 juveniles each with initial average weights of 12.09 ± 0.22 g in 405-L aquaria and maintained at 25.0 ± 2.0°C for 8 weeks. Fish fed the basal diet (10 IU vitamin A kg,1 diet) exhibited poor appetite and activity, whereas these signs were not observed in any group fed vitamin A-supplemented diets. Weight gain, feed efficiency and hepatosomatic index increased significantly with increases in the dietary vitamin A level, reaching a peak with the vitamin A 1050 IU kg,1 diet, and then decreasing. Muscle chemical compositions were not affected by the dietary vitamin A levels. Vitamin A concentrations in liver and muscle increased significantly as the vitamin A levels increased within a range of 10,4100 IU kg,1 diet; above this level there were no significant changes. Broken-line regression analysis of weight gain and liver vitamin A concentration against the dietary vitamin A level showed that juvenile Amur sturgeon required a minimum of 923 IU vitamin A kg,1 in the diet for maximal growth, and 1981 IU kg,1 for highest liver vitamin A accumulation. [source] Isolation and preliminary characteristics of ,- N -acetylglucosaminidase in the sperm of Siberian sturgeon (Acipenser baerii) and rainbow trout (Oncorhynchus mykiss)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2008B. Sarosiek Summary The aim of this study was to characterize the enzyme ,- N -acetyglucosaminidase (,-NAGase) in the milt and spermatozoa extracts from Siberian sturgeon and rainbow trout. After ion exchange chromatography one protein peak showed ,-NAGase activity in sturgeon milt plasma and sperm extracts of both species. Surprisingly, two protein peaks showing ,-NAGase activity were found in rainbow trout milt plasma. The molecular mass of ,-NAGase was estimated by gel filtration as 127 kDa for rainbow trout spermatozoa, 271 kDa for sturgeon spermatozoa, and 74 kDa for milt plasma from both species. The kinetic parameters were determined for milt plasma and sperm extracts. The optimum pH of the ,-NAGases was 3.8 for sturgeon milt plasma, 4.4 for sturgeon sperm extract, and 4.4,4.8 for milt plasma and sperm extract from rainbow trout. Km value of the ,-NAGases was 0.212, 0.563, 0.779 mm for sturgeon milt plasma, sturgeon sperm extract or rainbow trout extract, respectively. The ,-NAGase from sperm extracts in both species showed 100% activity even after incubation at 56°C by 20 min, whereas its activity was decreased to 23% in sturgeon milt plasma and to 2% in trout milt plasma. [source] Identification of Acipenseriformes species in tradeJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2008A. Ludwig Summary Sturgeons and paddlefishes (Acipenseridae) are highly endangered freshwater fishes. Their eggs (sold as caviar) are one of the most valuable wildlife products in international trade. Concerns of overharvesting and the conservation status of many of the 27 extant species of Acipenseriformes led to all species being included on the CITES Appendices in 1998. Since then international trade in all products and parts from sturgeon and paddlefish has been regulated. However, despite the controls on trade, unsustainable harvesting continues to threaten many populations. Illegal fishing and trade continues to be a threat to the management of these fish. To enforce the regulation of legal trade and prevention of illegal trade, the development of a uniform identification system for parts and derivates of Acipenseriformes has been identified as an urgent requirement. Ideally this system should be suitable for (i) identification at the species-level of caviar and other products from Acipenseriformes; (ii) population identification; (iii) source identification (wild vs aquaculture); and (iv) determining the age of caviar because strict timeframes govern its international trade. This paper reviews the techniques currently available and their potential to be used in an identification system for Acipenseriformes species and their products in trade. A review of all available identification techniques has shown that there is not a single method that can meet all requirements (see i,iv), and it does not appear to be feasible to develop such a method in the near future therefore the most appropriate methods need to be developed for each. Considering the advantages and disadvantages of all techniques reviewed in this document, the following conclusions can be drawn: (i) for the identification of species, approaches are recommended that target mitochondrial cytochrome b sequences (RFLP, nested PCR or direct sequencing). However, they show limitations for the detection of hybrids (although natural hybrids are rare, the number of artificially produced hybrids in aquaculture is increasing) and for the differentiation of the following closely related species complexes: Acipenser gueldenstaedti,Acipenser baerii,Acipenser persicus,Acipenser naccarii; Acipenser medirostris,Acipenser mikadoi; and Scaphirhynchus albus,Scaphirhynchus plathorhynchus,Scaphirhynchus suttkusi; (ii) the identification of different populations of the same species is currently not feasible because genetic data are incomplete for most populations, and stocking and release programmes, which have become more and more common, often result in a mixture of phenotypes and genotypes, thereby impeding the creation and application of such a population identification system; (iii) source identification based on genetic approaches can be excluded at present because there are no genetic differences between wild and hatchery-raised fish. This is the result of the continuing restocking of natural populations with captive fish and vice versa. However, because rearing (i.e. environmental) conditions are different, methods focusing on differences in water quality or food seem to be more appropriate (for example differences in fatty acid