• 수산해양기술연구
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• 제27권1호
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• pp.1-12
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• 1991

적분방식에 의한 어군량추정법을 실험적으로 검증하기 위하여, 실험수조에서 50 kHz와 200 kHz의 주파수를 대상으로 모의어군의 분포밀도와 초음파산란강도의 관계를 검토하고, 또 계량어군탐지기의 정도를 개선하기 위한 문제들에 대하여 고찰을 행한 결과를 요약하면 다음과 같다. 1. 어체의 모의표적으로 이용한 steel ball (직영 35mm)의 실측 echo 파형은 이론 echo 파형과 잘 일치하였다. 2. 5 종류의 주파수에 대하여 고등어 (체장 36cm)의 반사주파수특성을 조사한 결과, 측정주파수가 변화함에 따라 어체에 의한 echo 신호의 진폭과 파형이 크게 변동하고 있음을 알 수 있었다. 3. 송수파기의 음속 내에서 5개/m 상(3)와 30개/m 상(3)의 표적 군이 서로 상하로 존재할 때, 상부 표적군의 존재에 의해 하부 표적군의 echo level이 -0.43 dB 감쇠하는, 소위 그늘효과(shadowing effect)가 발생하였다. 4. 동지나해에서 정박 중에 탐지한 고밀도 어군의 echo신호와 그 어군직하의 해저에서 산란된 echo 신호를 상호 연관시켜 분석한 결과, 어군층내에서 발생한 어군감쇠와 다중산란효과가 해저 echo 신호의 변동에 큰 영향을 미치고 있음을 알 수 있었다. 5. 정치망의 원통에 인망한 정어리의 단위체적당에 대한 분포밀도가 36마리/m 상(3)였을 때, 해저기녹이 소실되는 어군감쇠현상과, 어군 echo 신호가 해저까지 신장되는 다중산란현상이 동시에 발생하였다. 6. 50kHz와 200kHz의 주파수에서 표적군의 평균체적산란강도(:dB)와 표적의 분포밀도($\rho$:개/m 상(3))의 간에 다음의 회귀직선식을 얻었다. 50kHz : =-46.2+13.7 Log($\rho$). 200kHz : =-43.9+13.4 Log($\rho$). 7. 표적의 분포밀도가 5, 10, 15, 20, 25, 30 개/m 상(3)였을 때, 적분방식에 의한 추정치는 50kHz에서 2.0, 8.1, 9.9, 14.1, 19.2, 26.7 개/m 상(3)이었고, 200kHz에서는 2.0, 8.0, 9.1, 15.0, 20.1, 24.1 개/m 상(3)이었으며, 단위체적당에 분포하는 표적의 수가 많을수록, 그 추정치의 정도가 높아지는 경향을 나타내었다. 또한, 양주파수에서 분포밀도의 추정치는 실제보다 약 30%정도 과소추정되었다.

• 수산해양기술연구
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• 제42권1호
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• pp.30-37
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• 2006

Black rockfish and goldeye rockfish are commercially important fish species due to the increasing demand in Korea. When estimating the abundance of stocks for these species acoustically, it is of crucial importance to know the target strength(TS) to length dependence. In relation to these needs, TS measurement was conducted on black rockfish and goldeye rockfish in an acrylic salt water tank using 70kHz and 120kHz split beam echo sounders. The TS for these two species under the controlled condition was simultaneously measured with the swimming movement by DVR system and analyzed as a function of fish length(L). The results obtained are summarized as follows: The best fit regression of TS on fish length of black rockfish was TS=19.38 Log(L, cm)-70.46 ($r^2=0.71$) at 70kHz and TS=22.39 Log(L, cm)-70.40 ($r^2=0.64$) at 120kHz and in the standard form TS=20 Log(L, cm)-71.29 ($r^2 = 0.70$) at 70kHz and TS=20 Log(L, cm)-66.88 ($r^2=0.57$) at 120kHz. The best fit regression of TS on fish length of goldeye rockfish was TS=17.10 Log(L, cm)-68.28 ($r^2=0.37$) at 70kHz and TS=24.39 Log(L, cm)-73.74 ($r^2=0.59$) at 120kHz and in the standard form TS=20 Log(L, cm)-72.03 ($r^2=0.32$) at 70kHz and TS=20 Log(L, cm)-67.68 ($r^2=0.64$) at 120kHz. An empirical model for fish TS(dB) averaged over the dorsal aspect of 115 fishes of black rockfish and goldeye rockfish and which spans the fish length(L, m) to wavelength($\lambda$, m) ratio between 8 and 30 was derived : TS=34.12 Log(L)-14.12 Log($\lambda$)-23.83, ($r^2=0.90$).

