• Environmental and Resource Economics Review
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• v.19 no.4
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• pp.771-804
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• 2010

This paper estimates optimal production of fish stock using discrete time bio-economic model to make zero profits or to maximize economic profits with maintaining sustainable resource levels under an open access and a sole owner. Particularly, this study generates optimal yields and efforts of large purse seine fisheries which catch mackerel and jack mackerel by using the logistic growth function, Cobb-Douglas production function, fisheries cost and profit functions. As a result, optimal yields of mackerel and jack mackerel under ecological equilibrium of a sole owner were approximately 172,512 tons and 16,937 tons respectively. Also, optimal fishing efforts of mackerel and jack mackerel under the same situation were about 8,508 hauls and 4,915 hauls respectively. In conclusion, the paper suggests that the large purse seine should reduce fishing efforts and increase fish stock to generate higher net present value in optimally managed fishery than that of the present large purse seine.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.47-60
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• 1975

For the calculation of population parameter and estimation of recruitment of a fish population, an application of multiple regression method was used with some statistical inferences. Then, the differences between the calculated values and the true parameters were discussed. In addition, this method criticized by applying it to the statistical data of a population of bigeye tuna, Thunnus obesus of the Indian Ocean. The method was also applied to the available data of a population of Pacific saury, Cololabis saira, to estimate its recuitments. A stock at t year and t+1 year is, $N_{0,\;t+1}=N_{0,\;t}(1-m_t)-C_t+R_{t+1}$ where $N_0$ is the initial number of fish in a given year; C, number o: fish caught; R, number of recruitment; and M, rate of natural mortality. The foregoing equation is $$\phi_{t+1}=\frac{(1-\varrho^{-z}{t+1})Z_t}{(1-\varrho^{-z}t)Z_{t+1}}-\frac{1-\varrho^{-z}t+1}{Z_{t+1}}\phi_t-a'\frac{1-\varrho^{-z}t+1}{Z_{t+1}}C_t+a'\frac{1-\varrho^{-z}t+1}{Z_{t+1}}R_{t+1}......(1)$$ where $\phi$ is CPUE; a', CPUE $(\phi)$ to average stock $(\bar{N})$ in number; Z, total mortality coefficient; and M, natural mortality coefficient. In the equation (1) , the term $(1-\varrho^{-z}t+1)/Z_{t+1}$s almost constant to the variation of effort (X) there fore coefficients $\phi$ and $C_t$, can be calculated, when R is a constant, by applying the method of multiple regression, where $\phi_{t+1}$ is a dependent variable; $\phi_t$ and $C_t$ are independent variables. The values of Mand a' are calculated from the coefficients of $\phi_t$ and $C_t$; and total mortality coefficient (Z), where Z is a'X+M. By substituting M, a', $Z_t$, and $Z_{t+1}$ to the equation (1) recruitment $(R_{t+1})$ can be calculated. In this precess $\phi$ can be substituted by index of stock in number (N'). This operational procedures of the method of multiple regression can be applicable to the data which satisfy the above assumptions, even though the data were collected from any chosen year with similar recruitments, though it were not collected from the consecutive years. Under the condition of varying effort the data with such variation can be treated effectively by this method. The calculated values of M and a' include some deviation from the population parameters. Therefore, the estimated recruitment (R) is a relative value instead of all absolute one. This method of multiple regression is also applicable to the stock density and yield in weight instead of in number. For the data of the bigeye tuna of the Indian Ocean, the values of estimated recruitment (R) calculated from the parameter which is obtained by the present multiple regression method is proportional with an identical fluctuation pattern to the values of those derived from the parameters M and a', which were calculated by Suda (1970) for the same data. Estimated recruitments of Pacific saury of the eastern coast of Korea were calculated by the present multiple regression method. Not only spring recruitment $(1965\~1974)$ but also fall recruitment $(1964\~1973)$ was found to fluctuate in accordance with the fluctuations of stock densities (CPUE) of the same spring and fall, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.7 no.3
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• pp.105-114
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• 1974

