• Ocean and Polar Research
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• v.23 no.3
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• pp.305-310
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• 2001

This paper describes a floating fish reef technology for enhancement of fisheries productivity in the muddy areas. The floating fish reef was composed of main fish cage, anchor rope and concrete anchor blocks. Main fish cage was made up of 12 steel buoys measuring 0.37m in diameter and 1.5m long, polyethylene (PE) netting and circular steel rings. Each steel buoy had buoyancy of 110kgf. The size of main fish cage was 1.96 m in diameter and 3.75m in length. Monitoring on its durability was made for eight months after installation. The steel buoys fixed on main fish cage and nettings were observed to be kept safely. The wet weight of fouling organisms per unit area$(m^2)$ was 26.6kgf after eight months. Reduction in the cross-section of steel buoys and circular steel rings of main fish cage were not found. In addition, any cracks on the concrete anchor blocks were not observed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.735-739
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• 2010

This study investigated a method for monitoring fishes immigrating to upper streams from the sea in relation to water level with elapsed time, and measured fish behavior patterns and swimming speed in a fishing boat gateway using an acoustic camera system. This method was employed due to difficulties, linked to high turbidity, of using only underwater optical systems for monitoring fish migrating to brackish water. Results showed that fish length distribution showed high correlation between haul sampling and an automatic counting algorithm supported by the DIDSON software program. These results will help to maximize the effects of fish run management by increasing understanding of the amount of major fish species migrating in relation to durable water levels.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.2
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• pp.105-113
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• 2020

The fish influx and behavioral properties at a set-net off Goseong, South Korea were investigated using an imaging sonar. As a result, the average influx of fish was 33.9% at day time and 66.1% at night time, respectively, which indicated that a majority of fish entered into a playground in the set-net at night. The fish behavioral properties such as target (fish) length, range, orientation and major-axis angle were examined and compared among survey dates (4, 5, and 6 June 2019) using the statistical analysis tool (analysis of variance, ANOVA). The behavioral properties presented differently sometime of survey dates. This is preparatory study to support fish behavior properties in a set-net. It is expected that more elaborated behavioral information of fishes in the set-net is beneficial for designing and deploying a set-net fishing gear as well as general fish behavior research in the future.

• Journal of fish pathology
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• v.19 no.1
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• pp.1-6
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• 2006

Numerous large whitish cysts were found on the scale of wild mullet, Mugil cephalus captured in Jin-Hae bay of southern coastal sea of Korea. The cyst consisted of many trophozoites, mature spores and interstitial tissues of host origin. Spores were 8.25 ㎛ (7.26-9.35) in length, 6.3 ㎛ (5.63-6.78) in width, 4.34 ㎛ (3.96-5.04) in thickness. Polar capsules were 4.45㎛ (3.8-5.4) in length and 2.35 ㎛ (1.62-2.86) in width, and the length of polar filament was about 39.57 ㎛ (26.3-56.33). Based on the spore morphology and the host & tissue specificity, the present specimens were identified as Myxobolus episquamalis Egusa, Maeno & Sorimachi, 1990. Deformation of bony plate of the scales and infiltration of inflammatory cells were observed in the histological sections.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.3_4
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• pp.103-104
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• 1971

A cod, Gadus macrocephalus TILESIUS was studied on the length-weight relationship. The fish were sampled from those caught by set nets for cod in the Yellow Sea during the period from April 1964 to May 1964. The data for this study were taken from 247 fish. The relationship between the body length (X) in mm and body weight(Y) in g is indicated as follow : 160mm to 339mm : $Y=0.000001225X^{3.42706}$

• Korean Journal of Ichthyology
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• v.36 no.1
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• pp.20-29
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• 2024

Hemitripterus villosus, a promising aquaculture fish species, is facing declining stocks. This study aims to provide normative standards for skeletal development to address persistent skeletal deformities in farmed fish. Specimens utilized in the study underwent artificial insemination with captured fish, and the resulting larvae and fry were preserved in a formalin solution. The skeletal ossification process commenced immediately after hatching, affecting the parasphenoid, premaxillary, maxillary, and dentary structures at an average total length of 13.65±0.71 mm (n=5). By sixty-five days post-hatching, ossification extended to the ethmoid and supraorbital, completing the head's development at an average total length of 21.24±0.50 mm (n=5). Clavicle ossification occurred at seven days post-hatching, corresponding to an average total length of 14.61±0.52 mm (n=5). At forty-four days post-hatching, the ossification of 4 actinosts took place, completing the shoulder girdle, with an average total length of 18.15±0.61 mm (n=5). Vertebral ossification initiated at ten days post-hatching, with an average total length of 14.80±0.65 mm (n=5). By fifty-four days post-hatching, 39 vertebral columns were ossified, reaching an average total length of 18.67±0.54 mm (n=5). Vertebral development was complete at sixty days post-hatching, with an average total length of 20.25±0.45 mm (n=5). This study sheds light on the skeletal development of H. villosus, providing valuable standards and fundamental data for understanding skeletal deformities in this species.

