Heeyong Kim

Dominant causes on the catch fluctuation of a set net fishery in the mid-south sea of Korea

The annual and monthly fluctuation in the species composition and the catch abundance of dominant species were analyzed using the daily sales slip catch data by a set net in the offshore waters off Dolsan Island in Yeosu from March 2004 to December 2011. Mean catch from 2004 to 2011 is 372M/T and the maximum and the minimum catch are 526 M/T in 2005 and 27 2M/T in 2009, respectively. The dominant species were Engraulis japonicus mainly in spring and Scomberomorous niphonius in Autumn and therefore the set net catch that is dominated by S. niphonius`s catch was much higher in autumn than in spring. Through comparative analyses for the environmental factors to the annual catch fluctuation, it is revealed that the water temperature variation affected the recruitment property of S. niphonius to the fishing ground but the effect of typhoon on the catch fluctuation was not distinct. Furthermore, the big blooming event of jellyfish, particularly Nemopilema nomurai, that occurred in 2009 showed a tendency of faster appearance and later extinction until December. The occurring characteristic of N. nomurai became a direct cause that brought about the lowest total catch in 2009 since the dominant species catch of the set net fishery was concentrated mostly in Autumn.

Recruitment characteristics of jack mackerel , Trachurus japonicus , in the waters around the Geumo Islands by using both sides fyke nets

Species composition of fishes and the recruitment properties of jack mackerel , Trachurus japonicus , in the waters around the Geumo Islands in the mid -South Sea were investigated by using both sides fyke nets every month from February to December 2010. During study period , a total of 30,503 fishes (1,380.4 kg ) were collected and classified into 2 classes , 16 orders , 61 families and 121 species . The dominant species was jack mackerel occupying 80.5% of total individuals and 44.4% of total biomass . The fork length range of jack mackerel was 5.5 －26.8 cm and individuals about 6 cm was appeared only in the middle and southern area of the Geumo Islands in May . The new recruitment of jack mackerel appeared from May in the waters around the Geumo Islands is probably caused by the warm water intrusion associated with the development of stratification due to the extinction of seasonal coastal cold waters by the increase of solar radiation heat . Furthermore , the jack mackerels less than 6 cm recruiting in the mid -South Sea in spring were considered as mixed ones by individuals spawned in the East China Sea and in the waters around the Jeju Island considering the collected time , migration period and spawning time of them .

Age and Growth of Marbled sole, Pleuronectes yokohamae (Günther) in the southern waters of Korea

The age and growth of the Marbled sole, Pleuronectes yokohamae were investigated using left sagittal otoliths of 832 individuals collected in the mid-southern waters of Korea from January 2006 to April 2007. The seasonal changes in the ratio of an translucent zone to interval between annular rings revealed that the boundaries between translucent and opaque parts of the otolith were annual growth rings formed between May and June once a year. The spawning period was November to March and therefore the duration from fertilization to the complete formation of the annual growth ring became fifteen months. The parameters of von Bertalanffy growth equations estimated using the average standard length at each age are the of 48.04cm, K of 0.1406/year and of -0.5116 for female and 26.14cm, 0.3056/year and -0.8202 for male, respectively. Finally, it is suggested that the growth of female is faster than that of male from age-2.

Study for fishery management measure on gape net with wings with catch composition in the water of Jin-do

In this study, we conducted field surveys to investigate and analyze species and length composition of catch from gape net with wings being set in two areas - Masari, Supomri - located in southern part of Jin-do for understanding fishing characteristics of gape net with wings fishery from March to September of 2011. And with those results, we attempted to propose fishery management strategy to harvest fisheries resources continuously. Catch obtained from field surveys comprised total 78 species, which accounted for 53 species of fish, 20 species of crustacean, 4 species of cephalopod and one of polychaete. As to species composition in weight, it showed that there was 88.5% for pisces, 9.0% for cephalopoda and 2.5% for crustacea. As to catch specifics by area, there was 36 species (596,891 individual, 456,551g) of pisces, 17 species (35,815 individual, 12,909g) of crustacea and 3 species (2,876 individual, 3,004g) of cephalopoda in Masari area. In Supumri area, there was 41 species (396,898 individual, 281,457g) of pisces, 15 species (16,113 individual, 7,772g) of crustacea and 4 species (6,792 individual, 72,329g) of cephalopoda and one polychaeta (36 individual, 11g). Catch of anchovy by month recorded on high level on June, July, September in both areas. When considering size composition by month, it was found that new populations recruit to these fishing grounds on June and September. Most of bycatch species including hairtail (Trichiurus lepturus), dotted gizzard shad (Konosirus punctatus), conger eel (Leptocephalous), Pacific sandlance (Ammodytes personatus), horse mackerel (Trachurus japonicus) were juvenile, and grass puffer (Takifugu niphobles), Kammal thryssa (Thryssa kammalensis), Japanese sardinella (Sardinella zunasi) were also small in size. As a result, it is considered that gape net with wings fishery which is likely to catch juvenile needs to be set fishing prohibit period for conserving above stocks during the period excluding main fishing periods of anchovy or fisheries management such as expanding mesh size for preventing juvenile catch.