• 수산해양기술연구
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• 제28권4호
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• pp.371-379
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• 1992

In order to analyse the mesh selectivity for the trawl net, the fishing experiment was carried out by the training ship Saebada in the southern Korea Sea and the East China Sea from June 1991 to August 1992. The trawl net used in experiment has the trouser type of cod-end with cover net, and the mesh selectivity was examined for the five kinds of the opening mesh size in its cod-end part. The selection curves and the selection parameters were calculated by using a logistic function, S=1/(1+exp super(-(aL+b))), and in this case, a and b are the selection parameters and L is the body length of the target species of fishes. In this report, the four species of aquatic animals were analysed because the catch data were enough to calculate normally the selection curves and the selection parameters, and the results obtained are summarized as follows: 1. Trachurus japonicus; Selection parameters a and b in each cases of the opening mesh size of 51.2mm, 70.2mm, 77.6mm, 88.0mm and 111.3mm were respectively 0.5050 and -5.4283, 0.3018 and -4.9590, 0.3816 and -7.3659, 0.2695 and -5.7958, 0.2170 and -5.1226. 2. Photololigo edulis ; Selection Parameters a and b in each cases of the former mesh sizes were respectively 0.7394 and -6.1433, 0.3389 and -4.2366, 0.3286 and -5.1002, 0.2543 and -5.0049, 0.1795 and -4.8040. 3. Trichirus lepturus; Selection curves in the opening mesh size of 111.3mm was calculated unnormally. The selection parameters in the other opening mesh sizes were respectively 0.3790 and -5.2891, 0.2071 and -4.9164, 0.1292 and -3.1733, 0.1153 and -3.8497 in the order of former mesh sizes except 111.3mm. 4. Todarodes pacificus ; Selection curve in case of the opening mesh sizes, 70.2mm and 111.3mm were calculated unnormally. In the order cases of the opening mesh sizes, the selection parameters were respectively were 0.5766 and -6.0169, 0.3735 and -5.4633, 0.2771 and -5.7718 in the order of former mesh sizes except 70.2mm and 111.3mm.

• 수산해양기술연구
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• 제52권3호
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• pp.209-219
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• 2016

The survey was conducted to investigate biomass and distribution of fisheries resources using a quantitative echo sounder and a fixed gillnet around Marado coast of Jeju to obtain the scientific basic data for dispute resolution with a large purse seine fishery and coastal fishing and policy establishment of reasonable fisheries resources. Hydroacoustic surveys were conducted six times (November 28~29, 2015 (night), February 23~24, 2016 (night) and March 3~4, 2016 (night/day), March 30~31, 2016 (night/day)) using a quantitative echo sounder. The pelagic fish densities were relatively higher around Marado in November 2015, February 2016 and March 3~4, 2016. However, demersal fish densities were relatively higher in Jeju coastal waters on March 30~31, 2016. Catch data using fixed gill net were used to calculate biomass. Based on the hydroacoustic data, fish length-weight function and target strength information of dominant fish, the biomass of fishes were estimated as follow: 5.64 ton CV = 70.2% at night on November 28-29 2015, 7.14 ton CV = 35.8% of pelagic fish and 530.77 ton CV = 34.6% of demersal fishes at night on February 23-24 2016, 2.34 ton CV = 56.7% of pelagic fish and 571.93 ton CV = 40.3% of demersal fish at daytime, 1.39 ton CV = 48.4% of pelagic fish and 194.59 ton CV = 54.3% of demersal fish at night on March 3~4 2016, 0.37 ton CV = 72.9% of pelagic fish and 338.79 ton CV = 99.7% of demersal fish at daytime, 0.24 ton CV = 21.3% of pelagic fish and 68.61 ton CV = 53.8% of demersal fish at night on March 30~31 2016.

