• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.6
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• pp.929-939
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• 2015

We studied the characteristics of age and growth of the Goldeyes rockfish Sebasetes thompsoni in the Ulleungdo and Dokdo areas by using 730 otoliths from February 2013 to February 2014. The lowest value of the marginal index was found in June once a year. The spawning period was estimated as April. Therefore, the duration from fertilization to the complete formation of the first annual growth ring is fourteen months. From the parameters calculated using the weighted average length of the year ring formation, the growth of S. thompsoni was demonstrated by the von Bertalanffy growth equation as $L_t=34.68(1-e^{-0.2113(t+0.7683)})$ for females and $L_t=29.79(1-e^{-0.2163(t+1.7964)})$ for males, $L_t=32.84(1-e^{-0.25(t+0.57)})$ for combined sex. Comparing with growth performance index(${\Phi}$) from these 4 offshore areas, parameter of S. thompsoni in Ulleungdo area was 2.4087, that of in Tong-yeong was 2.2835, that of in Aomori was 2.4077 and in Niigata was 2.3927. As a result, the value of Dokdo and Ulleungdo areas showed the highest.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.3
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• pp.377-385
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• 2015

The age and growth of the skipjack tuna Katsuwonus pelamis were determined using otoliths sampled from a Korean tuna purse seine fishery in the Western and Central Pacific Ocean from January 2005 to September 2006. A total of 312 otoliths were used to estimate the ages of skipjack tuna, which ranged from 1 to 7 years. The relationships between otolith ring radius (R) and fork length (FL) for female, male, and sex combined were FL = 19.74R + 1.50 ($r^2=0.54$), FL = 17.66R + 6.35 ($r^2=0.47$), and FL = 18.83R + 3.36 ($r^2=0.53$), respectively. The back-calculated fork lengths of each age ($FL_{year}$) were $FL_1=36.2cm$, $FL_2=43.3cm$, $FL_3=48.3cm$, $FL_4=52.6cm$, $FL_5=56.5cm$, $FL_6=60.8cm$, and $FL_7=63.2cm$. The relationships between fork length (FL) and total weight (TW) for female, male, and sex combined were $TW=0.00001FL^{3.19}(r^2=0.95)$, $TW=0.00001FL^{3.17}(r^2=0.95)$, and $TW=0.000009FL^{3.23}(r^2=0.95)$, respectively. The von Bertalanffy growth parameters of skipjack tuna estimated in this study were $L_{\infty}=77.4cm$, K = 0.176/year, and $t_0=-2.569years$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.1
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• pp.39-44
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• 2014

This study aimed to find an optimal diluent and cryoprotective agent (CPA) during cryopreservation of common Korean bitterling Acheilognathus signifier sperm. The bitterling is an endangered species in Korea, and this study will enable conservation and further technical development of artificial seed production. We tested the effects of cryopreservation and toxicity by the type of diluent and CPA. The optimal combination of diluent and CPA for cryopreservation was 300 mM glucose+10% methanol, resulting in a survival rate and sperm activity index (SAI) of $96.3{\pm}1.5%$, and $3.0{\pm}0.0$ respectively, and no significant difference compared to fresh sperm. The survival rate and SAI of post-thawed sperm was $9.7{\pm}1.5%$, $0.8{\pm}0.3$ respectively, which was significantly higher than had been achieved with other diluents and CPAs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.279-288
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• 2005

The mesh selectivity of drum net traps for Buccinum opisoplectum Dall caught in the eastern sea of Korea was described. Several experiments were conducted between July 2003 and March 2004 and the data obtained from the experiment was fitted by SELECT (Share Each Length class's Catch Total) model with unequal fishing and sampling efforts. The selection curve was determined to be 'estimated fishing efficiency' by model deviance rather than AIC. However the fishing efficiency between 20mm and 35mm mesh size did not seem to be different. The $L_{50}$ lengths of the selectivity for the 55mm and 75mm mesh size were 65.4mm and 96.0mm, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.194-202
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• 2011

Maturation and spawning of the Shotted halibut, Eopsetta grigorjewi was investigated based on the samples captured in South Korean waters from January 2008 to December 2009. Gonadosomatic index began to increase in December, and reached maximum between January to March. After spawning it began to decrease from May. Reproductive season was estimated to January-April, with peak in February. Fecundity was proportional to the size of the female, with the clutch size varying from 170,000 eggs in the smallest female (total length, 28.9cm) to 1,300,000 eggs in the largest (total length, 41.5cm). Size at 50% sexual maturity (TL50), determined from mature females, was 28.8cm. Annual reproductive cycles of this species could be divided into six successive stages; immature stage (May-October), nucleolus stage (November-January), yolk vesicle stage (January-February), vitellogenic and ripe stage (January-April) and spent stage (April-May).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.917-922
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• 2013

