Optimal Stock Size and Harvest Rate in Multistage Life History Models

1986 ◽  
Vol 43 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Elie Moussalli ◽  
Ray Hilborn
Keyword(s):  
Life History ◽  
Survival Rates ◽  
Harvest Rate ◽  
Recruitment Curve ◽  
Stock Size ◽  
Entire Life ◽  
Density Dependent ◽  
Optimal Harvest ◽  
History Of ◽  
The Relationship

If the life history of a population consists of a sequence of density-dependent stages linked by density-independent survival rates, and if the density-dependent stages take the form of the Beverton–Holt stock and recruitment curve, then a single Beverton–Holt curve will describe the entire life history. The relationship between the parameters of any stage in the life history and the optimal harvest rate and optimal stock size is analyzed. Increasing survival rates will always increase the optimal harvest rate, but may increase or decrease the optimal stock size. Increasing the habitat capacity will increase the optimal stock size and leave the optimal harvest rate unaffected. An example of changing freshwater survival rates by Salmonid Enhancement is shown, as is an example of changing ocean survival rate. As we acquire a better understanding of the determinants of survival and habitat capacity, we should adjust harvest rates and stock size as the environment changes.

scholarly journals Calculation of LTC Premiums Based on Direct Estimates of Transition Probabilities

2005 ◽  
Vol 35 (2) ◽  
pp. 455-469 ◽  
Author(s):  
Florian Helms ◽  
Claudia Czado ◽  
Susanne Gschlößl
Keyword(s):  
Life History ◽  
Generalized Estimating Equations ◽  
Transition Matrix ◽  
Transition Probabilities ◽  
State Model ◽  
Link Function ◽  
History Of ◽  
The Relationship ◽  
Pseudo Values ◽  
Almost Unbiased

In this paper we model the life-history of LTC-patients using a Markovian multi-state model in order to calculate premiums for a given LTC-plan. Instead of estimating the transition intensities in this model we use the approach suggested by Andersen et al. (2003) for a direct estimation of the transition probabilities. Based on the Aalen-Johansen estimator, an almost unbiased estimator for the transition matrix of a Markovian multi-state model, we calculate so-called pseudo-values, known from Jackknife methods. Further, we assume that the relationship between these pseudo-values and the covariates of our data are given by a GLM with the logit as link-function. Since the GLMs do not allow for correlation between successive observations we use instead the “Generalized Estimating Equations” (GEEs) to estimate the parameters of our regression model. The approach is illustrated using a representative sample from a German LTC portfolio.

scholarly journals Echoes of Past Revolutions: Architecture, Memory, and Spectral Politics in the Historic Districts of Port-au-Prince

2020 ◽  
Vol 17 ◽  
Author(s):  
Vincent Joos
Keyword(s):  
Life History ◽  
The Political ◽  
Middle Classes ◽  
Historic Districts ◽  
Entire Life ◽  
Political Landscape ◽  
Four Books ◽  
Small House ◽  
History Of ◽  
Federal Prosecutor

Abstract This article explores the life history of Ulrick Rosarion, a Haitian federal prosecutor who built his career during the Duvalier dictatorship. Rosarion lived his entire life in a small house of downtown Port-au-Prince, in a neighborhood formerly inhabited by the Black middle-classes that gained prominence in the political and administrative sphere during the dictatorship (1957-1986). Rosarion was also a writer who produced four books of nationalist poetry. Based on interviews and readings of his literary production, and beyond, through an exploration of architectural forms and material remnants echoing the dictatorship, this paper explores how an idealized version of the dictatorship today haunts the political landscape of Haiti. Moreover, this article argues that the state takes on a sensual form that allows for the diffusion and/or rupture of past ideologies.

scholarly journals Married Dostoevsky? The History of Relations between V.V. Rozanov and A.P. Suslova

2021 ◽  
Vol 26 (3) ◽  
pp. 398-413
Author(s):  
Alexey Nicolaeyvich Varlamov
Keyword(s):  
Life History ◽  
Documentary Evidence ◽  
Scientific Level ◽  
Literary Research ◽  
The Brothers Karamazov ◽  
History Of ◽  
Brothers Karamazov ◽  
The Relationship ◽  
Objective Study ◽  
Deep Interest

The article examines in detail the history of the relationship between A.P. Suslova and V.V. Rozanov in connection with the notion existing in the historical and literary science that Rozanovs marriage to Suslova was based on his deep interest in the work of F.M. Dostoevsky and his desire in such an unusual way to penetrate deeper into the secrets of the life and work of the author of The Idiot and The Brothers Karamazov. However, an appeal to various documentary evidence shows that Rozanovs marriage motives came from the warehouse of his nature and constituted a complex of rather complex reasons, among which the human, and not literary, research principle still dominates. The desire for a benevolently objective study of the life history of A.P. Suslova makes it possible to clarify at the modern scientific level the important facts of the biography of F.M. Dostoevsky and V.V. Rozanov, to free them from the stratifications of legends and myths.