• Ecology and Resilient Infrastructure
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• 제9권1호
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• pp.68-76
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• 2022

본 연구에서는 금강수계 미호천 유역에서 어류 서식지적합도지수 (HSI)를 산정하고 환경생태유량을 산정하였다. 이를 위해 미호천의 상류와 하류를 대표할 수 있는 2개 지점 (St.3과 St.8)을 선정하고, 어종별 수심과 유속 등 물리적서식지 정보를 구축해 서식지적합도지수를 산정하였다. 서식지적합도지수는 채집된 개체수와 유량조사 결과를 수심과 유속의 관계를 이용해 WDFW 방법으로 산정하였고, 대표어종 선정시 우점종인 피라미 (Zacco platypus)와 유량에 민감한 유영성 어종으로 결정하였다. 단일종인 피라미의 경우 수심 범위는 0.1 - 0.5 m, 유속 범위는 0.2 - 0.5 m/s 이고, 유영성 어종인 경우 수심 범위는 0.2 - 0.5 m, 유속 범위는 0.2 - 0.5 m/s 이다. 미호천의 대표지점인 St.3과 St.8에서 대표어종인 유영성군집 및 피라미에 대한 유량 (Discharge)-가중가용면적 (WUA) 관계 곡선 및 서식지적합도 분포를 모의하였다. 미호천 상류 St.3에서 가중가용면적이 최대값을 나타내는 최적유량은 유영성 군집이 4.0 m³/s, 피라미가 2.7 m³/s 로 모의되었다. 하류지점인 St.8에서는 유영성 군집이 8.8 m³/s, 피라미가 7.6 m³/s 로 모의되었다. 두 지점 모두 유영성군집 어종의 최적유량이 크게 산정되었다. 이는 유영성 군집의 서식지적합도지수가 피라미의 서식조건보다 더 빠른 유속을 필요로 하기 때문이다. 최소유량 산정에서도 피라미의 유량이 더 작고, 보다 더 많은 가중가용면적을 제공하는 것으로 평가된다. 군집 어류의 경우 수심과 유속의 범위를 좁게 산정하면 필요유량이 증가하고 가중가용면적은 상대적으로 감소한다. 따라서 군집어류에 대한 서식지적합도지수 산정시 범위를 좁게 설정하는 것보다 모든 어종의 서식지를 포함하는 지수를 산정하는 것이 유리하다.

• 한국환경과학회지
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• 제16권8호
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• pp.973-983
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• 2007

The eco-hydrologic effects of maintenance water supply on Oncheon stream are studied using hydrologic, hydraulic and ecologic models. SWMM (Storm Water Management Model) is used for long-term simulation of runoff quantity and water quality from Oncheon stream watershed. Using the output hydrologic variables from SWMM, HEC-RAS (River Analysis System) is then used to simulate the hydraulics of water flow through Oncheon stream channels. Such hydrologic, hydraulic and water quality output variables from SWMM and HEC-RAS are served as input data to execute PHABSIM (Physical Habitat Simulation) for the purpose of predicting the micro-habitat conditions in rivers as a function of stream flow and the relative suitability of those conditions to aquatic life. It is observed from the PHABSIM results that the weighted usable area for target fishes has the maximum value at $2m^3/s$ of instream flow. However, mid and down stream areas that have concrete river bed and covered region are unsuitable for fish habitat regardless of instream flow increment. The simulation results indicate that the simple maintenance water supply is limited in its effect to improve the ecological environment in Oncheon stream. Therefore, it is imperative to improve water quality and to recover habitat conditions simultaneously.

