• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.158-162
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• 2011

Growth and spawning ecology of Cobitis lutheri (Teleoste: Cobitidae) were investigated in the Samcheon Stream, Mangyeong River, Jeollabuk-do, Korea from 2005 to 2006. Age group of C. lutheri estimated from the total length indicated that the 40 ~ 60 mm group is 1 year old, the 60 ~ 80 mm group is 2 years old, and the 80 ~ 110mm group is 3 ${\leq}$ years old. The sex ratio (Male/Female) was 0.78, and the female was 20 ~ 30 mm larger than the male. Lamina circularis at the base of pectoral fins in the males as a secondary sexual character was created 12 months after hatching. A change of lateral coloration of males was observed from April to September. The spawning season was early to middle July with water temperatures of $24{\sim}26^{\circ}C$. The average number of eggs was $1,127{\pm}453$ with the egg diameter of $1.09{\pm}0.02$ mm.

• Korean Journal of Ichthyology
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• v.21 no.1
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• pp.15-22
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• 2009

An artificial breeding method was carried out to investigate development of eggs and the early life history of Iksookimia longicorpa. The eggs of the female were obtained by injecting gonadotropin (LHRH) and fertilizingby the dry method in the laboratory. The mature eggs were separate, demersal, light yellowish, and averaged $1.53{\pm}0.07mm$ in diameter. In water temperature of $23{\sim}25^{\circ}C$, the eggs hatched in 50~72 hours after fertilization, and their lengths reached $5.1{\pm}0.23mm$ in total length. On Day 4 after hatching, they averaged $7.1{\pm}0.47mm$ in total length and their yolk sacs were completely absorbed. From 25 days after hatching, they attained a juvenile stage reaching $12.8{\pm}0.49mm$ in total length. On the 100th dayafter hatching, their band patterns and external form were similar to those of adults, and they averaged $38.5{\pm}2.95mm$ in total length.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.94-100
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• 2017

Three pseudo-silver eels (PS1~PS3) were found by analysis of silvering index and biological characteristics of 454 eels, Anguilla japonica, collected from the 9 sites of Korean fresh and brackish waters from September 2014 to August 2015. Two specimens (PS1~PS2) from Lake Soyang and one (PS3) from Geum river estuary were identified as pseudo-silver eel showing a large difference between silvering index and GSI. The external morphology of the pseudo-silver eels were in S2 (late silver eel) stage, but they were classified into Y1 (yellow eel) and Y2 (late yellow eel) stage in GSI, Gut index, Eye index and Y2 stage in gonadal development and mean egg diameter.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.296-305
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• 2018

Maturity and spawning of the pointhead flounder, Hippoglossoides pinetorum were investigated on the basis of samples collected in the coastal waters off Gangwon-do, East Sea from January 2012 to December 2013. The average total length of H. pinetorum was 25.0 cm and 21.9 cm for females and males, respectively. The spawning period was from May to July according to monthly changes gonadosomatic index (GSI) and maturity stages. The spawning period in Gangwon-do was delayed relatively to that in Gyeongbuk-do. The mature egg diameter ranged between $300-700{\mu}m$. The relationship between TL and fecundity (F) was F = 63.574 TL - 1471.3 ($R^2=0.7603$), that is, the larger total length, the more fecundity H. pinetorum had. We estimated that the TLs at 50% group maturity were 25.6 cm for females and 19.9 cm for males. The spawning ecology by sea area should be considered efficient resource management for H. pinetorum. Furthermore, it is necessary to study more on the relationships among growth, maturity and water temperature variations in the East Sea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.67-73
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• 2019

We presented detailed morphological descriptions of the eggs, larvae and juvenile of Acanthaphritis unoorum based on specimens collected with bongo nets from Korean waters during the period May 2017-July 2018. We collected 18 individuals including eggs (n= 4, 0.77-0.85 mm in egg diameter), preflexion larvae (n= 6, 4.11-6.31 mm in standard length, SL), flexion larvae (n= 4, 6.60-7.82 mm SL), postflexion larvae (n= 3, 8.94-13.46 mm SL), and one juvenile (n= 1, 14.67 mm SL). The mitochondrial (mt) DNA 16S rRNA sequences of the eggs, and the cytochrome c oxidase subunit I (COI) sequences of the larvae were identical to those of A. unoorum adults (genetic distances <0.01). The A. unoorum larvae and the juvenile that we collected were morphologically similar to those of Dactylopsaron dimorphicum, but the A. unoorum specimens were readily distinguishable by the presence of lateral melanophores. This is the first record of A. unoorum in Korean waters. We propose a new Korean name for A. unoorum: "O-ri-bu-ri-nuntung-i".

• Korean Journal of Ichthyology
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• v.34 no.1
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• pp.16-24
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• 2022

The eggs development and early life history of Sarcocheilichthys variegatus wakiyae was investigated. The adult fishes were collected in Yeongsangang River, Damyang-gun, Jeollanam-do, Korea, and their spawning inducement was carried by sex maturation hormone (Ovaprim) injections. Spawning amount was mean 31±3.5 Mature eggs were cicular in shape and mean 2.40±0.05 mm in diameter. Hatching period of the embryo was 230 to 240 hours after fertilization under water temperature of 22℃. The newly hatched larvae were 10.7±0.19 mm in total length (TL). 3 days after hatching, postlarvae was measured 12.0±0.13 mm in TL and the tip of the caudal fin was bent at 45°. 11 days after hatching, it was measured 14.6±0.13 mm in TL, and transferred to juvenile as the number of fins (iii7 dorsal fin, iii6 anal fin, i7 ventral fins) reached a constant number of each part.