Age and growth of the black rockfish, Sebastes inermis, in the Jeonnam marine ranching area in the southern Sea of Korea

Characteristics of age and growth of the black rockfish, Sebastes inermis sampled in the Jeonnam Marine Ranching Area (JMRA) around Geumo Islands south of Yeosu were investigated using 642 otoliths from March 2009 to February 2010. The opaque zone was formed in September once a year and hence it was used as an annulus. The parturient period was December to January, and therefore the duration from fertilization to the complete formation of the opaque zone was nineteen months. From the parameters calculated using the average length when the year ring was formed, growth of S. inermis were expressed by von Bertalanffy growth equation as

The Pulation Structure of the Pacific Cod (Gadus macrocephalus Tilesius) Based on Mitochondrial DNA Sequences

To assess population structure and genetic diversity among the Pacific cod (Gadus macrocephalus), we investigated mtDNA COI gene sequences of 7 populations. Samples were obtained from Sokcho, Wolsung, Geojedo, Yeosu, Geomundo and Westsouth in 2008 and 2009 (n=28). The sequence analysis of 28 individual samples showed 8 haplotypes, ranging in sequence divergence by pairwise comparisons from 0.2 to 2.2% (1 bp 11 bp). The Ga1 haplotype was found in Wolsung, Geojedo, Yeosu, Geomundo and Westsouth, and was regarded as the main haplotype of Korean Pacific cod. Ga2, Ga3, Ga6 and Ga7 haplotypes were found only in Sokcho. In the PHYLIP analysis, 8 haplotypes formed two independent groups: cladeA consisted of Ga2, Ga3, Ga6 and Ga7 haplotypes, whereas cladeB contained Ga1, Ga4, Ga5 and Ga8 haplotypes. The genetic relationship between the two groups was weakly supported by bootstrap analysis ( m =infinite) and a very low level of geographic distance (F ST =-0.0123-(-0.0423)) were observed. The estimates of genetic distance between Sokcho and the other localities were all statistically significant (p<0.05, p<0.01, p<0.001), indicating a limited mtDNA-based gene flow between Sokcho and other regions. The finding of the lowest genetic diversity in the Sokcho population (nucleotide diversity=0.00589) may be a result of relatively small population size and interrupted gene flow to other localities. Consequently, the overall considerable migration of Pacific cod population in Korea caused a genetically homogeneous structure to form, although a distinct population was found in this study.

Understanding the Migration Path of Spanish Mackerel Scomberomorus niphonius using Catch Distributions

우리나라의 삼치어획은 주로 남해와 동중국해에서 이루어지 지만 서해와 우리나라 동해남부(Lee et al., 2011) 및 동해의 일 본 연안 측에서도(Nishikawa et al., 2014; Tojima et al., 2013) 어획되어 우리나라 주변 대부분의 해역에 분포한다고 할 수 있 다. 삼치의 어획량은 일본에 비해 상당히 높은 수준이지만 삼치 에 대한 연구는 대부분 삼치의 식성, 연령 및 성숙·산란에 관한 연구들로(Huh et al., 2006; Kim, 1972; Baek et al., 2007) 자 원생물학적 연구(Inoue et al., 2007; Nishikawa et al., 2014; Tojima et al., 2014) 외에 자원생태학적인 분야에도(Kishida, 1989; Tameishi et al., 2005; Ueda and Tekiba, 2009) 다양한 연구가 수행된 일본과는 달리 상당히 제한된 분야에 국한되어 수행되었다. 삼치는 우리나라 서해와 남해의 연안 표층에서 어 군을 형성하며 이동하는 대표적인 회유성 어종으로 봄에 서해 와 남해의 연안으로 이동하여 산란을 하고, 가을에 월동을 위 해 남쪽으로 이동한다고 보고되었다(Chyung, 1977; Yamada et al., 1986). 하지만, 지금까지 우리나라 주변 해역에 분포·회 유하는 삼치의 자세한 어획분포특성이나 회유특성에 대해 연구 된 바가 없었다. 삼치를 동중국해계군과 세토내해계군으로 나 누고 있는 일본의 경우는 동해의 일본 연안이나(Tojima et al., 2013; Inoue et al., 2007) 세토내해 삼치를 대상으로 이동·회유 특성 연구가 수행되었다(Kishida, 1989). 동해 일본 연안과 세 토내해 등 제한된 해역에서 수행된 삼치의 이동·회유특성 연구 결과를 고려해볼 때, 우리나라 주변해역에서 삼치의 분포·이동 또한 산란과 월동을 위한 회유특성을 보일 것으로 추정되며, 이 러한 회유특성을 기반으로 계절적인 이동특성의 추정도 가능 할 것으로 판단된다. Lee et al. (2011)은 환경변화에 따른 삼치 어획량 변동에 관한 연구에서 서해로 북상하던 삼치 어군의 감소와 달리 동해로 북 상하는 어군이 과거에 비해 늘고 있어 우리나라 연근해를 회유 하는 삼치의 이동경로가 동해 쪽으로 확대되고 있다고 설명했 다. 동해의 일본측 연안의 경우에도 1998년 이후 삼치 어획량 이 증가하기 시작하여 2003년에는 서쪽연안, 2007년에는 북쪽 어획특성을 이용한 삼치(Scomberomorus niphonius)의 회유경로 추정 김희용·임유나*·송세현·김영혜

