Sturgeon Populations Research Articles

If you build it, will they come? Spawning habitat remediation for sturgeon

Habitat loss is a widely recognized contributor to global declines in sturgeon populations yet habitat remediation has been limited for this highly endangered group of fish. In support of future sturgeon restoration efforts, this review examines habitat remediation needs and uncertainties. Consideration of the bio‐spatial scale of remediation identified needs ranging from local to the whole river scale. Additionally, the context of remediation ranges from reintroducing sturgeon to habitats where they have been extirpated to conservation of currently functional habitat. While multiple remediation scales and contexts are discussed, the focus on spawning and early rearing habitat and associated biological and physical monitoring reflects the range of current projects and the importance of early rearing habitats. Four case studies are presented that examine four distinct remediation contexts (mitigation, rejuvenation, re‐creation, repatriation) and three bio‐spatial scales (whole river, spawning reach, spawning location) under which remediation has been attempted. Evaluation of existing remediation works indicates that many show limited long‐term success, which is most often a response to substrate infilling in remediated habitats. Material presented in this review will help align sturgeon research and monitoring approaches in support of effective remediation. The limited number of remediation projects to‐date attests to the importance of learning from existing projects and cross‐species comparisons, to maximize the effectiveness of future restoration efforts.

Seaward migration behavior of juvenile second filial generation Chinese sturgeon Acipenser sinensis in the Yangtze River, China

Second filial generation (F2) Chinese sturgeon from hatcheries have been released to restock the endangered natural population of this fish ever since full-cycle artificial breeding was first achieved in 2009. However, our knowledge of the habitat use and migration tactics of hatchery-bred F2 Chinese sturgeon is poor, as is our understanding of the effects of releasing these hatchery-bred sturgeon on the natural population. Acoustic telemetry data and recapture information were therefore collected to study the seaward migration behavior and distribution of hatchery-bred juvenile F2 Chinese sturgeon. Acoustic monitoring showed that the released F2 juveniles dispersed gradually and migrated down the Yangtze River at a ground migration speed of 24.2–125.9 km/day (mean 88.5 km/day). The range of swimming depths used by the F2 Chinese sturgeon during downstream migration depended on the river reaches considered, but the mean depth was 10.4 m (range 0.2–32.3 m). It was found that F2 Chinese sturgeon juveniles prefer to swim in the middle and upper layers of the water. Twenty-one of the 61 (34%) acoustically tagged F2 juveniles arrived at the estuary area. Recapture information indicated that the cultured F2 Chinese sturgeon adopted a similar distribution strategy to the wild Chinese sturgeon larvae in the estuary area. Knowledge of the migration and distribution patterns of the hatchery-bred juvenile F2 Chinese sturgeon should help to illuminate the consequences of restocking the natural population of Chinese sturgeon with cultured F2 juveniles, and thus point the way to an effective protection strategy for this species in the Yangtze River.

Divergent migration within lake sturgeon (Acipenser fulvescens) populations: Multiple distinct patterns exist across an unrestricted migration corridor.

Population structure, distribution, abundance and dispersal arguably underpin the entire field of animal ecology, with consequences for regional species persistence, and provision of ecosystem services. Divergent migration behaviours among individuals or among populations are an important aspect of the ecology of highly mobile animals, allowing populations to exploit spatially or temporally distributed food and space resources. This study investigated the spatial ecology of lake sturgeon (Acipenser fulvescens) within the barrier free Huron-Erie Corridor (HEC), which connects Lake Huron and Lake Erie of the North American Laurentian Great Lakes. Over 6years (2011-2016), movements of 268 lake sturgeon in the HEC were continuously monitored across the Great Lakes using acoustic telemetry (10years battery life acoustic transmitters). Five distinct migration behaviours were identified with hierarchical cluster analysis, based on the phenology and duration of river and lake use. Lake sturgeon in the HEC were found to contain a high level of intraspecific divergent migration, including partial migration with the existence of residents. Specific behaviours included year-round river residency and multiple lake-migrant behaviours that involved movements between lakes and rivers. Over 85% of individuals were assigned to migration behaviours as movements were consistently repeated over the study, which suggested migration behaviours were consistent and persistent in lake sturgeon. Differential use of specific rivers or lakes by acoustic-tagged lake sturgeon further subdivided individuals into 14 "contingents" (spatiotemporally segregated subgroups). Contingents associated with one river (Detroit or St. Clair) were rarely detected in the other river, which confirmed that lake sturgeon in the Detroit and St. Clair represent two semi-independent populations that could require separate management consideration for their conservation. The distribution of migration behaviours did not vary between populations, sexes, body size or among release locations, which indicated that intrapopulation variability in migratory behaviour is a general feature of the spatial ecology of lake sturgeon in unfragmented landscapes.

