• Title/Summary/Keyword: Population dynamic

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Duality in an Optimal Harvesting Problem by a Nonlinear Age-Spatial Structured Population Dynamic System

  • Kim, Yong-Kuk;Lee, Mi-Jin;Jung, Il-Hyo
    • Kyungpook Mathematical Journal
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    • v.51 no.4
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    • pp.353-364
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    • 2011
  • Duality in the optimal harvesting for a nonlinear age-spatial structured population dynamic model is studied in the framework of optimal control problem. In this paper the duality theory that displays the conjugacy of the primal problem is established and an application is given. Duality theory plays an important role in both optimization theory and methodology and the results may be applied to a realistic biological system on the point of optimal harvesting.

A Quantative Population Dynamic Model for Estimating Damages in Fishery Production in the Benthic Ecosystem of Abalone Culture Grounds (전복양식장 저서생태계의 훼손으로 인한 어업자원의 생산감소량 추정 모델)

  • KANG Yong Joo;ZHANG Chang Ik
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.36 no.4
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    • pp.409-416
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    • 2003
  • Marine populations are maintained through the processes of spawning, growth, recruitment, natural death and fishing in a marine ecosystem. Based upon each of these processes, a quantitative population dynamic model was developed to estimate damages in fishery production due to accidents in a fishing ground. This model was applied for the abalone culture grounds in Korean waters. Three components of damages were identified in the ecosystem of the abalone culture grounds, namely, physical damages in the substratum of the fishing ground, biological damages in the structure and function of the ecosystem, and damages in fishery production. Considering these three components the processes and durations of damages in fishery production were determined. Because the abalone population is composed of multiple year classes, damages influence all the year classes in the population, when they occur The model developed in this study is: $$y=(n_{\lambda}+1){\times}Y_E\;-\;\sum\limits^{n_\lambda-n_c}_{l=0}\;y_{n_c/i}$$ where, y is the expected damages in fishery production during the period of restoration of the damaged abalony population, $Y_E$ is the annual equilibrium yield, $n_{\lambda}$ is the maximum age in the population, $t_s$ is the year of damage occurrence, $n_c$ is the age at recruitment, and $\sum\limits^{n_\lambda-n_c}_{l=0}\;y\;_{n_c/i}$ is total expected lifetime catch of year classes which were recruited during the restoration period.

Development of Western Cherry Fruit Fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), after Overwintering in the Pacific North West Area of USA (미국 북서부지역에 발생하는 서부양벚과실파리의 발생 월동 후 발생 동태에 관한 연구)

  • Song, Yoo-Han;Ahn, Kwang-Bok
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.9 no.4
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    • pp.217-227
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    • 2007
  • The western cherry fruit fly, Rhagoletis indifferens Curran (Diptera:Tephritidae), is the most important pest of cultivated cherries in the Pacific Northwest area of the United States, being widely distributed throughout Oregon, Washington, Montana, Utah, Idaho, Colorado and parts of Nevada. The control of R. indifferens has been based on calendar sprays after its first emergence because of their zero tolerance for quarantine. Therefore, a good prediction model is needed for the spray timing. This study was conducted to obtain the empirical population dynamic information of R. indifferens after overwintering in the major cherry growing area of the Pacific Northwest of the United States, where the information is critically needed to develop and validate the prediction model of the fruit fly. Adult fly populations were monitored by using yellow sticky and emergence traps. Larvae growth and density in fruits were observed by fruit sampling and the pupal growth and density were monitored by pupal collection traps. The first adult was emerged around mid May and a large number of adults were caught in early June. A fruit had more than one larva from mid June to early July. A large number of pupae were caught in early July. The pupae were collected in various period of time to determine the effect of pupation timing and the soil moisture content during the winter. A series of population density data collected in each of the developmental stage were analyzed and organized to provide more reliable validation information for the population dynamic models.

