• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.1
• /
• pp.132-138
• /
• 1997

In order to obtain the basic information for seedling production of surf clam, Spisula sachalinensis, annual reproductive cycle was investigated from March 1994 to May 1995. S. sachalinensis was dioecious. The gonads are located between the digestive diverticula and muscle tissue of the foot. The condition factor was reached its maximum (0.19) in June, and then decreased to 0.16 in July. In November, the value was the lowest and then increased slowly. The age and minimum size for sexual maturation were 2 years old and about 50 mm in shell length, respectively. However, less than $10\%$ of sexually undifferentiated individuals were larger than 80 mm in shell length. On the other hand, the size of mature oocytes was ranged to $50\~60{\mu}m$ in diameter and testis-ova was observed in testis of the mature stage. Annual reproductive cycle could be classified into five successive stages : multiplicative (October to January), growing (February to April), mature (April to June), spawning (June and July) and degenerative and resting (August and September) stages.

• Journal of Aquaculture
• /
• v.17 no.1
• /
• pp.30-38
• /
• 2004

To estimate the spawning period the annual change of gonadosomatic index (GSI) were examined from January 2000 to December 2001. Fecundity, spawning frequency and egg diameter were measured by ocular observation. Germ cell differentiation during gametogenesis, the reproductive cycle and the first sexual maturity of greenling Hexagrammos otakii were observed under light microscopy from January to December, 2000. GSI began to increase in August and reached the maximum in November when ovary was getting mature. The reproductive cycle of H. otakii can be divided into five successive stages in females: early growing stage (July), late growing stage (July to August), mature stage (September to October), ripe and spent stage (September to December), and recovery and resting stage (December to June). Males showed four successive stages : growing (June to August), mature (August to October), ripe and spent (September to December), and recovery and resting stage (December to May). According to the frequency distributions of egg diameter in spawning season, H. otakii could be one of polycyclic species spawning 2 times or more during one spawning season. Number of total eggs and mature eggs in the absolute fecundity were related to the standard length and body weight, respectively. Number of total eggs and mature eggs in relative fecundity were also proportional to the standard length, but rather these numbers decreased with body weight. Percentages of first sexual maturity of females and males in greenling were over 50% from 19.1 to 21.1cm in length, and 100% for fish over 25.1cm in length. Therefore, both sexes are ready to reproduce after one year old.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.6
• /
• pp.835-842
• /
• 2013

Flathead flounder Hippoglossoides dubius is a commercially important fish in the coastal waters of Gangwon Province, which is its spawning ground and breeding habitat. A total of 1,669 gonads were sampled monthly from February 2011 to May 2013 to investigate ecological characteristics, such as variations in maturation and spawning by gonad index, visual maturity stage, histological observations and oocyte diameter. Males were numerically dominant over females in the fishing grounds year round. The spawning season was from January to April, and the peak was from February to March. Oocyte number as a measure of fecundity was between 27,372 and 915,209 eggs with a length range of 26.0-48.7 cm TL, while the largest oocyte grew to 0.9-1.4mm in egg diameter during its spawning season. The relationship between fecundity and total length was $F=0.0016TL^{5.2539}$. The smallest mature lengths of the females and males were 28.4 and 22.6 cm respectively, and the 50% mature lengths of females and males were 32.9, 26.9 cm respectively.

• The Korean Journal of Malacology
• /
• v.27 no.3
• /
• pp.273-282
• /
• 2011

The ultrastructural characteristics of germ cells during spermatogenesis and mature sperm morphology in male Pinctada martensii were investigated by transmission electron microscope observation. The morphologies of the sperm nucleus and the acrosome of this species are the oval shape and cone shape, respectively. Spermatozoa are approximately $47-50{\mu}m$ in length including a sperm nucleus (about $1.24{\mu}m$ in length), an acrosome (about $0.60{\mu}m$ in length), and tail flagellum (about $45-47{\mu}m$). The axoneme of the sperm tail shows a 9+2 structure. In P. martensii in Pteriidae, a special substructure showing a thick and wide triangular shape which is composed of electron-dense opaque material (occupied about 50% of all, the upper part of the acrosomal vesicle), appeared in the upper region (part) of the acrosomal vesicle, while the lower region (part) of the acrosomal vesicle is composed of electron-lucent material. Thus, this special structure, which exist in the upper part of the acrosomal vesicle in P. martensii, is somewhat different from those of other subacrosomal vesicle in other families in subacrosomal vesicles. Therefore, we assume that the existence of a special substructure showing a thick and wide triangular shape in the acrosomal vesicle of the spermatozoon can be used as a key characteristic for identification of P. martensii or other species in Pteriidae in subclass Pteriomorphia. The number of mitochondria in the midpiece of the sperm of this species are five (exceptionally sometimes four), as one of common characteristics appear the same number of mitochondria in the same families of superfamilyies. This species in Pteriidae does not contain the axial rod and satellite fibres which appear in the species in Ostreidae in subclass Pteriomorphia. These characteristics can be used for the taxonomic analysis of the family or superfamily levels as a systematic key or tools.