Habitat Quantity Required to Support Self‐Sustaining Lake Sturgeon Populations: an Alternative Hypothesis

AbstractCiting the capacity of anadromous sturgeon species to undertake lengthy spawning migrations, Auer (1996) hypothesized that a minimum of 250–300 km of barrier‐free lake and river habitat might be required to support self‐sustaining populations of Lake SturgeonAcipenser fulvescens. Twenty years later, the biological understanding of this potamodromous species has improved considerably, but there has been minimal effort to reconcile the barrier‐free hypothesis with the persistence of Lake Sturgeon populations in impounded habitats and improve the understanding of what constitutes a functional population‐level habitat unit for this species of conservation concern. Herein, POPAN mark–recapture models and sequential length‐frequency histograms were used to examine contemporary Lake Sturgeon abundance and population trajectories in three small reaches (230, 50, and 10 river kilometers [rkm]) of the Nelson and Winnipeg rivers (Manitoba), developed for hydroelectric power generation. Approximately two decades after harvest closures, results indicate that population recovery is occurring in all three reaches examined. Mechanisms other than in situ reproduction or recruitment (i.e., stocking and immigration) for increasing abundance are confidently discounted. Based on these results and other observations of contemporary persistence of Lake Sturgeon populations in impounded environments as well as recent genetic observations indicative of historical population structuring along the flow axes of naturally fragmented Boreal Shield rivers, it is contended that the barrier‐free hypothesis should no longer be cited as a “rule of thumb” with regard to the habitat quantity required to support self‐sustaining Lake Sturgeon populations. Rather, the concept of an uninterrupted “spawn–drift–settle–establish” habitat sequence as the cornerstone of a functional population‐level habitat unit may have broader relevance to species recovery initiatives and management. Given appropriate geomorphologic and hydraulic conditions, Lake Sturgeon populations can thrive—and in Boreal Shield rivers likely have for thousands of years—in lake, river, or impoundment sections as small as 10 rkm.

Genetic differentiation of spring-spawning and fall-spawning male Atlantic sturgeon in the James River, Virginia.

Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus, Acipenseridae) populations are currently at severely depleted levels due to historic overfishing, habitat loss, and pollution. The importance of biologically correct stock structure for effective conservation and management efforts is well known. Recent improvements in our understanding of Atlantic sturgeon migrations, movement, and the occurrence of putative dual spawning groups leads to questions regarding the true stock structure of this endangered species. In the James River, VA specifically, captures of spawning Atlantic sturgeon and accompanying telemetry data suggest there are two discrete spawning groups of Atlantic sturgeon. The two putative spawning groups were genetically evaluated using a powerful microsatellite marker suite to determine if they are genetically distinct. Specifically, this study evaluates the genetic structure, characterizes the genetic diversity, estimates effective population size, and measures inbreeding of Atlantic sturgeon in the James River. The results indicate that fall and spring spawning James River Atlantic sturgeon groups are genetically distinct (overall FST = 0.048, F’ST = 0.181) with little admixture between the groups. The observed levels of genetic diversity and effective population sizes along with the lack of detected inbreeding all indicated that the James River has two genetically healthy populations of Atlantic sturgeon. The study also demonstrates that samples from adult Atlantic sturgeon, with proper sample selection criteria, can be informative when creating reference population databases. The presence of two genetically-distinct spawning groups of Atlantic sturgeon within the James River raises concerns about the current genetic assignment used by managers. Other nearby rivers may also have dual spawning groups that either are not accounted for or are pooled in reference databases. Our results represent the second documentation of genetically distinct dual spawning groups of Atlantic sturgeon in river systems along the U.S. Atlantic coast, suggesting that current reference population database should be updated to incorporate both new samples and our increased understanding of Atlantic sturgeon life history.

Spring habitat use by stocked one year old European sturgeon Acipenser sturio in the freshwater-oligohaline area of the Gironde estuary

