Recovery and management options for spring/summer chinook salmon in the Columbia River basin

Construction of four dams on the lower Snake River (in northwestern United States) between 1961 and 1975 altered salmon spawning habitat, elevated smolt and adult migration mortality, and contributed to severe declines of Snake River salmon populations. By applying a matrix model to long-term population data, we found that (i) dam passage improvements have dramatically mitigated direct mortality associated with dams; (ii) even if main stem survival were elevated to 100%, Snake River spring/summer chinook salmon (Oncorhynchus tshawytscha) would probably continue to decline toward extinction; and (iii) modest reductions in first-year mortality or estuarine mortality would reverse current population declines.     

Global assessment of organic contaminants in farmed salmon

The annual global production of farmed salmon has increased by a factor of 40 during the past two decades. Salmon from farms in northern Europe, North America, and Chile are now available widely year-round at relatively low prices. Salmon farms have been criticized for their ecological effects, but the potential human health risks of farmed salmon consumption have not been examined rigorously. Having analyzed over 2 metric tons of farmed and wild salmon from around the world for organochlorine contaminants, we show that concentrations of these contaminants are significantly higher in farmed salmon than in wild. European-raised salmon have significantly greater contaminant loads than those raised in North and South America, indicating the need for further investigation into the sources of contamination. Risk analysis indicates that consumption of farmed Atlantic salmon may pose health risks that detract from the beneficial effects of fish consumption.     

Differences in thermal tolerance among sockeye salmon populations

Climate change-induced increases in summer water temperature have been associated with elevated mortality of adult sockeye salmon (Oncorhynchus nerka) during river migration. We show that cardiorespiratory physiology varies at the population level among Fraser River sockeye salmon and relates to historical environmental conditions encountered while migrating. Fish from populations with more challenging migratory environments have greater aerobic scope, larger hearts, and better coronary supply. Furthermore, thermal optima for aerobic, cardiac, and heart rate scopes are consistent with the historic river temperature ranges for each population. This study suggests that physiological adaptation occurs at a very local scale, with population-specific thermal limits being set by physiological limitations in aerobic performance, possibly due to cardiac collapse at high temperatures.     

日本知床半岛海域细鳞大马哈鱼和大马哈鱼的移动生态调查

在北海道知床半岛周边海域,用小型数据记录器监测细鳞大马哈鱼Oncorhyncus gorbuscha和大马哈鱼O.keta的回归游泳行为,探讨其与环境水温的关系。数据记录间隔时间为1 s,连续记录时间为226 h。于2008年8月至10月期间,在知床沿岸放流了带有数据记录器的洄游途中的大马哈鱼和细鳞大马哈鱼个体(分别为30尾和5尾),分别有13尾、3尾个体被捕获。研究表明:试验个体有一系列的上浮和下沉行为,并且频繁地回到表层水面,垂直移动中的深潜水是对表层高水温和暖流分层水中的一种适温调节行为。因此,尽管表层水温较高,性成熟后的大马哈鱼仍会回到表层水面寻找其产卵场所。     

野生亚东鲑群体遗传多样性及其种质来源研究

以褐鳟(Salmo trutta)日本品系和亚东鲑群体为研究对象,通过测定上述两个群体8个微卫星标记和线粒体D-loop基因多态性,综合分析日本品系和亚东鲑群体遗传多样性及其种质来源。结果表明,褐鳟日本品系等位基因数为2~10个,亚东鲑群体为4~9个,平均有效等位基因数分别为3.1304和3.8988;观测杂合度范围分别为0.3404~0.7128和0.1020~0.8776,其中褐鳟日本品系平均观测杂合度为0.5612,亚东鲑群体为0.5510,期望杂合度分别为0.4671~0.7794和0.5216~0.7932;褐鳟日本品系多态信息含量(PIC)为0.3680~0.7440,平均为0.5964,而亚东群体PIC为0.4660~0.8370,平均为0.5926。研究分析褐鳟、亚东鲑线粒体D-loop基因序列和欧洲褐鳟已知五个地理居群D-loop基因序列,日本品系褐鳟和亚东鲑与欧洲大西洋居群褐鳟聚在一支,亲缘关系最近。     

Genomic signatures predict migration and spawning failure in wild Canadian salmon

Long-term population viability of Fraser River sockeye salmon (Oncorhynchus nerka) is threatened by unusually high levels of mortality as they swim to their spawning areas before they spawn. Functional genomic studies on biopsied gill tissue from tagged wild adults that were tracked through ocean and river environments revealed physiological profiles predictive of successful migration and spawning. We identified a common genomic profile that was correlated with survival in each study. In ocean-tagged fish, a mortality-related genomic signature was associated with a 13.5-fold greater chance of dying en route. In river-tagged fish, the same genomic signature was associated with a 50% increase in mortality before reaching the spawning grounds in one of three stocks tested. At the spawning grounds, the same signature was associated with 3.7-fold greater odds of dying without spawning. Functional analysis raises the possibility that the mortality-related signature reflects a viral infection.     

