Confounding of Gear Selectivity and the Natural Mortality Rate in Cases where the Former is a Nonmonotone Function of Age

1994 ◽  
Vol 51 (12) ◽  
pp. 2654-2664 ◽  
Author(s):  
Grant G. Thompson
Keyword(s):  
Mortality Rate ◽  
Decision Theory ◽  
Response Function ◽  
Time Frame ◽  
Natural Mortality ◽  
Expected Loss ◽  
The Third ◽  
Gear Selectivity ◽  
Parameter Values ◽  
Suboptimal Strategies

An "exponential–logistic" selectivity function is presented in which a single parameter (γ) determines whether gear selectivity is asymptotic (γ = 0) or reaches a maximum at finite age (γ > 0). The function is used to develop a model in which both γ and the natural mortality rate M are formally indeterminate and in which the coming year's catch limit can be viewed as a response function of either estimated γ or estimated M. Decision theory is then used to derive the optimal catch. The optimal catch is shown to increase with the degree of uncertainty surrounding M, although this conclusion may depend on the short managerial time frame assumed. Three "suboptimal" strategies are also considered: (1) setting catch at the level corresponding to the expected value of M, (2) setting catch at the minimum of the response function, and (3) setting catch at the level corresponding to γ = 0. The first suboptimal strategy never results in a catch greater than the optimum and always results in a lower expected loss than the second. The performance of the third strategy (relative to the others) depends on parameter values.

An Application of Computers to the Estimation of Exploited Populations

1969 ◽  
Vol 26 (1) ◽  
pp. 179-189
Author(s):  
K. Radway Allen
Keyword(s):  
Mortality Rate ◽  
Age Distribution ◽  
The Other ◽  
Population Estimates ◽  
Distribution Data ◽  
Natural Mortality ◽  
Computer Programme ◽  
Total Catch ◽  
The Third

This paper describes a computer programme for the estimation of the size of exploited populations by methods described in Allen (1966, J. Fish. Res. Bd. Canada 23: 1553–1574). Although these methods were originally developed for use on whale populations, they are applicable to any other populations where suitable data are available. The essential data are the total catch, the catch for a known amount of effort, and the age distribution of the catch, all for a series of years. An estimate of natural mortality rate is also required but population estimates may be obtained for up to 10 values of this parameter in a single computer run.The entire programme incorporates six subroutines, as well as the main controlling programme. One subroutine reads in the catch and effort data, a second reads in the age distribution data for each year and, if necessary, converts it according to a predetermined transformation from age expressed in terms of whale ear-plug laminations to age in years. The third subroutine estimates the rate of recruitment as the proportion of newly recruited animals in the catch for each year, using the method of Allen (1966). The other three subroutines derive population estimates, using the "q," modified DeLury, and actual and expected catch methods (Allen, 1966). As many sets of data as desired may be processed in a single computer run.

Some Methods for Estimating Ocean Mortality of Pacific Salmon and Applications

1965 ◽  
Vol 22 (1) ◽  
pp. 33-51 ◽  
Author(s):  
R. A. Fredin
Keyword(s):  
Mortality Rate ◽  
Freshwater Fish ◽  
Pacific Salmon ◽  
Mortality Rates ◽  
Natural Mortality ◽  
Bristol Bay ◽  
The Third

Three methods for estimating oceanic natural mortality rates of Pacific salmon under certain survival conditions are presented. Estimates of ocean mortality rates of Bristol Bay and Karluk sockeye are given. The mortality rate during the year immediately preceding the last 2 months of ocean life of Bristol Bay sockeye that migrated to sea as 3-freshwater fish in 1956 and returned as mature 3-ocean fish in 1959 is estimated to be 28.9%. The average ocean mortality rate during the penultimate year of life of 3-ocean Bristol Bay sockeye is estimated to be 19.5% for the years 1956–57 to 1960–61. The natural mortality rate during the third year of ocean life of 3-freshwater Karluk sockeye is estimated to be 28.2%. Corresponding estimates of average monthly instantaneous mortality rates are 0.028, 0.018, and 0.031, respectively.

The Measurement of Performance in Probabilistic Diagnosis IV. Utility Considerations in Therapeutics and Prognostics

1981 ◽  
Vol 20 (02) ◽  
pp. 80-96 ◽  
Author(s):  
J. D. F. Habbema ◽  
J. Hilden
Keyword(s):  
Decision Theory ◽  
Figure Of Merit ◽  
Acute Abdominal Pain ◽  
Theory Approach ◽  
Expected Loss ◽  
Patient Benefit ◽  
Evaluation Approach ◽  
Average Loss ◽  
Actual Decision ◽  
Probabilistic Diagnosis

It is argued that it is preferable to evaluate probabilistic diagnosis systems in terms of utility (patient benefit) or loss (negative benefit). We have adopted the provisional strategy of scoring performance as if the system were the actual decision-maker (not just an aid to him) and argue that a rational figure of merit is given by the average loss which patients would incur by having the system decide on treatment, the treatment being selected according to the minimum expected loss principle of decision theory.A similar approach is taken to the problem of evaluating probabilistic prognoses, but the fundamental differences between treatment selection skill and prognostic skill and their implications for the assessment of such skills are stressed. The necessary elements of decision theory are explained by means of simple examples mainly taken from the acute abdomen, and the proposed evaluation tools are applied to Acute Abdominal Pain data analysed in our previous papers by other (not decision-theoretic) means. The main difficulty of the decision theory approach, viz. that of obtaining good medical utility values upon which the analysis can be based, receives due attention, and the evaluation approach is extended to cover more realistic situations in which utility or loss values vary from patient to patient.

