scholarly journals Viability of the vaquita, Phocoena sinus (Cetacea: Phocoenidae) population, threatened by poaching of Totoaba macdonaldi (Perciformes: Sciaenidae)

2021 ◽  
Vol 69 (2) ◽  
Author(s):  
Miguel A. Cisneros-Mata ◽  
Juan A. Delgado ◽  
Demetrio Rodríguez-Félix
Keyword(s):  
Gulf Of California ◽  
Population Viability Analysis ◽  
Policy Recommendations ◽  
Demographic Stochasticity ◽  
Term Survival ◽  
Factors Affecting ◽  
Viability Analysis ◽  
Age Structured ◽  
Totoaba Macdonaldi

Introduction: Despite extensive science-based conservation policy recommendations, with fewer than 20 individuals remaining, the vaquita (Phocoena sinus) -endemic to the Gulf of California- is the world’s most endangered marine mammal due to incidental catch in fishing nets and whether it can recover is unclear. Objective: Assess expectations for vaquita over the next two decades. Methods: We identified factors affecting the vaquita, constructed life tables, derived demographic parameters for different scenarios and conducted a population viability analysis using stochastic age-structured matrix Leslie models. Results: Analytical results indicate that the vaquita net growth rate is particularly sensitive to juvenile survival. We find that intensive, ongoing bycatch in gillnets used to poach totoaba (Totoaba macdonaldi) over the past decade brought the vaquita population to its current critically low size. Currently this seems to be exacerbated by demographic stochasticity and a potential Allee effect. Conclusions: If totoaba poaching is eliminated immediately, demographically, vaquita can recover; its long-term survival will depend on its uncertain genetic status, although a recent study found encouraging results in this regard.

Population viability analysis shows spotted-tailed quolls may be vulnerable to competition

2013 ◽  
Vol 35 (2) ◽  
pp. 180 ◽  
Author(s):  
A. S. Glen ◽  
C. R. Dickman
Keyword(s):  
Population Viability Analysis ◽  
Population Viability ◽  
Case Scenario ◽  
Worst Case ◽  
Term Survival ◽  
Exploitation Competition ◽  
Viability Analysis ◽  
Probability Of Survival ◽  
Abundance And Distribution

Competition between carnivores can strongly affect their behaviour, abundance and distribution. Recent analyses suggest a strong likelihood of competition between eutherian predators and the endangered spotted-tailed quoll (Dasyurus maculatus), although experiments are required to confirm this. If competition does occur, what are its likely effects on the long-term survival of spotted-tailed quoll populations? We used population viability analysis (PVA) to predict the fate of a hypothetical quoll population under various scenarios of competition. PVA showed that spotted-tailed quoll populations may be susceptible to extinction when faced with high densities of competitors. Model scenarios simulating exploitation competition and/or intraguild killing greatly reduced the population’s probability of survival, leading in the worst-case scenario to almost certain extinction.

scholarly journals Can we reestablish a self-sustaining population? A case study on reintroduced Crested Ibis with population viability analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yashuai Zhang ◽  
Fang Wang ◽  
Zhenxia Cui ◽  
Min Li ◽  
Xia Li ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Carrying Capacity ◽  
Wild Population ◽  
Population Viability Analysis ◽  
Population Viability ◽  
Viability Analysis ◽  
Crested Ibis ◽  
Reintroduced Population

Abstract Background One of the most challenging tasks in wildlife conservation and management is clarifying which and how external and intrinsic factors influence wildlife demography and long-term viability. The wild population of the Crested Ibis (Nipponia nippon) has recovered to approximately 4400, and several reintroduction programs have been carried out in China, Japan and Korea. Population viability analysis on this endangered species has been limited to the wild population, showing that the long-term population growth is restricted by the carrying capacity and inbreeding. However, gaps in knowledge of the viability of the reintroduced population and its drivers in the release environment impede the identification of the most effective population-level priorities for aiding in species recovery. Methods The field monitoring data were collected from a reintroduced Crested Ibis population in Ningshan, China from 2007 to 2018. An individual-based VORTEX model (Version 10.3.5.0) was used to predict the future viability of the reintroduced population by incorporating adaptive patterns of ibis movement in relation to catastrophe frequency, mortality and sex ratio. Results The reintroduced population in Ningshan County is unlikely to go extinct in the next 50 years. The population size was estimated to be 367, and the population genetic diversity was estimated to be 0.97. Sensitivity analysis showed that population size and extinction probability were dependent on the carrying capacity and sex ratio. The carrying capacity is the main factor accounting for the population size and genetic diversity, while the sex ratio is the primary factor responsible for the population growth trend. Conclusions A viable population of the Crested Ibis can be established according to population viability analysis. Based on our results, conservation management should prioritize a balanced sex ratio, high-quality habitat and low mortality.

scholarly journals Factors Affecting Long Term Survival for Metastatic Gastric Cancer Treated with Chemotherapy