• 한국수산과학회지
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• 제50권4호
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• pp.421-428
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• 2017

The spatial distribution and abundance of fish species was estimate near Dok-do, East Sea of Korea by conducting midwater trawl survey with hydroacoustic method. Acoustic and midwater trawl data were collected onboard the R/V Tamgu 21 during 7-8 March 2016. Acoustic data were collected at the frequencies of 38 and 120 kHz and converted to nautical area scattering strength ($m^2/nmile^2$). Species are distributed mainly over an extent of 30-55 m, generally around southwest of Dok-do; the squid Watasenia scintillans was the dominant species found. The length-weight function and target strength of squid and other fishes were used to estimate the W. scintillans stock at 2499.1 tons and other fish at 43.8 tons during the winter season. The hydroacoustic method offers an approach for the determination of the biomass and vertical and spatial distributions of species aggregating near Dok-do, East Sea of Korea.

• 수산해양기술연구
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• 제48권2호
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• pp.107-117
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• 2012

Korean large purse seine fishery catches chub mackerel, sardine, jack mackerel, Spanish mackerel, etc. which are mainly pelagic fish species. The proportion of chub mackerel was 60% over in Korean large purse seine fishery. Sea surface temperature (SST) increased $0.0253^{\circ}C$ per year and total rising rate was $0.759^{\circ}C$ from 1980 to 2009 in the southern sea of Korea, where is mainly fishing grounds of Korean large purse seine. It was that p<0.01 level was statistically significant. It is northward movement that the center of fishing grounds of chub mackerel by Korean large purse seine fishery moved 4.57km/yr. It was rapidly northward movement about 7.1km/yr, 8.13km/yr to move Spanish mackerel and bluefin tuna fishing grounds. However, the fishing grounds of jack mackerel were moved further south in the 2000s than the 1980s. Catch of tunas and bluefin tuna consistently increased in Korean waters. There was a significantly positive correlation between SST and catch of bluefin tuna in the fishing grounds of Korean waters.

• 한국수산과학회지
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• 제36권6호
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• pp.686-694
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• 2003

Monthly fish samples were collected using bottom gill nets and analyzed to study species composition and seasonal variation of fish assemblages in the coastal waters off Gadeok-do, Korea in 1998. During the study period, a total of 49 fish species representing 30 families were collected. The fish assemblages predominantly consisted of Limanda yokohamae, which accounted for $53.3\%$ of the number of individuals and $42.2\%$ in the biomass. The fish species, which had over 100 individuals, included Cynoglossus abbreviatus, Ditrema temmincki, Hexagrammos otakii, and Stephanolepis cirrhifer. These four species accounted for $24.1\%$ of the number of individuals and $24.3\%$ of the biomass. More fish species were collected in May and June than in any other months. The number of individuals and the amount of biomass peaked in April and May and reached a low in August. While the predominance of L. yokohamae caused the lowest species diversity by number of individuals in April, the predominance of Platycephalus indicus caused the lowest species diversity by biomass in July. Although gill nets show a strong selectivity for the target species or for size, gill nets can be used as an alternative fishing gear to collect fish in waters with rough bottoms, like rocky reefs, where other kinds of fishing gear such as trawls can not be used.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.26-26
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• 2012

The Kurobe river, which runs through eastern Toyama Prefecture is one of the most famous rivers for wild water because of its steep slope in the range from 1/5 to 1/120. This river forms an alluvial fan in the range up to 13 kilometers from the sea. In this region, significant seepage flow occurs and thus the stream sometimes been intermitted. Moreover, the amount of seepage flow seems to vary with the groundwater level of the region. To keep the river environment healthy for flora and fauna, especially to conserve good condition for spawning of fishes, an appropriate environmental flow should be maintained in the river. To achieve this target, controlling of the upstream reservoir has to be studied in depth. One of the major problems to decide the amount of water to be released from the reservoir to maintain the environmental flow is to estimate the amount of water leaked into the groundwater from the river. This phenomenon is affected by the river flow rate as well as the groundwater level in the alluvial fan and the conditions vary in space and time. Thus, a grid-based hydrological cycle analysis model NK-GHM has been applied to clarify the hydrological cycle componentsin this area including seepage/discharge from/to the river. The model was tested by comparing with river flow rate, groundwater levels and other observations and found that the model described those observations well. Consequently, the seepage from the Kurobe river was found significant but it was also found that the groundwater in this region has been preserved by the recharge from the irrigation water supply into paddy fields in the alluvial fan.