• Korean Journal of Environment and Ecology
• /
• v.35 no.2
• /
• pp.115-125
• /
• 2021

This study surveyed the population ecology of Acheilognathus chankaensis (Pisces: Acheilognathinae) in the vicinity of the Churyeongcheon (Stream) and Seomjingang (River) in Jeonbuk, Korea, from February 2006 to May 2007. The survey found the habits mainly in the slow-flowing waters having sand, mud, and gravel bottoms. Age groups estimated by the standard length-frequency distribution of the population indicated that the one-year-olds were 30-46 mm long, the two-year-olds were 47-58 mm long, the three-year-olds were 59-68 mm long, and the four-year-olds were longer than 69 mm. The gonadosomatic index (GSI) and the ratio of ovipositor length/standard length were the highest in March (♀: 12.9%, ♂: 5.0%) and in April (46.3%), respectively. The ratio of mature egg diameters that were 1.6 mm was highest in May (13.2%). The comprehensive analysis of spawning characteristics showed that the spawning season was from March to June with water temperatures in 11.5-22.5℃, and the sex ratio of female:male was 1:1.13. The fecundity in the ovaries and the number of mature eggs were 318±174.5 (50~583) and 220±139.2 (50~406), respectively. The size of the mature eggs was 2.04±0.110 mm on the long axis and 1.55±0.100 mm on the short axis for the study period. Gut contents of A. chankaensis were mainly phytoplankton such as the genera Fragilaria, Synedra, Navicular, Cymbella (Bacillariophyceae), and Cosmarium (Chlorophyceae).

• Fisheries and Aquatic Sciences
• /
• v.23 no.6
• /
• pp.16.1-16.10
• /
• 2020

This study was conducted in Lake Hayq between January and December 2018. The objectives of this study were to determine the growth, condition, sex ratio, fecundity, length at first sexual maturity (L₅₀), and spawning seasons of common carp (Cyprinus carpio). Monthly fish samples of C. carpio were collected using gillnets of stretched mesh sizes of 4, 6, 7, 8, 10, and 13 cm and beach seines of mesh size of 6 cm. Immediately after the fish were captured, total length (TL) and total weight (TW) for each individual were measured in centimeters and grams, respectively, and their relationship was determined using power function. Length at first maturity (L₅₀) was determined for both males and females using the logistic regression model. The spawning season was determined from the frequency of mature gonads and variation of gonadosomatic index (GSI) values of both males and females. Fecundity was analyzed from 67 mature female specimens. The length and weight relationship of C. carpio was TW = 0.015TL^2.93 for females and TW = 0.018TL^2.87 for males that indicate negative allometric growth in both cases. The mean Fulton condition factor (C_F) was 1.23 ± 0.013 for females and 1.21 ± 0.011 for males. The value of C_F in both cases was > 1 that shows both sexes are in good condition. Among the total 1055 C. carpio collected from Lake Hayq, 459 (43.5%) were females and 596 (56.5%) were males. The chi-square test showed that there was a significant deviation between male and female numbers from 1:1 ratio (χ²= 22, df = 11, P > 0.05) within sampling months. The length at first sexual maturity (L₅₀) for females and males were 21.5 and 17.5 cm, respectively. Males mature at smaller sizes than females. The spawning season of C. carpio was extended from February to April, and the peak spawning season for both sexes was in April. The average absolute fecundity was 28,100 ± 17,462. C. carpio is currently the commercially important fish while Nile tilapia fishery has declined in Lake Hayq. Therefore, this baseline data on growth, condition, and reproductive biology of common carp will be essential to understand the status of the population of carp and design appropriate management systems for the fish stock of Lake Hayq, Ethiopia, and adjacent countries.

