• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.23-32
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• 2019

This study investigated the scour characteristics of artificial reef according to unreinforced and reinforced artificial reefs through laboratory test and numerical analysis. In this study, geogrid was used as a reinforcement of seabed. Three different reinforced areas were selected; one time, three times and five times bottom area of artificial reef. Two-dimensional water channel test was carried out to investigate scour patten of sand and silt grounds. Numerical analysis was also performed to see the velocity vector and scouring patten around artificial reef which was same condition with experiment. The numerical results were in good agreements with the experimental test results. It was found that the geogrid-installed soft ground under artificial reef tends to reduce scour, compared to unreinforced soft ground.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.208-214
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• 2008

This study monitored a variety of marine communities during monthly or bimonthly censuses from February 1999 to August 2000. The communities investigated included artificial reefs composed of various substrates, which were placed on an area of sandy bottom at 8, 10, and 13m depths in Muronohana, Ikata, Shikoku, Japan. Economically important shell fishes, such as the turban shell and abalone, appeared on the artificial reefs after 1 month of construction. Shell fishes were recorded at levels of five to 20 individuals per reef. A total of 37 species (4 orders, 19 families) were identified during the experimental period. Apagon semilineatus, Trachurus japonicus, Pteragogus sp., and Pterogobius elapoides accumulated over an average of 100 individuals during the study period. Apagon semilineatus, Pteragogus sp., and P. elapoides accumulated over 1,000 individuals on all artificial reefs in May 1999. Trachurus japonicus reached well over 500 individuals in the artificial iron reef during June and July 2000. Higher monthly variation in fish abundance occurred during periods of high temperature, as compared to periods of low temperature between December 1999 and March 2000. More fish were observed in the artificial iron reef than in the artificial concrete reef, because the former offered a broader inner space and the shadows of the roofs served as a shelter for fish.

• Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.276-282
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• 2024

The present study was conducted to investigate the behavior and distribution characteristics of fishes near an artificial reef close to the waters of Uljin marine ranch. A 200-kHz, dual-beam frequency transducer was attached to the side of a ship for acoustic measurements. The fish formed small groups in the bottom layer near the artificial reef around the afternoon-sunset period; at night, the fish did not form groups and remained individually scattered. During dawn-sunrise and morning, the fish formed groups again and were found near the upper and middle layers of the artificial reef. High density of fish occurred near the middle of the nautical zone during morning, afternoon-sunset, and dawn-sunrise, periods; at nighttime, the distribution was uniform across the entire zone. Moreover, the mean Nautical Area Scattering Coefficients (NASC, m²/nmi²) value was highest during dawn-sunrise at 400.2 m²/nmi², similar during night and morning (100.5 m²/nmi²), and lowest during afternoon-sunset (20.1 m²/nmi²). The present study is expected to provide the background for understanding the behavioral characteristics of fish living near artificial reefs and estimating the density and biomass of fish.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.139-145
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• 2011

Hydro-acoustic survey was carried out to estimate a fish distribution at marine ranching area and aggregated fish schools at artificial reef area in Oeyeondo, Korea. The survey system was set up with DGPS system, scientific echo sounder (EK60, Simrad Co.), and ECDIS (Mecys. Co. LTD). A track survey and a random survey was respectively applied to the marine ranching area (474.4ha) and to the artificial reef area (within a radius of 300m). As the result, fish distribution and MVBS values in marine ranching area showed that created fisheries resources didn't come to be abundant yet as to appear fish distribution in all of the area. In the artificial reef area, it was, however, able to detect many fish school signals on the top of and around artificial reefs and to confirm the luring effect of artificial reefs.

• Journal of Ocean Engineering and Technology
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• v.21 no.5
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• pp.61-67
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• 2007

As part of the government's fishery resource creation policy, fishing ground creation projects have been undertaken in Korea's major seashore fishing spots since the 1970s, where artificial reefs constructed using new materials that make up for the weakness of concrete reefs have been used. In this study, the stability of these artificial reefs when acted upon by external forces, their ability to attract and gather fish, and their economic feasibility were examined. For this purpose, an experimental artificial steel reef was constructed and was installed in an area of the sea. Then the corrosion of the experimental material attached to it was investigated. The efficiency of the artificial steel reef was then verified by examining its functionality, removal, and burying, as well as the speed of insertion of living things into its structure and its ability to attract and gather fish.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.2
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• pp.126-139
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• 2007

In the autumn of 2000 and spring of 2001, field surveys were conducted to estimate the effectiveness of artificial reefs (type cube, $2{\times}2{\times}2m^3$) that were established in the four islands of Bangnyeong, Socheong, Daeyeonpyeong and Ganghwa in Kyonggi Bay, the west coast of Korea during 1995 and 1996. The condition of reefs was examined through SCUBA diving and a side-scan sonar. Much of the reefs in Daeyeonpyeong and Ganghwa area were buried in bottom sediment. Despite an intensive search in Bangnyeong area, even a cluster of reefs was not found and most of them seemed to be buried by sand waves. Thus an appropriate investigation on the sediment transport should be included in pre-assessment for the expected performance and protection of artificial reefs. Distribution of average CPUE in natural fishing ground (control) was estimated by bootstrapping simulation and possible comparison of CPUE between control and reef areas (treatment) were made in Bangnyeong and Socheong (Experiment I). Positive reef effect was detected in Socheong but CPUE of treatment in Bangnyeong was varied between or lower than the 99% CPUE confidence intervals of the control. Control/treatment abundance and biomass of fishes and invertebrates were tested by paired t-test and sign test (Experiment II). Only four cases among 22 showed significant positive effect. Based on the results, the cube artificial reef in Socheong was inferred as an affirmative one. Floor type was hypothesized to be one of the probable agents in determining the effectiveness of artificial reefs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.273-281
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• 2013