Species Composition of Fish Collected by a Gape Net with Wings in the Coastal Waters of Jindo, Korea

【Species composition of the fish in the coastal waters of Jindo was determined using monthly sample collection by a gape net with wings in 2014. Of a total of 41 fishes collected, the dominant species were Engraulis japonicus, Thryssa kammalensis, Sardinella zunasi, Leiognathus nuchalis, Amblychaeturichthys hexanema, Neosalanx anderssoni, Acanthogobius flavimanus. The former three species were the migratory species and the other four species were the resident species. These 7 fishes accounted for 99.6% of the total number of individuals collected. Monthly species composition did not show a clear seasonal trend. The peak number of individuals occurred in May, lowest in November. Fish were divided into four groups by the cluster analysis.】

Species Composition of Bycatch Fishes Collected by a Gape Net with Wings in the Coastal Waters of Dolsan-do, Yeosu, Korea

The species composition of bycatch species in the coastal waters of Yeosu were determined by monthly sample collection using a gape net with wings in 2014. Of a total of 32 fishes collected, the dominant species were Ammodytes personatus, Conger myriaster leptocephali, Sebastes inermis, Trichiurus lepturus, Thryssa kammalensis, Leiognathus nuchalis, Syngnathus schlegeli, Thryssa adelae and Hexagrammos otakii. These 9species accounted for 95.2% of the total number of individuals collected. Most of the fish caught were juveniles and small fishes. Based on the results of multidemensional scaling (MDS) analysis, the bycatch fishes were divided into five group.

Spatial and temporal variations of the trophodynamics of anchovy (Engraulis japonicus) in the southern coastal waters of Korea using fatty acid trophic markers

The abundance and proportion of specific fatty acids differ among fundamental groups of lower trophic levels. Some prey fatty acids are transferred directly to predators. In this study, fatty acid compositions of juvenile, young, and adult anchovies (Engraulis japonicus) were evaluated as trophic markers for feeding environments in four regions (Tongyeong, Namhaedo, Yeosu, and Jindo) of the southern coastal waters of Korea. The condition factor (CF) increased with advancing life stage, and the gonad somatic index (GSI) peaked in May. C14:0, C16:0, C18:0, C16:1n-7, C18:1n-9, C20:1n-9, C20:5n-3, and C22:6n-3, among other saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) were predominant in all life stages. We observed geographic eastward and life-stage dependent trends wherein C14:0, C16:1n-7 C18:1n-9, and C20:5n-3 fatty acids increased, while C22:6n-3 decreased during development from juvenile to adult in most season. Indicating Calanus copepod trophic markers, MUFA 20:1n-9 and 22:1n-9, were high in the upwelling area of the southwestern sea, but low in southern coastal areas. High MUFA 18:1n-9 and SFA 16:0 in all areas suggests a significant dietary input from non-calanoid copepods in the southern coastal waters of Korea. High dependence on dinoflagellate harmful algal blooms (HABs) was detected in the ratios of major fatty acids (C20:5n-3/C22:6n-3 and C16:1n-7/C16:0) in juvenile and young fish. These results indicate that life stage- and area-specific fatty acid compositions may be explained by regional feeding environments, which influence juvenile and young fish growth and adult maturation in the southern coastal waters of Korea.