2016 ◽  
Vol 16 (2) ◽  
pp. 97
Author(s):  
Seong Kyeong Lim ◽  
Kyoungwon Jung ◽  
Moo In Park ◽  
Jae Hyun Kim ◽  
Sung Eun Kim ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Metastatic Gastric Cancer ◽  
Term Survival ◽  
Long Term Survival ◽  
Factors Affecting

scholarly journals Factors Affecting Long-Term Survival in Acute Myeloid Leukemia

2020 ◽  
pp. 1-2
Author(s):  
Yi-Qian ZHU ◽  
CHEN Bao-An ◽  
Cheng Jian ◽  
Yi-Qian ZHU
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Remission Rate ◽  
Term Survival ◽  
Long Term Survival ◽  
Factors Affecting ◽  
Chemotherapy Drugs ◽  
Common Malignancy ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a common malignancy of the blood system, and most patients are so ill that they often die if they are untreated in time. In recent years, with the improvement of chemotherapy drugs and methods, the complete remission rate has been significantly improved, but the long-term survival rate still has great room for improvement. This review summarized the influencing factors related to the long-term survival of AML patients through reading and sorting out multiple pieces of literature.

Age-structured models in a random environment

2019 ◽  
pp. 194-213
Author(s):  
Louis W. Botsford ◽  
J. Wilson White ◽  
Alan Hastings
Keyword(s):  
Time Series ◽  
Environmental Variability ◽  
Extinction Risk ◽  
Population Viability Analysis ◽  
Leslie Matrix ◽  
Vital Rates ◽  
Viability Analysis ◽  
Practical Concern ◽  
Probability Of Extinction ◽  
Age Structured

Most ecological populations exist in a randomly fluctuating environment, and these fluctuations influence vital rates, thus changing population dynamics. These changes are the focus of this chapter. The primary practical concern about environmental variability is the possibility that it could cause a population to go extinct, so the chapter describes several approaches to estimating the probability of extinction. The first is the small fluctuations approximation (SFA) to describe the growth of a population with a randomly varying Leslie matrix. The results reveal that randomly varying populations grow more slowly on average than the equivalent deterministic population. Further applications of the SFA examine how correlated variation in different vital rates affects the probability of extinction, when variability is too large to use the SFA, and how it has been applied to population time series. Finally, several other approaches to estimating extinction risk—also known as population viability analysis—are compared.

64 STATISTICAL ANALYSIS OF PROGNOSTIC FACTORS AFFECTING LONG-TERM PROGNOSIS AFTER ENDOSCOPIC TREATMENT OF ESOPHAGEAL VARICES

2020 ◽  
Vol 33 (Supplement_1) ◽  
Author(s):  
T Nishimura
Keyword(s):  
Prognostic Factors ◽  
Esophageal Varices ◽  
Endoscopic Treatment ◽  
Survival Period ◽  
Term Survival ◽  
Gastroesophageal Varices ◽  
Long Term Survival ◽  
Factors Affecting ◽  
Long Term Prognosis

Abstract   Gastroesophageal varices are present in approximately 50% of patients with cirrhosis, and their rupture is a life-threatening complication. However, mortality rates have declined due to the progress in the management of these patients. Especially advances in endoscopic treatment have contributed to the improved survival rates. In this study, we investigated the prognostic factors associated with long-term survival after endoscopic treatment for esophageal varices. Methods The subjects were 260 patients who underwent initial endoscopic treatment for esophageal varices in our hospital between January 1997 and June 2019. Among them, 160 successfully followed up. The patients’ characteristics were: mean age, 65.4 years (29–85); 109 men and 51 women; and median survival period, 53 months. For analysis, subjects were divided into long-term survival and non-long-term survival groups (n = 59 for each) with a 53-month survival period as a cut-off value. Results The long-term/non-long-term survival group had a preoperative Child-Pugh score of 6.2 ± 1.1/7.4 ± 2.0 (p < 0.01) and hepatocellular carcinoma (HCC) presence rate was 25.4%/55.9% (p < 0.01), significantly higher in the non-long-term group. Analysis of the factors affecting survival period using Cox proportional hazards model showed that Child-Pugh score B or C [hazard ratio(HR):2.0143, p < 0.05], total bilirubin value≧ 2 [HR:2.5573, p < 0.05], and presence of HCC [HR:2.2450, p < 0.01] were noted as significant factors. Only presence of HCC was found to be a significant factor affecting the long-term survival using multiple logistic regression analysis [odds ratio:0.3463, p < 0.05]. Conclusion Our study revealed that liver function and the presence of HCC affect long-term prognosis after endoscopic treatment for esophageal varices.

Factors affecting long-term survival following renal artery stenting

2007 ◽  
Vol 69 (7) ◽  
pp. 1037-1043 ◽  
Author(s):  
Mark C. Bates ◽  
John E. Campbell ◽  
Patrick A. Stone ◽  
Michael R. Jaff ◽  
Mike Broce ◽  
...  
Keyword(s):  
Renal Artery ◽  
Term Survival ◽  
Long Term Survival ◽  
Factors Affecting ◽  
Renal Artery Stenting
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