东江鲤鱼种群动态及其最大持续渔获量的研究

本文研究东江鲤鱼的种群动态并进行渔业生物学分析。用Von Bertalanffy生长方程可以表达东江鲤鱼体长、体重与年龄的关系,L=39.308R-42.611,L_t=851[1-e(-0.173(t 0.0394))]W_t=19171.5[1-e~(-0.173(t 0.0394))]~3。通过渔获物统计资料计算种群的自然死亡率D=0.27和捕捞死亡率E=0.25,并分析比较产卵力及产卵群体的结构类型。通过比较各种捕捞强度和最小捕捞规格的不同的总渔获量和群体的相对数量,提出获得持续渔获量的捕捞强度F=0.35及最小捕捞年龄t=2。     

Work-Related and Non-Work-Related Injury Deaths in the U.S.: A Comparative Study

This study assesses the percentage of traumatic fatalities attributable to work-related causes in the US, by cause of death and population demographics. The 1993-1998 Vital Statistics Mortality data from the National Center for Health Statistics were used. There were 848,945 traumatic fatalities (E800-E999) among the general population 16 years or older in the US during this time; of these, 32,044 were work-related accounting for 3.8% of all the fatalities. The work-related percentage varied from 62.7% for machine-related deaths to 0.7% for suicides, from 4.9% for males to 1.0% for females, from 9.8% in Alaska to 1.5% in Arizona, from 4.2% for decedents with 1 to 4 year college educations to 2.9% for decedents with high school or less, from 4.4% for races other than white and black to 2.6% for black. Mean age-at-death was 42 years for work-related vs. 48 years for non-work-related fatalities. This difference is more pronounced for deaths from falls (45 years vs. 78 years). Conversely, victims of work-related homicide were older than non-work-related (41 years vs. 33 years). A more complete understanding of the burden of traumatic fatalities attributable to work-related causes requires consideration of the total work-related percentage, causes of death, and population demographics.     

Harvest mortality in North American mallards: A reply to Sedinger and Herzog

Sedinger and Herzog (2012) evaluated the evidence for the impact harvest mortality may have on North American duck populations. While doing that, they questioned our review (Pöysä et al. 2004 ) and conclusion that harvest mortality in North American mallards (Anas platyrhynchos) may have shifted from compensatory to additive over the period from the 1960s to the 1980s. In this reply, we correct Sedinger and Herzog's misrepresentations of our 2004 paper and argue that our interpretations of the results published at that time have not been invalidated. © 2013 The Wildlife Society.     

Interaction of maternal protein and carbon monoxide on pup mortality in mice: implications for global infant mortality

BACKGROUND: The United States Surgeon General declared 2005 as the "Year of Healthy Child." To improve the health of all children, we need to start before pregnancy, with their mothers. Unfortunately, protein deficiency in the diets of poor pregnant mothers in developing countries is widespread. Carbon monoxide (CO) pollution is serious public health problem in developed and developing countries. METHODS: A two-way factorial experimental design was used. Mice were maintained on 27%, 16%, 8%, or 4% protein diets. Dams were exposed to 0 ppm (control), 65 ppm, or 125 ppm CO in air, in environmental chambers for 6 hr/day during the first 2 weeks of pregnancy. Controls were also subjected to environmental chamber conditions. Food and water were available at all times. Animals were allowed to deliver, and data on pup mortality was recorded. RESULTS: Litter size was not affected by CO exposure, but was directly related to the dietary protein levels. Pup weight was inversely related to the CO exposure level, and directly related to the dietary protein levels. Pup mortality on date of birth was increased by CO exposure and was inversely related to the dietary protein levels. Pup mortality at 1 week of age was increased by CO exposure and 55% of all pups died in 125 ppm CO exposed group. Pup mortality at 1 week of age was inversely related to dietary protein levels. All pups in the 4% dietary protein and in all concentrations of CO died. All pups in the 8% protein group and in all CO concentrations died except in 125 ppm CO group. Pup mortality in the 16% dietary protein group ranged from 14.8% in 0 ppm to 36.8% in 65 ppm CO groups. Pup mortality in the 27% dietary protein group ranged from 14.3% in the 0 ppm to 41.1% in the 125 ppm CO groups. CONCLUSIONS: DATA suggest that protein deficiency and CO exposure enhance pup mortality. The protein and CO also interact to increase pup mortality in 16% and 27% protein groups. Carbon monoxide exposure, along with protein deficiency during gestation, may be contributing factors for high rates of infant mortality in developing countries. The results of the study also suggest that un-vented combustion for heating and cooking, ambient pollution, and biomass smoke may have a major impact on the health of children worldwide; and may explain the causes of high infant mortality in poor countries and some sections of the United States population.     