Identification and change of microflora during the fermentation of anchovy Engraulis japonica, under the halophilic circumstance were investigated. The change of salinity and pH in meat and juice which decide the environment for microorganism and decomposition of nitrogenous compound which functions as a nutrient source were also discussed by measuring the content of total-N, amino-N, nonprotein-N, TMA and VBN, The fresh anchovy was mixed with rock salt (20 percent w/w) and stocked for six months. Through the fermentation lag phase of viable cells extended for 20 days that was obviously larger compared with other circumstances, hereafter increased to reach the maximum value of $5\times10^4$ total count per gram at 35 day stock. The stationary phase proceeded for 25 days. 540 strains were isolated and among them 11 genus of bacteria, 3 genus of yeasts, were identified and other 2 yeast strains of unidentified. At the initial stage of fermentation, Pseudomonas, and Helobacterium prevalently grew, at the middle stage, they disappeared rapidly and Pediococcus and yeasts completely dominated, where they are assumed to get directly involved with fermentation of fish, The PH value tended to decrease in the progress of fermentation and at 100 day stock it showed the minimum value of 5.5 to 5.6 in both meat and juice. The highest salinity of meat decreased to 18 percent, while in juice it decreased to 28 percent since 50 days stock. The content of total-N in meat gradually decreased to 2.8 percent, while in juice it increased to 2.3 percent at 100 day stock, However nonprotein-N was 1.8 percent and amino-N was 1.1 Percent. Since 100 days stock, the increasing rate of amino-M is too low it could be judged to entered the final stage of fermentation, In the first 20 days stock, the increase of VBN and TMA can be explained by the growth of putrefactive bacteria such as pseudomonas on the meat before salts penetrate into the fish meat, while reincrement after 100 days stock, is explained by decomposition of free amino acid due to the reactions of bacteria and enzymes.

• Ocean and Polar Research
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• v.41 no.4
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• pp.233-250
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• 2019

A re-assessment of the age structure of the population of the Antarctic icefish Pseudochaenichthys georgianus based on body length data covering the years 1976-2009 and including larvae and postlarvae collected in 1989 and 1990 allowed us to define age groups 0, I, and II as containing fish with respective body lengths of 6-9 cm, 15-27 cm and 27-39 cm. Age at maturity (first spawning) was found to occur in age group III at body lengths that have been falling from 50.1 cm in 1979 to 45.4 cm in 1992. Considering postlarvae together with adult fish, the v. Bertalanffy growth curve parameters were determined as L_∞ = 60.62 cm, k = 0.4, t₀ = 0.25. Although the reasons for a maturity at shorter body lengths is not fully understood a host of environmental factors like increasing water temperatures and possibly changes in currents, interspecific competition, food availability, etc. are likely to be involved. Global warming (and not primarily overfishing) is likely to have been responsible for the disappearance of larger fish in the surface waters of South Georgia since 1977, for virtually all commercial fishing stopped in the early 1990s. On the other hand, the appearance of numerous younger spawning individuals suggests that larvae do survive in the colder deeper water below 200 m. The biomass of Ps. georgianus oscillates with a 4-year periodicity in contrast to that of the coexisting icefish Chaenocephalus aceratus: the former with a lower biomass in warm years and a higher one in cold years. The biomass of the third species of icefish in the region, i.e. Champsocephalus gunnari, also oscillates, but with a longer periodicity than that involved in the biology of the other two and its biomass increases in contrast to the other two species. The result is that the biomass all three species considered together is rather stable.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.1
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• pp.53-73
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• 2007

There exists historically intimate relationship between the fisheries of the three countries of Northeast Asia in terms of the same fishing ground and similar resources. This means that if one of the countries fail to manage their fisheries properly, it will harm the others. Especially, if the EEZ straddling and Trans-Boundary Fish Stocks aren't managed by the cooperation of the three countries, the exhaustion of resources will be more likely to be accelerated. Considering the aspects mentioned, this paper refers to the necessity of fisheries cooperation between Korea, China, and Japan. Next, it analyzed the joint control cases of Norway/Russia Management of Shared Fish Stocks in the Barents Sea, Management of South Tasman Rise in Orange roughy, Agreement on Fisheries between the European Economic Community and the Kingdom of Norway, Conservation and management of pollack resources in the central Bering Sea, and drew a conclusion for ourselves. Last of all, it suggests a step-by-step strategy of promoting joint control between three countries, and the plan of the establishing and managing the organization of joint fisheries control. About the joint control, "The Joint Statement of promoting collaboration between Korea, China, and Japan" has been announced at ASEAN in October 7th, 2003 and the summit talk of the three countries. In the joint statement, the three countries came to an agreement which says, "Cooperation in Fishery Resource Conservation : The three countries will cooperate, bilaterally or trilaterally, to promote the sustainable use and conservation of fishery resource through the effective fishery management". Not only the consistent collaboration between the government is necessary, but also continuous exchange and related study on a Non-governmental level is also needed for the viable outcome in the near future. When deducting the result for the joint fisheries control, this writer hopes the contents of this study will be helpful.

