• 한국수산과학회지
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• 제41권1호
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• pp.61-67
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• 2008

Acoustic technology is commonly used to estimate the biomass and distribution of fisheries resources in coastal areas and the open ocean. Acoustic surveys were conducted on 24-26 May and 20-21 June, 2005, and 15-18 June and 27-30 July, 2006, near the Tongyoung, Geojae, and Namhae anchovy fishing grounds using a dual beam echo sounder. Information was obtained on the distributions of adult and juvenile anchovy (depth and position). We calculated and compared anchovy biomass using simple summation. In this study, all backscatter was attributed to anchovy. We assumed that the average target strength of anchovy was -70 dB and the average body weight was 3 g in May and June 2005, and that the target strength of anchovy was -65 dB and the average body weight was 5 g for pelagic individuals in July 2006. The anchovy biomass in May 2005 was estimated to be 0.147 million tons using the traditional method, while using the summation method, the estimated anchovy biomass was 0.062 million tons in June 2005, 0.21 million tons in June 2006, and in 0.43 million tons in July 2006.

• 수산해양기술연구
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• 제51권1호
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• pp.86-93
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• 2015

Anchovy (Engraulis japonicus) is one of the most important species in the South Sea of South Korea. In order to estimate the biomass of anchovy, acoustic surveys, concurrently with trawling, were conducted in April, July, and September of 2013 and February of 2014 off the coast of Tongyeong and Yeosu. However, anchovies were found only during spring (April) and winter (February) surveys. To display only anchovy species confirmed by trawls on empty spaced echograms, virtual echograms were created. Three target strength (TS) values of anchovy were used: TS_z = 20 log L - (20/3) log (1+z/10) - 67.6 (Zhao et al.), TS_y =20 log L - 72.9 (Yoon et al.), TS_f = 20 log L - 71.9 (Foote). For anchovy schools combined with other species e.g., hairtail, squid, and Korean pomfret, their TS values were used to calculate an average TS. As a result, the anchovy biomass in the winter survey was approximately 75,000 tons (TS_z), 90,000 tons (TS_f), 114,000 tons (TS_y), respectively. The biomass in spring was 9,000 tons (TS_z), 9,200 tons (TS_f), 10,000 tons (TS_y). The sampling variance of spring was 70% and of winter was 30%. In order to manage anchovy resource sustainably, larvae and adult anchovy should be separately surveyed, the optimal area, date, and time for acoustic survey should be investigated, and the biomass survey should be done for relatively long and regular base.

• 한국수산과학회지
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• 제42권3호
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• pp.290-296
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• 2009

Acoustic technologies are commonly used to estimate biomass and distribution of fisheries resources in coastal areas and the open ocean. The pelagic species of Engraulis japonica, Scomber japonicus and Sardinops melanosticta spawn migrate to the southern part of the Sea of Korea and capture of these three species comprise 50% of the total abundance in Korean waters. Since 1970, anchovy landings have increased to 0.2 million tons in 1990, 0.27 million tons in 2001, and 0.25 million tons in 2003. Acoustic surveys were conducted on 24-26, May and 20-21, June 2005 around the Tongyeong, Geojae, and Namhae anchovy fishing ground using a dual beam echo sounder (DT-5000, 200 kHz Biosonics). Using this approach, information was obtained on the distribution (depth and position) of zooplankton, and adult and juvenile anchovy. We calculated and compared anchovy biomass using simple summation and geostatistic methods to assess the advantages and constraints of the two techniques.

• 한국어류학회지
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• 제17권3호
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• pp.205-216
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• 2005

한국 남해안에서 2003년~2004년의 4월, 6월, 8월에 멸치 알의 분포 및 해양환경 특성을 비교하고 냉수대 형성과의 관계를 분석하였다. 조사해역의 수온은 $10.2{\sim}30.7^{\circ}C$, 염분은 25.7~34.7, 클로로필은 $0.14{\sim}0.67{\mu}g/L$, 동물플랑크톤은 $111.52{\sim}262.37mg/m^3$의 범위였다. 멸치 알은 수온 $14.7{\sim}26.9^{\circ}C$와 염분 31.0~34.6 범위에서 주로 나타났고, 봄에서 여름으로 진행될수록 고수온과 저염분역에서 출현하였으며, 동물부유생물 생산의 증가와 함께 알의 평균분포밀도도 높아졌다. 2004년 8월의 멸치산란장은 외양의 난류수와 연안 냉수대간의 수온전선 외해측 해역에 집중되는 경향을 보이므로 연안역의 냉수대형성이 멸치 산란장분포의 제한요인이 되는 것으로 분석되었다.

• 한국어류학회지
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• 제18권1호
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• pp.36-44
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• 2006

2003년 6월부터 10월에 걸쳐 제주해협 동부해역에서의 멸치 난 자치어 분포패턴과 기상요인을 포함한 해양환경의 특성들에 대해 조사하였다. 조사기간 동안 멸치 난들은 주로 연안에 근접한 해역에서 풍부하게 출현하고 있었고, 전체 난 출현량의 약 85% 정도가 7월과 8월에 발생하고 있어서 이번 연구해역에서 멸치의 주산란기는 여름철로 추정되었다. 크기별 멸치 자치어의 분포현황을 살펴본 결과, 비교적 20 mm TL 이상의 자치어들은 연구해역의 동쪽에서 상대적으로 높은 비율로 출현하고 있었다. 멸치의 주산란기인 여름철 연구해역 내 기상현황을 보면 바람인 경우 대부분 10 m/s 미만의 약한 풍속의 바람이 지속적으로 불고 있었고, 연간 강수량 중 37% 정도가 7월과 8월에 집중되고 있었다. 멸치 난 자치어 출현량과 해양 환경요인들과의 상관관계 분석 결과, 난 출현량은 클로로필 a 농도와 요각류 생물량과 유의한 양의 상관관계를 보인 반면 자치어 출현량은 수온과는 유의한 양의 상관관계, 염분과는 유의한 음의 상관관계를 보여주고 있었다.

