• Fisheries and Aquatic Sciences
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• 제10권3호
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• pp.150-158
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• 2007

Data on squid catches, water temperature, and climatic factors collected for the Northwest and subtropical North Pacific were analyzed to examine the influence of oceanic and climatic conditions in spawning grounds on catches of Japanese common squid, Todarodes pacificus, in the East (Japan) Sea. The main spawning ground was divided into four sub-areas: the South Sea of Korea (R1), the southern waters off Jeju, Korea (R2), the southwestern part of Kyushu, Japan (R3), and the northern part of Okinawa, Japan (R4). Interannual and decadal fluctuations in water temperatures correlated well with squid catches in the East/Japan Sea. In particular, water temperatures at a depth of 50 to 100 m in sub-areas R3 and R4 showed higher correlation coefficients (0.54 to 0.59, p<0.01) in relation to squid catches in the East/Japan Sea than for R1 and R2, which had correlation coefficients of 0.40 or less (p>0.05). Air temperature and wind velocity fluctuations in each sub-area are correlated with water temperature fluctuations and were closely connected with variations in the surface mixed layers. Water, air temperatures and wind velocities at the main spawning grounds are linked to the Southern Oscillation Index (SOI) with higher signals in the ca. 2-4-year band. Strong changes in a specific band and phase occurred around 1976/77 and 1986/87, coincident with changes in squid catches.

• 수산해양기술연구
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• 제33권2호
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• pp.97-108
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• 1997

황해와 동중국해역에서 근해안강망에 의해 어획되는 황아귀의 어획량 변동과 어장 분포, 그리고 산란 생태를 구명한 결과는 다음과 같다. 황아귀는 연중 어획되며, 이중 많이 어획되는 시기는 겨울철, 가장 적게 어획되는 시기는 여름철인 것으로 나타났다. 황아귀의 어장은 황해와 동중국해에 널리 분포하고 있으며, 중심어장은 일향초 주변 해역으로 어획량이 50 M/T 이상, CPUE가 5kg/haul 이상, C.V는 0.6~0.7의 범위로 낮게 나타났다. 황아귀의 산란시기는 3월과 4월경이며, 이때의 산란장은 일향초와 제주도 사이해역에서 형성되는 것으로 추정되었다. 황아귀의 어장은 월별에 따라 이동하는 현상을 나타내었는데, 즉, 겨울에는 황해저층냉수와 대마난류수의 남하로 어장은 제주도 서방해역에 주로 분포한다. 또 산란시기인 3월과 4월경이 되면, 일향초 부근 해역으로 어장이 밀집하지만, 산란이 끝난 5월이후가 되면 수온의 상승과 더불어 어장은 황해와 동중국해역으로 널리 분산되는 것으로 나타났다.

• 한국어류학회지
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• 제25권2호
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• pp.135-140
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• 2013

잉어과에 속하는 모래주사 Microphysogobio koreensis는 현재 환경부에 의해 멸종위기종 2급으로 지정되어 보호받고 있는 고유종이다. 본 연구에서는 모래주사의 산란장 하상구조 등의 산란 미소서식 환경을 조사하였다. 이들의 산란 서식처는 큰돌, 작은돌, 자갈, 잔자갈 등으로 구성된 Bb type이며, 수심은 약 0.3~1.0 m, 유속은 빠른 $0.5{\pm}0.2$ m/sec으로 나타났다. 실제로 산란이 일어나는 산란장은 수심이 $0.4{\pm}0.1$ (0.4~0.6)m로 얕은 반면에 유속은 $0.8{\pm}0.1$ (0.6~0.9) m/sec로 빨랐으나 수정란이 부착되어 있는 장소는 오히려 0.4 m/sec로 느렸다. 산란은 수온이 $20^{\circ}C$가 되는 5월초에 이루어졌으며, 자갈 표면이나 틈 사이에 알을 낳는다. 이러한 산란장의 특성은 수정란이 휩쓸려 나가지 못하게 하는 기능과 함께 산소공급을 원활하게 하는 역할을 할 것으로 생각된다. 그러나 산란시기 이후에 모래주사들은 이 산란장에서 거의 출현하지 않는 특징을 보여 모래주사 개체들은 산란 후 댐호나 수심이 깊은 하류로 이동하는 것으로 추정된다.