Post release habitat selection was studied on forty eight 10-month-old hatchery reared European sturgeon (mean fork length 31.0 cm ± 3.0) in the tidal part of their native catchment using acoustic telemetry. Most of the fish reached the oligohaline estuary within 2–4 days (70 km downstream the release site). Seventy four percent of the fish migrated rapidly downstream of the estuary into mesohaline waters while 26% selected habitat in the freshwater/oligohaline part of the estuary based on their linearity and residency indices. We focused on individual habitat use of these fish. The home range size (HR) was calculated using two methods: the kernel utilization distribution (KUD) which is driven by the maximum detection location density, and the Brownian Bridge (BB) approach which allows the time component of the trajectory path to be taken into account. The average 50% HR KUD was 5.6 ± 2.7 km2 (range 1.1–10.3 km2) and it was estimated to be 6 times larger using the 50% HR BB method (average reaching 31.9 ± 20.7 km2, range 5.2–77.8 km2). Habitat characterization (available prey, substrate and depth) in the studied area was described and the Ivlev electivity index was calculated using the habitat within the 50% HR BB for each individual. Despite the spatial use of different core areas among the fish tagged, we observed a convergence in habitat preference. For substrates, sturgeons showed avoidance of gravel and large rocks as well as fine and medium gravel. There was a significant preference for sand, silts and clay. For depth, they exhibited a preference firstly for the 5–8 m depth range and secondly for the 2–5 m range, a strong avoidance of depth range 8–20 m and a slight avoidance of shallow (0–2 m) and intertidal areas. For prey, individual variability was high. The most homogenous results were found for annelid polychaeta, with a slight preference for areas with this group of preys which are abundant in the saline estuary. For some individuals, a preference for areas with crustacea or nematodea and avoidance for areas with mollusks, insects or oligochaeta occured. We explain our results in light of foraging behavior and adaptation to the wild environment after captivity.For sturgeon population restoration projects in western Europe, these habitat preferences are key-features needed to evaluate the essential habitat availability for A. sturio juveniles in the tidal area at the front of the freshwater/saline transition waters.

Evidence of natural reproduction of Atlantic sturgeon in the Connecticut River from unlikely sources.

Atlantic Sturgeon is listed under the U.S. Endangered Species Act as five Distinct Population Segments (DPS). The “endangered” New York Bight (NYB) DPS is thought to only harbor two populations; one in the Hudson River and a second smaller one in the Delaware River. Historically, the Connecticut River probably supported a spawning population of Atlantic Sturgeon that was believed extirpated many decades ago. In 2014, we successfully collected pre-migratory juvenile specimens from the lower Connecticut River which were subjected to mitochondrial DNA (mtDNA) control region sequence and microsatellite analyses to determine their genetic relatedness to other populations coastwide. Haplotype and allelic frequencies differed significantly between the Connecticut River collection and all other populations coastwide. Sibship analyses of the microsatellite data indicated that the Connecticut River collection was comprised of a small number of families that were likely the offspring of a limited number of breeders. This was supported by analysis of effective population size (Ne) and number of breeders (Nb). STRUCTURE analysis suggested that there were 11 genetic clusters among the coastwide collections and that from the Connecticut River was distinct from those in all other rivers. This was supported by UPGMA analyses of the microsatellite data. In AMOVA analyses, among region variation was maximized, and among population within regions variation minimized when the Connecticut River collection was separate from the other two populations in the NYB DPS indicating the dissimilarity between the Connecticut River collection and the other two populations in the NYB DPS. Use of mixed stock analysis indicated that the Connecticut River juvenile collection was comprised of specimens primarily of South Atlantic and Chesapeake Bay DPS origins. The most parsimonious explanation for these results is that the Connecticut River hosted successful natural reproduction in 2013 and that its offspring were descendants of a small number of colonizers from populations south of the NYB DPS, most notably the South Atlantic DPS. Our results run contrary to the belief that re-colonizers of extirpated populations primarily originate in proximal populations.

Bayesian Hierarchical Multi-Population Multistate Jolly–Seber Models With Covariates: Application to the Pallid Sturgeon Population Assessment Program

ABSTRACT Estimating abundance for multiple populations is of fundamental importance to many ecological monitoring programs. Equally important is quantifying the spatial distribution and characterizing the migratory behavior of target populations within the study domain. To achieve these goals, we propose a Bayesian hierarchical multi-population multistate Jolly–Seber model that incorporates covariates. The model is proposed using a state-space framework and has several distinct advantages. First, multiple populations within the same study area can be modeled simultaneously. As a consequence, it is possible to achieve improved parameter estimation by “borrowing strength” across different populations. In many cases, such as our motivating example involving endangered species, this borrowing of strength is crucial, as there is relatively less information for one of the populations under consideration. Second, in addition to accommodating covariate information, we develop a computationally efficient Markov chain Monte Carlo algorithm that requires no tuning. Importantly, the model we propose allows us to draw inference on each population as well as on multiple populations simultaneously. Finally, we demonstrate the effectiveness of our method through a motivating example of estimating the spatial distribution and migration of hatchery and wild populations of the endangered pallid sturgeon (Scaphirhynchus albus), using data from the Pallid Sturgeon Population Assessment Program on the Lower Missouri River. Supplementary materials for this article are available online.