Virtual Population Analysis (VPA) Equations for Nonhomogeneous Populations, and a Family of Approximations Including Improvements on Pope's Cohort Analysis

1986 ◽  
Vol 43 (12) ◽  
pp. 2406-2409 ◽  
Author(s):  
Alec D. MacCall
Keyword(s):  
Mortality Rate ◽  
Population Analysis ◽  
Seasonal Pattern ◽  
Cohort Analysis ◽  
Natural Mortality ◽  
Close Approximation ◽  
Virtual Population Analysis ◽  
Virtual Population ◽  
Special Case

A set of "backward" virtual population analysis (VPA) equations relates catch (Ct) from continuous fishing between times t and t + 1 to population n size (Nt, Nt+1) when a portion of the stock is unavailable to fishing. The usual VPA equations become a special case where the entire stock is available (i.e. the stock is homogeneous). A close approximation to the VPA equations is Nt = Nt+1 exp(M) + CtM/(1 − exp(−M)), which has properties similar to Pope's "cohort analysis" and is somewhat more accurate in the case of a continuous fishery, especially if the natural mortality rate (M) is large. Much closer simple approximations are possible if the seasonal pattern of catches is known.

Neonatal Intensive Care

Curationis ◽  
1981 ◽  
Vol 4 (1) ◽  
Author(s):  
Lyn Acres
Keyword(s):  
Intensive Care ◽  
Mortality Rate ◽  
Old Age ◽  
Neonatal Intensive Care ◽  
Perinatal Period ◽  
Third Trimester ◽  
Newborn Period ◽  
The Third

THE events of the third trimester of pregnancy labour, delivery and the newborn period undoubtedly influence the whole of one’s life. Old age excluded, the highest mortality rate occurs in the perinatal period.

Movement, Growth and natural mortality rate of the Red Spot King Prawn, Penaeus longistylus Kubo, from the Great Barrier Reef Lagoon

1990 ◽  
Vol 41 (3) ◽  
pp. 399 ◽  
Author(s):  
MCL Dredge
Keyword(s):  
Growth Rate ◽  
Mortality Rate ◽  
Great Barrier Reef ◽  
Annual Variation ◽  
Growth Parameters ◽  
Natural Mortality ◽  
Barrier Reef ◽  
Fishing Mortality ◽  
Nursery Areas ◽  
Reef Lagoon

Movement, growth and natural mortality rate of the red spot king prawn, Penaeus longistylus, occurring in waters of the Great Barrier Reef off Townsville, Queensland, were investigated in a series of tagging experiments. Adult P. longistylus did not migrate after leaving nursery areas. Their growth rate was slower than that of the conspecific species P. plebejus, and significant inter-annual variation in growth parameters was observed. The natural mortality rate, assessed by sequential tagging experiments that eliminated the possibility of confounding with the rate of fishing mortality, was estimated to be 0.072 (week-1).

Influence of errors in natural mortality estimates in cohort analysis

1997 ◽  
Vol 54 (7) ◽  
pp. 1608-1612 ◽  
Author(s):  
G Mertz ◽  
R A Myers
Keyword(s):  
Mortality Rate ◽  
Similar Pattern ◽  
Cohort Analysis ◽  
Transient Behavior ◽  
Natural Mortality ◽  
Exact Formulation ◽  
Fishing Mortality ◽  
Bias Factor ◽  
Special Case ◽  
Mortality Estimates

The accuracy of the estimation of cohort strength from catch data may be greatly degraded if a poor estimate of the natural mortality rate is entered into the calculation. A straightforward, exact formulation for the error in cohort reconstruction due to a misspecified natural mortality rate is presented. The special case of constant fishing mortality is particularly transparent, allowing the error to be segmented into easily interpreted terms. A change in the fishing mortality may result in a distinct hump in the transient behavior of the bias factor, rather than a simple monotonic adjustment. This implies a similar pattern in estimated cohort strength.

scholarly journals POPULATION DYNAMICS OF MALAYAN LEAF FISH (Pristolepisgrooti Blkr.) IN RANAU LAKE, SOUTH SUMATRA

2018 ◽  
Vol 24 (2) ◽  
pp. 125
Author(s):  
Sevi Sawetri ◽  
Subagdja Subagdja ◽  
Dina Muthmainnah
Keyword(s):  
Mortality Rate ◽  
Growth Parameters ◽  
Total Mortality ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Frequency Data ◽  
Length Frequency ◽  
Lake Ecosystems ◽  
Exploitation Rate ◽  
Length Frequency Data

