• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.47 no.3
• /
• pp.194-202
• /
• 2011

Maturation and spawning of the Shotted halibut, Eopsetta grigorjewi was investigated based on the samples captured in South Korean waters from January 2008 to December 2009. Gonadosomatic index began to increase in December, and reached maximum between January to March. After spawning it began to decrease from May. Reproductive season was estimated to January-April, with peak in February. Fecundity was proportional to the size of the female, with the clutch size varying from 170,000 eggs in the smallest female (total length, 28.9cm) to 1,300,000 eggs in the largest (total length, 41.5cm). Size at 50% sexual maturity (TL50), determined from mature females, was 28.8cm. Annual reproductive cycles of this species could be divided into six successive stages; immature stage (May-October), nucleolus stage (November-January), yolk vesicle stage (January-February), vitellogenic and ripe stage (January-April) and spent stage (April-May).

• Journal of Environmental Science International
• /
• v.22 no.1
• /
• pp.37-45
• /
• 2013

The monthly variations of blood characteristics and RNA/DNA of black sea bream, Acanthopagrus schlegeli, habituated in Geojae costal area were analysed to determine health condition of natural stocks in terms of gonad maturation and spawning season from March 2010 to February 2011. Spawning season determinated by gonadosomatic index is from June to August. RNA/DNA ratio of black sea bream muscle was strongly correlated with spawning season. During the gonad maturation RNA/DNA ratio in dorsal muscle tissue was decreased contrast to rapid increase during spawning season. Blood composition factors increased in terms of gonad maturation are aspartate aminotransferase, cholesterol, triglyceride, total protein, glucose, globulin, alkaline phosphatase and inorganic phosphate. Other blood factors increased during spawning season are alanine aminotransferase, blood urea nitrogen, uric acid and lactate dehydrogenase.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.4
• /
• pp.413-418
• /
• 2014

The effect of a bopyrid isopod Argeia pugettensis, on the growth and reproduction of the Kuro shrimp Argis lar was investigated. A commercial caridean shrimp in the East Sea of Korea, A. lar, was sampled monthly off Pohang with a bottom trawl from July 2009 to June 2011. During the study period, 7,988 individuals were sampled. These shrimp were parasitized by a bopyrid isopod Argeia pugettensis. The overall infection rate was 3.3%, although it declined in the larger size classes. It did not change monthly. The carapace lengths of the host and parasite were positively correlated. There was a significant difference in growth between infested and non-infested shrimp. The infested shrimp also had a lower gonadosomatic index (GSI) and breeding rate. These results suggest that the parasites affected the growth and reproduction of Argis lar.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.37 no.1
• /
• pp.51-56
• /
• 2004

Age and growth of three-lined tonguefish (Cynoglossus abbreviatus) were studied using samples from the waters off Yosu, Korea, from June to December, 2001. Sagittal otoliths had relatively clear annuli. Each annulus was formed once a year in April. The peak of the gonadosomatic index occurred also in April. The oldest fish observed in this study was 5 years old for females and 4 years old for males. The relationship between the otolith radius (R) and total length (L) was as follows: L=14.921R-2.5318 for females and L=13.527R-0.5584 for males. The relationship between total length and body weight (W) was as follows: $W=0.0008L^{3.54}$ for females and $W=0.0029L^{3.14}$ for males. The growth in length of the fish was expressed by the von Bertalanffy's growth equation as: $$L_t=44.54(1-e^{-0.16(t+2.69)})\;for\;females\;and\;L_t=41.52(1-e^{-0.15(t+3.34)})\;for\;males$$.

• Fisheries and Aquatic Sciences
• /
• v.8 no.1
• /
• pp.17-26
• /
• 2005

The ultrastructure of germ cells during spermatogenesis and the structural changes in the epithelial cells of the seminal vesicle with testicular development in male Neptunea (Barbitonia) arthritica cumingii were investigated monthly based on electron microscopic and histologic observations. N. arthritica cumingii (Gastropod: Buccinidae) undergoes internal fertilization and possesses a modified type of spermatozoon, which is approximately 20$\mu$m long. The axoneme of the tail flagellum consists of nine peripheral pairs of microtubules and one central pair. Many spermatozoa occur in the acini of the testis in the ripe stage and are transported to the seminal vesicles in the accumulating phase. In males, the monthly gonadosomatic index began to increase in September and reached a maximum in February. Subsequently, it decreased rapidly after April. The testis of this species can be classified into four developmental stages: the active (August to September), ripe (October to July), copulation (April to July), and recovery (July to August) stages. Structural changes in the epithelial cells of the seminal vesicles of this species could be classified into three phases: (1) S-I (resting), (2) S-II (accumulating), and (3) S-III (spent) phases. The morphology and structure of the epithelial cells of the seminal vesicle differed in each phase; the cells were cuboidal, squamous, or columnar in the resting, accumulating, or spent phases, respectively.