Rethinking the influence of hydroelectric development on gene flow in a long-lived fish, the Lake Sturgeon Acipenser fulvescens.

Many hydroelectric dams have been in place for 50 - >100 years, which for most fish species means that enough generations have passed for fragmentation induced divergence to have accumulated. However, for long-lived species such as Lake Sturgeon, Acipenser fulvescens, it should be possible to discriminate between historical population structuring and contemporary gene flow and improve the broader understanding of anthropogenic influence. On the Winnipeg River, Manitoba, two hypotheses were tested: 1) Measureable quantities of former reservoir dwelling Lake Sturgeon now reside downstream of the Slave Falls Generating Station, and 2) genetically differentiated populations of Lake Sturgeon occur upstream and downstream, a result of historical structuring. Genetic methods based on ten microsatellite markers were employed, and simulations were conducted to provide context. With regards to contemporary upstream to downstream contributions, the inclusion of length-at-age data proved informative. Both pairwise relatedness and Bayesian clustering analysis substantiated that fast-growing outliers, apparently entrained after residing in the upstream reservoir for several years, accounted for ~15% of the Lake Sturgeon 525–750 mm fork length captured downstream. With regards to historical structuring, upstream and downstream populations were found to be differentiated (FST = 0.011, and 0.013–0.014 when fast-growing outliers were excluded), and heterozygosity metrics were higher for downstream versus upstream juveniles. Historical asymmetric (downstream) gene flow in the vicinity of the generating station was the most logical explanation for the observed genetic structuring. In this section of the Winnipeg River, construction of a major dam does not appear to have fragmented a previously panmictic Lake Sturgeon population, but alterations to habitat may be influencing upstream to downstream contributions in unexpected ways.

Genetic characterization of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus, in the Edisto River, South Carolina and identification of genetically discrete fall and spring spawning

Once widely abundant, most subpopulations of the endangered Atlantic sturgeon are now estimated to be only 1–10% of their historical levels. The Edisto River has been sampled for a long period and extensively for juvenile Atlantic sturgeon from separate spring- and fall-spawned cohorts. Our objectives are to characterize the genetic diversity, stability, adaptive potential, and potential genetic structure of Atlantic sturgeon in the Edisto River and to identify any past bottlenecks experienced by this species, as well as to conduct forward simulation modeling of the population under multiple population trajectories. Our results indicate that fall- and spring-spawned Atlantic sturgeon in the Edisto River are genetically distinct (overall $${{F}_{ST}}$$ = 0.092) with little gene flow or admixture between groups, both of which are diverse from a neutral genetic marker standpoint. Genetic diversity of both groups is on the higher end of published population diversity values. A lack of inbreeding and recent bottlenecks also bode well for these two groups of sturgeon, although future projections indicate a loss of allelic richness and genetic diversity even with population stability. Our effective population size estimates are moderate compared to published estimates for other Atlantic sturgeon populations. The most significant finding of our research is the genetic distinctness of the fall- and spring-spawned Atlantic sturgeon in the Edisto River, which may have several important ramifications for management of the species, including re-evaluating the demarcation of distinct population segments.

Habitats for the Atlantic sturgeons in Russia

Abstract The critically endangered Atlantic sturgeon, Acipenser sturio, inhabited the Russian section of the Baltic Sea basin until recent times. Eight rivers were indicated as their habitats in local literature. The Atlantic surgeon disappeared in Russia because of overfishing, not because of habitat loss. Nowadays, potential spawning grounds for sturgeons occur in six rivers of the Russian section of the Baltic Sea basin. The largest river (Neva) is not blocked by dams and the whole river provides the ecological requirements of sturgeons on a stretch 75 km long. Restocking of other sturgeon species in Russia demonstrated that the release of reared fishes into the sea is ineffective, whereas the release into rivers could result in successful acclimatization. Recent climatic changes are rather favourable for sturgeon restocking in the Baltic Sea area. The main problem for the restoration of sturgeon populations is the intensive fishery.

Resolving microsatellite genotype ambiguity in populations of allopolyploid and diploidized autopolyploid organisms using negative correlations between allelic variables.

A major limitation in the analysis of genetic marker data from polyploid organisms is non-Mendelian segregation, particularly when a single marker yields allelic signals from multiple, independently segregating loci (isoloci). However, with markers such as microsatellites that detect more than two alleles, it is sometimes possible to deduce which alleles belong to which isoloci. Here, we describe a novel mathematical property of codominant marker data when it is recoded as binary (presence/absence) allelic variables: under random mating in an infinite population, two allelic variables will be negatively correlated if they belong to the same locus, but uncorrelated if they belong to different loci. We present an algorithm to take advantage of this mathematical property, sorting alleles into isoloci based on correlations, then refining the allele assignments after checking for consistency with individual genotypes. We demonstrate the utility of our method on simulated data, as well as a real microsatellite data set from a natural population of octoploid white sturgeon (Acipenser transmontanus). Our methodology is implemented in the R package polysat version 1.6.

