A Method of Estimating Natural and Fishing Mortalities

1958 ◽  
Vol 15 (4) ◽  
pp. 749-758 ◽  
Author(s):  
J. E. Paloheimo
Keyword(s):  
Age Groups ◽  
Mortality Rates ◽  
Correction Factors ◽  
Fishing Mortality ◽  
Age Classes ◽  
Simple Method ◽  
Virtual Population ◽  
Population Size Estimates ◽  
Available Information ◽  
Size Estimates

A simple method of estimating instantaneous natural and fishing mortality rates is given. It uses the maximum of the available information. The method requires data on numbers caught by age-classes, and data on (effective) effort for a series of years. For each year-class is calculated the weighted sum of catches from all age-groups from a given age on, and these sums are used as estimates of year-class strengths. The weighting factors depend on the instantaneous fishing and natural mortality rates; the best values of mortality rates are arrived at by iteration. When statistics are not complete a correction factor can be applied. This method is compared with Fry's "virtual" population size estimates; in both cases the basic statistics are catches. We have, however, introduced correction factors to allow for varying fishing intensities and incomplete statistics at older ages.

Estimation of Effective Effort from Catch-at-Age Data

1993 ◽  
Vol 50 (11) ◽  
pp. 2421-2428 ◽  
Author(s):  
J. E. Paloheimo ◽  
Yong Chen
Keyword(s):  
Age Groups ◽  
Simulated Data ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
A Value ◽  
Basic Equations ◽  
Highly Correlated ◽  
High Degree ◽  
Two Age Groups

We present a method for estimating effective efforts or fishing mortality rates based on a linearized version of the catch equation. Catch-at-age for at least two age groups over a series of years is required. The method presupposes a value for natural mortality rate (M). The method is validated using simulated data with an appropriate error structure. The algorithm always converges to a set of effective efforts that are compatible with the known catches. Nevertheless, the solution to the basic equations is not unique although the different solutions are typically highly correlated. If the M assumed by the algorithm is the same as the actual M the iterated effective efforts are typically very close to the true effective efforts or fishing mortality rates. If the assumed M is too high or too low the pattern of effective efforts is still recovered to a high degree of accuracy, typically 0.90 < r < 1.00, even though M may be off by as much as 60%. When data for three or more age groups are available the method is extended to at least squares procedure that takes into account the increasing uncertainty of catches with age.

scholarly journals Age, growth and mortality of the European Seabass, (Dicentrarchus Labrax) in Bardawil lagoon, North Sinai, Egypt

2021 ◽  
pp. 042-046
Author(s):  
El-Desoki Menna O ◽  
Younis Younis M ◽  
A Youssef El-Dakar ◽  
Ahmed Salem M ◽  
Ahmed Kassem S ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Age Groups ◽  
Dicentrarchus Labrax ◽  
Mortality Rates ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
European Seabass ◽  
Exploitation Rate ◽  
The Relationship ◽  
North Sinai

Age, growth, and mortality of European Seabass (Dicentrarchus labrax) were studied from a small-scaled fishery of Bardawil lagoon, (North Sinai, Egypt). 181 specimens (16.6 to 35 cm total Length and 39.8 to 367.2 g total weight). The relationship between length and weight was W = 0.0054L3.1428. Age was determined by otoliths and age groups I to IV years were observed. Growths in length and weight at the end of each year were calculated. The growth parameters of von Bertalanffy equation were calculated as (L∞ = 48.69 cm, K = 0.1677 yr -1 and t0 = -0.447 yr -1). Growth performance index was calculated (φ = 2.60 for length and 1.25 for weight). Mortality rates were 0.867 yr-1, 0.25 yr1and 0.617 yr-1 for total, natural and fishing mortality, respectively. The currently exploitation rate E = 0.712 yr-1 indicating that, the population of this species is being heavily exploited.

scholarly journals Using Routinely Available Information to Estimate Tropical Cyclone Wind Structure

2016 ◽  
Vol 144 (4) ◽  
pp. 1233-1247 ◽  
Author(s):  
John A. Knaff ◽  
Christopher J. Slocum ◽  
Kate D. Musgrave ◽  
Charles R. Sampson ◽  
Brian R. Strahl
Keyword(s):  
Tropical Cyclone ◽  
Satellite Imagery ◽  
Global Model ◽  
Error Statistics ◽  
Simple Method ◽  
Wind Structure ◽  
Practical Research ◽  
Data Location ◽  
Available Information ◽  
Size Estimates

Abstract A relatively simple method to estimate tropical cyclone (TC) wind radii from routinely available information including storm data (location, motion, and intensity) and TC size is introduced. The method is based on a combination of techniques presented in previous works and makes an assumption that TCs are largely symmetric and that asymmetries are based solely on storm motion and location. The method was applied to TC size estimates from two sources: infrared satellite imagery and global model analyses. The validation shows that the methodology is comparable with other objective methods based on the error statistics. The technique has a variety of practical research and operational applications, some of which are also discussed.

