Sukyung Kang

Changes in ecosystem components induced by climate variability off the eastern coast of the Korean Peninsula during 1960–1990

To understand the variations of ecosystem components in response to changing environment, especially relating to a shift in the climate regime during mid 1970s, we analyzed the physical and biological time-series data collected from the eastern part of the Korean Peninsula during 1960-1990. The Northeast Pacific Pressure Index (NEPPI) in winter seasons showed a negative correlation (r=-0.384, p<0.05) with SOI in summer. The standardized chronologies of tree ring-width showed high correlations with precipitation of Ulleung Island and Kangrung city (r=0.408, p<0.05; r=0.410, p<0.05) and seawater temperatures (r=0.407, p<0.05). Sharp increases in tree growth appeared in 1969, 1973, 1979, 1983, and 1987. Among these years, all except 1979 seem to have a close connection with the El Nino which had persisted more than five seasons. Air temperatures in spring at Ulleung Island and Kangrung area appeared comparatively higher during the intense Aleutian low period after 1976. The Mixed Layer Depth (MLD) was shallower (18.2 m) and less variable during 1961-1975 compared to that (26.1 m) of 1976-1990. The shallower MLD in spring during the earlier period resulted in the higher chl a concentration than in the later years. Consequently, estimated zooplankton biomass in spring tended to decrease from the 1960s to the late 1980s in accordance with the phytoplankton decreases. In the East Sea, composition changes in fish species as well as fish catches were observed. Catches of pollock, sardine, and saury had good correlations with annual NEPPI.

Climate variability and its effects on major fisheries in Korea

Understanding in climate effects on marine ecosystem is essential to utilize, predict, and conserve marine living resources in the 21s t century. In this review paper, we summariz ed t h e past history and current status of Korean fisheries as well as the changes in climate and oceanographic phenomena since the 1960s. Ocean ecosystems in Korean waters can be divided into three, based on the marine commercial fish catches; the demersal ecosystem in the Yellow Sea and the East China Sea, the pelagic ecosystem in the Tsushima Warm Current from the East China Sea to the East/Japan Sea, and the demersal ecosystem in the northern part of the East/Japan Sea. Through the interdisciplinary retrospective analysis using available fisheries, oceanographic, and meteorological information in three important fish communities, the trend patterns in major commercial catches and the relationship between climate/ environmental variability and responses of fish populations were identified. Much evidence revealed that marine ecosystems, including the fish community in Korean waters, has been seriously affected by oceanographic changes, and each species has responded differently. In general, species diversity is lessening, and mean trophic level of each ecosystem has decreased during the last 3~4 decades. Future changes in fisheries due to global warming are also considered for major fisheries and aquaculture in Korean waters.

Reproduction of the jack mackerel, Trachurus japonicus Temminck et Schlegel in the coastal waters around Jeju Island, Korea: Maturation and spawning

was investigated based on the samplescaptured in the coastal waters around Jeju Island from January 2007 to December 2008. Gonadosomatic indexbegan to increase in March, and reached a maximum between April to June. After spawning it began to decreasefrom August. Reproductive season was estimated to March-July, with peak in April. Fecundity was proportionalto the size of the female, with the clutch size varying from 33,493 eggs in the smallest female(FL27.0cm) to627,061 eggs in the largest(FL40.6cm). Size at 50% sexual maturity(FL

Size-class Estimation of the Number of Walleye Pollock Theragra chalcogramma Caught in the Southwestern East Sea during the 1970s-1990s

Walleye pollock Theragra chalcogramma fisheries in Korean waters have changed dramatically during the last three decades: the highest catches occurred in 1981, followed by continuous decreases through the 1990s, ending with a complete collapse of the population in the 2000s. The major spawning ground of walleye pollock is located in North Korean waters, and some juveniles (called nogari in Korean,

Ecological relationship between environmental factors and Pacific cod (Gadus macrocephalus) catch in the southern East/Japan Sea

The habitat characteristics of Pacific cod (Gadus macrocephalus) and the ecological relationship between Pacific cod catch and environmental parameters in the southern East/Japan Sea were investigated. Pacific cod is sexually matured at age of 4–5. The highest catch of Pacific cod off the eastern Korean Peninsula occurred in seawater temperature range of 0–4°C and salinity range of 33.8–34.2 practical salinity unit at 100 m. The Cross-Correlation Function analysis showed that there was a significant negative correlation between Pacific cod catch and February seawater temperature at 75 m nearby spawning area with a time lag of 5 years in Korean waters (r = –0.360, p < 0.05). The annual catch of Pacific cod also had a significant correlation (p < 0.05) with zooplankton biomass in coastal nursery areas with a time lag, i.e., the highest ones, r = 0.432 and r = 0.452, for total zooplankton biomass in June of 5 years ago, and for euphausiids abundance in February of 4 years ago from the period when Pacific cod was caught, respectively. Furthermore, total catches of Pacific cod in the southern East/Japan Sea (i.e., sum of Korean and Japanese catches) were negatively correlated with winter Arctic Oscillation Index, and the highest negative correlation (r = –0.364, p < 0.05) was shown with a time lag of 4 years. Considering sexual maturation at ages 4–5, such statistical analyses imply that biotic and abiotic environmental factors during the early life stages of Pacific cod have a significant influence on recruitment after 4–5 years of spawning.

Erratum to: Isolation and characterization of polymorphic microsatellite markers for genetic analysis of chub mackerel (Scomber japonicus)

Chub mackerel, Scomber japonicus, is a species of major importance to fisheries, particularly in eastern Asia. To aid in the sustainable management of this fisheries resource, we isolated eight novel microsatellite loci from the fish and examined their polymorphisms to estimate genetic variability. Genetic variability differed at each locus. The number of alleles ranged from 5 to 14, and observed and expected heterozygosity ranged from 0.43 to 1.00 and 0.50 to 0.86, respectively. One locus showed significant Hardy–Weinberg disequilibrium. No linkage disequilibrium was found. The high variability revealed in this study suggests that these microsatellite markers could prove to be a useful tool for further conservation genetics studies.