• 수산해양기술연구
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• 제32권3호
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• pp.223-234
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• 1996

Distribution of Anchovy was analyzed from the experimental operations by the small anchovy drag net fishery in the coastal area of Yang yang - gun and Myongju - gun of Kangwon Province from October to December, 1994. Temperature ranged from $11.4^{\circ}C.$to $17.4^{\circ}C.$throughout the experimental period. Fishes caught by experimental operation vessels were composed of anchovy, Clupanodon Punctatus, Pleuronectidae, Tetraodantidae, Acanthopagrus Schlegeli etc., and the anchovy occupied more than 99.6% of the total catch. Anchovy was characterized by the most abundance of the catch for the individual less than 6cm and the gradual increase after October for those larger than 6cm. CPUE(catch per tow) of anchovy was 684kg in October, 784kg in November, 1,590kg in December and mean CPUE of 3 months from October to December was 1,066kg. Fishing grounds of anchovy were formed in coastal area, from $37^{\circ}$45'N to $38^{\circ}$04'N, off Kangwon Province. Distribution density of anchovy in Chumunjin - up, Kyohang - ri Sachon - myon, and Sachonjin - ri coasts was higher than the other areas. Anchovy caught in this surveyed area was recruited from July to September at the length class between 2cm and 3cm, and grew to the sizes between 4cm and Bem in October, between 5cm and tcm in November, between tcm and Bem in December. Recruitment of anchovy increased from July to September and suddenly decreased after September. Individual number of the population was the largest during the period from August to October and gradually decreased after October. Biomass continuously increased after August, and was the largest in December.

• 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.

• 수산해양교육연구
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• 제18권1호
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• pp.19-30
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• 2006

For fishery stock assessment and optimum sustainable yield of anchovy in Korea, surplus production(SP) models and a maximum entropy(ME) model are employed in this paper. For determining appropriate models, five traditional SP models-Schaefer model, Schnute model, Walters and Hilborn model, Fox model, and Clarke, Yoshimoto and Pooley (CYP) model- are tested for effort and catch data of anchovy that occupies 7% in the total fisheries landings of Korea. Only CYP model of five SP models fits statistically significant at the 10% level. Estimated intrinsic growth rates are similar in both CYP and ME models, while environmental carrying capacity of the ME model is quite greater than that of the CYP model. In addition, the estimated maximum sustainable yield(MSY), 213,287 tons in the ME model is slightly higher than that of CYP model (198,364 tons). Biomass for MSY in the ME model, however, is calculated 651,000 tons which is considerably greater than that of the CYP model (322,881 tons). It is meaningful in that two models are compared for noting some implications about any significant difference of stock assessment and their potential strength and weakness.

• 한국수산과학회지
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• 제47권5호
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• pp.671-681
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• 2014

The distribution and abundance of coastal fish species in Asan Bay, Korea, were estimated from hydroacoustic survey and net catches. Acoustic data were collected with 38 and 200 kHz from July to October of 2012, and converted to the nautical area scattering coefficient (NASC, $m^2/mile^2$) for $0.25n{\cdot}mile$ along ten transects. Japanese anchovy Engraulis japonicus was the dominant specie in the net catches. The virtual echogram technique was used to distinguish E. japonicus from other species based on the differences in the mean volume backscattering strength (${\Delta}MVBS$) at 38 and 200 kHz. Engraulis japonicus and other fishes are mainly distributed in the center channel and outer part of Asan Bay. E. japonicus tends to move from inner to outer Asan Bay in summer and fall. From NASC data, the target strength and length-weight function of E. japonicus and other fishes were used to estimate the E. japonicus stock at 24.1-93.3 tons, and other fish at 40.6-88.4 tons from July to October 2012. The estimated anchovy biomass compared well with the cumulative catch weight from stow net catches. The hydroacoustic method offers an approach to understanding spatial/temporal structure and estimating the biomass of fish aggregations in coastal areas.

• 한국수산과학회지
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• 제47권6호
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• pp.983-996
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• 2014

Fish catches by a set net from January 2007 to November 2009 were analyzed to assess fish species composition and seasonal variations in the coast of Gijang, Korea. Over 389 kg fish representing 78 species, 45 families and 17 orders were collected during three years of the study. Dominant species were jack mackerel Trachurus japonicus, anchovy Engraulis japonicus and herring Clupea palasii, and these three species comprised 67.3% of the total number of individuals and 60.7% of the total biomass. Size distribution of the dominant species for jack mackerel, anchovy and herring ranged from 2.2 cm to 22.6 cm, from 2.5 cm to 14.8 cm, from 4.0 cm to 29.0 cm in fork length, respectively. Anchovy was the only species that occurred throughout all seasons in the Gijang coast. Generally, species richness was highest in spring (April to June) when sea temperature began to increase.