Inequalities and Impact of Socioeconomic-Cultural Factors in Suicide Rates Across Italy

Crisis ◽  
2011 ◽  
Vol 32 (4) ◽  
pp. 178-185 ◽  
Author(s):  
Maurizio Pompili ◽  
Marco Innamorati ◽  
Monica Vichi ◽  
Maria Masocco ◽  
Nicola Vanacore ◽  
...  
Keyword(s):  
Suicide Rate ◽  
Age Groups ◽  
Premature Death ◽  
Mortality Rates ◽  
Mortality Data ◽  
Italian Population ◽  
Comprehensive Overview ◽  
Suicide Rates ◽  
Younger Age ◽  
Age And Sex

Background: Suicide is a major cause of premature death in Italy and occurs at different rates in the various regions. Aims: The aim of the present study was to provide a comprehensive overview of suicide in the Italian population aged 15 years and older for the years 1980–2006. Methods: Mortality data were extracted from the Italian Mortality Database. Results: Mortality rates for suicide in Italy reached a peak in 1985 and declined thereafter. The different patterns observed by age and sex indicated that the decrease in the suicide rate in Italy was initially the result of declining rates in those aged 45+ while, from 1997 on, the decrease was attributable principally to a reduction in suicide rates among the younger age groups. It was found that socioeconomic factors underlined major differences in the suicide rate across regions. Conclusions: The present study confirmed that suicide is a multifaceted phenomenon that may be determined by an array of factors. Suicide prevention should, therefore, be targeted to identifiable high-risk sociocultural groups in each country.

Estimating the population size of people who inject drugs in Ho Chi Minh City, Vietnam: A two-survey capture-recapture exercise (Preprint)

2019 ◽  
Author(s):  
Abu Abdul-Quader
Keyword(s):  
Population Size ◽  
Illicit Drugs ◽  
People Who Inject Drugs ◽  
Care Service ◽  
Ho Chi Minh City ◽  
Size Estimation ◽  
Population Size Estimates ◽  
Capture Recapture ◽  
The City ◽  
Size Estimates

BACKGROUND Population size estimation of people who inject drugs (PWID) in Ho Chi Minh City (HCMC), Vietnam relied on the UNAIDS Estimation and Projection Package and reports from the city police department. The two estimates vary widely. OBJECTIVE To estimate the population size of people who inject drugs in Ho Chi Minh City, Vietnam METHODS Using Respondent-driven sampling (RDS), we implemented two-source capture-recapture method to estimate the population size of PWID in HCMC in 2017 in 7 out of 24 districts. The study included men or women aged at least 18 years who reported injecting illicit drugs in the last 90 days and who had lived in the city the past six months. We calculated two sets of size estimates, the first assumed that all participants in each survey round resided in the district where the survey was conducted, the second, used the district of residence as reported by the participant. District estimates were summed to obtain an aggregate estimate for the seven districts. To calculate the city total, we weighted the population size estimates for each district by the inverse of the stratum specific sampling probabilities. RESULTS The first estimate resulted in a population size of 19,155 (95% CI: 17,006–25,039). The second one generated a smaller population size estimate of 12,867 (95% CI: 11,312–17,393). CONCLUSIONS The two-survey capture-recapture exercise provided two disparate estimates of PWID in HCMC. For planning HIV prevention and care service needs among PWID in HCMC, both estimates may need to be taken into consideration together with size estimates from other sources.

82 The Significant Burden of Burn Injuries in the Middle East: An Epidemiological Study of Nineteen Countries over 27 Years

2021 ◽  
Vol 42 (Supplement_1) ◽  
pp. S56-S57
Author(s):  
Zachary J Collier ◽  
Yasmina Samaha ◽  
Priyanka Naidu ◽  
Katherine J Choi ◽  
Christopher H Pham ◽  
...  
Keyword(s):  
Middle East ◽  
Age Groups ◽  
Mortality Rates ◽  
Burn Injuries ◽  
Burn Care ◽  
Life Years ◽  
Significant Burden ◽  
Mortality Ratio ◽  
Incident Cases ◽  
Age And Sex