• Journal of Aquaculture
• /
• v.17 no.2
• /
• pp.128-132
• /
• 2004

Reproductive cycle of the brown sole, Limanda herzensteini was investigated by means of histological methods. The testis showed the presence of seminiferous tubule. The tubule consisted of many testicular cysts, each of which contained numerous germ cells - all at the same developmental stage. The ovary consisted of several ovarian lamellae and the oogonia originated from the inner surface of the ovarian lamella. Oocyte development was group-synchronous. Gonadosomatic index (GSI) of the male and female was the highest in January and March, respectively. Reproductive cycle could be classified into the growing (June-September), maturation (October-December), ripe and spent (January-March), and recovery and resting (April-May).

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.3
• /
• pp.141-146
• /
• 2007

We investigated the reproductive cycle of the striped eel catfish Plotosus lineatus. Specimens were sampled in the coastal waters of Sungsan and Jocheon, east of Jeju, Korea, from September 2001 to August 2002. The gonadosomatic index (GSI) in females and males were reached a maximum in June $(14.18{\pm}10.38)$ and July $(0.35{\pm}0.12)$, respectively. Based on histological observations and GSI variation, the reproductive cycle was classified into the following successive stages: in females, growing (September-April), mature (April-June), spawning (June-July), and degenerative and recovery (July-September) and in males, growing (August-December), mature (September-May), spent (April-July), and degenerative and recovery (June-August). The total length at 100% maturity exceeded 15 cm and the fecundity ranged from 525 to 1176 eggs. The fecundity was correlated positively with total length and body weight. Histological observations of the gonads suggest that this species is a spring-summer spawner with group-synchronous type oocyte development.

• Fisheries and Aquatic Sciences
• /
• v.10 no.4
• /
• pp.171-178
• /
• 2007

We analyzed the compositions of proximate and total fatty acids in the reproductive organs of male (testis, vas deferens, seminal vesicle, and spermatophore sac) and female (ovary, oviduct, oviducal gland, and nidamental gland) common squid. The protein contents were 12.1-22.7 and 13.2-19.4% for males and females, respectively, and the lipid contents were 1.0-2.7 and 2.1-8.0%, respectively. The prominent fatty acids in all reproductive organs were 22:6n-3, 20:5n-3, 16:0, 20:1n-9, 18:0, 18:1n-9, and 20:4n-6. Females had 28.6-32.0% of 22:6n-3 and 11.3-22.6% of 20:5n-3, while males had 20.8-26.8% of 22:6n-3 and 14.4-28.7% of 20:5n-3. These results indicate that the reproductive organs of both male and female squid are potential sources of n-3 polyunsaturated fatty acid.

• Development and Reproduction
• /
• v.21 no.2
• /
• pp.223-228
• /
• 2017

This study investigated the effect of different photoperiods (14L: 10D, 12L:12D and 10L:14D) on the gonadal development and GtH mRNA expression in the pituitary of damselfish. The results showed that gonadosomatic index (GSI) was significantly lower in shot photoperiod (10L:14D), in comparison with other photoperiodic group during the spawning season. After 60 days treatment, histological analysis of gonad tissue showed that the gonad of 10L:14D and 12L: 12D treatment groups were resting phase with spermatogonia and perinucleolus stage oocytes but the gonad of 14L:10D treatment group was still ripe phase with spermatozoa and mature stage oocyte. The $FSH{\beta}$ and $LH{\beta}$ mRNA expression in pituitary drastically decreased shot photoperiod treatment from July (spawning period). These results suggest that photoperiod is considered to be the most effective environmental factor in controlling the reproductive cycle of damselfish.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.3
• /
• pp.404-409
• /
• 2016

We investigated the maturation and spawning of Sebastes thompsoni in the coastal waters off Ulleungdo, based on samples collected by gill net from March 2013 to February 2014. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity, and total length (TL) at 50% group maturity. The average TLs of female and male S. thompsoni were 22.6 cm and 22.5 cm, respectively. The main parturition period of females was during March and April. The GSI of females began to increase in January, and reached a maximum in March. The GSI of male reached a maximum between January and February. The spawning period of males was shorter than that of females. The egg diameter during gestation stage was 1.4±2.1 mm. The TL of females at 50% group maturity was 22.3 cm.