A study for species composition and abundance of the fish assemblages in the coastal Sacheon Bay, Korea were conducted using monthly collection by a shrimp beam trawl from March 2015 to February 2016. The number of individuals, biomass and species diversity indices fluctuated with the station and month. Of all 73 species collected, the dominant species in terms of numbers were Liparis tanakae, Zoarces gillii, Amblychaeturichthys hexanema, Ricuzenius pinetorum and Pleuronichys cornutus. The peak number of fishes occurred in March and April, whereas the biomass of fishes was highest in April. The numbers and biomass of fishes were lower in February corresponding with the low temperature, and diversity indices were highest in June. Due to those seasonal difference in abundance of the dominant species, fish community were divided into three main groups. In addition, seasonal difference by station of fish community were devided into four main groups. Juvenile fishes of coastal Sacheon were presented during the study period. It presented that the study area served as an important role in spawning and nursery ground for fisheries resource.

비순환식 고형배지경에서 배액이 토양과 지하수 오염을 발생시키는 문제를 해결하고자 그동안 연구된 데이터를 바탕으로 배액 최소화 재배방식을 확립을 위해 본 연구는 토마토 코이어 수경재배농가 시설에서 FDR 센서, 적산일사량 센서 및 타이머를 이용하여 토마토를 재배하며 급배액량, 생육 및 생산량을 비교하였다. 정식 후 88일까지 일일 식물체당 평균 급액량은 처리구에 따른 큰 차이가 없었다. 하지만 정식 후 88일 이후 107일 까지 TIMER, FDR, IR 제어구 각각의 일일 식물체당 평균 급액량은 IR(2125mL) > TIMER(2063mL) > FDR(1983mL) 수준이었고 108일부터 120일 까지는 IR(2000mL) > TIMER(1664mL) > FDR(1500mL) 수준 이었다. 배액률은 TIMER 제어구의 경우 5~12%, FDR 센서 제어구의 경우 0~7%, IR 제어구의 경우 12~19% 수준으로 IR > TIMER > FDR 순이었다. 정식 후 88일 이후부터는 FDR과 IR 제어구가 급액량에 상이한 결과를 보였는데, 이는 재배 후기 즉, 5월 20일 이후 (정식 후 94일) 누적일사량의 증가로, IR 제어구에서는 급액이 증가된 반면 FDR 센서 처리구는 적심 이후 30일이 경과된 6월 2일경부터 IR 제어구 보다 일일 급액량이 평균 500mL 적게 공급된 결과이다. 식물체 생육 및 상품과 수량도 급액방식에 따른 통계적 유의차는 없었지만, 당도는 FDR 처리구에서 TIMER 처리구에 비해 약 11%, IR 처리구에 비해 약 18% 높았다.

The diet composition of juvenile Trachurus japonicus were studied using 195 specimens collected from 2013 (May, June, July, and September) to 2014 (May, June, and July) in the coastal waters of Geumodo, Yeosu, Korea. The size of juvenile T. japonicus ranged from 4.3 to 15.2 cm in body length (BL). Juvenile T. japonicus was carnivorous and crustaceans predators that consumes mainly consumed copepods. Its diet also included small quantities of decapods, cirripedians, nematods, chaetognathans, fishes, amphipods, cumaceans, ostracods and euphausiids. The graphical method for feeding strategy revealed that juvenile T. japonicus is an opportunistic and specialized predator on copepods, especially Corycaeus. affinis, and showed narrow niche width. Juvenile T. japonicus showed ontogenetic diet change. Small size group individuals (4.3–8.0 cm BL) mainly consumed copepods. The portion of this prey item decreased in the large size group (8.0–15.2 cm BL), and this decrease was paralleled with increased consumption of decapods.

This study was performed to estimate biomass and to provide management plan through population ecological characteristics, including survival rate, instantaneous coefficient of natural and fishing mortalities, and age at first capture of Flathead grey mullet, Mugil cephalus, in the coastal waters of Yeosu. Survival rate (S) of the flathead grey mullet was 3.671. The instantaneous coefficients of natural mortality (M) and fishing mortality (F) was estimated to be 0.325 /year, 0.962 /year for flathead grey mullet. Also fist capure age of flathead grey mullet was 3.61year. The current biomass of the flathead grey mullet in the study area was estimated to be 19.6 M/T and F0.1 and F40% were estimated 0.340 /year, 0.225 /year. For the stock assessment result, flathead grey mullet was not overfished but overfishing.

