• 수산경영론집
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• 제49권4호
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• pp.19-36
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• 2018

Overstock in aquaculture is a matter of concern in aquaculture management. To sort fish based on fingerling size in case of overstocking is an important problem in aquaculture farm. This study aims to determine the amount of fry overstock and sorting time in aquaculture farm. This study builds a mathematical model that finds the value of decision variables to optimize objective function summing up the fingerling purchasing cost, aquaculture farm operating cost and feeding cost under mortality and farming period constraints. The proposed mathematical model involves following biological and economical variables and coefficients: (1) number of fingerlings, (2) sorting time, (3) fish growth rate and variation, (4) mortality, (5) price of a fry (6) feeding cost, and (7) possible sorting periods. Numerical simulation is presented herein. The objective of numerical simulation is to provide decision makers to analyse and comprehend the proposed model. When extensive biological data about growth function of fry becomes available, the proposed model can be widely applicable to real aquaculture farms.

• Fisheries and Aquatic Sciences
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• 제22권12호
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• pp.31.1-31.12
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• 2019

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student's t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9-11.5 cm total length and 1.0-27.3 g for Nakwa Lagoon and 5.6-12.8 cm total length and 3.2-29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03 mm per day to 0.01-0.02 mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.

• 수산경영론집
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• 제48권3호
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• pp.47-59
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• 2017

Fish mortality is the most important success factor in aquaculture management. To order fingerlings considering the effect of mortality is a important problem in aquaculture farm. This study is aimed to decision the number and size of fry in aquaculture farm. This study build the mathematical model that finds the value of decision variable to minimize total cost that sums up the fingerling purchasing cost, aquaculture farm operating cost and feeding cost under mortality constraint. The proposed mathematical model involve biological and economical variables: (1) number of fingerlings (2) fish growth rate (3) mortality (4) price of a fry (5) feeding cost, and (6) possible order period. Numerical simulation model presented here in. The objective of numerical simulation is to provide for decision makers to analyse and comprehend the proposed model. When extensive biological and cost data become available, the proposed model can be widely applied to yield more accurate results.

• 수산경영론집
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• 제47권4호
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• pp.1-13
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• 2016

Fish mortality is the most important success factor in aquaculture management. To analyze the effect of mortality considering biological and economic condition is a important problem in land-based aquaculture. This study is aimed to analyze the effect of mortality for duration of cultivation in land-based aquaculture. This study builds the mathematical model that finds the value of decision variable to minimize cost that sums up the water pool usage cost, sorting cost, fingerling cost and feeding cost under critical standing corp constraint. The proposed mathematical model involves many aspects, both biological and economical: (1) number of fingerlings (2) timing and number of batch splitting event, based on (3) fish growth rate, (4) mortality, and (5) several farming expense. Numerical simulation model presented here in. The objective of numerical simulation is to provide for decision makers to analyse and comprehend the proposed model. When extensive biological and cost data become available, the proposed model can be widely applied to yield more accurate results.

• Journal of applied mathematics & informatics
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• 제6권1호
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• pp.127-142
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• 1999

This paper develops a methematical model for growth and exploitation of a schooling fish species using a realistic catch-rate function and imposing a tax on the catch to control harvesting. Fishing effort is assumed to depend on the net revenue. The steady states of the system are determined and their local and global stabil-ity are discussed. Taking the tax as a control variable; the optimal harvest policy is formulated and solved as a control problem. The results are illustrated with the help of a numerical example.

• 한국어병학회지
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• 제15권1호
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• pp.37-42
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• 2002

Effect of mercury (Hg) toxicity on survival, growth, feed efficiency and oxygen consumption were examined in the juvenile olive flounder. Paralichthys olivaceus. Fishes were exposed to sublethal concentrations of Hg ranging from 0 to 0.13mg/L for 6 weeks. Hg reduced survival rate in a concentration and exposure period-dependent way and suddenly reduction occurred at Hg concentrations greater than 0.05mg/L after 6 weeks. Growth rate and feed efficiency also significantly decreased at greater than 0.028 and 0.05 mg/L respectively. Oxygen consumption rate was significantly decreased to 25 and 32% than that of the control at the Hg concentration of 0.05 and 0.13 mg/L respectively. These results suggest that Hg toxicity inhibit physiological function including growth, feed efficiency and oxygen consumption in the juvenile olive flounder, resulting in survival failure at high concentration.

• ALGAE
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• 제22권3호
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• pp.235-240
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• 2007

The red tide-causing flagellate Chattonella anticfua can cause mass fish kills by their clogging in fish gills. Thisstudy examined the nutrient requirements of C. antiqua isolated from Korea. C. anticfua displayed maximum growthat the day five, followed by a decrease in cell density. Nitrate and nitrite were the preferred nitrogen sources, alonewith adenosine diphosphate for phosphorus compounds. In medium that contained ammonium, a significantdecrease in cell density was observed. Half-saturation constants, Ks, calculated from the maximum growth ratewere 4.94 U|M for NC>3 and 0.79 flM for P04. The growth of C. antiqua was not within the function of the N:P ratio (RU= 0.29). With an N:P ratio as low as 10, the increase in cell density was apparent, with a higher division rate. At lev-els above 50 fiM of NaNOg or 8 ;uM of NaHUPCU, the growth rates were somewhat decreased. Phosphate was thelimiting factor for C. antiqua growth since the starvation of phosphate had brought about a rapid decrease in celldensity in semi-continuous culture. Studies about the temporal modification of the efficiency of nitrate or phosphateuptake may be necessary to explain the bloom dynamics of C. antiaua.