Weed Population Dynamic in Orchard and Their Control by Sequential Application of Oxyfluorfen (과수원(果樹園)의 잡초발생(雜草發生) 동태(動態)와 Oxyfluorfen의 처리시기별(処理時期別) 방제효과(防除效果))

  • Kim, Kil Ung;Kwon, Soon Tae;Choi, Dae Ung;Lee, Sang Back;Kim, Dong Kyun
    • Current Research on Agriculture and Life Sciences
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    • v.4
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    • pp.22-26
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    • 1986
  • This study was conducted to investigate weed population dynamic in orchard and to establish an appropriate application time for oxyfluorfen. 28 weed species including Persicaria hydropiper was observed to be problem weeds in orchard. P. hydropiper was on single dominant species which increased importance value of 13.7 on May 15 to 60.79 on August 10, followed by Calystegia hederacea, Alopecurus aequalis, Capsella bursa-pastoris, Roripa islandica, Echinochloa crus-galli, Potulaca olearcea, Elusin indica. Simpson's index increase from 0.11 on May 1 to 0.40 of August 10, indicating the dominance of specific weed species. The effective herbicide to control these weeds was oxyfluorfen at 5kg prod./ha applied at pereemergence treatment on March 25, showing more than 90% control for 120 days after application. Preemergence application of oxyfluorfen at 3kg prod./ha on March 25 followed by paraquat 3kg prod./ha applied on June 25 as the foliar application can maintain the clean orchard for a year, showing on of the promising and applicable control system. The most appropriate rate and time for oxyfluorfen seemed to be 5kg prod./ha applied on March 25.

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The avifauna at Chunsoo bay (Seosan A and B area)

  • Cho, Sam-Rae
    • Journal of Environmental Science International
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    • v.12 no.2
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    • pp.163-170
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    • 2003
  • Seosan A, B area is located on 36°42' of north parallel and 126°27' of east longitude. It consisted of broad artificial lakes and reclaimed agricultural lands; there is Ganwalho lake in A area and Bunamho lake in B area. Total birds surveyed four times in 2001 at the A area are 105,580 of 11 orders, 28 families, 89 species. Among them, resident species were 21 species including Pica pica. Twenty species including Cuculus canorus were summer migrants, and 30 species including Platalea leucorodia were winter migrants. Seventeen species including Limosa limosa were occasionally species. And Rostratula benghalensis was an unconfirmed species. Species diversity index (H') was 0.72; species equally common index (e/sup H'/) was 2.06. In January, maximum observed 102,121 individuals. However in July 52 species were observed most variously. There were total 81,152 birds observed with 11 orders, 22 families, and 71 species at the B area. Fifteen species including Falco tinnumculus were resident species. Summer migrants were 18 species including Ixobychus sinensis. Winter migrants were 25 species including Ciconia boyciana. Thirteen species including Tringa glareola were occasionally species. Species diversity index (H') was 0.281; species equally common index (e/sup H'/) was 1.325. In January, maximum observed 78,433 individuals. However in Silly 42 species were observed most variously.

A Bioeconomic Analysis on the Effectiveness of Total Allowable Catch(TAC) Policy under the Rebuilding Plan (자원회복계획 하에서의 총허용어획량(TAC) 어업정책 효과에 관한 생물경제학적 분석 -미국 멕시코만의 Yellowedge Grouper 어업을 사례로-)

  • Kim, Dohoon
    • Environmental and Resource Economics Review
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    • v.12 no.4
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    • pp.663-686
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    • 2003
  • This study is aimed at analyzing the effectiveness of TAC policy using a bioeconomic model. A surplus-production model is used as a population dynamic model, from which the yellowedge grouper is estimated to be overfished. As a result, a 10-year rebuilding plan using the TAC policy is established. According to the result of model, under the well-enforced system, the target stock biomass is achieved during the rebuilding period. Especially, in order to accomplish the target stock biomass, the annual quota should be allocated much less than 342 tons that NMFS recommended. The NPV over a 25-year under the TAC policy Is predicted to be less than under the status quo. The economic gains under the variable-catch TAC policy is less than under the constant-catch TAC policy as the interest rate decreases, while the NPV under the constant-catch is greater than under the variable-catch TAC policy when the interest rate is high.