Swimming performance in juvenile shortnose sturgeon (Acipenser brevirostrum): the influence of time interval and velocity increments on critical swimming tests.

The most utilized method to measure swimming performance of fishes has been the critical swimming speed (UCrit) test. In this test, the fish is forced to swim against an incrementally increasing flow of water until fatigue. Before the water velocity is increased, the fish swims at the water velocity for a specific, pre-arranged time interval. The magnitude of the velocity increments and the time interval for each swimming period can vary across studies making the comparison between and within species difficult. This issue has been acknowledged in the literature, however, little empirical evidence exists that tests the importance of velocity and time increments on swimming performance in fish. A practical application for fish performance is through the design of fishways that enable fish to bypass anthropogenic structures (e.g. dams) that block migration routes, which is one of the causes of world-wide decline in sturgeon populations. While fishways will improve sturgeon conservation, they need to be specifically designed to accommodate the swimming capabilities specific for sturgeons, and it is possible that current swimming methodologies have under-estimated the swimming performance of sturgeons. The present study assessed the UCrit of shortnose sturgeon using modified UCrit to determine the importance of velocity increment (5 and 10 cm s-1) and time (5, 15 and 30 min) intervals on swimming performance. UCrit was found to be influenced by both time interval and water velocity. UCrit was generally lower in sturgeon when they were swum using 5cm s-1 compared with 10 cm s-1 increments. Velocity increment influences the UCrit more than time interval. Overall, researchers must consider the impacts of using particular swimming criteria when designing their experiments.

From continuous to occasional: Small-scale natural reproduction of Chinese sturgeon occured in the Gezhouba spawning ground, Yichang, China