• Journal of Marine Life Science
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• v.7 no.1
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• pp.55-59
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• 2022

This study was conducted to provide basic information on the sexual mature and reproductive biology of Trichiurus lepturus. During the oogenesis, size of oocyte and nucleus showed the increase tendency but size ratio of nucleolus to nucleus was decreased. In the result of H-E stain, the stainability of the cytoplasm was changed from basophilic to eosinophilic. The egg diameter of initial vitellogenic oocyte was about 63.2 (±12.7) ㎛. In the cytoplasmic cortex, eosinophilic yolk nucleus was observed. The size of mature oocyte was 216.6 (±24.7) ㎛ and GVBD (germinal vesicle breakdown) was observed. The size of ripe oocyte was 317.9 (±80.9) ㎛ and the thickness of zona radiata was 4.2 (±1.7) ㎛. The oocyte developmental type is considered to belong to the group synchronous type. The accumulation of yolk in the oocyte, like most teleost, is thought to be of two types: exogenous and endogenous accumulation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.927-937
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• 2022

The reproductive characteristics of Pacific anchovy, Engraulis japonicus were investigated using samples randomly collected from the southern waters of Korea between January and December 2021. We analyzed monthly changes in maturity stages, gonadosomatic index (GSI), egg diameter, fecundity, and fork length (FL) at sexual groups maturity of 50%, 75% and 97.5%, and sex ratio (female:male). GSI value showed two peaks in May and August; however, microscopic analysis of E. japonicus gonad tissue revealed that the spawning period was from March to October. The main spawning seasons for the entire populations were from April to June and August to September. The overall sex ratio was female-biased (1 females, 0.89 male). The fecundity (F) of female anchovies ranged from 429 eggs at an FL of 8.0 cm to 13,824 eggs at an FL of 14.9 cm and the relationship between FL and F was 0.0788FL^4.422. The FL at 50% group maturity was 8.26 cm for female anchovies. Based on the results, we suggest that the reproductive cycle in Pacific anchovies may be related to pulses in water temperature and the sexual cycle of the fish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.3
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• pp.315-323
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• 2023

The maturity and spawning of the large yellow croaker Larmichthys crocea were investigated using samples randomly collected in the Jeju coastal area, Korea. We analyzed monthly changes in maturity stages, gonadosomatic index (GSI), and egg diameter. Additionally, we verified fecundity by size class and total length (TL) at sexual group maturity at 50%, 75%, and 97.5%, as well as by sex ratio (female vs. male). The overall sex ratio of females to males was 1:0.42. The GSI values showed a peak in October, but the spawning season, revealed by the microscopic analysis of gonadal tissue of L. crocea was from October 2021 to March 2022, with the main spawning period from October to November. The fecundity (F) of female L. crocea ranged from 39,232 eggs at 20 to 29.9 cm to 251,003 eggs at 50 to 59.9 cm, with the relationship between TL and F being 80.244TL-1641.6. In females, TL at 50%, 75%, and 97.5% maturity was 22.4, 24.3, and 29.0 cm, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.3
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• pp.206-218
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• 1984

The gonadal development and gametogenesis of shad, Konosirus, punctatus (TEMMINCK et SCHLEGEL) were studied by comparing with various quantitative indices, such as seasonal changes of gonadosomatic index, fatness, egg-diameter composition, first maturing size, and by comparing with histological changes of gonad and gonadotrophs(GTH) in pituitary. The materials were monthly sampled from Dadaepo at the estuary of the Nakdong river in Korea from September, 1982 to October, 1983. The ovary of shad is a pair of sac-shaped organs revered with a fibromuscular capsule and consisting of numerous sacs. The type of testicular structure is lobular type with development of germ cells, mesenchymal tissue on the lobuli. The gonadosomatic index (GSI) is rather low till March, but increases in April and reaches to peak in June in females and May in males. And it suddenly falls in July. The gonads become active on the increase of water temperature and spawning season ends before high water temperature. After spawning, the small oocytes continue to remain as they are untill the growing period next year. The reproductive cycle includes the successive stages of growing from March to April, mature from April to May, ripe and spawning in June, and recovery and resting from July to February next year. In egg-diameter composition of an ovary taken in the spawning season, 2-3 modes were recognized with some batches shown in an ovary. An individual shad spawns twice or more in a month-spawning season. The individual spawning interval is estimated to be ten days or less. Changes of fatness are corelated with those of water temperature that affect on the condition of feeding, but less corelated with spawning. The percentage of mature of female and male fish, are $50\%$ in 17.0-18.0 cm and $100\%$ in 18.0-19.0 cm. GTH cells are activated from growing period and decrease their activity at pre-spawning season with peak activity for mature period.