Rapid evolution of egg size in captive salmon

Captive breeding and release programs, widely used to supplement populations of declining species, minimize juvenile mortality to achieve rapid population growth. However, raising animals in benign environments may promote traits that are adaptive in captivity but maladaptive in nature. In chinook salmon, hatchery rearing relaxes natural selection favoring large eggs, allowing fecundity selection to drive exceptionally rapid evolution of small eggs. Trends toward small eggs are also evident in natural populations heavily supplemented by hatcheries, but not in minimally supplemented populations. Unintentional selection in captivity can lead to rapid changes in critical life-history traits that may reduce the success of supplementation or reintroduction programs.     

Production of trout offspring from triploid salmon parents

Many salmonids have become at risk of extinction. For teleosts whose eggs cannot be cryopreserved, developing techniques other than egg cryopreservation to save genetic resources is imperative. In this study, spermatogonia from rainbow trout were intraperitoneally transplanted into newly hatched sterile triploid masu salmon. Transplanted trout spermatogonia underwent spermatogenesis and oogenesis in male and female recipients, respectively. At 2 years after transplantation, triploid salmon recipients only produced trout sperm and eggs. With use of these salmon as parents, we successfully produced only donor-derived trout offspring. Thus, by transplanting cryopreserved spermatogonia into sterile xenogeneic recipients, we can generate individuals of a threatened species.     

Satellite tagging and cardiac physiology reveal niche expansion in salmon sharks

Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2 degrees to 24 degrees C, and they spend winter periods in waters as cold as 2 degrees to 8 degrees C. Functional assays and protein gels reveal that the expression of excitation-contraction coupling proteins is enhanced in salmon shark hearts, which may underlie the shark's ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas.     

Thermal lability of beta galactosidase from pink salmon liver

The effect of heat on the stability of a protein isolated from a cold-water fish was tested by following the decrease in enzymatic activity of beta galactosidase, purified from livers of Pacific pink salmon. The thermal stability is pH-dependent; it is highest at pH 4 and lowest at neutral pH, where only 30 percent of the activity remains after 10 minutes at 40 degrees C. Comparative experiments demonstrate greater thermal stability of beta galactosidase from rat liver.     

保护区及周边居民对野猪容忍性的影响因素——以黑龙江凤凰山国家级自然保护区为例

以黑龙江凤凰山国家级自然保护区为例,于2010年9、10月份,采用问卷调查法和实地考察法相结合的形式,调查该保护区及周边地区野猪危害农田的情况,以及居民对野猪的容忍性和认知度。结合Mann-Whitey U检验和Kruskal-Wallis H检验方法比较各个因素对保护区及周边居民野猪容忍性的影响差异,用主成分分析法对主要影响因素进行辨析。结果表明:农田收入比例、文化程度、人均农田面积以及野猪毁田面积是影响居民对野猪容忍性的主要因素。被访问的居民中,66.19%的居民希望野猪种群减少或消失;63.38%的居民赞同或者完全赞同保护措施;毁田事件发生后,46.48%的居民赞同或完全赞同捕杀野猪;在村外遇见野猪时,66.20%的居民不赞同或者完全不赞同捕杀野猪;在山野遇见野猪时,65.59%的居民不赞同或者完全不赞同捕杀野猪,说明遇到野猪的地点对居民所持捕杀态度基本没有影响。     

Impacts of climatic change and fishing on Pacific salmon abundance over the past 300 years

The effects of climate variability on Pacific salmon abundance are uncertain because historical records are short and are complicated by commercial harvesting and habitat alteration. We use lake sediment records of delta15N and biological indicators to reconstruct sockeye salmon abundance in the Bristol Bay and Kodiak Island regions of Alaska over the past 300 years. Marked shifts in populations occurred over decades during this period, and some pronounced changes appear to be related to climatic change. Variations in salmon returns due to climate or harvesting can have strong impacts on sockeye nursery lake productivity in systems where adult salmon carcasses are important nutrient sources.     

Edge effects and the extinction of populations inside protected areas

Theory predicts that small populations may be driven to extinction by random fluctuations in demography and loss of genetic diversity through drift. However, population size is a poor predictor of extinction in large carnivores inhabiting protected areas. Conflict with people on reserve borders is the major cause of mortality in such populations, so that border areas represent population sinks. The species most likely to disappear from small reserves are those that range widely-and are therefore most exposed to threats on reserve borders-irrespective of population size. Conservation efforts that combat only stochastic processes are therefore unlikely to avert extinction.     

Impacts of salmon on riparian plant diversity

The study of natural gradients in nutrient subsidies between ecosystems allows for predictions of how changes in one system can affect biodiversity in another. We performed a large-scale empirical test of the role of Pacific salmon (Oncorhynchus spp.) in structuring riparian plant communities. A comparison of 50 watersheds in the remote Great Bear Rainforest of British Columbia's central coast in Canada shows that salmon influence nutrient loading to plants,shifting plant communities toward nutrient-rich species, which in turn decreases plant diversity.These effects are mediated by interactions between salmon density and the physical characteristics of watersheds. Predicting how salmon affect terrestrial ecosystems is central to conservation plans that aim to better integrate ecosystem values into resource management.     

