• Korean Journal of Ichthyology
• /
• v.2 no.1
• /
• pp.36-46
• /
• 1990

Samples were obtained with a set net during 7 months between March and October in 1987 off the coast of Hwasun, southern part of Cheju Island. Most of organisms, representing 36 species, were less than 20cm(96%) in length, and 30g(74%) in weight. The four most abundant species were jack mackerel, Trachurus japonicus ; squid, Todarodes pacificus ; mackerel, Scomber japonicus ; and Apogon semilineatus, which comprised about 89% of the total individuals and about 70% of the total weight. Diversity index, the number of species and information index for individual were high in early spring, even though biomass was not abundant. On the other hand, diversity index and information index for individual were relatively high in August in spite of low occurrence of the species number. A cluster analysis of 24 species which appeared more than twice during the 7 samplings were illustrated from the similarity matrix. All of the 24species were grouped at the 0.14 similarity level. They were divided into four groups at 0.50 level.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.45 no.4
• /
• pp.243-250
• /
• 2009

Maturation and spawning of the jack mackerel, Trachurus japonicus was investigated based on the samples captured in the coastal waters around Jeju Island from January 2007 to December 2008. Gonadosomatic index began to increase in March, and reached a maximum between April to June. After spawning it began to decrease from August. Reproductive season was estimated to March-July, with peak in April. Fecundity was proportional to the size of the female, with the clutch size varying from 33,493 eggs in the smallest female(FL=27.0cm) to 627,061 eggs in the largest(FL=40.6cm). Size at 50% sexual maturity(FL50), determined from mature females, was 26.6cm FL. Annual reproductive cycles of this species could be divided into six successive stages; immature stage(September-December), nucleolus stage(January-February), yolk vesicle stage(February-March), vitellogenic stage(March-April), ripe stage(April-July) and spent stage(July-September).

• Journal of Aquaculture
• /
• v.8 no.3
• /
• pp.221-229
• /
• 1995

Two long term feeding trials using moist pellet diet were conducted to study the growth pattern of Korean rockfish (Sebastes schiegeli). Two groups of the fish with initially averaging of 6.8g and 11.0g were stocked in the indoor FRP tanks, and were fed with moist pellet for 22 months and 10 months, respectively. It took approximately 11 months and 23 months after parturition to grow up to 200g and 500g of average body weight, respectively. Average body weight of fish increased almost linearly, and no significant growth stagnation was observed even in winter (the lowest water temperature was $11^{\circ}C$) and summer (the highest water temperature was $25^{\circ}$) seasons. Growth rate, feed intake and protein intake decreased gradually with fish size up to approximately 200g of average body weight, and these values were remained relatively consistent afterward.

• Korean Journal of Ichthyology
• /
• v.7 no.2
• /
• pp.101-108
• /
• 1995

Four specimens of Megalaspis cordyla(Linnaeus) belonging to the family Carangidae and three specimens of Champsodon snyderi Franz belonging to the family Champsodontidae were collected for the first time from Nam-hae and Pusan, Korea. Megalaspis cordyla is similar to other genera, but differs in some morphological charac-ters : the presence of finlets, the beginning portion and shape of scutes, and the length of pec-toral fin. A new Korean name "Ko-d$\breve{u}$ng-ka-ra-ji" is proposed for the M. cordyla. Champsodon snyderi is differs from C. capensis in the number of pectoral fins and the pres-ence of scale on cheek ; from C. longipinnis in having a pale spinous dorsal fin ; from C. guen-theri and C. machaeratus in having 11 lower gill rakers, 19 soft dorsal fin rays. A new Korean name "Ak-$\hat{o}$-chi" is proposed for the C. snyderi.

• Korean Journal of Ichthyology
• /
• v.24 no.1
• /
• pp.20-26
• /
• 2012

The feeding habits of john dory, $Zeus$ $faber$, were studied using 462 specimens collected in the coastal waters of Geomun-do, Korea. The size of the specimens ranged from 7.8 to 40.2cm in standard length (SL). $Z.$ $faber$ was a piscivore that consumes mainly teleosts such as $Trichiurus$ $lepturus$, $Scomber$ $japonicus$, $Callanthias$ $japonicus$ and $Trachurus$ $japonicus$. Of the fish species $T.$ $lepturus$ was the most preferred prey. Its diet also includes cephalopods, shrimps and euphausia. Smaller individuals (<15 cm SL) fed mainly on fishes and cephalopods. The proportion of cephalopods decreased as body size increased, whereas the consumption of fishes gradually increased. Fishes accounted for almost stomach contents of larger individuals (more than 15 cm SL).

