Survival rates of radio-collared female polar bears and their dependent young

1995 ◽  
Vol 73 (7) ◽  
pp. 1312-1322 ◽  
Author(s):  
S. C. Amstrup ◽  
G. M. Durner
Keyword(s):  
Adult Female ◽  
Survival Rates ◽  
Beaufort Sea ◽  
First Year ◽  
Human Populations ◽  
Polar Bears ◽  
Adult Males ◽  
Kaplan Meier ◽  
Second Year ◽  
Sea Survival

Polar bears (Ursus maritimus) are hunted throughout most of their range. In addition to hunting, polar bears of the Beaufort Sea region are exposed to mineral and hydrocarbon extraction and related human activities such as shipping, road building, and seismic testing. As human populations increase and demands for polar bears and other arctic resources escalate, reliable estimates of survivorship of polar bears are needed to predict and manage the impacts of those activities. We used the Kaplan–Meier model to estimate annual survival (with 95% confidence intervals) for radio-collared female polar bears and their dependent young that were followed during a 12-year study in the Alaskan Beaufort Sea. Survival of adult female polar bears was higher than had been previously thought: Ŝ = 0.969 (range 0.952–0.983). If human-caused mortalities were deleted, the computed survival rate was 0.996 (0.990–1.002). Survival of young from den exit to weaning was 0.676 (0.634–0.701). Survival during the second year of life, 0.860 (0.751–0.903), was substantially higher than during the first year, 0.651 (0.610–0.675). Shooting by local hunters accounted for 85% of the documented deaths of adult female polar bears. Conversely, 90% of documented losses of young accompanying radio-collared females were not directly caused by humans. Deaths of dependent young were independent of litter size (P = 0.36), indicating that parental investment in single cubs was not different from investment in litters of two or more. Precise estimates of the survival of independent juveniles and adult males still need to be developed.

Effects of adults on survival and recruitment of Peromyscus leucopus

1987 ◽  
Vol 65 (10) ◽  
pp. 2519-2523
Author(s):  
Gregory H. Adler ◽  
Mark L. Wilson ◽  
Michael J. DeRosa
Keyword(s):  
Adult Female ◽  
Adult Male ◽  
Peromyscus Leucopus ◽  
Survival Rates ◽  
Adult Males ◽  
Control Grid ◽  
Young Males ◽  
Young Females ◽  
Breeding Seasons ◽  
And Control

A population of Peromyscus leucopus (white-footed mouse) in northeastern Massachusetts was manipulated for 3 years to determine the effects of adults on survival and recruitment. Two experimental grids were established, from which either all adult males or all adult females were removed continually. The effects of these two manipulations were compared with demography on a control grid. Manipulations had no apparent effect on breeding intensity of young, survival rates of adults, or residency rates of adults and young. Recruitment of adult males was higher on the adult male removal grid than on the control grid. Recruitment rates of adult males and of young males and young females were lower on the adult female removal grid than on the control grid. Survival rates of young males were higher on the adult female removal grid than on the control grid; this effect may have been due to either reduced adult female residency or adult male recruitment. All differences between experimental and control grids were noted only during breeding seasons. Adult males apparently limited recruitment of adult consexuals. The effects of manipulations on other measured parameters were inconclusive because of high immigration rates of adult males onto the adult male removal grid and reduced recruitment of adult males and decreased production of young on the adult female removal grid.

scholarly journals Variability of demographic parameters and population dynamics of Atlantic salmon Salmo salar L. in a south-west French river

2003 ◽  
Vol 60 (2) ◽  
pp. 356-370 ◽  
Author(s):  
J. Dumas ◽  
P. Prouzet
Keyword(s):  
Survival Rate ◽  
Survival Rates ◽  
Maximum Yield ◽  
First Year ◽  
South West ◽  
Salmon Population ◽  
Second Year ◽  
First Year Of Life ◽  
French River ◽  
Good Agreement

Abstract The abundance of the salmon population in the Nivelle River was assessed for 11 cohorts during all the stages of their life cycle, from eggs to spawners. A stochastic life history model was used to simulate the changes in numbers at each stage over several years and to evaluate the parameters of a Ricker-type Stock and Recruitment (S–R) relationship. Parameters necessary for managing the exploitation of the species were also estimated. The results indicated that an average deposition of 611 700 eggs (values varying in a proportion of 1 to 3, depending on the year) produced 4870 0+ parr in autumn (variation from 1 to 5.6); 71.8% of which belonged to the group of future 1-year old smolts. The age 1+ parr were eight times less numerous. Survival from egg to 0+ parr was on average 0.97%, but highly variable (varying from 1 to 15). It was density-dependent and followed Ricker S–R model with an optimum of 7800 parr for a survival rate of 3%. During their second year, the survival of 1+ parr reached 53.4% and varied little. The adult runs of complete cohorts amounted to 196 maiden salmon (range, 88 to 382) and previous spawners comprised only 0.9% of adults. Grilse (1 year in the sea) constituted the majority (88.7%). The overall survival rates from 0+ parr to adult returns (6.2% on average) varied three-fold. The majority was females among the grilse (56.2%) and 2-sea-year salmon (88.6%); all 3-sea-year adults were female. Eggs deposited per female averaged 4200, 8500 and 12 750 eggs in each age group, respectively. Simulations of population abundances at various life stages were in good agreement with the observed data. The S–R relationship revealed the low productivity and the vulnerability of this stock, mainly due to the low survival rate of the young during their first year of life. The maximum yield of 12.2% of recruits could be obtained from a deposition of 1 424 000 eggs, which is twice the present average level.