composition). So far, very few studies have been conducted and therefore, source identification methods merit further exploration; and (iv) the age of a product in trade cannot be detected by DNA-based methods and protein profiling is undoubtedly impractical due to hard-to-perform, labour-and cost-intensive methods, which are highly susceptible to protein degradation. Arising from the limits discussed above, the next steps in the development of a uniform sturgeon identification system are proposed to be the following: (i) designation of qualified reference laboratories at national levels in (re-) exporting and importing countries. These should be approved through a standardized testing procedure, for instance a ring test on blind samples. Registered laboratories should be published and disseminated and their accreditations should be subject to certain guarantees regarding quality, economic independence and scientific rigour. Operational procedures have to be determined and standardized among reference laboratories; (ii) establishment of reference collections that are accessible to the reference laboratories containing DNA analyses results and information on the location and availability of tissue samples. This is highly recommended as an important step towards a population identification system and indispensable for a general species identification system; (iii) creation of a website access to the reference collections containing the reference database information about genetic samples, comparable to NCBI, which provides background data: sample location; population information; citation; available genetic data; location of archival storage; currently treated and distributed caviar and status of analysis. This website should also be a forum for the exchange of knowledge on and experiences with identification systems, species and population status information, relevant scientific research, etc.; and (iv) the outcome of the trade identification tests should be made available to the reference laboratories for future reference. The universal caviar labelling system could incorporate an indication of the verification of the consignment. In view of the lack of knowledge and the great need to develop a uniform identification system for Acipenseriformes with regard to the importance of the international caviar trade, further scientific guidance and appropriate research is strongly recommended. Progress should be assessed and exchanged on a regular basis. [source] Sturgeons in Greece: a reviewJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2008I. Paschos Summary In the past, sturgeons were practically unknown in Greece, both to the public and to scientists, the latter not having had the opportunity to study wild populations of the four native species. Populations of stellate sturgeon (,cipenser stellatus Pallas, 1771), Adriatic sturgeon (Acipenser naccarii Bonaparte, 1836), and beluga sturgeon (Huso huso L., 1758) gradually collapsed by the end of the 1970s. Only the River Evros (Thrace, N.W. Greece) sustained a small fishery and caviar canning operation with European sturgeon (A.,sturio L., 1758) until 1975. Collapse of stocks was mainly attributed to overfishing, pollution and damming. Sturgeons became widely known after initial farming efforts by the Municipal Hatchery at Lake Ioannina in 1992. Broodstock or fertilized eggs of species with high aquaculture potential, such as sterlet (Acipenser ruthenus L., 1758), Russian sturgeon (Acipenser gueldenstaedtii Brandt, 1833), bester hybrid (A.,ruthenus ×H. huso), paddlefish (Polyodon spathula Walbaum, 1792), Siberian sturgeon (Acipenser baerii Brandt, 1869) and white sturgeon (Acipenser transmontanus Richardson, 1836) were imported into Greece between 1992 and 2004. Hatchery technology, larval rearing and production systems are reviewed in this paper and, despite problems, past and present efforts appear to meet a particular interest of the aquaculture sector as well as of those interested in the restoration of wild stocks. [source] Molecular systematics of Scaphirhynchinae: an assessment of North American and Central Asian Freshwater Sturgeon SpeciesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007C. B. Dillman Summary The sturgeon subfamily Scaphirhynchinae contains two genera of obligate freshwater sturgeon: Scaphirhynchus and Pseudoscaphirhynchus, from North America and Central Asia, respectively. Both genera contain morphologically variable species. A novel data set containing multiple individuals representing four diagnosable morphological variants for two species of Pseudoscaphirhynchus, P. hermanni and P. kaufmanni, was generated. These data were used to test taxonomic hypotheses of monophyly for the subfamily Scaphirhynchinae, monophyly of both Scaphirhynchus and Pseudoscaphirhynchus, monophyly of P. hermanni and P. kaufmanni, and monophyly of the recognized morphological variants. Monophyly of the subfamily Scaphirhynchinae is consistently rejected by all phylogenetic reconstruction methodologies with the molecular character set while monophyly of both river sturgeon genera is robustly supported. The molecular data set also rejects hypotheses of monophyly for sampled species of Pseudoscaphirhynchus as well as monophyly for the recognized intraspecific morphological variants. Interestingly both Scaphirhynchus and Pseudoscaphirhynchus demonstrate the same general pattern in reconstructed topologies; a lack of phylogenetic structure in the clade with respect to recognized diversity. Despite rejection of monophyly for the subfamily Scaphirhynchinae with molecular data, reconstructed hypotheses from morphological character sets consistently support monophyly for this subfamily. Disparities among the data sets, as well as reasons for rejection of monophyly for Scaphirhynchinae and species