• Parasites, Hosts and Diseases
• /
• v.36 no.3
• /
• pp.199-202
• /
• 1998

Neoplasioporus zocconis (Yamaguti, 1934) (Trematoda: Opecoelidae) was found from the intestine of the pale chub, Zacco platypus, for the first time in Korea. The worms were characterized morphologically by oval body shape, bipartited seminal vesicle, sinistrally located genital pore, and lobed ovary, and distinguished from the two other species of Neoplagioporous by body shape and distribution of vitelline follicles. The morphological characteristics, except the ovary, well corresponded to those of the previous descriptions. The morphological difference of the ovary was considered as a character of geographical phenotypic variation.

• Korean Journal of Environmental Biology
• /
• v.27 no.4
• /
• pp.397-405
• /
• 2009

We assessed the physical habitat conditions of pale chub (Zacco platypus) considering various stream order in the Geum river basin. Field monitoring was conducted for ecological and habitat conditions for 28 sites from October 2007 to October 2008. The number of Z. platypus sampled during this period was 2,362. In more than 3rd stream, water depth and velocity showing the highest number of samples were 0.8 m and $0.8\;m\;s^{-1}$, respectively. In addition, the highest number of samples was observed under the condition of total length (TL) (8~10 cm), velocity ($0.3\;m\;s^{-1}$), water depth (0.4 m), substrate size (send, 0.1~1.0 mm~coarse gravel, 50.0~100.0 mm) and habitat type (run). Based on the monitoring data (n=1059) the relationship between body weight (BW) and TL in male and female were estimated as $BW=0.0068{\times}TL^{3.0274}$ ($r^2=0.9102$) and $BW=0.0075{\times}TL^{2.9995}$ ($r^2=0.8517$), respectively. Growth equations on days after parturition (DAP) to the TL were estimated as TL=0.0108DAP+1.5795 ($r^2=0.9721$). By equations (TL 6.9 cm), BW were 2.7 g (male) and 2.4 g (female), and DAP was about 490 days.

• Korean Journal of Ichthyology
• /
• v.35 no.2
• /
• pp.113-120
• /
• 2023

The diet composition of chub mackerel Scomber japonicus were studied using 959 specimens collected in the coastal waters of Jeju Island, Korea from January to November 2022. The size of the specimens ranged from 22.8 to 45.8 cm in total length. S. japonicus were fed mainly on euphausiids that constituted 77.7% in IRI. Fishes were the second largest prey component. Its diet also includes small quantities amphipods, copepods, shrimps, crabs and cephalopods. The diet composition of S. japonicus showed changes in season. The euphausiids feeding rate was highest in summer, whereas the proportion of fishes was higher in winter than in other seasons. The proportion of fishes has increased as the body size of S. japonicus increased, whereas the proportion of euphausiids decreased gradually. As the body size of S. japonicus increased the mean weight of prey per the stomach (mW/ST) tended to increase significantly (One-way ANOVA, P<0.05).

• Korean Journal of Ichthyology
• /
• v.35 no.4
• /
• pp.278-284
• /
• 2023

The feeding characteristics of chub mackerel, Scomber japonicus was studied using 827 specimens caught in the Yellow Sea of Korea during Autumn season from October to December 2021 and September to November 2022. The size of the specimens ranged from 21.1 to 45.1 cm in total length. S. japonicus was a carnivore that consumed mainly on fishes, such as Engraulis japonicus (%IRI=67.9). Its diet also includes small quantities of copepods, amphipods, euphausiids, cephalopods, mysids, shrimps, and crabs, etc. The estimated trophic level of S. japonicus was 3.84. The proportion of fish had increased as the body size of S. japonicus increased, whereas those of euphausiids, copepods and amphipods decreased gradually. As the body size of S. japonicus increased, the mean weight of prey per the stomach (mW/ST) tended to increase (One-way ANOVA, F=2.382, P<0.05).

• The Korean Journal of Zoology
• /
• v.32 no.3
• /
• pp.232-241
• /
• 1989

Two cytosol malate dehydrogenase allelomorphs are found in the Dark Chub, Zacco temmincki, a freshwater fish inhabiting Korean waters. Mdh-1MM(hereafter referred to as A-type) is distributed along the south and southeastern parts of Korea, whereas the B-type(Mdh-1MS) is found everywhere except the southeast. Several syrnpatric populations can be found in the southern areas with no hybridization between them. The pattern of geographic distribution would indicate that A-type is superior adaptation to colder water temperature; this is collaborated by evidence collected from a sympatric length of the Tongchon stream, Namhae. The relative warmth of the water along this portion of the stream's length was determined its altitude and the time of year. Frequency of B-types found was directly proportional to the relative warmth of the water and inversely proportional to the nurnber of A-types found in the sarne station. Current data tends to suggest that the B-type of Zacco temrnincki first differentiated from Zacco platypus approximately one million years ago (Yang et al., 1984) while A-type subsequently branched from B-type 300,000 years later(Yang and Mm, 1987) through a progressive adaptation toward colder temperature.