The Malayan leaf fish or locally named as kepor (Pristolepis grooti) is one of important biotic components in Ranau Lake ecosystems. This study aimed to estimate population dynamic and exploitation rate of kepor in Ranau Lake, South Sumatera. The population parameters are estimated based on length frequency data which were collected in March to October 2013. Growth parameters and fishing mortality rates were calculated using FiSAT software package. The results showed that kepor’s growth was negative allometric, which tended to gain length faster than weight. Kepor population was dominated (42%) by individual length of 10.0 to 11.0 cm. Predicted length infinity (L) was 17.28 cm with high value of growth rates (K) of 1.4 year-1. The natural mortality rate (M) is 2.57 year-1, the fishing mortality rate (F) is 5.36 year-1 and total mortality rate (Z) is 7.93 year-1. The exploitation rate of Malayan leaf fish in Ranau Lake (E = 0.68 year-1) has passed the optimum score.  

scholarly journals ANÁLISIS DEL CRECIMIENTO Y LA MORTALIDAD DE ANISOTREMUS INTERRUPTUS (GILL) (PERCIFORMES: HAEMULIDAE) EN LA COSTA DE COLIMA, MÉXICO

2016 ◽  
Vol 33 ◽  
Author(s):  
Elaine Espino Barr ◽  
Manuel Gallardo Cabello ◽  
Fernando González Orozco ◽  
Arturo Garcia Boa
Keyword(s):  
Mortality Rate ◽  
Growth Parameters ◽  
Total Mortality ◽  
Condition Index ◽  
First Year ◽  
The Third ◽  
Second Year ◽  
First Year Of Life ◽  
Mortality Analysis

This paper deals with the growth and mortality analysis of the burrito grunt A n i s o t remus interru p t u s on the coast of Colima, México. The estimated growth parameters are: L¥ = 50.59 cm; W¥ = 5,051.04 g; k = 0.147 years- 1; to = -0.916 years; A0 . 9 5 = 19.46 years. Most of the growth occurred during the first year of life, when the grunt grows 12.52 cm, the second year it grows 4.95 cm and the third, 4.60 cm. The highest value of the condition index took place between February and September. The total mortality rate (Z) was calculated as 0.53 years- 1. These values are basic for the plan of administration of the fishery of this species.

scholarly journals Drug Overdose Trends among Black Indiana Residents: 2013-2017

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Raven Helmick
Keyword(s):  
Mortality Rate ◽  
Drug Overdose ◽  
Rate Increase ◽  
Mortality Rates ◽  
Time Frame ◽  
Minority Population ◽  
Racial Inequalities ◽  
Specific Mortality ◽  
Overdose Mortality ◽  
Overdose Deaths

ObjectiveTo understand trends in race-specific mortality rates between blacks and whites to discover any racial inequalities that might exist for drug overdose deaths. To delve into the types of drugs that are prominently involved in black drug overdose deaths from 2013-2017 in the state of Indiana.IntroductionBlack Hoosiers, the largest minority population in Indiana, make up almost 10% of the state’s population, and accounted for 8% of the total resident drug overdose deaths from 2013-2017 compared to whites at 91%. However, a closer look at race-specific mortality rates might reveal racial inequalities. Therefore, the purpose of this project was to analyze drug overdose morality rates among white and black Hoosiers to discover possible racial inequalities and to discover trends in drug involvement in overdose deaths among blacks.MethodsDrug overdose deaths that occurred in Indiana between 2013 and 2017 were identified using the underlying and contributing cause of death ICD-10 codes and abstracted from the Indiana State Department of Health’s annual finalized mortality dataset. Race-specific drug overdose death rates were calculated and compared among racial groups. Drug overdose deaths in blacks were examined for trends over time and by the types of drugs involved.ResultsBetween 2013 and 2017, drug overdose mortality rates for whites increased from 17.05 to 27.28 per 100,000. Blacks saw a higher rate increase during this same time frame: from 10.74 to 30.62 per 100,000, surpassing the mortality rate of whites by the end of 2017. Drug overdose deaths in blacks increased 197% from 2013-2017 and drug specific mortality rate increases were seen across all drug category’s. Opioids, which were involved in 61% of the 2017 drug overdose deaths among blacks, had a rate increase from 3.05 to 18.62 per 100,000 between 2013 and 2017. Drug specific overdose mortality rate increases were also seen for overdoses involving cocaine (1.76 to 10.62 per 100,000), benzodiazepines (0.32 to 3.08 per 100,000), and psychostimulants other than cocaine (0.16 to 1.69 per 100,000) such as amphetamines.ConclusionsWhile white Hoosiers had higher drug overdose mortality rates between 2013 and 2016, black Hoosiers had a greater mortality rate increase and surpassed the mortality rate in whites in 2017. Opioids, the most frequently involved substance in overdose deaths among blacks from 2013-2017, showed increasing rates during this time period. However, increases in drug specific overdose mortality rates for cocaine, benzodiazepines, and psychostimulants other than cocaine also call for public health attention. These results promote the inclusion of minority health experts in drug overdose prevention efforts and issue a call for future prevention efforts to be targeted toward the state’s largest minority population. 

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