甘草野生种群遗传多样性的AFLP分析

 【目的】甘草具有重要的药用、工业和生态价值,目前处于濒危状态,进行遗传多样性研究可以为甘草资源的保护和利用奠定基础。【方法】利用AFLP分子标记对来自中国甘草主产区的16个野生种群共320个单株进行遗传多样性研究。【结果】（1）利用15对AFLP引物共扩增出759条谱带,其中多态性谱带527条,多态性条带百分率为69.43％;（2）Nei’基因多样性指数为0.13～0.19,种群总体多样性指数为0.25;Shannon多态性信息指数的变异范围在0.19～0.28,总体为0.39;宁夏地区甘草种群遗传多样性水平最高,甘肃酒泉种群的遗传多样性水平最低。（3）AMOVA分析表明甘草种群间的遗传变异占总变异的18.64％,种群内变异占67.16％。利用UPGMA聚类可将供试16个群体划分为3类,聚类结果表现出明显的地域性。【结论】该研究明确了中国野生甘草遗传多样性处于中等偏下水平,种群内广泛的变异能够为野生资源保护和良种选育提供理论依据。     

Serologic and molecular survey for major viral pathogens in grazing hybrid wild boars in Northeast China

Hybrid wild boar husbandry is an important component of livestock production in Northeast China. However, the current disease situation of these animals is largely unknown due to a lack of disease surveillance. The present study was conducted to determine the prevalence of several important viral diseases in the hybrid wild boar population of Northeast China. Between September 2015 to December 2016, 169 blood and 61 tissue samples were collected from apparently healthy hybrid wild boars from farms in Jilin, Inner Mongolia and Heilongjiang provinces. ELISA detected serum antibodies against classical swine fever virus(CSFV), porcine reproductive and respiratory syndrome virus(PRRSV), pseudorabies virus(PRV), porcine circovirus type 2(PCV2) and Japanese encephalitis virus(JEV), but not against African swine fever virus(ASFV), with PCV2 having the highest seropositive rate(87.2–100% in different farms). RT-PCR or PCR performed on the processed samples detected only PCV2, with 33.1%(56/169) of blood samples and 32.8%(20/61) of spleen samples being positive, respectively, indicating widespread PCV2 infection in hybrid wild boars. Phylogenetic analysis of 15 PCV2 ORF2 sequences showed that they belong to genotypes PCV2a, PCV2b and PCV2d, with nucleotide and deduced amino acid homologies of 88.5–100% and 88.1–100%, respectively.     

枇杷果实育种目标性状在杂种后代中的表现

对黄金块与解放钟为亲本的有性正反交后代的果实进行分析,研究了育种目标性状:单果重(60g以上)、果皮色泽(橙红色)、可溶性固形物含量(12%以上)、可食率(72%以上)在杂种后代中的表现.结果表明:杂种后代单果重、果皮色泽、可溶性固形物含量、可食率达到育种目标的后代分别占杂种后代总数的14.93%、53.73%、20.90%、47.76%;同时达到四个育种目标性状的杂种后代数量为1株.     

Rapid evolution of reproductive isolation in the wild: evidence from introduced salmon

Colonization of new environments should promote rapid speciation as a by-product of adaptation to divergent selective regimes. Although this process of ecological speciation is known to have occurred over millennia or centuries, nothing is known about how quickly reproductive isolation actually evolves when new environments are first colonized. Using DNA microsatellites, population-specific natural tags, and phenotypic variation, we tested for reproductive isolation between two adjacent salmon populations of a common ancestry that colonized divergent reproductive environments (a river and a lake beach). We found evidence for the evolution of reproductive isolation after fewer than 13 generations.     

Aging in the natural world: comparative data reveal similar mortality patterns across primates

Human senescence patterns-late onset of mortality increase, slow mortality acceleration, and exceptional longevity-are often described as unique in the animal world. Using an individual-based data set from longitudinal studies of wild populations of seven primate species, we show that contrary to assumptions of human uniqueness, human senescence falls within the primate continuum of aging; the tendency for males to have shorter life spans and higher age-specific mortality than females throughout much of adulthood is a common feature in many, but not all, primates; and the aging profiles of primate species do not reflect phylogenetic position. These findings suggest that mortality patterns in primates are shaped by local selective forces rather than phylogenetic history.     

Optimal design of culling compensation policy under the African swine fever — Based on simulations of typical pig farms in China

This paper aims to optimize the culling compensation policy from a micro perspective through scenario simulation. Based on an investigation of 273 pig farms in eight regions, four typical pig farms were constructed according to farm size and breeding mode, representing the swine producers in China. Besides, a decision objective function of pig farms facing suspected African swine fever (ASF) outbreaks was constructed. This study used a mathematical programming model to design and simulate scenarios based on compensation standards and local implementation levels, aiming to incentivize pig farms to report epidemics. The results show that the optimal decisions on epidemic reports differed among typical farms and by herd daily age. The results suggest the following adjustments for optimizing culling compensation policies: (1) to set culling compensation standards based on the market value and (2) to maintain a high level of epidemic surveillance capability in the animal husbandry and veterinary sector.