Abstract Introduction Despite ongoing improvements in burn care around the world, the burden of burn morbidity and mortality has remined a significant challenge in the Middle East due to ongoing conflicts, economic crises, social disparities, and dangerous living conditions. Here, we examine the epidemiology of burn injuries in the Middle East (ME) relative to socio-demographic index (SDI), age, and sex in order to better define regional hotspots that may benefit most from sustainability and capacity building initiatives. Methods Computational modeling from the 2017 Global Burden of Disease (GBD17) database was used to extrapolate burn data about the nineteen countries that define the ME. Using the GBD17, the yearly incidence, deaths, and Disability-Adjusted Life Years (DALYs) from 1990 to 2017 were defined with respect to age and sex as rates of cases, deaths, and years per 100,000 persons, respectively. Mortality ratio represents the percentage of deaths relative to incident cases. Data from 2017 was spatially mapped using heat-mapping for the region. Results Over 27 years in the ME, an estimated 18,289,496 burns and 308,361 deaths occurred causing 24.5 million DALYs. Burn incidence decreased by 5% globally but only 1% in the ME. Although global incidence continued to decline, most ME countries exhibit steady increases since 2004. Compared to global averages, higher mortality rates (2.8% vs 2.0%) and DALYs (205 vs 152 years) were observed in the Middle East during this time although the respective disparities narrowed by 95% and 42% by 2017. Yemen had the worst death and DALY rates all 27 years with 2 and 2.2 times the ME average, respectively. Sudan had the highest morality ratio (3.7%) for most of the study, twice the ME average (1.8%), followed by Yemen at 3.6%. Sex-specific incidence, deaths, and DALYs in the ME were higher compared to the global cohorts. ME women had the worst rates in all categories. With respect to age, all rates were worse in the ME age groups except in those under 5 years. Conclusions For almost three decades, ME burn incidence, deaths, DALYs, and mortality rates were consistently worse than global average. Despite the already significant differences for burn frequency and severity, especially in women and children, underreporting from countries who lack sufficient registry capabilities likely means that the rates are even worse than predicted.

scholarly journals Mortality Associated with Idiopathic Pulmonary Fibrosis in Northeastern Italy, 2008–2020: A Multiple Cause of Death Analysis

2021 ◽  
Vol 18 (14) ◽  
pp. 7249
Author(s):  
Alessandro Marcon ◽  
Elena Schievano ◽  
Ugo Fedeli
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Cause Of Death ◽  
Age Groups ◽  
Mortality Rates ◽  
Annual Percent Change ◽  
Northeastern Italy ◽  
Mortality Ratio ◽  
The Impact ◽  
Related Mortality

Mortality from idiopathic pulmonary fibrosis (IPF) is increasing in most European countries, but there are no data for Italy. We analysed the registry data from a region in northeastern Italy to assess the trends in IPF-related mortality during 2008–2019, to compare results of underlying vs. multiple cause of death analyses, and to describe the impact of the COVID-19 epidemic in 2020. We identified IPF (ICD-10 code J84.1) among the causes of death registered in 557,932 certificates in the Veneto region. We assessed time trends in annual age-standardized mortality rates by gender and age (40–74, 75–84, and ≥85 years). IPF was the underlying cause of 1310 deaths in the 2251 certificates mentioning IPF. For all age groups combined, the age-standardized mortality rate from IPF identified as the underlying cause of death was close to the European median (males and females: 3.1 and 1.3 per 100,000/year, respectively). During 2008–2019, mortality rates increased in men aged ≥85 years (annual percent change of 6.5%, 95% CI: 2.0, 11.2%), but not among women or for the younger age groups. A 72% excess of IPF-related deaths was registered in March–April 2020 (mortality ratio 1.72, 95% CI: 1.29, 2.24). IPF mortality was increasing among older men in northeastern Italy. The burden of IPF was heavier than assessed by routine statistics, since less than two out of three IPF-related deaths were directly attributed to this condition. COVID-19 was accompanied by a remarkable increase in IPF-related mortality.

scholarly journals Some biological properties of spiny eel (Mastacembelus mastacembelus, Banks & Solander, 1794) living in the Upper Euphrates River Basin, Turkey

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mehmet Zülfü Çoban ◽  
Mücahit Eroğlu ◽  
Mustafa Düşükcan
Keyword(s):  
River Basin ◽  
Growth Parameters ◽  
Age Groups ◽  
Mortality Rates ◽  
Biological Properties ◽  
Von Bertalanffy ◽  
Growth Type ◽  
Euphrates River ◽  
Fish Samples ◽  
Exploitation Rate

AbstractThis study was carried out to determine some bioecological characteristics of Mastacembelus mastacembelus, which is the only species of Mastacembelidae family living in Turkey. Fish samples were caught between 2014–2018 from Keban Dam Lake, one of the most important reservoirs of the upper Euphrates Basin. In totally, 348 Mastacembelus mastacembelus individuals were examined, including 178 males and 170 females. The age distributions were defined between the I–XV age groups. Total lengths ranged from 14.20 to 81.80 cm in males and from 15.60 to 77.30 cm in females. Total length–weight relationships were calculated as W = 0.0083 × TL2.6516 for males, W = 0.0043 × TL2.8310 for females and W = 0.0063 × TL2.7256 for all population, and the growth type was estimated as “negative allometric”. The von Bertalanffy growth parameters for all individuals were computed as L∞ = 90.99, k = 0.13, t0 = − 0.45. The total (Z), natural (M), fishing (F) mortality rates and exploitation rate (E) were estimated as Z = 0.313, M = 0.270, F = 0.043 and E = 0.137, respectively. The length at first capture (Lc) was found as 50.72. The optimum, maximum and economic yields were calculated as E0.5 = 0.361; Emax = 0.776; E0.1 = 0.664, respectively.

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