• Journal of Aquaculture
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• v.12 no.4
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• pp.309-315
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• 1999

In order to understand the initial feeding time of larvae red marbled rockfish, Sebastiscus tertius changes of mouth size were investigated. Also, the fecundity of different size of red marbled rockfish broodstocks was measured. The broodstocks of red marbled rockfish, S. terius of $32.3\pm6.52 cm$ and larger than 45cm in total length spawned 296,648 and 600,000 larvae, respectively. About 50% was normal healthy larvae among the spawned ones. Mouth sizes calculated by the angle mouth opening and upper jaw length for newly spawned red marbled rockfish larvae were 0.263, 0.197 and 0.132 mm at D, 0.75D and 0.5D, respectively, when the upper jaw length was 0.186mm. Thereafter, 20 days old larvae showed 0.822, 0.617 and 0.411 mm in calculated mouth length at D, 0.75D and rockfish larvae grows, their upper jaw length gradually increased. 2 days old red marbled rockfish larvae possibly stated to feed rotifers and lasted their feeding for the another 35days, relatively long periods compared with other larvae fish. And 25 days old larvae possibly fed the newly hatched Artemia nauplii and lasted their feeding for the another 20 days, like other larvae fish. The proper supplying time of artificial feeds for the red marbled rockfish larvae seemed to be around 10 days after spawning.

• The Journal of the Acoustical Society of Korea
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• v.25 no.3E
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• pp.101-109
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• 2006

Besides dorsal-aspect target strength (TS) of the fish, side-aspect TS information is also acoustically important parameter in fisheries acoustics. In this study, the side-aspect TS of 11 black sea bream (Acanthopagurus schlegeli) were measured using a split beam echosounder of 120, 200, and 420 kHz; total length of the fish ranged from 12.4 to 23.7 cm, and wet weight from 27.5 to 229.8g. For the precise TS measurement with side-aspect angle, we used anesthetized and tethered specimens of known size while being rotated through $360^{\circ}C$ by means of a carousel structure. The side-aspect TS measurements of the fish were conducted by rotating the fish in the horizontal plane at 50 interval. The ping interval was 0.2 second and elapsed time at each angle was 30-60 second. As a result, the measured side-aspect TS data were fitted by sinusoidal function. The relationships between fish length and near full side-aspect TS were as follows: $TS_{120kHz}= 21.46 log (TL)-67.5 (r = 0.70), \;TS_{200 kHz}= 31.03 log (TL)-76.9 (r=0.83),\;TS_{420 kHz}= 30.79 log (TL)-72.2 (r = 0.77)$. For comparison, theoretically estimated side-aspect TS from the Kirchhoff ray mode (KRM) model, which based on swimbladder and body morphology, were compared with the measured TS.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.701-710
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• 2016

We examined the inter-annual changes in the community structure of fish in the Yeosu coast during the spring fishing period (May June) from 2008 to 2015. Using a both sides fyke net, we collected 74 taxa, of which the dominant species was Trachurus japonicus. In the years 2009-2010 and 2015, when the relative abundance of T. japonicus decreased, the fish species diversity increased, as estimated from the rarefaction curve and beta-diversity, resulting in a significant difference in the fish community structure between two year groups: one comprising 2009-2010 and 2015 and the other comprising 2008 and 2011-2014. T. japonicus may be a keystone species that plays a critical role in temporal changes in the community structure of fish caught by fyke nets along the southern coast of Korea. Obvious modes in the length-frequency of T. japonicus smaller than fork length (FL) 10 cm were observed continually during the study, while the frequency of T. japonicus bigger than FL 15 cm declined rapidly after 2010. The new recruitment of smaller T. japonicus before and after 2010 appeared beginning in June and May, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.4
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• pp.283-291
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• 1994

This paper describes about the behavior of the Striped mullet (Mugil cephalus) in the setnet by telemetry techniques. The telemetry system consists of a pinger of 50KHz, three omni-directional hydrophones and ultrasonic receivers, a single board computer for the signal processing, two RF transceivers for the data comunication and a personnel computer. The fish tagged the pinger was tracked by the LBL method, and its location was calculated by the hyperbolic method. The fish escaped from sea surface to 7m deep right after release and had been swum near the sea surface after 30 minutes being released. Also, in horizontal movements, the fish stayed long time around the enterance of the square net in setnet, and showed the escaping behavior repeatly. The average speed of the fish was about 0.41m/sec(1.1 times of the body length)