scholarly journals Experimental reduction of food quality is not compensated with increased food intake in high-arctic muskoxen (Ovibos moschatus)

2012 ◽  
Vol 108 (8) ◽  
pp. 1337-1340 ◽  
Author(s):  
Arnoldus Schytte Blix ◽  
John Ness ◽  
Hans Lian ◽  
Terry V. Callaghan
Keyword(s):  
Food Intake ◽  
Body Mass ◽  
Adult Female ◽  
Food Quality ◽  
High Arctic ◽  
First Year ◽  
Ovibos Moschatus ◽  
Ad Libitum ◽  
Second Year

A total of four barren adult female muskoxen (Ovibos moschatus) were used over a period of 2 years for the purpose of the present study. During the first year, the natural changes in appetite (ad libitum intake of standard pelleted reindeer feed) and body mass were determined in two of the animals. During the second year, the effect of reduced food quality on ad libitum food intake was tested in all four animals in July when the appetite had been found to be at a high. We found that the experimentally reduced food quality was not compensated with increased food intake in these large high-Arctic herbivores.

scholarly journals Oropharyngeal Cancer Survival: A Population-Based Study of Patients Diagnosed between 1978 and 2002

ISRN Oncology ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Dyego Leandro Bezerra de Souza ◽  
María Milagros Bernal ◽  
Javier Jerez Roig ◽  
Maria Paula Curado
Keyword(s):  
Oropharyngeal Cancer ◽  
Cancer Survival ◽  
Survival Rates ◽  
Age Groups ◽  
Relative Survival ◽  
Population Based ◽  
First Year ◽  
Population Based Study ◽  
Kaplan Meier ◽  
One Year

Objective. This paper aims at studying oropharyngeal cancer survival from the Population-Based Cancer Registry of Zaragoza, Spain, for the 1978–2002 period. Methods. The survival rates were calculated by the Kaplan-Meier method, and the automated calculation method of the Catalan Institute of Oncology was utilized to obtain the relative survival. Results. The oropharyngeal cancer survival rate was 61.3% in the first year and 33.9% in the fifth year. One-year relative survival was 62.2% (CI 95%: 57.4–67.4), and five-year relative survival was 36.6% (CI 95%: 31.8–42.1). Comparison of survival rates by sex revealed statistically significant differences (P value = 0.017) with better survival in women. There were no differences when comparing the three age groups and the three studied time periods 1978–1986, 1987–1994, and 1995–2002. Conclusions. The data suggests that there were no significant changes in oropharyngeal cancer survival in the province of Zaragoza throughout the years.

Comparison of the life cycle of potato cyst nematode (Globodera rostochiensis) pathotype Ro1 on selected potato cultivars

Biologia ◽  
2007 ◽  
Vol 62 (2) ◽  
Author(s):  
Marek Renčo
Keyword(s):  
Life Cycle ◽  
Globodera Rostochiensis ◽  
Potato Cultivars ◽  
First Year ◽  
Adult Males ◽  
Experimental Conditions ◽  
Second Stage ◽  
Growing Seasons ◽  
Second Year ◽  
Two Peaks

AbstractThe life cycle of Globodera rostochiensis pathotype Ro1 was studied under experimental conditions on selected potato cultivars (Korela, Albina, Vivaldi, Veronika, Vera, Monalisa, Victoria, Maranca, Désirée) in Slovakia during two growing seasons. Two peaks of second stage juveniles (J2) were found in the soil; the first peak three and four weeks after planting in the first and second year, respectively. The last J2 were found on 23 September. The number of J2 found in the second peak was much higher. First J2 associated with roots were observed 18 days, on middle early and seritonous cultivars 34 days after planting, but fourth stage juveniles (J4) were observed 40 days after planting in both cultivar groups. First adult males were found in soil 43 and 46 days after planting, respectively, and the last males two weeks later. White females filled with eggs were observed on roots 61 days after planting. The cycle from hatching of J2 in the soil to the hatching of J2 from brown cysts required 68 days in the first year and 60 days in the second year.