scholarly journals Syair Perahu Karya Hamzah Fansuri Dalam Kaitannya Dengan Budaya Maritim di Singkel

PANALUNGTIK ◽  
2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Laila Abdul Jalil ◽  
Nuralam
Keyword(s):  
Life History ◽  
Data Collection ◽  
Historical Archaeology ◽  
Research Use ◽  
Literature Study ◽  
Literary Works ◽  
The Past ◽  
Maritime Culture ◽  
History Of ◽  
The Relationship

Hamzah Fansuri lived in the early era of the peak of the Aceh Darussalam kingdom. The Kingdom of Aceh Darussalam at that time visited by many traders from Arab, Parsi, Turkish, Bengal (India), Siamese, Portuguese, and Spain. Hamzah Fansuri is a Sufism scholar who developed Islamic teaching trough his poems. One of his poems is Syair Perahu. Syair Perahu besides containing Sufism also is related to the trade and wealth of Singkel sea. The discovery of foreign ceramics along the Singkel river is one proof of trade in the past. This research use method of manuscript study. The reason for choosing text studies is because Hamzah Fansuri produced many literary works in the form of poetry. The approach used in this study is historical archaeology to reveal the maritime culture of Singkel trough Syair Perahu by Hamzah Fansuri. Data collection is done trough literature study by collecting books, documents, and paper relating to the life history of Hamzah Fansuri and and literary works that he produces. The purpose of this reseach is to determine the relationship between Syair Perahu and maritime culture of Singkel. Based on a study of Syair Perahu, it is known that Hamzah Fansuri not only discusses the Sufism but also provides information about Singkel and trade in its time.

Escapement goal analysis and stock reconstruction of sockeye salmon populations (Oncorhynchus nerka) using life-history models

2008 ◽  
Vol 65 (10) ◽  
pp. 2269-2278 ◽  
Author(s):  
Robert B. Lessard ◽  
Ray Hilborn ◽  
Brandon E. Chasco
Keyword(s):  
Life History ◽  
Sockeye Salmon ◽  
Model Estimate ◽  
Policy Variable ◽  
Optimal Harvest ◽  
Spawning Stock ◽  
Maximum Sustained Yield ◽  
History Of ◽  
Stock Recruitment

We compare life-history models with the Beverton–Holt approach of escapement goal analysis. We model the life history of a sockeye salmon ( Onchorhynchus nerka ) population from a spawning stage, through juvenile and adult stages, and ending with adults that return to spawn. We fit models to data by statistically comparing predicted and observed numbers of four dominant adult ages. Posterior estimates of parameters from Markov chain Monte Carlo simulations are then used to assess optimal harvest policies. We search for policies that produce the highest average yield. We find that it is possible to detect density dependence with a life-history model where analysis of Beverton–Holt stock–recruitment relationship fails to do so. We find that Beverton–Holt relationships produce policies and long-term yield estimates that are inconsistent with empirical trends. Conversely, we find that optimal spawning stock sizes and maximum sustained yield estimates using the life-history model estimate are consistent with the historical behavior of fisheries examined. Adding smolt data to the analysis does not substantially change predicted optimal spawning stock size, but decreases the variance in estimated posterior parameter distributions and policy variable distributions.

Root life history of non-dehiscent sesame (Sesamum indicum L.) cultivars and the relationship with canopy development

2019 ◽  
Vol 241 ◽  
pp. 107560 ◽  
Author(s):  
Romain M. Gloaguen ◽  
Annie Couch ◽  
Diane L. Rowland ◽  
Jerry Bennett ◽  
George Hochmuth ◽  
...  
Keyword(s):  
Life History ◽  
Sesamum Indicum ◽  
Canopy Development ◽  
History Of ◽  
The Relationship

Chromosome cycle in the gregarine Stylocephalus mesomorphi Dev.