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.4
• /
• pp.637-643
• /
• 2015

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.

• Korean Journal of Ichthyology
• /
• v.19 no.2
• /
• pp.132-141
• /
• 2007

A total of 27 fish species were collected by a gill net in Masan Bay. The dominant fish species were Konosirus punctatus, Mugil cephalus, Engraulis japonicus, Psenopsis anomala, Lateolabrax japonicus, Leiognathus nuchalis, Chelon affinis, Trachurus japonicus, and these accounted for 87.6% of the total numbers. The numerically dominant fish species made up 95.4% of biomass. These were primarily juvenile species or early larger species. Temporal variation in both species composition and abundance was large: the peak number of fishes occurred in March 2005 and July 2005, whilst biomass of fishes was the highest in September 2005 and November 2005. Fish numbers as well as biomass was lowest in November 2005. Temporal changes in the abundance of fishes corresponded with temperature. A gill net can be used as an alternative fishing gear to collect pelagic fishes commercially, although a gill net has a strong selectivity for the target fish species or for size.

• Korean Journal of Ichthyology
• /
• v.22 no.3
• /
• pp.186-194
• /
• 2010

Seasonal variation in species composition and abundance of fish assemblage in the coastal waters off Gori were determined using monthly samples collected by a three-side fyke net in 2006. Of a total of 59 fishes collected, the dominant species were Trachurus japonicus, Mugil cephaIus, Konosirus punctatus, Apogon lineatus, Chelidonichthys spinosus, Ditrema temmincki, Sebastes schlegeli and Apogon semilineatus. These 8 fishes accounted for 92.7% of the total number of individuals collected. The number of fish species, number of individuals, biomass and species diversity indices fluctuated with the seasons. The peak number of fishes occurred in December, whereas biomass of fishes was the highest in March. The number and biomass of fishes were lower in January corresponded with the low temperatures, and the diversity indices were lower in December than in any other month.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.35 no.2
• /
• pp.178-195
• /
• 1999

The species composition and seasonal variation in abundance of fishes in the Nakdong River estuary were investigated monthly from February 1987 to January 1988. During the study period, 23,008 specimens belonging to 100 species were collected. The most abundant fish species were Repomucenus valenciennei, Pholis fangi, Leiognathus nuchalis, Trachurus japonicus, and Sardinella zunasi. These five species comprised 63.0% of total fishes and 47.8% of total biomass collected. The seasonal dominant fish species were P. fangi and R. valenciennei in spring, R. valenciennei and Cynoglossus joyneri in summer, Thryssa kammalensis and Apogon lineatus in fall, and R. valenciennei, L. nuchalis and S. zunasi in winter. The number of fish species, number of individuals collected, and species diversity indices fluctuated with the seasons. The number of species and number of individuals decreased significantly in the upper estuary. While temperature was an important factor which influenced on seasonal fluctuation of the fish community, salinity determined the spatial distribution of fishes.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.24 no.4
• /
• pp.150-157
• /
• 1988

The oceanographic condition around the set net fishing ground in Yeosu Bay was investigated by the oceanographic observation in June, July and August, 1988. Also the catch of the set net was analized by daly catch data of the three set net fishing ground from April to September, 1988. The results obtained are as follows: 1) The coastal surface water is high temperature and low salinity through the influence of land, and the off shore water and bottom water are low temperature and high salinity. 2) The eddy current and the sharp thermocline in June appeared in August at the set net fishing ground, and a good catch appeared in June and August. 3) The surface temperature and salinity at the set net fishing ground are 11$^{\circ}C$ to 27$^{\circ}C$ and 31.60$\textperthousand$ to 34.80$\textperthousand$. The surface temperature and salinity of a maximum good catch are 21$^{\circ}C$ and 33.80$\textperthousand$ to 33.99$\textperthousand$ respectively. 4) The dominant species of fish were spanish mackerel, scad, anchovy, sardine, common mackerel, hairtail, crab, yellow tail, in order of catch.