Analysis of Growth of Atlantic Salmon (Salmo salar) in a Small Newfoundland River

1978 ◽  
Vol 35 (1) ◽  
pp. 60-68 ◽  
Author(s):  
E. M. P. Chadwick ◽  
T. R. Porter ◽  
P. Downton
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Survival Rates ◽  
River System ◽  
First Year ◽  
Commercial Fishery ◽  
Atlantic Salmon Salmo Salar ◽  
Dependent Relationship ◽  
Survival Density ◽  
Sea Survival

Growth and sea survival rates decreased with increasing smolt age, with survival being 12, 6, and 3% for 3+, 4+, and 5+ smolt, respectively. All spawning fish were grilse, which suggests that older smolt became large salmon and were thus more vulnerable to the commercial fishery. A density-dependent relationship was observed for 3+ smolt in their 1st yr of growth, but not for older smolt; younger smolt probably spend their juvenile life in a more productive but space-limiting part of the river. Variation between river-system environments may be responsible for the opposing results of studies on Atlantic salmon (Salmo salar) life history. Key words: Salmo salar, growth, sea survival, density dependence, first-year growth, age at smoltification

scholarly journals Does fox control improve red–legged partridge (Alectoris rufa) survival? An experimental study in Northern Spain

2012 ◽  
Vol 35 (2) ◽  
pp. 395-404
Author(s):  
A. Mateo–Moriones ◽  
◽  
R. Villafuerte ◽  
P. Ferreras ◽  
◽  
...  
Keyword(s):  
Survival Rates ◽  
Generalist Predators ◽  
First Year ◽  
Alectoris Rufa ◽  
Predator Control ◽  
Pica Pica ◽  
Chick Survival ◽  
Northern Spain ◽  
Second Year ◽  
Fox Control

This work evaluates the effectiveness of fox control as a method to improve the survival of red–legged partridge (Alectoris rufa). We radio–tracked 89 adult partridges and their chicks (62 few days old chicks and 46 over one–month–old chicks) and monitored their nests (N = 45) on two hunting estates in northern Spain over two years. Generalist predators (red fox, Vulpes vulpes, and magpie, Pica pica) were selectively controlled on one half of each estate during the first year, and on the other half in the second year. We estimated the effect of predator control on survival rates. Predator control did not improve survival rates for adult partridges and nests, but it improved chick survival, especially for chicks over one–month old.

scholarly journals Winter Survival and Second-year Spring Yields of Day-neutral Strawberry Are Influenced by Cultivar and the Presence of Low Tunnels

2021 ◽  
pp. 1-12
Author(s):  
Kaitlyn M. Orde ◽  
Rebecca Grube Sideman
Keyword(s):  
New England ◽  
Survival Rates ◽  
Fruit Production ◽  
First Year ◽  
Marketable Yield ◽  
Plant Survival ◽  
San Andreas ◽  
Second Year ◽  
Low Tunnels ◽  
Direct Market

Day-neutral (DN) strawberry (Fragaria ×ananassa) cultivars have potential to produce high yields in New England and greatly extend the period of regional strawberry production each year. However, DN strawberries have primarily been evaluated as an annual crop in cold climates; thus, winter hardiness and subsequent second-year spring yields are not well understood. Separate DN plantings were established as dormant bare-rooted plants in Durham, NH (U.S. Department of Agriculture hardiness zone 5b) in 2017 and 2018. During their first year of growth and fruit production, plants were grown under one of two cover treatments: a plastic-covered low tunnel or the traditional open field environment (open beds). In November, plants were covered with either straw much (Winter 2017–18) or rowcover (Winter 2018–19) for low-temperature protection during the winter months. In the spring of the second year when winter protection was removed, the same cover treatments (low tunnel or open bed) were re-administered to plants. Plant survival was affected by year and cultivar, with average survival rates of 82% and 98% in Spring 2018 and Spring 2019, respectively. Plant survival ranged from 34% (‘Monterey’) to 99% (‘Aromas’) in 2018, and 92% (‘Albion’) to 100% (‘San Andreas’ and ‘Seascape’) in 2019. Cultivar significantly affected total and marketable yields in both years, and marketable yields ranged from 35.8 to 167.3 g/plant in 2018 and 121.6 to 298.6 g/plant in 2019. The greatest marketable yields were produced by ‘Aromas’, ‘Cabrillo’, ‘San Andreas’, ‘Seascape’, and low-tunnel ‘Sweet Ann’. In 2019, ‘Cabrillo’, ‘San Andreas’, and ‘Seascape’ produced greater marketable yields during the 6-week second-year season than they had during the plants’ first year of fruit production the previous year, which spanned 18 weeks. Low tunnels hastened fruit ripening in the spring and result in earlier fruit harvests, and in 2019, marketable yields were significantly greater under low tunnels for the first 1 to 3 weeks, depending on cultivar. Total and marketable yields were unaffected by low tunnels in 2018, but were significantly greater under low tunnels in 2019. For cultivars in the 2019 experiment, the increase in marketable yield under low tunnels (compared with open beds) ranged from 92.3 to 166.5 g/plant, except for Sweet Ann, for which marketable yields were 256.6 g/plant greater under low tunnels than on open beds. Using a conservative direct market rate of $4.50/lb, the second-year spring yields produced in the present study had a direct market value of between $3899/ha and $95,647/ha, depending on cultivar and year. We demonstrate that it is not only possible to overwinter DN strawberry plants in northern New England, but that the second-year yield may even exceed first-year production. The results from the present study indicate great potential for profitability from an overwintered DN crop.