Species Composition and Seasonal Variations of Fishes Collected by Set Net in Coastal Waters of Gijang, Korea

부산 연안의 수심은 동해와 남해의 분기점인 송정해수욕장을 기준으로 동해안은 급격한 수심의 증가가 이루어진다(Hwang et al., 2006). 기장 주변 해역은 동해안 남부와 남해안 동부에 위 치하는 해역으로 서·남해안과 비교하여 조석차가 2.0 m 이하 인 소조차 해안으로 분류되고 있다. 따라서 물리적인 환경 특성 상 파랑의 영향을 우세하게 받기 때문에 여름철에는 해류와 바 람의 영향을 받아 저층수의 용승에 의한 냉수대가 자주 출현하 며, 이로 인해 풍부한 영양염이 공급되어 생산력이 높다. 그리고 대마난류의 영향으로 겨울에도 비교적 높은 수온을 나타내어 다른 해역에 비해 많은 어종들이 출현한다(Beack et al., 2010; Kim et al., 2011; Yoo et al., 2013). 정치망은 어군이 내유하기를 기다려 잡는 수동적인 어법으로 주로 이동성이 강하고 떼를 지어 다니는 회유성 어종들이 많이 어획 된다. 정치망의 어획물은 그 지역의 해황의 변화에 영향을 받으며, 회유하여온 어류들의 발육단계에 따른 분포 및 회유 특 성을 파악할 수 있는 정보를 제공한다(Kim et al., 2003). 그리 고 정치망 어장이 설치되는 연안은 수심이 얕고 육상과 인접하 기 때문에 수온의 변동폭이 크고, 이러한 환경변화에 민감한 반 응을 보이는 수산자원의 특성상 계절변화에 따라 정치망 어구 에 어획되는 어류의 양이 크게 달라진다(Cha et al., 2001; Cha et al., 2004). 지금까지 수행된 정치망 어구에 의한 연구를 살펴보면 지역별 로는 거제도(Cha, 1999; Cha, 2009), 제주도(Cha et al., 2001; Cha et al., 2008), 여수(Kim et al., 2003; Hwang et al., 2006; Kim et al., 2013), 동해 고성(Ryu et al., 2005), 남해(Cha et al., 2007; Cha, 2009), 거문도(Cha, 2010) 등의 연구가 있다. 그리 고 기장해역이 포함된 동해 남부연안의 어류 종조성에 관한 연 구는 울산 정치망(Han et al., 2002), 포항 삼중자망(Han et al., 2002), 고리 원자력발전소 취수구 스크린(Gil et al., 2004), 울 진 정치망(Chun et al., 2009), 울진 저인망(Lee, 2011), 왕돌초 홑자망(Lee et al., 2008), 고리 삼각망(Beack et al., 2010), 영일 만 자망(Hong et al., 2008)에 의한 연구 등이 있다. 이와 같이 정치망에 의한 연구는 많이 수행되었으나 대부분 남해 해역에 집중되어 있다. 그리고 남해와 동해의 분기점인 부 기장 연안 정치망에 어획된 어류의 종조성 및 계절변동

A study on fluctuation of the fishing grounds of target fishes by the Korean large purse seine fishery

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Behavioral patterns and in-situ target strength of the hairtail ( Trichiurus lepturus ) via coupling of scientific echosounder and acoustic camera data

The present study focuses on the influence of target strength (TS) changes in the swimming angle of the hairtail (Trichiurus lepturus). We measured in-situ TS at 38 and 120 kHz with luring lamps at a fishing ground for jigging boats near the coastal waters of Jeju-do in Korea. Swimming angle and size of hairtails were measured using an acoustic camera. Results showed that mean preanal length was estimated to be 13.5 cm (SD = 2.7 cm) and mean swimming tilt angle was estimated to be 43.9° (SD = 17.6°). The mean TS values were −35.7 and −41.2 dB at 38 and 120 kHz, respectively. The results will assist in understanding the influence of swimming angle on the TS of hairtails and, thus, improve the accuracy of biomass estimates.

Environmental variability and chum salmon production at the northwestern Pacific Ocean

Chum salmon, Oncorhynchus keta, are distributed widely in the North Pacific Ocean, and about 76% of chum salmon were caught from Russian, Japanese, and Korean waters of the northwestern Pacific Ocean during the last 20 years. Although it has been speculated that the recent increase in salmon production was aided by not only the enhancement program that targeted chum salmon but also by favorable ocean conditions since the early 1990s, the ecological processes for determining the yield of salmon have not been clearly delineated. To investigate the relationship between yield and the controlling factors for ocean survival of chum salmon, a time-series of climate indices, seawater temperature, and prey availability in the northwestern Pacific including Korean waters were analyzed using some statistical tools. The results of cross-correlation function (CCF) analysis and cumulative sum (CuSum) of anomalies indicated that there were significant environmental changes in the North Pacific during the last century, and each regional stock of chum salmon responded to the Pacific Decadal Oscillation (PDO) differently: for Russian stock, the correlations between PDO index and catch were significantly negative with a time-lag of 0 and 1 years; for Japanese stock, significantly positive with a timelag of 0–2 years; and for Korean stock, positive but no significant correlation. The results of statistical analyses with Korean chum salmon also revealed that a coastal seawater temperature over 14°C and the return rate of spawning adults to the natal river produced a significant negative correlation.