• Korean Journal of Ichthyology
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2005

A new chub, Zacco koreanus sp. nov., is described on the basis of 104 specimens from six localities in Korea. The new species is distinguished from other Zacco species by the following characteristics: 9~10 scales above lateral line to dorsal fin origin, yellowish anterolateral side of body, no hemicircular red blotch on the upper margin of the eyes, reddish anterior margin of pectoral fin, larger orbit diameter and narrow interorbital width. The new species is widely distributed in the most streams of Korea, except the Yeongsan R., while Zacco temminckii is restricted in the Dongjin R., Yeongsan R., Seomjin R., Tamjin R. and Nakdong R. in Korea. When the two species occurred sympatrically in the same stream, Z. koreanus sp. nov. prefered mostly rapid lotic environments while Z. temminckii inhabited lentic ones. The Korean Z. temminckii was redescribed herein. A key to the Zacco species of Korea and Japan is provided.

• Journal of fish pathology
• /
• v.9 no.1
• /
• pp.15-19
• /
• 1996

The mature spores of present Myxobolus sp. was ovoid in front view with no distinct redges of folds, lemon-shaped in side view with a straight sutural ridge. Spore valves showed symmetrical and smooth. Spores were 9 to $12{\mu}m$ (Mean=$10.4{\pm}0.7$, n=50)in length, 6 to $9{\mu}m$ (Mean=$7.7{\pm}0.6$, n=50) in width and 5.0 to $7.5{\mu}m$ (Mean=6.2, n=7) in thickness. Two polar capsules of spore were pyriform in shape, equal or mearly equal in size, 3 to $6{\mu}m$(Mean=$4.6{\pm}0.6$, n=50) in length, 2 to $3{\mu}m$(Mean=$2.2{\pm}0.3$, n=50) in width, Polar filaments of spore were composed with six to seven coils within capsules. Extended polar filaments were 55 to $135{\mu}m$ (Mean=78.7, n=50)in length. The shape and measurements of the present Mysobolus sp. spores were very similar with the spore of M. cyprinicola Reuss, 1906.

• Analytical Science and Technology
• /
• v.23 no.5
• /
• pp.492-497
• /
• 2010

In this study, mercury concentrations in freshwater fish from Lake An-dong basin were investigated and were compared with the results of the national freshwater fish monitoring survey. The mercury concentrations of fish from Lake An-dong were in the range of 37~611 ng/g and Korean piscivorous chub, the top predator showed the highest average mercury concentrations, $198{\pm}97\;ng/g$. Most of fish caught from upstream of Lake An-dong were herbivorous and omnivorous, and goby minnow and pale chub showed relatively lower mercury concentrations of $21{\pm}16\;ng/g$ and $33{\pm}24\;ng/g$, respectively. Especially, mercury concentrations of long nosed barbel and largemouth bass caught from Lake An-dong were found to be higher than those of the average of the national survey monitoring data.

• Korean Journal of Ecology and Environment
• /
• v.44 no.4
• /
• pp.364-372
• /
• 2011

The pale chub (Zacco platypus) is generally found in Asian countries, such as Korea, Japan, and China. Nevertheless, very little information exists about the genes involved in the metabolism of xenobiotics in this species. This species is useful in monitoring the environmental impact on various pollutants in freshwater as a sentinel fish species. We cloned the full-length cDNA sequence of xenobiotic metabolizing cytochrome P450 1A (CYP1A) gene from Z. platypus and characterized it. Tissue distribution and timedependent induction of CYP1A were studied by real-time RT-PCR. Induction pattern of CYP1A was studied by exposing the fish to an arylhydrocarbon receptor agonist, ${\beta}$-naphthoflavone (BNF). The liver showed the highest level of expression in basal state as well as BNF- treated fish. However, appreciable levels of expression were also recorded in Gill and kidney and the least level of expression was observed in the eye. The results of the time-course study revealed an induction in the liver, brain, and gills after 6 h and 12 h in most of the tissues. This study provides an insight into the xenobiotics metabolizing system of Z. platypus and offers baseline information for further research related to biomarker, stress, and adaptive response of this ecologically important fish species in the freshwater environment.

• Journal of Aquaculture
• /
• v.21 no.4
• /
• pp.234-238
• /
• 2008

We studied the effects of temperature and salinity on the egg development and hatching rate of chub mackerel Scomber japonicus under laboratory culturing condition. The fertilized eggs were transparent, spherical, separate in shape and turned out to be separately and floated, and they contained one oil globule. Fertilized eggs are $0.91{\sim}1.33\;mm$ in diameter. The time of egg development was positively proportional to water temperature with 70 hrs, 48 hrs, 42 hrs, 34 hrs, after fertilization in $16^{\circ}C$, $20^{\circ}C$, $24^{\circ}C$, $28^{\circ}C$, respectively. Hatching rate was highest with the range of $20{\sim}24^{\circ}C$ and $33{\sim}35\;psu$. The relation between the time of egg development (t: hour) and water temperature (T:$^{\circ}C$) was represented by the mathematical formulae. The mean biological minimum temperature was $6.9^{\circ}C$.