The movement patterns of fish aggregations swimming freely near artificial reefs on August 24, 2006, at Suyeong Man, Busan, Korea, were acoustically investigated and analyzed. Acoustic surveys were conducted using a 70kHz split-beam echo sounder, 330 kHz side-scan sonar and a 310 kHz imaging sonar. Algorithms for tracking the movement of fish aggregations swimming in response to artificial reefs were developed. The travel direction and the swimming speed for two aggregations of fish were estimated from the trajectory orientations of echo responses recorded by the imaging sonar.The first group was floating just above the reef structure, while remaining in the midwater column, and the second group was swimming through and around artificial reefs near the seabed. The mean swimming speed was estimated to be 0.40 m/s for the midwater fish aggregation and 0.17 m/s for the bottom aggregation close to artificial reefs. These results suggest that the swimming behavior of fish aggregations passing close to artificial reefs near the seabed displayed a slower moving pattern than fish floating just above the reef structure in the midwater column.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.535-548
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• 1994

Community structures and fish densit were investigated on three different types of artificial reefs, dice, turtle artificial reef and tubes, constructed in the Korean waters. Variations of fish fauna according to type of artificial reef and the proper artificial reef in each area for optimizing harvest were discussed. Fish were captured by trammel gill net during May, June, September and November, 1988 and both identified and counted. Fourty-five fish species were found in the artificial reefs. Of these, Sebastes spp., Hexagrammos otakii, Pleuronectidae, Navodon modestus and Stephanolepis cirrhifer showed high occurrence-frequency. The dominant species groups were coastal settlement, demersal or rock fishes such as Pleuronectidae, Rajiformes, Stephanolepis cirrhifer, Navodon modestus, Hexagrammos otakii and Sebastes spp. in all of the Artificial reefs except the oceanic area of southern waters. Scomber japonicus was predominant in the oceanic area of southern waters. Composition of demersal, rock and pelagic fishes were different depending on the types of artificial reef. Dice artificial reefs were occupied by rock fish, on the other hand turtle artificial reefs were dominated by dermersal fish. Fish density was high at the dice artificial reef in all survey areas except the middle area of Eastern waters, with high fish density evident in the Tube artificial reef. Fish community structures were remarkably different between Dice and Turtle artificial reefs. The Tube artificial reef showed intermediate characteristics between the above two types of artificial reefs. The coastal areas of Southern waters and the middle and southern areas of Western waters revealed similar fish fauna. Results from the oceanic areas of Southern waters were well associated with the middle and southern areas of Eastern waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.6
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• pp.947-959
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• 2015

Variations in the species composition, biomass and size distribution of fisheries resources in the Uljin marine ranching area were investigated using trammel nets at two stations (artificial reef and natural rocky area) from 2009 to 2010. During the survey, a total of 74 species were sampled with a mean density of 132 ind./net and mean biomass of 21.56 kg/net. In the natural rocky area, a total of 45 species were sampled at a mean density of 202 ind./net and mean biomass of 28.81 kg/net, while in the artificial reef area, samples included a total of 56 species, with means of 62 ind./net and 14.30 kg/net. The dominant species, comprising over 3% of the total number of individuals, were Suberites ficus (30.8%), Ovalipes punctatus (19.2%), Paralichthys olivaceus (11.7%), Pleuronectes herzensteini (4.7%), Kareius bicoloratus (3.5%), Pseudopleuronectes yokohamae (3.5%) and Eopsetta grigorjewi (3.0%). The dominant species, in terms of biomass, comprising over 5% of the total biomass, were P. olivaceus (22.1%), S. ficus (18.7%), O. punctatus (7.2%), Hexagrammos otakii (6.6%), P. yokohamae (5.7%), K. bicoloratus and P. herzensteini (5.3%). A cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on the Bray-Curtis similarity of fourth root transformed data for number of species and individuals, was divided into two groups: the artificial reef area (group A) and the natural rocky area (group B).

• The Journal of Fisheries Business Administration
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• v.38 no.3
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• pp.67-88
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• 2007

This study is to estimate the factor weights for a successful sea-ranching project using the Analytical Hierarchy Process. Furthermore, it investigates the policy implications revealed by the differences in group opinions throughout fishermen, government officials, researchers and the scholars when the weights are assessed. The hierarchy is constructed for the 3 levels of factors which must be evaluated for a successful sea-ranching project. The top level of factors is divided by the ecological factors and the socioeconomic factors. As the middle level of factors, there are 3 factors such as the choice of fish, the habitat environment and the production technology under the ecological factors and another 3 factors such as the stability of fishery society, economic factors, and the law & system under the socio-economic factors. And then, at the bottom level of the hierarchy, the economic factors have two different sub-factors such as the fishing revenue and cost. The law & system has also 3 sub-factors such as the accessibility to sea-ranching area, fishing method, and surveillance. The fishermen and government officials show us quite opposite tendencies in assessments of the weights while both the researchers and scholars reveal almost the same opinions positioned at somewhere between first two groups. The study also reports the evaluations of efficiency measures for resource recovery methods among the sea-ranching project, artificial reef, release of fish seeds, and marine protection area. Both the sea-ranching project and marine protection area have the same efficiency in terms of resource recovery while the artificial reef and release of fish seeds are revealed as somewhat less efficient methods comparing to the former two methods.