PDF HTML阅读 XML下载 导出引用 引用提醒 从连续到偶发：中华鲟在葛洲坝下发生小规模自然繁殖 DOI: 作者: 作者单位: 中国水产科学研究院 长江水产研究所, 农业部淡水生物多样性保护重点实验室, 湖北 武汉 430223 作者简介: 吴金明(1984-),男,博士,研究方向为濒危鱼类保护.E-mail:jinming@yfi.ac.cn;王成友(1984-),共同第一作者,男,博士,研究方向为濒危鱼类保护.E-mail:wangcy@yfi.ac.cn 通讯作者: 中图分类号: S932 基金项目: 国家自然科学基金项目（31602160）；公益性行业（农业）科研专项（201203086）；国家自然科学基金应急管理项目（51641909） From continuous to occasional: Small-scale natural reproduction of Chinese sturgeon occured in the Gezhouba spawning ground, Yichang, China Author: Affiliation: Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture; Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:中华鲟（Gray）为国家一级重点保护野生动物，典型的溯河洄游产卵鱼类。历史上，中华鲟在长江上游及金沙江下游产卵，由于葛洲坝修建阻隔了其洄游通道，1981年以后在葛洲坝下形成了比较稳定的产卵场，1982-2013年，每年均有自然繁殖发生。由于其栖息生境退化，每年洄游进入长江的中华鲟繁殖亲本逐年减少，2013-2015年连续3年在已知葛洲坝下中华鲟产卵场未监测到中华鲟自然繁殖活动。2016年11-12月的野外监测发现，中华鲟在宜昌葛洲坝下已知产卵场发生了自然繁殖。其中底层网具采集到中华鲟鱼卵（卵膜）67粒、仔鱼22尾；解剖食卵鱼发现，10尾食卵鱼类共摄食中华鲟卵454粒；水下视频观测到5处中华鲟卵黏附底质位点。根据采集到的鱼卵发育期及采集位点推算，产卵时间为2016年11月24日凌晨，产卵场位于葛洲坝大江电厂以下约300 m的江段内，产卵日水温为19.7℃，流量为6610 m3/s，水位为39.7 m。 Abstract:The critically endangered Chinese sturgeon (Gray), a large anadromous fish, is strictly protected in Chinese waters, where it is deemed to be a national treasure. Mature individuals enter the Yangtze River estuary from July to August, before entering their spawning ground the following year from October to November. Historically, sturgeon spawned in the upper reaches of the Yangtze and lower reaches of the Jinsha Rivers, but construction of Gezhouba Dam (the first dam in the Yangtze mainstream) blocked this migratory route. A relatively stable spawning ground has since developed below this dam. From 1982, the Yangtze River Fisheries Research Institute has conducted annual monitoring of natural breeding of sturgeon within the newly formed spawning ground. Between 1982 and 2013, sturgeon spawned annually, though both fecundity and frequency of reproduction declined. Whereas the number of mature fish arriving at the spawning ground annually exceeded 2 000 individuals in the early 1980 s (near the closure of Gezhouba Dam), it also dropped to fewer than 100 individuals in recent years. Prior to impoundment of the Three Gorges Reservoir (1984-2003), sturgeon spawned on average 1.8 times per year, though this decreased to 1.1 times during impoundment (2004-2012). Although controlled propagation and augmentation of sturgeon stocks has been performed from as early as 1983, both mark-recapture and molecular genetic identification reveal more than 90% of juvenile within the Yangtze estuary originated from natural reproduction. Thus, it is critical that natural reproduction of the fish may be maintained in the only knowing spawning ground.Though there was an apparent interruption in sturgeon spawning between 2013 and 2015 at this only known spawning ground, we report a resumption of spawning in 2016, during which time 67 egg (or egg membrane) and 22 larval sturgeon were collected by bottom draft-net, and 454 eggs were found in the stomachs of 10 egg-preying fishes. Underwater camera observations also revealed five sites with fertilized sturgeon eggs adhering to the substratum. The spawning ground was 300 m downstream of the Dajiang power plant (Gezhouba Dam). Spawning likely occurred during the early morning of November 24; estimated fecundity was less than two million; water temperature at the time of spawning was 19.7℃; and the flow and water level were 6610 m3/s and 39.7 m, respectively.Recent monitoring indicates the Chinese sturgeon has changed from being a "continuous" to an "accidental" spawner, and that this is likely to continue. Increased water temperature was probably the main reason for the failed spawning between 2013 and 2015, as the Three Gorges Reservoir significantly altered water temperature within the middle reach of the Yangtze River, but other factors, such as navigation, waterway regulation, overfishing and environmental pollution, have also reduced environmental quality at the spawning ground and may have contributed to spawning failures. Without effective environmental management, the natural population of Chinese sturgeon is at high risk of extinction.In 2015 the Ministry of Agriculture issued the "Chinese Sturgeon Rescue Action Plan" to protect Chinese sturgeon, which introduced several conservation programs, such as artificial restocking, habitat management and restoration, and the prohibition of fishing. Artificial restocking of Chinese sturgeon would also be improved by increasing the number and size of released individuals, thereby increasing their survival. In the middle and lower reaches of the Yangtze River, port, waterway, shipping and other construction projects should be managed to avoid any negative impact on the habitat and migration of Chinese sturgeon. In particular, environmental protection of Hubei Yichang Chinese Sturgeon Natural Reserve needs strengthening to maintain the hydrological conditions of spawning grounds. Additionally, improvement and rebuilding of Chinese sturgeon spawning grounds would facilitate -protection of Chinese sturgeon. 参考文献 相似文献 引证文献

The Experience of Taking Control over the Illegal Turnover of the Sturgeon Fishes, Committed by Forms of Organized Crime, Applied Abroad

The presented article takes a look at the problems of resisting the illegal turnover of the sturgeon fishes, committed by forms of organized crime. At present, when the moratorium on fishing the sturgeon species in the Caspian has been adopted, poaching continues to be the only source of the illegal turnover of the products, made from the sturgeon fishes, and at the same time, it is the major threat to the sturgeon populations, and the poaching takes organized forms. The author considers the causes and circumstances that lead to the emergence of organized forms and committing illegal fishing of the sturgeon fishes in the Ural River and the part of the Caspian that belongs to Kazakhstan, and why the illegal turnover of sturgeon flesh and roe persists. Among the main causes of the illegal turnover and poaching, the author names the unemployment problems of the local population, the high demand on the products made from the sturgeon fishes abroad, the insufficient government control over the issue. The experience of implementing some organizational and law-enforcement measures has been examined, that are applied in different states, in order to prevent the poaching violations, as regards the sturgeon fishes and the illegal turnover of the sturgeon products. As the directions of improving the legal basis, introducing harsher criminal responsibility for poaching is suggested, and a set of organizational measures for putting an end to the illegal turnover of the products from the sturgeon fishes.