• Fisheries and Aquatic Sciences
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• v.26 no.9
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• pp.569-581
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• 2023

The morphology and genetic identification of Rasbora lateristriata and Rasbora argyrotaenia between cultivated and wild populations has never been reported. This study compares morphology and cytochrome c oxidase (COI) genes between farmed and wild stock Rasbora spp. in Java and Sumatra island, Indonesia. We analyzed the truss network measurement (TNM) characters of 80 fish using discriminant function analysis statistical tests. DNA was extracted from muscle tissue of 24 fish specimens, which was then followed by polymerase chain reaction, sequencing, phylogenetic analysis, fixation index analysis, and statistical analysis of haplotype networks. Basic Local Alignment Search Tool analysis validated the following species: R. lateristriata and R. argyrotaenia from farming (Jogjakarta); Rasbora agryotaenia (Purworejo), R. lateristriata (Purworejo and Malang), Rasbora dusonensis (Palembang), and Rasbora einthovenii (Riau) from natural resources. Based on TNM characters, Rasbora spp. were divided into four groups, referring to four distinct characters in the middle of the body. The phylogenetic tree is divided into five clades. The genetic distance between R. argyrotaenia (Jogjakarta) and R. lateristriata (Malang) populations (0.66) was significantly different (p < 0.05). R. lateristriata (Purworejo) has the highest nucleotide diversity (0.43). R. argyrotaenia from Jogjakarta and Purworejo shared the same haplotype. The pattern of gene flow among them results from the two populations' close geographic proximity and environmental effects. R. argyrotaenia had low genetic diversity, therefore, increasing heterozygosity in cultivated populations is necessary to avoid inbreeding. Otherwise, R. lateristriata (Purworejo) had a greater gene variety that could be used to develop breeding. In conclusion, the middle body parts are a distinguishing morphometric character of Rasbora spp., and the COI gene is more heterozygous in the wild population than in farmed fish, therefore, enrichment of genetic variation is required for sustainable Rasbora fish farming.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.563-565
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• 2020

Turbot Scophthalmus maximus can be cultured at a higher density and has a faster growth rate than olive flounder Paralichthys olivaceus, making it an attractive alternative for flounder farmers in Korea. As it is a relatively new species to Korean farming environments, there is no general farming protocol, which takes multiple generations to develop, for turbot in Korea. Nevertheless, we applied breeding technology to develop a stock, which we considered first-generation turbot. Then we compared its growth rate (an important economic trait) to different populations (the original stock of Korean turbot, French turbot, and Chinese turbot). The four different populations were grown in similar culture conditions. First-generation Korean turbots grew about 28% faster than all others. We will continue to select for important traits such as color, disease resistance, and heat tolerance in this turbot broodstock; we believe that with the appropriate selection process, Korean turbot should become competitive in the markets, and will become a major farming species in the Korean aquaculture industry.

• Korean journal of food and cookery science
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• v.18 no.1
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• pp.13-19
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• 2002

This study was performed to develop natural spices using Cheongung (Cnidium officinale) which is one of the Korean medicinal plants, Cnidium of officinale is a perennial plant of the Umbelliferae family and is widely distributed in Korea. The overall acceptances of flavor and color, and the masking effects on meaty and fishy flavor of Cnidium officinale were investigated by sensory evaluation. The overall acceptances of fresh Cnidium officinale were the highest, followed by freeze dried and hot air dried samples. The meaty and fishy flavor of cooked pork and fish were significantly reduced by the addition of fresh, hot air dried and freeze dried Cnidium officinale. Cnidium officinale showed similar or higher masking effects on meaty and fishy flavor compared with black pepper.

• Animal cells and systems
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• v.14 no.1
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• pp.37-44
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• 2010

Black sea bream, Acanthopagrus schlegelii, is a commercially important fish in Korea. As a preliminary investigation into the effect of hatchery rearing for stock enhancement, we examined genetic diversity between wild and farmed black sea bream populations from Jeju using six microsatellite markers. High levels of polymorphism were observed between the two populations. A total of 87 different alleles were found at the loci, with some alleles being unique. Allelic variability ranged from 8 to 22 in the wild population and from 7 to 17 in the farmed one. Average observed and expected heterozygosities were estimated at 0.87 and 0.88 in the wild sample. The corresponding estimates were 0.83 and 0.86 in the farmed sample. Although a considerable loss of rare alleles was observed in the farmed sample, no statistically significant reductions were found in heterozygosity or allelic diversity in the farmed sample, compared with the wild one. Significant genetic heterogeneity was found between the wild and farmed populations. These results suggest that more intensive breeding practices for stock enhancement may have resulted in a further decrease of genetic diversity. Thus, it is necessary to monitor genetic variation in bloodstock, progeny, and target populations and control inbreeding in a commercial breeding program for conservation. This information may be useful for fisheries management and the aquaculture industry.

• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.258-260
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• 2017

The morphomeristic features of Gadus macrocephalus was compared using fish samples from Jinhae Bay in the South Sea and Boryeong in the Yellow Sea, Korea. In total, 332 individuals were sampled from 2 locations to investigate the differences in the morphomeristic features and determine applicability of it as a means of stcok discrimination of G. macrocephalus. No significant differences in the number of vertebrae, 1st to 3rd dorsal-fin soft rays, 1st and 2nd anal-fin soft rays, pectoral-fin soft ray, pelvic-fin soft ray, and gill raker were found between two populations from Jinhae Bay and Boryeong. The results of present study revealed that morphomeristic features of G. macrocephalus was not applicable for stock discrimination.