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A Quantitative Method for Estimating Damages in Fishery Production due to Artificial Environmental Deterioration in the Tidal Flat Fishing Grounds (천해어장에서 인위적 환경훼손에 의한 어업생산 감소량 추정방법)

  • PARK Joo Seok;KANG Yong Joo;ZHANG Chang Ik
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.36 no.4
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    • pp.402-408
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    • 2003
  • A quantitative method was suggested for estimating damages in fishery production due to the diffusion and deposition of suspended silt and clay by various construction processes in tidal flat fishing grounds. Marine populations are maintained through the process of spawning, growth, recruitment, natural death and death by fishing each year. All of the year classes of the population in a fishery ground could be affected when damages occur by human activities such as land filling or reclamation. The propose of this study is to calculate damages in terms of fishery production using a quantitative population dynamic method. If the maximum age in the population is $X_\lambda,$ the starting year of damage is $t_s,$ and the ending year of damage is $t_e,$ the number of year classes damaged is $t_{s-n\lambda}-t_e,$ Many year classes present in the year $t_s,$ and so if damages occur, they Influence all the year classes which are present in the population. Damaged year classes in year $t_e$ would still be in the population until the year $t_{e+n\lambda}$, where $n_{\lambda}$ is the oldest age class. If the expected yield of a year class is constant, the total yield from year classes in the fishing ground during the construction periods can be calculated as follows: $Y_\Phi=[(t_e-t_s+1)+n_c]{\cdot}Y_E+\sum\limits^{n_\lambda-n_c}_{l=1}\;\sum\limits^{n_\lambda-n_c}_{l=i}\;Y_{n_c+i}$ This method was applied for damage estimation in the production of Ruditapes philippinarum in a tidal flat fishing ground.

Biomass estimation of sailfin sandfish, Arctoscopus japonicus, in Korean waters (한국 연근해 도루묵, Arctoscopus japonicus의 자원량 추정)

  • Lee, Sung-Il;Yang, Jae-Hyeong;Yoon, Sang-Chul;Chun, Young-Yull;Kim, Jong-Bin;Cha, Hyung-Kee;Choi, Young-Min
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.42 no.5
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    • pp.487-493
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    • 2009
  • Available ecological and fishery data of sailfin sandfish, Arctoscopus japonicus, was examined to ascertain its population dynamic parameters in Korean waters. The instantaneous coefficient of total mortality (Z) was estimated to be 1.361/yr, and annual survival rate (S) was 0.256. The estimated instantaneous coefficient of natural mortality (M) was 0.482/yr, and the instantaneous coefficient of fishing mortality (F) for recent years was calculated to be 0.879/yr from Z and M values. Age at first capture was estimated to be 1.958 years. These parameters, in conjunction with catch landings data between 1991 and 2008, were used to estimate annual biomass using a biomass-based cohort analysis. The biomass of A. japonicus was estimated at approximately 7,600 mt in 1991, but since 1994 decreased to below 4,000 mt by 2001. After 2002 they started to increase gradually, and showed the level of more than 5,000 mt in recent years.

Analysis of the Effect of Temperature on the Pesticide Efficacy and Simulation of the Change in the Amount of Pesticide Use (온도가 농약효과에 미치는 영향분석 및 농약사용량 예측 모의실험)

  • Mo, Hyoung-ho;Kang, Ju Wan;Cho, Kijong;Bae, Yeon Jae;Lee, Mi-Gyung;Park, Jung-Joon
    • Korean Journal of Environmental Biology
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    • v.34 no.1
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    • pp.56-62
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    • 2016
  • Pest population density models are very important to monitor the initial occurrence and to understand the continuous fluctuation pattern of pest in pest management. This is one of the major issues in agriculture because these predictions make pesticides more effective and environmental impact of pesticides less. In this study, we combined and predicted the mortality change of pest caused by pesticides with temperature change and population dynamic model. Sensitive strain of two-spotted spider mite (Tetranychus urticae Koch) with kidney bean leaf as host was exposed to mixed acaricide, Acrinathrin-Spiromesifen and organotin acaricide, Azocyclotin, at 20, 25, 30, and $35^{\circ}C$, respectively. There was significant difference in mortality of T. urticae among pesticides and temperatures. We used DYMEX to simulate population density of T. urticae and predicted that the initial management time and number of chemical control would be changed in the future with climate change. There would be implications for strategies for pest management and selection process of pesticide in the future corresponding climate change.