Parasitology ◽  
1966 ◽  
Vol 56 (2) ◽  
pp. 199-208
Author(s):  
R. N. Desai
Keyword(s):  
Life History ◽  
Chromosome Number ◽  
The Other ◽  
Medium Size ◽  
Mitotic Chromosomes ◽  
Zygote Nucleus ◽  
Entire Life ◽  
Science College ◽  
History Of ◽  
Zoology Department

The gregarine Stylocephalus mesomorphi has a diploid chromosome number of 8. The diploid stage is represented only by the zygote nucleus before the metagamic divisions start. The other stages in the entire life history of this gregarine are haploid.The mitotic chromosomes are four in number, one being the longest, two of medium size and the fourth the smallest.I am grateful to Professor J. C. Uttangi, Head of the Zoology Department, Karnatak Science College, Dharwar, for the encouragement he gave me throughout this work. I am also greatly indebted to my colleague Dr M. J. Devadhar, for having given me many valuable suggestions.

Bone microstructure: quantifying bone vascular orientation

2007 ◽  
Vol 85 (1) ◽  
pp. 63-70 ◽  
Author(s):  
M. de Boef ◽  
H.C.E. Larsson
Keyword(s):  
Life History ◽  
Bone Microstructure ◽  
Quantitative Approach ◽  
Three Dimensions ◽  
History Of ◽  
Primary Bone ◽  
Novel Methods ◽  
Radial Index ◽  
The Relationship ◽  
Nonlinear Pattern

Bone microstructure often preserves a temporal record of the life history of the animal to which it belongs. Previously used bone microstructure metrics to differentiate between primary bone types are reviewed and tested with a broad sample of bone types. Two new metrics, the radial index and the longitudinal index, are developed to quantitatively differentiate bone types based on bone vascular orientation in three dimensions. All previously used metrics described the bone microstructure in a nonlinear pattern and were unable to separate bone types satisfactorily. The radial index and longitudinal index effectively differentiated bone types and described bone microstructure within a linear continuum. The continuous nature of the range of vascular orientation in bone microstructure necessitates a quantitative approach rather than the commonly used qualitative classifications. The radial index and longitudinal index, which objectively detect small differences in vascular orientation in three dimensions, are therefore preferable to other metrics for inter- and intra-specific comparisons of bone microstructure. These metrics offer novel methods to facilitate examinations of the relationship between primary bone type and ontogeny, biomechanics, and phylogeny.

The effect of adaptive change in the prey on the dynamics of an exploited predator population

2005 ◽  
Vol 62 (4) ◽  
pp. 758-766 ◽  
Author(s):  
Peter A Abrams ◽  
Hiroyuki Matsuda
Keyword(s):  
Prey Species ◽  
Maximum Size ◽  
Reproductive Rate ◽  
Small Range ◽  
Predator Population ◽  
Predator Species ◽  
Harvest Rate ◽  
Stock Size ◽  
Risk Of Predation ◽  
The Relationship

Mathematical models examine the relationship between harvesting effort and stock size for a predator species when the prey adapts to the risk of predation. In one set of models, the prey can increase its own reproductive rate if it increases its vulnerability to the predator. In the second set of models, each of two prey species has fixed characteristics, but changes in the average characteristics within the prey trophic level occur via shifts in the relative abundance of the two species. In both models, the equilibrium predator population can increase as harvest of that species increases. In the case of two-prey models, the predator's equilibrium population always increases with an increased harvest rate if the two prey coexist and share a single resource. The predator's equilibrium population often decreases from its maximum size to zero over a very small range of harvest rates, once those rates become high enough. Because increased stock size is often used to justify increased harvest rates, this relationship poses a risk that harvest rate will increase to the point where the stock quickly collapses. The results are relevant to understanding changes in the population size of a species experiencing declining environmental conditions.

scholarly journals Calculation of LTC Premiums Based on Direct Estimates of Transition Probabilities

2005 ◽  
Vol 35 (02) ◽  
pp. 455-469 ◽  
Author(s):  
Florian Helms ◽  
Claudia Czado ◽  
Susanne Gschlößl
Keyword(s):  
Life History ◽  
Generalized Estimating Equations ◽  
Transition Matrix ◽  
Transition Probabilities ◽  
State Model ◽  
Link Function ◽  
History Of ◽  
The Relationship ◽  
Pseudo Values ◽  
Almost Unbiased

In this paper we model the life-history of LTC-patients using a Markovian multi-state model in order to calculate premiums for a given LTC-plan. Instead of estimating the transition intensities in this model we use the approach suggested by Andersen et al. (2003) for a direct estimation of the transition probabilities. Based on the Aalen-Johansen estimator, an almost unbiased estimator for the transition matrix of a Markovian multi-state model, we calculate so-called pseudo-values, known from Jackknife methods. Further, we assume that the relationship between these pseudo-values and the covariates of our data are given by a GLM with the logit as link-function. Since the GLMs do not allow for correlation between successive observations we use instead the “Generalized Estimating Equations” (GEEs) to estimate the parameters of our regression model. The approach is illustrated using a representative sample from a German LTC portfolio.

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