• 자원ㆍ환경경제연구
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• 제13권4호
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• pp.717-734
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• 2004

본 연구는 생물경제학(bioeconomics)분석에 있어서 중요한 위치를 차지하는 생물학적 성장모델에 대한 계량적 접근을 시도하였다. 세계적으로 어류에 관한 생물학적 성장모델은 여러 연구자들에 의해 추정된 바 있으나, 갑각류나 패류와 관련된 적정 성장함수의 추정은 어류에 비해 크게 연구되어 있지 않은 실정이다. 이에 몇몇 연구자들에 의해 사용된 공통된 성장함수들(Linear, Log reciprocal, Double log, Polynomial, Linear with Interactions)을 생산방식과 지역별 환경요인을 감안하여 한국 참가리비(Patinopecten yessoensis)의 성장을 추정하는 데 응용해 보았으며, 가장 적절한 모델은 계량적 분석을 통하여 도출하였다. 분석결과 Log reciprocal 형태의 성장함수가 참가리비류에 가장 적합한 모델로 선정되었으며, 본 결과는 경영자의 최적 생산시기를 결정하는 데 이용되는 생물경제학 모델에 유용하게 응용될 수 있을 것으로 사료된다.

• 한국산학기술학회논문지
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• 제22권4호
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• pp.312-320
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• 2021

본 연구는 치어 돌가자미(Kareius bicoloratus) 성장에 도움을 줄 수 있는 사료첨가물 개발을 위해 갈색거저리유충 분말배지(5 %)에 어병 항균 기능을 가지는 유산균을 발효 한 후, 사료첨가물로써의 효능을 실험하였다. 어류 병원체(비브리오균, 연쇄상구균)에 대한 항균기능을 가진 유산균(LAB; L. plantarum, W. paramesenteroides, P. acidilactici)으로 발효한 갈색거저리 추출 발효물의 양어 성장 실증실험을 위해 총 600 마리의 치어 돌가자미(약 5~6 g)를 공시하여 100마리씩 수조 6개에 임의 배치한 후 각 3수조씩 대조군과 실험군으로 분류하여 6주간 평균 전장과 체중을 측정하였다. 6주 후에 대조군의 전장 평균은 8.26 cm, 실험군은 8.42 cm이며, 대조군의 체중 평균은 19.71 g, 실험군은 20.28 g으로 HeTm_LpWpPa 첨가에 있어 성장효과가 증대됨을 확인하였다. 6주간의 증체율은 대조군 223.26 %, 실험군 248.76 %로 HeTm_LpWpPa 첨가군이 25.5 %p 성장효과가 높고, 6주 동안의 일간성장률은 대조군 2.79 %/일, 실험군 2.98 %/일로 실험군이 0.19 %p 더 높았다. 또한 평균 체중 이하의 개체 수에 있어서도 3주째에는 대조군 27마리(9 %), 실험군 9마리(3 %)이고, 6주째에는 대조군 17마리(5.7 %), 실험군 3마리(1 %)로 실험군에서는 평균 체중 이하가 1 %로 균일한 성장 효과가 있었다. 이들 결과는 동애등에 유충 추출 유산균 발효물(HeTm_LpWpPa) 사료 첨가물의 10 % 내외까지 사용은 돌가자미를 포함하는 양어 치어의 성장 촉진에 유효할 것을 시사한다.

• 한국어류학회지
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• 제18권1호
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• pp.45-54
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• 2006

본 연구는 우리나라 주요 어종 중의 하나인 참조기의 이석을 이용하여 최근 어획되는 참조기의 연령과 성장을 추정하였다. 연구에 사용된 참조기의 이석은 제주도 근해에서 쌍끌이기선저인망어업에 의해 어획된 것으로 2002년 3월부터 12월 자료와 2005년 1, 2월 자료이다. 사용된 개체수는 1,175미였고, 연령사정에 이용된 개체수는 506미였다. 체장의 범위는 16.3~26.9 cm였으며, 연령은 수컷이 7세, 암컷이 8세까지 나타났다. 참조기의 전중 (Body Weight)와 체장 (Total Length)의 관계는 $BW=0.0044TL^{3.2502}$ ($R^2=0.97$)이었고, 암 수별로 체장에 대한 전중의 차이가 있었다(P<0.05). 참조기의 연령에 대한 체장 자료의 오차구조를 확인한 결과 합의 오차구조를 가지고 있었으며, 참조기의 성장식은 von Bertalanffy model을 사용하여 추정하였다. 비직선회귀 (non-linear regression) 방법을 이용하여 추정한 참조기의 성장식은 TL=33.88 ($1-e^{-0.20\;(t+2.39)}$ ($R^2=0.77$)이었다. 암 수간의 연령에 대한 체장의 상대성장에는 차이가 없는 것으로 나타났다(P>0.05).