Infant mortality in mother-reared captive chimpanzees at Taronga Zoo,Sydney

Infant mortality in mother-reared chimpanzees was examined from the records of Taronga Zoo, Sydney, Australia. Sex-specific mortality probabilities were calculated using standard demographic techniques. Male mortality was found to be considerably higher than female mortality. Using the same techniques, changes in infant mortality over time were calculated, with particular reference to changes that had occurred since the chimpanzees were transferred to a new open air enclosure in 1980. Mortality was found to have decreased dramatically since the move to the new enclosure, but the observed decline was exaggerated by the very high proportion of female infants. The main causes of infant death as ascertained from the zoo records were pneumonia and trauma. In addition, undetermined causes in the first day of life were numerous. An examination of the contexts of infanticide in wild and captive chimpanzees revealed slight differences, but factors such as aggression towards unfamiliar individuals and redirected aggression were common to both. Cannibalism in the zoo has so far been limited to the bodies of stillborn infants.     

Reducing discard mortality in an estuarine trawl fishery

A purpose-built, water-filled sorting tray was compared against a conventional dry tray for its utility in reducing discard mortality across a range of conditions in an Australian estuarine penaeid-trawl fishery, including the limits of typical delays in starting sorting (2 vs. 15 min). During nine days of fishing, up to 10 replicate deployments were done for each sorting method and delay. Bycatches (44 389 teleosts comprising 15 species) were assessed for their immediate mortalities, before 1346 live individuals (10 species) were released (to simulate discarding) into replicate cages and monitored for their short-term mortalities over five days. Appropriate controls were included for the most abundant economically-important species, yellowfin bream, Acanthopagrus australis. Most trawled-and-discarded teleosts followed a pattern of minimal differences in immediate mortalities between sorting methods for the short delay, but generally fewer deaths in the water tray than in the conventional tray during the longer delay. However, owing to a dominant and slightly protracted influence of the trawling process, comparable rates of deaths were observed for caged fish irrespective of their post-capture treatment. Mixed-effects logistic models applied to four key species (A. australis; silver biddy, Gerres subfasciatus; southern herring, Herklotsichthys castelnaui; and Port Jackson glassfish, Ambassis jacksoniensis) revealed that in addition to the method and delay in sorting, the weights of total catch and jellyfish, salinity and the size of fish also had significant impacts on mortality. For the longer delay in sorting in the water tray, the influences of some of the other factors were negated so that total mortalities of three of the modelled species were reduced by almost one quarter. We conclude that while unaccounted fishing mortality can be reduced via changes to onboard sorting procedures, this approach should only be applied ancillary to efficient gear selectivity.     

A joint explanation of infant and old age mortality

Journal of Biological Physics - Infant deaths and old age deaths are very different. The former are mostly due to severe congenital malformations of one or a small number of specific organs. On the...     

“Smothered” Infants—Neglect,Infanticide or SIDS? A Fresh Look at the 19th Century Mortality Schedules

Based on the U.S. Federal Mortality Schedules from the years 1850–1880 infant deaths <1 year were investigated in order to determine whether mortality attributed to “smothering” or “overlaying” followed known SIDS trajectories. By comparing a case sample of 2,236 smothered/overlaid deaths with an age-, regionally and time-matched control sample of all-cause infant deaths (N = 58,293), striking similarities with SIDS became apparent, which were not mimicked in the control sample. These epidemiological traits included a disproportionate vulnerability during the second to fourth month of life (Poisson RR 12.94, p < 0.001), a remarkable birth and death seasonality, as well as pronounced racial disparities. The study could also corroborate sex-specific discrepancies—such as differential impact of month of birth on age-at-death. Results of a Cox regression furthermore indicate that age, sex, race and death season were significant predictors of mortality. This strongly supports the hypothesis that these infant deaths represent empirical evidence of 19th century SIDS.     