scholarly journals P1517SURVIVAL ON DIALYSIS: SWITZERLAND IN COMPARISON WITH OTHER COUNTRIES - A FOLLOW UP

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Rebecca Winzeler ◽  
Patrice Max Ambühl
Keyword(s):  
Survival Rates ◽  
Age Groups ◽  
European Countries ◽  
Dialysis Patients ◽  
Survival Status ◽  
Kaplan Meier ◽  
Number Of Patients ◽  
Second Year ◽  
Two Age Groups

Abstract Background and Aims Survival in dialysis patients is substantially reduced compared to the general population. The aim of the present analysis was to compare the survival of Swiss dialysis patients with other countries with an additional year of follow up and a higher number of patients. Method Incident dialysis patients (hemo- or peritoneal dialysis; N=4525) from the Swiss dialysis registry were followed up from 2014 on until December 31, 2018 (mean follow up days=684). Deaths occurring during this time (N=976) were recorded and survival was examined using the Kaplan Meier method, censored for transplantation. Results Characteristics of the dialysis population stratified according to survival status are provided in Table 1. Dialysis patients in Switzerland have an approximately 8% higher survival in the first and second year after start of dialysis compared to other European countries (Annual ERA-EDTA Report 2016). In the oldest age group, it amounts to up to 13 and 14%, in the first and in the second year, respectively. The proportion in survival rates between genders is similar in Switzerland, as well as in Europe. Dialysis patients aged younger than 45 years have a worse survival in Switzerland compared to other European countries. Conclusion The markedly better survival in dialysis patients in Switzerland compared to other European countries could be confirmed with an additional year of follow up and more patients. Also, causes of death vary widely among European countries. With an additional year of follow up, data to analyze 5-year survival probability will be available for comparison with the ERA-EDTA report. In addition, we will be able to verify whether dialysis patients under 45 years in Switzerland have an increased mortality or whether this is due to the small number of patients in these two age groups.

Concentrations of mercury and polychlorinated biphenyls in blood of Southern Beaufort Sea polar bears (Ursus maritimus) during spring: variations with lipids and stable isotope (δ15N, δ13C) values

2011 ◽  
Vol 89 (11) ◽  
pp. 999-1012 ◽  
Author(s):  
Katrina K. Knott ◽  
Daryle Boyd ◽  
Gina M. Ylitalo ◽  
Todd M. O’Hara
Keyword(s):  
Polychlorinated Biphenyls ◽  
Body Condition ◽  
Neutral Lipids ◽  
Trophic Position ◽  
Beaufort Sea ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Adult Males ◽  
Blood Concentrations ◽  
Condition Indices

Polar bears ( Ursus maritimus Phipps, 1774) are exposed to heavy metal and lipophilic contaminants that are known to bioaccumulate and biomagnify. Few studies concurrently report both chemical classes in the same individuals and are thus unable to assess drivers of observed tissue concentrations, and the potential adverse biological responses to combined exposures. We examined blood concentrations of mercury (Hg) and the sum of seven polychlorinated biphenyls (Σ7PCB) from free-ranging Southern Beaufort Sea polar bears to assess which factors contributed to variations among cohorts (adult males, adult females, young) during spring. Concentrations of Hg ranged from 10.3 to 228.0 ng/g wet mass, but mean concentrations were similar between males and females independent of age. Concentrations of Σ7PCB (range 2.0–132.8 ng/g wet mass) were greater among females and young than among males. Toxicant concentrations were related to packed cell δ15N, an estimate of trophic position, after the inclusion of packed cell δ13C. Concentrations of Σ7PCB were also positively correlated with concentrations of neutral lipids (triglycerides and free fatty acids) and inversely correlated to body condition indices. Elevated concentrations of toxicants and lower body condition indices in females and young compared with males may be a sentinel to a changing arctic environment. Further assessment of the potential adverse health impacts of contaminants and nutritional stress in these cohorts is warranted.

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