Status of the Shortnose Sturgeon Population in the Savannah River, Georgia

AbstractThe federally endangered Shortnose Sturgeon Acipenser brevirostrum was once abundant in all major coastal river systems from the Saint John River, Canada, to the St. Johns River, Florida. During much of the 20th century, however, populations suffered major declines throughout their range from the combined effects of overfishing, pollution, and habitat loss. Although the species was a charter member of the Endangered Species Act, quantified population assessments are still lacking for many river systems throughout their range. Because river‐specific assessments are critical for evaluating species recovery, the objective of this study was to quantify abundance and annual recruitment of Shortnose Sturgeon occupying the Savannah River, Georgia. Anchored gill nets and trammel nets fished during slack tides were used to sample juvenile and adult Shortnose Sturgeon in their summer holding areas during 2013–2015. Huggins closed‐capture models in RMark were used to derive abundance estimates for each demographic group. The best models estimated that the Savannah River contained 81 (95% CI = 27–264) age‐1 juveniles in 2013, 270 (162–468) in 2014, and 245 (104–691) in 2015. The models also estimated the river to contain 486 (198–1,273) age‐2+ juveniles in 2013, 123 (69–235) in 2014, and 187 (81–526) in 2015. Similarly, the adult population was estimated to be 1,865 (784–4,694) individuals in 2013, 1,564 (1,005–2,513) in 2014, and 940 (535–1,753) in 2015. The results of this study provide the first population estimates available for Shortnose Sturgeon in the Savannah River. Additionally, the results suggest that the Savannah River likely contains the second largest population of Shortnose Sturgeon in Georgia. Future studies are needed in the Savannah River and other South Atlantic river systems to better evaluate Shortnose Sturgeon recovery status and the effects of river‐specific anthropogenic modifications.Received June 27, 2016; accepted September 29, 2016 Published online December 2, 2016

Status of scientific knowledge, recovery progress, and future research directions for the Gulf Sturgeon,Acipenser oxyrinchus desotoiVladykov, 1955

Summary The Gulf Sturgeon, Acipenser oxyrinchus desotoi, is an anadromous species of Acipenseridae and native to North America. It currently inhabits and spawns in the upper reaches of seven natal rivers along the northern coast of the Gulf of Mexico from the Suwannee River, Florida, to the Pearl River, Louisiana, during spring to autumn. Next to the Alligator Gar (Atractosteus spatula), the Gulf Sturgeon is currently the largest fish species occurring in U.S. Gulf Coast rivers, attaining a length of 2.35 m and weights exceeding 135 kg, but historically attained a substantially larger size. Historically, the spawning populations existed in additional rivers from which the species has been wholly or nearly extirpated, such as the Mobile and Ochlockonee rivers, and possibly the Rio Grande River. Most Gulf Sturgeon populations were decimated by unrestricted commercial fishing between 1895–1910. Subsequently most populations remained unrecovered or extirpated due to continued harvest until the 1970s–1980s, and the construction of dams blocking access to ancestral upriver spawning grounds. Late 20th Century harvest bans and net bans enacted by the several Gulf Coast states have stabilized several populations and enabled the Suwannee River population to rebound substantially and naturally. Hatchery supplementation has not been necessary in this regard to date. Sturgeon are resilient and adaptable fishes with a geological history of 150 million years. Research undertaken since the 1970s has addressed many aspects of Gulf Sturgeon life history, reproduction, migration, population biology, habitat requirements, and other aspects of species biology. However, many knowledge gaps remain, prominently including the life history of early developmental stages in the first year of life. Natural population recovery is evident for the Suwannee River population, but seems promising as well for at least four other populations. The Pascagoula and Pearl River populations face a challenging future due a combination of natural and anthropogenic factors. These two populations, and perhaps the Escambia River population, are particularly vulnerable to periodic mass mortality due to major stochastic events including hurricanes, flooding, hypoxia, and toxic spills. The present manuscript provides a comprehensive synthesis of knowledge regarding the Gulf Sturgeon at the organismal and population levels, identifying knowledge gaps as priorities for future research. Topics not treated in the present synthesis include morphology, internal biology, physiology, and endocrinology. Topics only briefly treated include parasites and diseases, contaminants, and sturgeon aquaculture.