of Scaphirhynchus and Pseudoscaphirhynchus with molecular characters are examined and a decreased rate of molecular evolution is found to be most consistent with the data. [source] Stock structure of pallid sturgeon analyzed with microsatellite lociJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007A. W. Schrey Summary Recovery efforts for the endangered pallid sturgeon (Scaphirhynchus albus) include supplementation of wild stocks with hatchery reared progeny. Identifying the extent of genetic stock structure, which has previously been detected in samples from the range extremes, will help to determine whether stock transfers might be harmful. DNA microsatellite genotypes were screened in pallid sturgeon from the upper Missouri River, lower Missouri River, middle Mississippi River and Atchafalaya River and analyzed using a combination of Bayesian model-based and more traditional F-statistic based methods to characterize genetic differentiation. Scaphirhynchus specimens were collected by researchers active in the recovery effort and genotypes were screened at 16 microsatellite loci. Because there is considerable genetic and morphological overlap between pallid sturgeon, shovelnose sturgeon, and their hybrids, a combination of morphological and genetic techniques were used to eliminate shovelnose and possible hybrids from the sample. Genetic differentiation was detected among samples (overall , = 0.050, P = 0.001). Pairwise ,, genetic distances, and Bayesian assignment testing reveal that pallid sturgeon from the upper Missouri River are the most distinct group with pairwise comparisons of pallid sturgeon among all the remaining samples exhibiting lower , values, higher genetic distances, and self assignment scores. Our results indicate that using local broodstock, when available, should be used for pallid sturgeon propagation. If local broodstock are not available, geographically proximate individuals would limit genetic differences between native and stocked individuals. [source] A guide to the embryonic development of the shovelnose sturgeon (Scaphirhynchus platorynchus), reared at a constant temperatureJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007R. E. Colombo Summary Described is the sequence and timing of embryologic development of shovelnose sturgeon, (Scaphirhynchus platorynchus) reared at a constant temperature 20 ± 0.5°C. Artificially spawned, fertilized eggs were held in a recirculating system. Embryos were sampled hourly during the first 48 h of development and every 3 h thereafter. Embryos were viewed and imaged at 35× magnification. The first cleavage furrow appeared 2 h post-fertilization; early (synchronous) cleavage was completed after 7 h. Blastulation concluded at 16 h when the dorsal blastopore lip formed. The slitlike blastopore appeared at 29 h, signifying the completion of gastrulation. At 33 h, the rudiments of the excretory system emerged, followed by closing of the neural tube at 36 h and formation of the s-shaped heart at 60 h. The body continued to elongate with mass hatch occurring at 102 h. After hatch, larvae swam into the water column and drifted in the flow for approximately 2 days after which the larvae became positively rheotaxic. After expulsion of the pigment plug, the larvae began exogenous feeding and other structures continued to develop. Metamorphosis was completed after 26 days of development. Because the shovelnose sturgeon possesses developmental patterns similar to those of other sturgeon, we can use this species as a model for the closely related pallid and Alabama sturgeon. [source] Estimation of gonad volume, fecundity, and reproductive stage of shovelnose sturgeon using sonography and endoscopy with application to the endangered pallid sturgeonJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007By J. L. Bryan Summary Most species of sturgeon are declining in the Mississippi River Basin of North America including pallid (Scaphirhynchus albus F. and R.) and shovelnose sturgeons (S. platorynchus R.). Understanding the reproductive cycle of sturgeon in the Mississippi River Basin is important in evaluating the status and viability of sturgeon populations. We used non-invasive, non-lethal methods for examining internal reproductive organs of shovelnose and pallid sturgeon. We used an ultrasound to measure egg diameter, fecundity, and gonad volume; endoscope was used to visually examine the gonad. We found the ultrasound to accurately measure the gonad volume, but it underestimated egg diameter by 52%. After correcting for the measurement error, the ultrasound accurately measured the gonad volume but it was higher than the true gonad volume for stages I and II. The ultrasound underestimated the fecundity of shovelnose sturgeon by 5%. The ultrasound fecundity was lower than the true fecundity for stage III and during August. Using the endoscope, we viewed seven different egg color categories. Using a model selection procedure, the presence of four egg categories correctly predicted the reproductive stage ± one reproductive stage of shovelnose sturgeon 95% of the time. For pallid sturgeon, the ultrasound overestimated the density of eggs by 49% and the endoscope was able to view eggs in 50% of the pallid sturgeon. Individually, the ultrasound and endoscope can be used to assess certain reproductive characteristics in sturgeon. The use of both methods at the same time can be complementary depending on the parameter measured. These methods can be used to track gonad characteristics, including measuring Gonadosomatic Index in individuals and/or populations through time, which can be very useful when associating gonad characteristics with environmental spawning triggers or with repeated examinations of individual fish throughout the reproductive cycle. [source] | ||||||||||||||||