Optimal harvesting for a population dynamics problem with age-structure and diffusion

2007 ◽  
Vol 25 (1-2) ◽  
pp. 35-50 ◽  
Author(s):  
Zhixue Luo
Keyword(s):  
Population Dynamics ◽  
Age Structure ◽  
Optimal Harvesting ◽  
And Diffusion

Population dynamics of harvested species with complex age structure (for Pacific salmons fish stocks as an example)

2006 ◽  
Vol 198 (3-4) ◽  
pp. 463-472 ◽  
Author(s):  
E.Ya. Frisman ◽  
E.V. Last ◽  
E.I. Skaletskaya
Keyword(s):  
Population Dynamics ◽  
Age Structure ◽  
Fish Stocks

OPTIMAL CONTROL FOR A NONLINEAR n-DIMENSIONAL COMPETING SYSTEM WITH AGE-STRUCTURE

2012 ◽  
Vol 05 (03) ◽  
pp. 1260008 ◽  
Author(s):  
ZHI-XUE LUO ◽  
JIAN-YU YANG ◽  
YA-JUAN LUO
Keyword(s):  
Optimal Control ◽  
Age Structure ◽  
Normal Cone ◽  
Equation System ◽  
Optimal Harvesting ◽  
Order Partial Differential Equation ◽  
Differential Equation System ◽  
Optimal Control Strategy ◽  
First Order

This paper is concerned with optimal harvesting control of a first order partial differential equation system representing a nonlinear n-dimensional competitive population model with age-structure. By the Ekeland's variational principle, the existence and unique characterization of the optimal control strategy are established. The optimality conditions for the control problem are obtained by the concept of the normal cone.

Optimal harvesting for periodic age-dependent population dynamics with logistic term

2009 ◽  
Vol 215 (7) ◽  
pp. 2701-2715 ◽  
Author(s):  
Laura-Iulia Aniţa ◽  
Sebastian Aniţa ◽  
Viorel Arnăutu
Keyword(s):  
Population Dynamics ◽  
Optimal Harvesting ◽  
Age Dependent

scholarly journals Optimal harvesting for nonlinear age-dependent population dynamics

2006 ◽  
Vol 43 (3-4) ◽  
pp. 310-319 ◽  
Author(s):  
Chun Zhao ◽  
Ping Zhao ◽  
Mian-Sen Wang
Keyword(s):  
Population Dynamics ◽  
Optimal Harvesting ◽  
Age Dependent

scholarly journals A fish for all seasons: Spatial and temporal variation in patterns of demographic heterogeneity for Retropinna retropinna

2021 ◽  
Author(s):  
◽  
Christopher McDowall
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
New Zealand ◽  
Age Structure ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Environmental Variation ◽  
Life Cycles ◽  
Demographic Heterogeneity ◽  
Demographic Attributes

<p>Demographic heterogeneity can have big effects on population dynamics, but for most species we have limited understanding of how and why individuals vary. Variation among individuals is of particular importance for stage-structured populations, and/or where species have ‘complex life-cycles’. This is especially relevant in the case of amphidromous fishes that typically spawn in river mouths and estuaries, develop at sea and return to freshwater to finish development. These fish face strong selection pressures as they negotiate challenges around dispersal and development in order to reproduce successfully. Quantifying variation amongst individual fish can improve understanding of their population dynamics and suggest possible drivers of variation.  I evaluate patterns and sources of variation in demographic attributes of the New Zealand smelt (Retropinna retropinna). R. retropinna is an amphidromous fish that is endemic to New Zealand. While most populations have a sea-going larval stage, a number of landlocked freshwater populations occur, with the largest landlocked population residing in Lake Taupo. Here R. retropinna are presented with a variety of littoral feeding/spawning habitats and environmental conditions that may vary across distinct regions of the lake. In addition, the protracted spawning period for this species in Lake Taupo (occurring over eight months of the year) provides additional scope for seasonal variation to influence demographic attributes of individuals.  I sampled R. retropinna from discrete coastal habitats (beach or river) that were located in the eastern, southern and western regions of the lake. I evaluated patterns of variation in the size-structure, age-structure and morphology of R. retropinna among habitats and/or regions across Lake Taupo. I used otoliths to reconstruct demographic histories (ages, growth rates, hatch dates) of individuals, and used a set of statistical models to infer spatial variation in demographic histories. I found differences in size and age structure between regions, and a temporal effect of hatch date on larval/juvenile growth rates.  In addition, I obtained samples of R. retropinna from a sea-going population at the Hutt river mouth (sampled fish were presumed to be migrating upstream after their development period in Wellington Harbour and/or adjacent coastal environments). While Lake Taupo is large, deep, fresh, oligotrophic and strongly stratified for 8-9 months outside of winter, Wellington Harbour is less than a sixth of the area, shallow, saline, eutrophic and never stratified. These greatly differing environmental conditions led me to expect that these systems’ R. retropinna populations would carry significantly different demographic attributes. I compared the hatching phenology, recruitment age, body morphology, and individual growth histories (reconstructed from otoliths) of R. retropinna sampled from Lake Taupo and Wellington Harbour. I explored the relationships between demographic variation and environmental variation (water temperature, chlorophyll a) for the two systems and found that this additional environmental information could account for much of the seasonal variation in daily otolith increment widths of R. retropinna. My results also suggest that while the two sampled populations likely share similar hatching and spawning phenologies, individuals from Lake Taupo tend to grow more slowly, particularly during winter, and end up smaller than sea-going fish sampled near Wellington. I speculate that these differences reflect variation in food supply (zooplankton may be limited in Lake Taupo over winter).  Overall, my results demonstrate a high degree of variation in morphological and life-history traits within a single species, potentially driven by an interaction between environmental variation and timing of development. My work contributes to a growing body of literature on demographic heterogeneity, and may help to inform the management of landlocked populations of R. retropinna in Lake Taupo.</p>

Insular Biogeographic Theory and Diffusion Models in Population Dynamics

1994 ◽  
Vol 45 (2) ◽  
pp. 177-202 ◽  
Author(s):  
R.S. Cantrell ◽  
C. Cosner
Keyword(s):  
Population Dynamics ◽  
Diffusion Models ◽  
And Diffusion

Dynamic modes of exploited limited population: results of modeling and numerical study

2016 ◽  
Vol 11 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Г.П. Неверова ◽  
G.P. Neverova
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Population Size ◽  
Age Structure ◽  
Birth Rate ◽  
Numerical Study ◽  
Dynamic Regime ◽  
Demographic Parameters ◽  
Current Population

The paper investigates the model of population dynamics with age structure and density dependence of birth rate. We consider two situations: 1) the population develops freely and 2) the population is exploited. It was shown that harvesting leads to the stabilization of the dynamics. There is multiregimism, i.e. different dynamic regimes are possible with the same values of demographic parameters. It is shown that even a single harvesting in the current population size could lead to a change of the observed dynamic regime.

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