• Fisheries and Aquatic Sciences
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• 제18권4호
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• pp.395-399
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• 2015

We observed seasonality and other characteristics of spawning in the greenling Hexagrammos agrammus off the coast of Tongyeong. Eleven spawning grounds were identified between November, 2013 and January, 2014. The fertilized eggs of H. agrammus were assigned to developmental stages I, II, III, and IV. Based on this classification, we showed that the spawning season extended from the end of October to mid-January. H. agrammus used diverse seaweed species attached to shallow bedrock as spawning substrata that provided good camouflage. Two to seven egg masses were fertilized around the holdfasts of individual seaweeds at depths of 1.2-4.0 m. We identified species-specific reproductive traits of H. agrammus during the spawning season, including strong parental care of the fertilized eggs.

• 한국수산과학회지
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• 제45권2호
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• pp.173-179
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• 2012

The common squid $Todarodes$ $pacificus$ is a dominant species in Korean waters, where it is captured preponderantly by the angling fishery. The spawning and nursery grounds of $T.$ $pacificus$ extend from the southern East Sea to the northern East China Sea. Consequently, the environmental conditions in this area during the spawning and nursery seasons might affect the abundance of $T.$ $pacificus$. This study, analyzed the relationship between the distribution of zooplankton and the abundance of $T.$ $pacificus$ and variation in the squid angling fishing grounds in Korean waters. There was a positive relationship between the fluctuations in zooplankton and the catch per unit effort (CPUE; $kg{\cdot}day^{-1}{\cdot}person^{-1}$) of the angling fishery in the East Sea of Korea. The main fishing season is from July to December and the CPUE was closely related to the zooplankton biomass in April in the East Sea. Recently, the center of the squid jigging ground has moved drastically from the area around Ulleung Island to the northern East Sea. We postulate that the fishing grounds of the squid angling fishery will move farther north with climate change.

• 수산해양기술연구
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• 제45권4호
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• pp.234-242
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• 2009

To develop the artificial spawning seaweeds of the sandfish, Arctoscopus japonicus, the effects by the material type of artificial spawning seaweeds were investigated at Dongsan port in Gangwon-do from December 2006 to March 2007. Sargassum fulvellum, S. horneri, rope and net were used as materials for artificial spawning seaweeds, and the most effective thing among them was S. fulvellum. A. japonicus began to attach the egg mass to artificial spawning seaweeds when sea temperature dropped below 10${^{\circ}C}$ in December, spawned heavily when it was around 8${^{\circ}C}$ in January, and completed the behavior when it started to increase over 10${^{\circ}C}$ in February. The hatching period of eggs was estimated to be about 60 days. The middle position in artificial spawning seaweed had the highest number of egg masses and the diameter of the egg mass ranged from 25mm to 62mm. Based on the result for the effects, the artificial spawning seaweeds of A. japonicus were developed and it is possible to use them to form seaweed forests or spawning grounds of other species.

• 수산경영론집
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• 제49권4호
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• pp.109-129
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• 2018

This study is to evaluate economic effect of the creation project of Octopus Ochellatu spawning and habitat ground in Taean County. The main results of this study are summarized as follows: first, the creation project cost of Octopus Ochellatus spawning and habitat ground invested in Taean from 2015 to 2017 was 3,400 million won. Second, The creation project of Octopus Ochellatus spawning and habitat ground directly provides fishing benefits, recreational boat fishing benefits, festival benefits, research and development benefits, and employment benefits. Third, on the basis of above benefits, the creation project of Octopus Ochellatus spawning and habitat ground has a net present value of 14,478 million won, internal rate of return 60.8%, and benefit-cost of 5.03 under a 4.5% social discount rate. Also, the creation project creates 47 jobs. This indicates that the creation project of Octopus Ochellatus spawning and habitat ground contributes not only to the increase in the income of coastal fishery, recreational boat fishing business and fishing villages but also to the job making. In conclusion, with all these results, a project for making spawning grounds and habitats in the specified region gives species more numerically abundant and this gives more profits to fishermen in the coastal area. In addition, this project helps to make attractions to visitors or people who came to those specified regions to participate in events or have recreation, which means it improves profits to that fishing village and improve a settlement condition.

