• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.48 no.2
• /
• pp.118-127
• /
• 2012

The reproductive ecology of the glowbelly, $Acropoma$ $japonicum$ was examined using 637 specimens collected monthly from January to December 2006 in the coastal waters off Gori, Korea. The specimens ranged in standard length (cm, SL) from 2.9 to 11.4cm for female, 2.7 to 10.5cm for male. The gonadosomatic index (GSI) of female was highest in September and decreased until December, and the spawning season lasted from August to November. The monthly sex was not different significantly ($x^2$-test, p>0.05). The size at 50% maturity was estimated at 6.0cm SL. $A.$ $japonicum$ was multiple spawner that spawn on more than one occasion in a single spawning season, and the maximum egg diameter was 0.75mm. Fecundity (F) ranged from 12,052 to 104,246 eggs, with the mean of 38,321 eggs. The relationships between fecundity and standard length (cm, SL), body weight (g, BW) were estimated as $F=86.278SL^{2.9652}$ ($R^2$=0.7970) and $F=3036BW^{1.0081}$ ($R^2$=0.7992), respectively.

• Korean Journal of Ichthyology
• /
• v.25 no.2
• /
• pp.135-140
• /
• 2013

Microphysogobio koreensis, an endemic Korean freshwater fishes belonging to Cyprinidae, is protected as a 2nd grade of endangered fishes by the ministry of the Environment. For this species, the study on the spawning microhabitat including structure of streambed and spawning grounds was carried out. The streambed that this species mainly lives consists of boulders, cobbles, and pebbles, the so-called Bb type, with a depth of 0.3 to 1.0 m and a rapid velocity of $0.5{\pm}0.2$ m/sec. But the main spawning grounds where the spawning is actually occurring, is relatively shallower, $0.4{\pm}0.1$ (0.4~0.6) m depth, and faster, $0.8{\pm}0.1$ (0.6~0.9) m/sec velocity, whereas the region that the fertilized eggs are attached are rather slowest to 0.4m/sec. The spawning starts at a water temperature of $20^{\circ}C$ in earlier May, laying their eggs on the cobbles' or boulders' surface or in between them. In particular, with a wide range of streambed structures, natural spawning grounds' environments may let the fertilized eggs not be swept from rapid current and secure efficient dissolved oxygen. The individuals, however, do not appear at the grounds any more after the spawning season, and it is expected that they may move into deeper water such as Lakes or lower streams.

• Korean Journal of Ichthyology
• /
• v.29 no.3
• /
• pp.197-204
• /
• 2017

Life history of the Siberian stone loach, Orthrias toni, were investigated using samples collected from Buk Stream, Goseong-gun, Gangwon-do, Korea. Growth was rapid between April and October when water temperature exceeded $10^{\circ}C$, but growth almost stopped from November-March when water temperature was below $10^{\circ}C$. Age groups for O. toni estimated by frequency distribution of total length in spawning season (May) indicated the 60~81 mm is 1-year old, the 82~99 mm group is 2-years old, the 100~119 mm is 3-years old, and the 120~140 mm is more than 4-years old. Total length range by sex was similar, and sex ratio (♂/♀) was 0.73. Spawning season according to the gonadosomatic index (GSI) was May with water temperature $14{\sim}17^{\circ}C$, and almost all fish were mature after one year old. Fecundity increased rapidly with age with an average of $4,460{\pm}3,302$ ($mean{\pm}SD$). Size of mature eggs was $0.87{\pm}0.03mm$ in diameter irrespective of age.

• Korean Journal of Ichthyology
• /
• v.5 no.2
• /
• pp.194-207
• /
• 1993

This paper deals with seasonal fluctuation of fish communities around the coast of Kunsan, Korea from 1992 to 1993. A total of 98 fish species with 82 genera, 47 families, and 14 orders were collected during the study. Among fishes caught by trawl net, Cynoglossus joyneri and Repomucenus ornatipinnis predominated throughout the year, and by long back net Harengula zunasi and Engraulis japonica except winter season. There is a difference between biomass caught by long back net and by trawl net, the former showing a peak in summer and the latter showing peaks in late spring and winter. This result appears to be due to the occurrences of Platycephalus indicus and Liparis tanakai for the spawning in investigated areas. Among the 14 species collected in the intertidal zone, 13 species of the family Gobiidae were mostly found in the spawning season. These results may suggest that the coastal area of Kunsan provides a good spawning ground for the coastal fishes. It is considered that the seasonal fluctuation of the abundance and species composition in fishes in this area is mainly affected by the water temperature and the bottom habitats.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.37 no.5
• /
• pp.393-399
• /
• 2004