Ecosystem alteration modifies the relative strengths of bottom-up and top-down forces in a herbivore population

1. Ecosystem alterations can affect the abundance, distribution and diversity of plants and animals, and thus potentially change the relative strength of bottom-up (the plant resource) and top-down (natural enemies) trophic forces acting on herbivore populations. 2. The hypothesis that alterations of the forest ecosystem associated with precommercial thinning have contributed to the increased severity of outbreaks of Neodiprion abietis (Harris), a sawfly defoliator, through the reduction of trophic forces acting on N. abietis larvae, was tested using exclusion techniques. 3. The relative contributions to N. abietis larval mortality of bottom-up and top-down forces both increased with increasing levels of defoliation and were both reduced by thinning. The reduction of bottom-up and top-down forces caused a 58% mean increase in N. abietis larval survival in thinned compared with untreated stands, which is less than would be expected by the sum of the effects of thinning on each source of mortality. Evidence indicates that the partly compensatory, partly additive nature of the mortality associated with trophic forces in the system under study is responsible for this discrepancy. 4. To our knowledge, this is the first study to show the impact of ecosystem alterations on the balance between bottom-up and top-down forces acting on an eruptive herbivore population along a gradient of host-plant defoliation, and how this can lead to increased outbreak severity. It is stressed that accurate estimates of the relative contributions of bottom-up and top-down forces to mortality cannot be obtained if the additive or compensatory nature of the mortality associated with these trophic forces is overlooked.     

Shedding new light on the life cycle of mackerel icefish in the Southern Ocean

Mackerel icefish have a widespread distribution in the Atlantic and Indian Ocean sectors of the low-Antarctic region. Biological characteristics differ considerably between populations in the southern Scotia Arc and those living further to the north. Fish living in the north mature 1 year earlier than in the south. They have a much shorter life span and die after they have spawned two to three times. The number of eggs produced per gram of body mass is higher in the north. Stocks have declined in most parts of the distributional range due to the impact of fishing and due to natural causes. Increases in populations of Antarctic fur seals at South Georgia and parts of the Indian Ocean appear to have led to increased predation on stocks of icefish. Shifts in hydrological regimes in the northern part of the distributional range have either started to lead or will lead to deteriorating living conditions for mackerel icefish in the near future. Fish stock assessment needs to take these constraints into consideration when providing advice on total allowable catches for fisheries management.     

La pêcherie de civelle (Anguilla anguilla) en Loire (France) en 1987: Evaluation des prises accessoires et impact halieutique. The Glass Eel (Anguilla anguilla) Fishery in the Loire Estuary (France) 1987: Estimate of By Catch and its Effects on Resources

By-catch is estimated by sampling the whole fishery (February to April 1987) on the basis of a survey of the fishing effort: 16 species of commercial interest are considered, among them 3 species are dominant: Flounder, sprat and brown shrimp (98,4% of the 49,3 million individuals). By-catch consists mainly of very young animals (larval or 0-group stages). An attempt is made to consider the ratio between by-catch and the potential natural mortality of juveniles.     

Density- and size-dependent mortality of a settling coral-reef damselfish (<Emphasis Type="Italic">Pomacentrus moluccensis</Emphasis> Bleeker)

Density-dependent mortality may regulate many populations, but due to an offshore larval phase in benthic marine organisms, it is often difficult to quantify the effects of mortality of arriving individuals. We added approximately 600 recruit-sized individuals onto coral reef that parallels patterns in naturally settling fish. Strong, positive density-dependent mortality occurred 3 days, 1–2 weeks, and 4 months after release. Since our study species was patchily distributed, we estimated both mean group size and overall density in a transect. Mortality was more strongly related to mean group size than overall density in a transect, indicating that recruit patchiness was important. Cohesive groups may suffer higher mortality than those spread over larger areas, even if overall density of the latter is greater. Aggregative responses of predators may occur in response to larger groups, so may have contributed to positive density-dependent mortality. Increased conspicuousness to predators and congeneric aggression are additional factors that may vary positively with group size. Tagging of recruits showed migration within but not between transects, so persistence was tantamount to survival. Standard otolith back-calculation techniques employed to reconstruct original size of tagged recruits that persisted 4 months after additions indicated that mortality was also size-dependent. Size-dependent mortality was apparent at the site with the highest mortality but not at the site with the lowest mortality, resulting in different mean body sizes of recruits between sites. Size-dependent mortality may influence estimation of growth and lead to onset of size-based maturity in these fish. Strong, positive density-dependent mortality may regulate recruitment, and if coupled with size-dependent mortality, may increase maturity rate, adding to reproductive schedules of those that survive.     

The past, present and future of childhood malaria mortality in Africa

During the past few years, there has been a historic series of declarations of renewed commitment to malaria control in Africa. Whether the burden of malaria is increasing in Africa is a moot point. This article attempts to re-construct the evidence for the trends in childhood mortality as a result of Plasmodium falciparum infection over the last century in Africa.     