• Animal cells and systems
• /
• v.13 no.3
• /
• pp.345-350
• /
• 2009

We have isolated and characterized a new insect chicken type (c-type) lysozyme gene from the common cutworm, Spodoptera litura. The full-length cDNA of Spodoptera lysozyme is cloned by rapid amplification of cDNA ends PCR (RACE-PCR). The isolated cDNA consists of 1039 bp including the coding region for a 142-amino acid residue polypeptide, which included a signal peptide of 21-amino acid residue and a mature protein of 121-amino acid residue. The predicted molecular weight of mature lysozyme and its theoretical isoelectric point from amino acid composition is 13964.8 Da and 9.05, respectively. The deduced amino acid sequence of Spodoptera lysozyme gene shows the highest similarity (96.7%) to Spodoptera exigua lysozyme among other lepidopteran species. Amino acid sequence comparison with other the c-type lysozymes, Spodoptera lysozyme has the completely conserved $Glu^{32}$ and $Asp^{50}$ of the active site and eight Cys residues are completely conserved in the same position as that of other lepidopteran lysozymes.

• Development and Reproduction
• /
• v.13 no.2
• /
• pp.123-132
• /
• 2009

The gonadosomatic index (GSI), fatness, ovarian development, first sexual maturity, and fecundity of the Korean anchovy Coilia nasus were investigated by histological observations and morphometric analysis from January to December, 2007. The GSI and fatness began to increase in February, and reached the maximum in June when the ovary was getting mature and spawning occurred. Thereafter these parametes rapidly decreased in July when spawning occurred. Therefore, monthly changes in the GSI and fatness were closely related to ovarian maturation and spawning. The duration of ovarian development in females can be classified into five successive stages: early growing stage (February to March), late growing stage (March to April), mature stage (May to June), ripe and spent stage (June to July), and recovery and resting stage (December to January). Maturation and spawning of this species occurred between June and July during the period of high seawater temperature-long day length. Percentages of first sexual maturity in female individuals were over 50% for fish ranging 24.1 to 27.0 cm in total length, and 100% for fish over 30.1 cm in total length. The number of total eggs and mature eggs in the absolute fecundity were increased with the increase of total length and body weight, respectively. The number of total eggs and mature eggs in relative fecundity were also proportional to total length, but rather these numbers decreased in the maximum body weight (126.0${\sim}$150.0 g).

• Korean Journal of Veterinary Service
• /
• v.32 no.1
• /
• pp.83-85
• /
• 2009

In a cross-sectional abattoir survey of bovine pulmonary diseases in Mymensingh, during September 2001 to April 2002, subclinical Dictyocaulus viviparous infection was found in mesoendemic level in Bangladeshi adult zebu cattle. The number of mature lung worms varied from $1{\sim}18$ in individual lungs. One to five mature lung worms were most frequent (74.2%) followed by 6 to 10(19.3%) and $11{\sim}18$ (6.5%). Of the total 123 mature worms collected from 31 lungs, there were 50 (40.7%) male and 73 (59.3%) female worms. The female lungworms (mean length 14.41mm) were significantly (P<0.01) larger than the male lungworms (mean length 11.28mm). The number of hydatid cysts varied from $1{\sim}80$ in individual lungs. One to five ($1{\sim}5$) cysts were recorded most commonly (76.0%) followed by $11{\sim}80$ (20.0%) and $6{\sim}10$ (4%). The size (diameter) of the hydatid cysts ranged from $2{\sim}12cm$. Of the total 203 hydatid cysts collected from 31 lungs 45 (22.2%) cysts were fertile and 158 (77.8%) cyst were sterile.

• Fisheries and Aquatic Sciences
• /
• v.21 no.11
• /
• pp.34.1-34.13
• /
• 2018

Sexual maturity ($L_{50}$), the length at which 50% of fish in a size class are mature, is a key aspect of domestication of new fish species because it guides the procedure for identification of appropriate broodstock size for artificial spawning. In this study, the $L_{50}$ was determined for 1083 Barbus altianalis samples obtained from Lake Edward and the Upper Victoria Nile. Gonads of freshly killed samples were examined macroscopically and verified with standard histological procedures for the maturation stages that were used to determine $L_{50}$. Oocytes and spermatogenic cell sizes were compared for fish obtained from both water bodies. Results indicated that there were no variations in macro gonad features observed for fish from Lake Edward and Upper Victoria Nile. Similarly, there were no significant differences in oocyte sizes (P > 0.05) between the two populations but significant differences in spermatogenic cell sizes were noted (P < 0.05) except for spermatozoa (P > 0.05). This however did not suggest peculiar differences between the two populations for staging the gonads. Consequently, no staging variations were suggested for both populations in determination of $L_{50}$. Sexual maturity was found in the same class size of fork length (FL) 20-24.9 cm and 35-39.9 cm for males and females from both water bodies, respectively. At this FL, however, males were too small, and for good selection of vigor broodstocks for spawning and conservation purposes, they are better picked from class size of 30-34.9 cm FL and above. These findings were crucial for integration of appropriate breeding size in spawning protocol by farmers and fisheries scientists conserving wild B. altianalis populations.