According to the catch condition of Scomberomorus niphonius in autumn season affected greatly, the catch price for the set net fishery. Catch production and the selling price were relatively even except 2009 showing a great big blooming jellyfish of Nemopliema nomurai in 2008~2011. The fishing cost of the set net fishery in Yeosu has increased gradually by the decrease of catch production and unexpected environmental change like as jelly fish blooming. The increase of fishing cost diminished net income and caused a negative impact in profitability. The lowest Fisheries ratio of gross profit to gross costs the set net fishery were appeared 60.2% in 2010, respectively.Bycatch was highest in 2008 and lowest in 2009. In general, the bycatch was occurred from May to July every year and when Scomber japonicus was most dominant in the catch price by bycatch had a advantage in the profit side. However, the catch increase of immature small fishes by the bycatch, which will bring about the decrease of fisheries resources. Finally, the present state in set net fisheries will act as a defect on the long-term management of fisheries resources.

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 L∞ of 48.04cm, K of 0.1406/year and t0 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.

In the application of the ecosystem-based fisheries assessment Jeonnam marine ranching ecosystem, two fisheries, funnel fishery and trap fishery, were selected as target fisheries. Black seabream, Acanthopagru schlegelii, rock bream, Sebastes inermis, gray mullet, Mugil cephalus, were selected as target species for the funnel fishery, and conger eel, Conger myriaster, was target species for the trap fishery. For assessing indicators of four management objectives, that is the maintenance of sustainability, biodiversity, habitat quality and socio-economic benefits, indicators were selected considering the availability of data, which were 5 indicators for sustainability, 3 indicators for biodiversity, 4 indicators for habitat, 2 indicators for socio-economic benefit. The Objective risk indices for sustainability and biodiversity of two fisheries were estimated at yellow zone, medium risk level. The objective risk indices for habitat and socio-economic benefit were estimated at green zone, safe level. The species risk indices (SRI) were estimated at yellow zone. The fishery risk indices (FRIs) were estimated at 1.143 and 1.400 for funnel net fishery and trap fishery, respectively. Finally the ecosystem risk index estimated at 1.184.

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.

The age and growth of the Pacific cod, Gadus macrocephalus were investigated using left sagittal otoliths of 682 individuals collected in the West Sea of Korea from January to December 2007. The seasonal changes in the ratio of an opaque zone to interval between annular rings revealed that the narrow translucent parts of the otolith were annual growth rings formed between February and March once a year. The spawning period was December to January and therefore the duration from fertilization to the complete formation of the opaque zone became thirteen months. From the parameters calculated using the average length when the year ring was formed, the estimated von Bertalanffy growth equations were Lt=100.0(1-e-0.1640(t+0.5247)) for females and Lt=64.6(1-e-0.3335 (t+0.3342)) for males when is total length in age t.

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.

Reproductive ecology of the sharp toothed eel, Muraenesox cinereus was investigated based on the samples captured in southern Korean waters from January 2010 to December 2011. Gonadosomatic index began to increase in April, and reached maximum between July to August. After spawning it began to decrease from October. Reproductive season was estimated to April-September, with peak in July. Fecundity was proportional to the size of the female, with the clutch size varying from 56,000 eggs in the smallest female (anal length, 27.0cm) to 1,400,000 eggs in the largest (anal length, 49.5cm). Size at 50% sexual maturity (AL50), determined from mature females, were 21.9cm. Annual reproductive cycles of this species could be divided into four successive stages; immature stage (October-February), maturing stage (March-May), mature stage (June-August) and spent stage (August-October).

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.

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 Lt=23.267 (1-e-0.4406(t+1.1971)) for females and Lt=22.030 (1-e-0.5312(t+0.6834)) for males when is total length in age t. Through the growth equations, the maximum length was determined as 23.27cm for females and 22.03cm for males and the growth factor as 0.4406/yr and 0.5312/yr, respectively. Finally, the growth of female S. inermis is larger than the one of male S. inermis.

The population variation of Spanish mackerel (Scomberomorus niphonius) according to its major prey abundance was analyzed using monthly catches of coastal set net fisheries in the southern waters off Gyeongsangnam-do and eastern waters off Gyeongsangbuk-do of Korea from 2006 to 2019. The abundance of Spanish mackerel and its prey species fluctuated almost simultaneously with time lags of +2 to -2 months between the set net fisheries in the southern and eastern waters. The generalized additive model revealed that the abundance of Spanish mackerel was influenced by its prey species such as hairtail and anchovy in southern waters, and common mackerel and horse mackerel in eastern waters. The model deviance explained 49% and 42% of Spanish mackerel abundance in southern and eastern waters respectively. These results suggest that the abundance of Spanish mackerel is affected by seasonal migratory prey fish species in the coastal areas and can be linked to their northerly migration.