Size and mortality rates of Glossina pallidipes in the semi-arid zone of southwestern Kenya

Seasonal changes in the mean size of tsetse, Glossina pallidipes Austen, as indicated by wing vein length, were monitored during 1983-86 at Nguruman, southwestern Kenya. Changes in size of nulliparous females and wing fray category 1 males were shown to be correlated with the relative humidity 2 months before they were captured. Soil temperature when flies were in the pupal stage had much less effect. Size dependent mortality was demonstrated, with the mean size of flies emerging from pupae significantly less than that of field-caught flies. This mortality must occur at emergence, since there was no evidence of size-dependent mortality once the flies became available to the trap. Size was correlated with density-independent mortality acting on the parent population 2 months previously. It might therefore be possible to use size as an index of the intensity of such mortality. This could be useful when assessing the level of additional mortality required to suppress tsetse populations.     

The Body Mass Index-Mortality Relationship in White and African American Women

Objective : To examine the association of body mass index to all-cause and cardiovascular disease (CVD) mortality in white and African American women. Research methods and procedures : Women who were members of the American Cancer Society Prevention Study I were examined in 1959 to 1960 and then followed 12 years for vital status. Data for this analysis were from 8,142 black and 100,000 white women. Body mass index (BMI) was calculated from reported height and weight. Associations were examined using Cox proportional hazards modeling with some analyses stratified by smoking (current or never) and educational status (less than complete high school or high school graduate). Results : There was a significant interaction between ethnicity and BMI for both all-cause (p<0.05) and CVD mortality (p<<0.001). BMI (as a continuous variable) was associated with all-dause mortality in white women in all four groups defined by smoking and education. In black women with less than a high school education, there were no significant associations between BMI mortality. For high school-educated black women, there was a significant association between BMI and all-cause mortality. Among never smoking women with at least a high school education, models using the lowest BMI as the reference indicated a 40% higher risk of all-cause mortality at a BMI of 35.9 in black women vs. 27.3 in white women. Discussion : The impact of BMI on mortality was modified by educational level in black women; however, BMI was a less potent risk factor in black women than in white women in the same category of educational status.     

Effects of larval density on a natural population of Culex restuans (Diptera: Culicidae): no evidence of compensatory mortality

1. This study investigated the effects of strong density dependence on larval growth, development, and survival of the mosquito Culex restuans (Theobald). It also tested the hypothesis that density reduction early in larval development could result in as many or more individuals surviving to adulthood (compensation or over‐compensation, respectively), or increased reproductive performance via rapid development and greater adult size. 2. In a field study of a natural population of C. restuans, the effects of a 75% lower density on percentage survivorship to adulthood, number of adults, development time, adult size, adult longevity, and size dependent fecundity were tested. 3. No evidence was found of compensation or over‐compensation in adult production, or of effects of lower density on percentage survivorship. Low density yielded significant increases in adult size, adult longevity, and size‐dependent fecundity, and a decrease in development time. 4. Estimated per‐capita population growth rate was significantly greater in the low‐density treatment than in the high‐density treatment. It is inferred that this difference was due to greater per‐capita resources, which increased female size and fecundity, and reduced development time. Greater per‐capita population growth could therefore result from early mortality of larvae, meaning that the hydra effect, which predicts greater equilibrium population with, as opposed to without, extrinsic mortality, may be possible for these mosquitoes.     

Devastating farmed abalone mortalities attributed to yessotoxin-producing dinoflagellates

A large dinoflagellate bloom in Walker Bay (South Africa) in January 2017 impacted 3 land-based abalone farms resulting in the death of several million animals. Satellite-derived images of Chl-a from the Ocean and Land Colour Imager (OLCI) on board the European Space Agency Sentinel-3 A showed bloom initiation in late December 2016 and dispersal in mid-February 2017. The bloom was dominated by two dinoflagellate species identified by light microscopy as Gonyaulax spinifera (Claparède & Lachmann) Diesing, 1866 and Lingulodinium polyedrum (Stein) Dodge, 1989. These morphologically based identifications were confirmed by phylogenetic analysis using partial sequences of the large subunit rDNA of both dinoflagellates. The appearance of yessotoxins (YTX) in abalone clearly coincided with increases in dinoflagellate concentrations. Yessotoxins in both the plankton and abalone were dominated by the two analogues homo-YTX and 45-hydroxy-YTX. The absence of toxins in a clonal culture of L. polyedrum implicated G. spinifera as the likely source of YTX. Toxin concentrations were found to be highest in the gills which showed the most significant pathology, including severe, generalized disruption of the gill epithelium characterized by degeneration and necrosis of epithelial cells accompanied by a modest inflammatory response. Some farms undertook pre-emptive or emergency harvesting to reduce financial losses.