• Fisheries and Aquatic Sciences
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• 제23권7호
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• pp.19.1-19.14
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• 2020

Three generalized additive models were applied to the distribution of anchovy eggs and oceanographic factors to determine the occurrence of anchovy spawning grounds in Korean waters and to identify the indicators of their occurrence using survey data from the spring and summer of 1985, 1995, and 2002. Binomial and Gaussian types of generalized additive models (GAM) and quantile generalized additive models (QGAM) revealed that egg density was influenced mostly by ocean temperature and salinity in spring, and the vertical structure of temperature, salinity, dissolved oxygen, and zooplankton biomass during summer in the upper quantiles of egg density. The GAM and QGAM model deviance explained 18.5-63.2% of the egg distribution in summer in the East and West Sea. For the principle component analysis-based GAMs, the variance explained by the final regression model was 27.3-67.0%, higher than the regular models and QGAMs for egg density in the East and West Sea. By analyzing the distribution of anchovy eggs off the Korean coast, our results revealed the optimal temperature and salinity conditions, in addition to high production and high vertical mixing, as the key indicators of the major spawning grounds of anchovies.

• 한국수산과학회지
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• 제40권6호
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• pp.394-410
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• 2007

Anchovy spawn from the end of May to mid-October, when the water temperature is $14.8-27.2\;^{\circ}C$ and the salinity is 26.0-33.6 psu. The main spawning season is between July to August, when the water temperature is $21.7-27.2\;^{\circ}C$ and the salinity is between 26.0-32.2 psu. The main spawning grounds of anchovy are coastal areas shallower than 50 m around the islands located in the Jeju Strait. Anchovy larvae are distributed near the fronts between Chuja-do, Jangsu-do, Yeoseo-do, and the open sea rather than in the spawning grounds. Anchovy eggs and larvae density increased in accordance with the high level of $Chlorophyll-{\alpha}$ during the summer season (July-August). In terms of the suspended sediment (SS) levels along the northern coast of the Jeju Strait, high densities of anchovy eggs (12.0-18.0 mg/L) were observed, mainly in the area affected by the coastal waters of the southern sea with high SS levels, while larvae (10.0-19.0 mg/L) tended to be distributed over a wide area with high SS levels, including the open sea. In terms of the dissolved oxygen (DO) content, eggs (5.4-6.8 mg/L) were observed in coastal areas with a high DO content, while larvae (4.2-6.4 mg/L) were distributed widely in areas with a relatively low DO content, from the southern coast to the open sea.

• 한국수산과학회지
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• 제46권6호
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• pp.835-842
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• 2013

Flathead flounder Hippoglossoides dubius is a commercially important fish in the coastal waters of Gangwon Province, which is its spawning ground and breeding habitat. A total of 1,669 gonads were sampled monthly from February 2011 to May 2013 to investigate ecological characteristics, such as variations in maturation and spawning by gonad index, visual maturity stage, histological observations and oocyte diameter. Males were numerically dominant over females in the fishing grounds year round. The spawning season was from January to April, and the peak was from February to March. Oocyte number as a measure of fecundity was between 27,372 and 915,209 eggs with a length range of 26.0-48.7 cm TL, while the largest oocyte grew to 0.9-1.4mm in egg diameter during its spawning season. The relationship between fecundity and total length was $F=0.0016TL^{5.2539}$. The smallest mature lengths of the females and males were 28.4 and 22.6 cm respectively, and the 50% mature lengths of females and males were 32.9, 26.9 cm respectively.