Changes in fishing ground of the large pair trawler were investigated by year, month and species off Korean waters. We used catch data by sea-block lat.${\times}$long.:$30^{\prime}{\times}30$) of the National Fisheries Research and Development Institute (NFRDI) and monthly fishing production statistics of Korean statistic information service from 1990 to 2007. In the 1990s, the demersal fish like Larimichthys polyactis, Collichthys sp, Portunus trituberculatus and Muraenesox cinereus were the dominant species, and in the 2000s, they were changed from demersal fish into pelagic fish like Scomberomorus niphonius, Scomber japonicus, Engraulis japonicus and Todarodes pacificus. Species composition of catch showed temporal variation by cluster analysis deviding into 4 period, 1990-1994, 1995-2000, 2001-2003 and 2004-2007. Fishing ground in the 2000s was decreased up to 2/3 in the 1990s, while the density of catch in the fishing ground in 2000s was higher than the 1990s.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.650-655
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• 2019

The age and growth of Muraenesox cinereus collected in the South Sea of Korea by Danish seine and coastal Long-line fisheries were determined from right sagittal otoliths between May 2018 and April 2019. Otoliths of 353 fish were observed under reflected light, and the edges of the opaque zone were considered to be the otolith ring. Monthly changes in the marginal index indicated that rings (opaque zones) were formed once a year from June to July. The estimated von Bertalanffy growth equation with growth parameters estimated from non-linear regression were L_t=138.37 (1-e^{-0.18(t+0.79)}) for females and L_t=99.00 (1-e^{-0.13(t+3.99)}) for males. The oldest female M. cinereus was 12 years old, and the oldest male was 8 years old.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.740-746
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• 2010

This study standardized the catch per unit effort (CPUE) of bigeye tuna (Thunnus obesus) caught by the Korean longline fishery in the Pacific Ocean. The study used a general linear model (GLM) to standardize the CPUE using catch and effort data aggregated by year, month, and $5{\times}5$ degrees of latitude and longitude in the tropical Pacific Ocean from 1982 to 2008 (except for 1988 and 1989). Explanatory variables in the GLM analysis included year, month, subtropical area, and number of hooks between floats (HBF). The study area and HBF were subdivided into three subtropical areas and six classes, respectively. During the study period, the standardized CPUE was significantly related to the nominal CPUE. The standardized CPUE declined sharply, as compared to the nominal CPUE, after the mid 1990s. In particular, the decline in the standardized CPUE in all subtropical areas in the 2000s was clearer than that of the nominal CPUE.

• Journal of Fisheries and Marine Sciences Education
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• v.19 no.3
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• pp.329-345
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• 2007

The purpose of this study was to classify the standard classification of fishery occupations base on KECO(Korean Employment Classification of Occupation) in Korea. The result of this study was as follows. First ranks was fisheries duties, second ranks were classified into five categories. That were administration duties management duties financial affairs duties, social service duties marketing duties individual service duties, construction duties civil engineering duties, machinery duties manufacture duties repairing duties, production duties. Third ranks classify based on second ranks. Administration duties management duties financial affairs duties were classified fishery administration, fishery management, fishery financial affairs. Social service duties marketing duties individual service duties were classified fishery social service, fishery marketing, fishery individual service. Construction duties civil engineering duties were classified fishery construction, fishery civil engineering. Machinery duties manufacture duties repairing duties were classified fishery machinery duties, fishery manufacture, fishery repairing. Production duties were classified fishery processing, marine products, fishery environment. Fourth ranks was classified according to third ranks.

• Korean Journal of Environmental Biology
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• v.33 no.4
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• pp.412-418
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• 2015

The objective of this study was to evaluate the effects of acute hypoxia on the physiological stress responses (plasma cortisol as the primary response, and hematocrit, hemoglobin, plasma glucose, sodium, chloride, osmolality, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as the secondary responses) of Korean rockfish. The mortality in Korean rockfish started at $0.7mg\;L^{-1}$ and $0.8mg\;L^{-1}$ levels at $12^{\circ}C$ and $20^{\circ}C$, respectively. And the time required for the mortality in experimental fish was 274 and 148 minutes at $12^{\circ}C$ and $20^{\circ}C$, respectively. Levels of hematocrit, hemoglobin, AST, ALT, ion concentration, osmolality, glucose and cortisol had significantly increased with decreasing dissolved oxygen at $12^{\circ}C$ and $20^{\circ}C$.