Annual reproductive cycle of Siganus canaliculatus was studied based on monthly variation of gonadosomatic index (GSI) and histological changes of gonads. Samples were monthly collected by a set net along the southern coast of Jeju Island, Korea from January to December, 1996. Variation of the monthly mean GSI values showed similar trends in female and male. The GSI values increased from June and reached a peak in the spawning season in July $(9.65{\pm}1.96\;in\;females,\;10.00{\pm}4.27\;in\;males)$, and decreased rapidly thereafter. Female hepatosomatic index (HSI) values ranged from $1.26{\pm}0.22\;(in\;April)\;to\;2.34{\pm}0.39$ (in July), and male HSI values ranged from $1.27{\pm}0.21\;(in\;April)\;to\;1.87{\pm}0.30$ (in October). Annual reproductive cycle was classified into the following successive stages: in female, growing stage (from February to June), mature stage (from June to July), ripe and spawning stage (from July to August), recovery stage (from August to March); and in male, growing stage (from January to June), mature stage (from June to July), ripe and spent stage (from July to August), and recovery stage (from August to April). Based on these data, this species has a group-synchronous oocyte development and one spawning season a year.

• Korean Journal of Ichthyology
• /
• v.12 no.3
• /
• pp.186-191
• /
• 2000

Population ecology of Abbottina springeri has been investigated from March to November, 1995 at Musimchon stream of Kadok-myon, Chongwon-gun, Chungchongbug-do. The favorite habitat was a sluggish area with muddy bottom, but larger individuals more than 60 mm in total length were also collected at rapids of low velosity. Judging from the total length frequency in this population on June, total length 30~50 mm group is one year old, 50~65 mm group is two years old, and longer than 65 mm is regarded over three years old. Sexual dimorphism was revealed conspicuously in genital papilla, nuptial tuberles and nuptial pigmentation in the males at spawning season. Peak season of spawning was June when the water temperature reaches $20\sim25^{\circ}C$ and they start spawning at the age of two. The sex ratio of female to male was 1:0.93. The mean of egg number and egg size in ovary were 652 and 0.43~0.06 mm respectively. According to the contents of stomach, this species feeds mainly on botton algae at all ages and some aquatic insects in adult.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.6
• /
• pp.394-410
• /
• 2007

Anchovy spawn from the end of May to mid-October, when the water temperature is $14.8-27.2\;^{\circ}C$ and the salinity is 26.0-33.6 psu. The main spawning season is between July to August, when the water temperature is $21.7-27.2\;^{\circ}C$ and the salinity is between 26.0-32.2 psu. The main spawning grounds of anchovy are coastal areas shallower than 50 m around the islands located in the Jeju Strait. Anchovy larvae are distributed near the fronts between Chuja-do, Jangsu-do, Yeoseo-do, and the open sea rather than in the spawning grounds. Anchovy eggs and larvae density increased in accordance with the high level of $Chlorophyll-{\alpha}$ during the summer season (July-August). In terms of the suspended sediment (SS) levels along the northern coast of the Jeju Strait, high densities of anchovy eggs (12.0-18.0 mg/L) were observed, mainly in the area affected by the coastal waters of the southern sea with high SS levels, while larvae (10.0-19.0 mg/L) tended to be distributed over a wide area with high SS levels, including the open sea. In terms of the dissolved oxygen (DO) content, eggs (5.4-6.8 mg/L) were observed in coastal areas with a high DO content, while larvae (4.2-6.4 mg/L) were distributed widely in areas with a relatively low DO content, from the southern coast to the open sea.