Status of Lake Sturgeon (Acipenser fulvescensRafinesque 1817) in North America

Summary Lake Sturgeon is a potamodromous, fluvial-dependent species from the family Acipenseridae, and one of the largest freshwater fishes within its North American range extending to the Great lakes, Mississippi River, and Hudson Bay drainages. Like almost all other sturgeon species, Lake Sturgeon populations throughout its range suffered mass declines or extirpation in the late 1800s into the early 1900s, due to extensive overexploitation and habitat loss and alteration. However, Lake Sturgeon are still present in low to high densities throughout their native range due primarily to factors including: the species long life span and resiliency, the remote location of many northern populations, long-term pro-active management programs effectively controlling exploitation, improved habitat and water-quality conditions, and recovery programs that have been in effect since the late 1970s. Recovery programs initiated in the late 1970s are now just beginning to show signs of natural recruitment from populations re-built with stocked fish. Large sustainable recreational Lake Sturgeon fisheries with annual harvests of up to 45 000 kg and a commercial fishery with an annual harvest of up to 80 000 kg still exist and are maintained for Lake Sturgeon due primarily to rigid regulations, harvest controls, enforcement, and user involvement. The prognosis for the species is generally good, although habitat loss and maintaining public interest in the species management and recovery continue to be the greatest threats to local and regional populations. Hydropower development, especially in the northern part of the species’ range, is especially challenging due to the potential negative impact this type of development can have on a long migrating fish like Lake Sturgeon. Advances in understanding Lake Sturgeon life history, habitat requirements, and distribution within and among water systems has strongly indicated that dams and Lake Sturgeon can co-exist, if the correct planning and necessary mitigative techniques are employed at each site on a case-by-case basis.

In situ assessment of lampricide toxicity to age-0 lake sturgeon

Abstract The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2′, 5-dichloro-4′-nitrosalicylanilide (niclosamide) are used to control sea lamprey (Petromyzon marinus), an invasive species in the Great Lakes. Age-0 lake sturgeon (Acipenser fulvescens), a species of conservation concern, share similar stream habitats with larval sea lampreys and these streams can be targeted for lampricide applications on a 3- to 5-year cycle. Previous laboratory research found that lake sturgeon smaller than 100 mm could be susceptible to lampricide treatments. We conducted stream-side toxicity (bioassay) and in situ studies in conjunction with 10 lampricide applications in nine Great Lakes tributaries to determine whether sea lamprey treatments could result in in situ age-0 lake sturgeon mortality, and developed a logistic model to help predict lake sturgeon survival during future treatments. In the bioassays the observed concentrations where no lake sturgeon mortality occurred (no observable effect concentration, NOEC) were at or greater than the observed sea lamprey minimum lethal concentration (MLC or LC99) in 7 of 10 tests. We found that the mean in situ survival of age-0 lake sturgeon during 10 lampricide applications was 80%, with a range of 45–100% survival within streams. Modeling indicated that in age-0 lake sturgeon survival was negatively correlated with absolute TFM concentration and stream alkalinity, and positively correlated with stream pH and temperature. Overall survival was higher than expected based on previous research, and we expect that these data will help managers with decisions on the trade-offs between sea lamprey control and the effect on stream-specific populations of age-0 lake sturgeon.

Sensitivity of lake sturgeon (Acipenser fulvescens) early life stages to 2,3,7,8-tetrachlorodibenzo-P-dioxin and 3,3',4,4',5-pentachlorobiphenyl.

The aquatic food web of the Great Lakes has been contaminated with polychlorinated biphenyls (PCBs) since the mid-20th century. Threats of PCB exposures to long-lived species of fish, such as lake sturgeon (Acipenser fulvescens), have been uncertain because of a lack of information on the relative sensitivity of the species. The objective of the present study was to evaluate the sensitivity of early-life stage lake sturgeon to 3,3',4,4',5-pentachlorobiphenyl (PCB-126) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure. Mortality, growth, morphological and tissue pathologies, swimming performance, and activity levels were used as assessment endpoints. Pericardial and yolk sac edema, tubular heart, yolk sac hemorrhaging, and small size were the most commonly observed pathologies in both TCDD and PCB-126 exposures, beginning as early as 4 d postfertilization, with many of these pathologies occurring in a dose-dependent manner. Median lethal doses for PCB-126 and TCDD in lake sturgeon were 5.4 ng/g egg (95% confidence interval, 3.9-7.4 ng/g egg) and 0.61 ng/g egg (0.47-0.82 ng/g egg), respectively. The resulting relative potency factor for PCB-126 (0.11) was greater than the World Health Organization estimate for fish (toxic equivalency factor = 0.005), suggesting that current risk assessments may underestimate PCB toxicity toward lake sturgeon. Swimming activity and endurance were reduced in lake sturgeon survivors from the median lethal doses at 60 d postfertilization. Threshold and median toxicity values indicate that lake sturgeon, like other Acipenser species, are more sensitive to PCB and TCDD than the other genus of sturgeon, Scaphirhynchus, found in North America. Indeed, lake sturgeon populations in the Great Lakes and elsewhere are susceptible to PCB/TCDD-induced developmental toxicity in embryos and reductions in swimming performance. Environ Toxicol Chem 2017;36:988-998. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.