• Journal of Ecology and Environment
• /
• v.29 no.3
• /
• pp.277-286
• /
• 2006

Population ecology of Cobitis tetralineata was examined at Churyeong Stream, Seomjin River, Korea. C. tetralineata inhabited on the sand bottoms with $10{\sim}20cm/see$ in current velocity, and $30{\sim}150cm$ in water depth. This species was active on the sand during the daylight hours from March to October, but they hibernated in the inside of the sand during the winter season. Sex ratio of female to male was 1:0.57, and female was $20{\sim}30mm$ (TL) larger than male. The age group of C. tetralineata (female) population showed that the $20{\sim}40mm$ group is 0+ years old, the $45{\sim}65mm$ group 1+ years old, the $65{\sim}90mm$ group 2+ years old, and the group longer than 90 mm over 3 years old. Males $13{\sim}14$ months old after hatching had lamina circularis at the base of its pectoral fin as a secondary sexual character. And in its spawning season, lateral color pattern of male was changed as a sexual dimorphism. The spawning season may be from late June to middle July, $22{\sim}26^{\circ}C$ water temperature. The average number of mature eggs in ovary was about $1,288{\pm}583(474{\sim}2,976)$, egg diameter was about $0.98{\pm}0.1mm$. C. tetralineata fed mainly on Chironomidae, Arcellidae, Branchioda and Algae. The feeding rate was the highest in April and September, but they did not fed in the winter.

• Korean Journal of Ecology and Environment
• /
• v.42 no.1
• /
• pp.58-66
• /
• 2009

The telemetry of eight adult manchurian trouts (Brachymystax lenok tsinlingensis) in the upper part of the Nakdong River, which is the southern limit of distribution of manchurian trout on the Korean peninsula, was used to examine migration patterns and evaluate characteristics of over-wintering and the spawning season between December, 2007 and May, 2008. Based on the tracking data, the tagged fish showed a limited migration between adjacent pools, moving only up to $8.6m\;day^{-1}$ during the winter season (December to February). Hydraulic conditions of over-wintering pool areas were, ca. 1m depth, slow moving surface water with areas of sand and gravel. The migration of tagged individuals was successful, moving up to $96.2m\;day^{-1}$ during the spawning season. Two tagged individuals (BL4, BL6) exhibited upstream migration, whereas others showed downstream movements. The timing of upstream migration of the two individuals was consistent with an increasing phases of water level and discharge. The fishes migrating toward the down stream moved to the wide pool areas downstream, where they spent the summer season for the growth.

• Korean Journal of Ichthyology
• /
• v.6 no.2
• /
• pp.222-236
• /
• 1994

Sexual maturation and spawning of the spottybelly greenling, Hexagrammos agrammus were histologically studied under photomicroscopy by considering changes in gonadosomatic index, hepatosomatic index and fatness, egg diameter composition, first sexual maturity and fecundity. The fish samples were collected monthly at the coastal area of Tongbaeksom, Pusan, Korea from July 1991 to July 1992. The gonadosomatic index(GSI) increased in September and reached the maximum value(female 4.31, male 1.61) in November when the gonad was mature and ripe. The values were decreased suddenly during the spawning season from December, and declined from January to August. The annual variations of hepatosomatic index(HSI) appeared to be correlated with those of GSI in female but were not significantly correlated in male. HSI in female began to increase in autumn with the increase of GSI, and reached the maximum in winter when the ovary was mature. Percentages of first sexual maturity in female and male fish were 50 % in 11.0~11.9 cm and 100 % in 13.0~13.9 cm groups. Both sexes participated in reproduction from one year old. H. agrammus was considered as a polycyclic species and spawns 3 times or more in the spawning season. Number of total and mature eggs in the absolute fecundity were proportional to standard length and body weight, respectively. Number of total and mature eggs in relative fecundity were also proportional to standard length, but rather decrease with increasing of body weight. Fatness coefficients reached the maximum value(female 15.32, male 15.14) in September(growing stage), and the values were sharply decreased after spawning. Thereafter, fatness values were gradually increased, therefore, the monthly changes in fatness coefficient closely correlated with the reproductive cycle. Sex ratios of female and male sexes of this species are showed 54.18 %, 45.82 %, respectively.