• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.110-116
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• 1970

The fresh_water shrimp, Palaemon modestua is one of the most important types of bait f[r fishing and can be found abundantly in the Nak-Dong River. The larval development of Palaemon modestua in the laboratory was reported by Liu (1949), Kown and Uno (1968), but they didn't give any ecological features in the natural environments. Shrimps were collected from the Nak-Dong River near Pusan, once a month from July to December 1953 and from February to June 1969 respectively. The following is a summary of the results: 1. They breed from April to September, mainly in July. 2. A generation of this type of shrimps appears to be approximately one year and after breeding they die off up untill the end of October. 3. The sex ratio (female=100) is $44.2\~95.5$ (mean 78.5) and goes down during spawning seasons. 4. The minimum size of the ovigerous female is approximately 0.5 gram in body weight, 29mm in body length and 7mm in carapace length. 5. Most shrimps of $31\~41mm$ In body length lay eggs. 6. The relationship between the boby length (X) and the number of eggs (Y) is: $$Y=0.0000203937X^{3.5668}$$ 7. The relationship between the body length (X) and the body weight (Y) is: $$Y=0.099801X^{2.85407}$$ in female. $$Y=0.004198X^{3.40614}$$ in Male. 8. The relationship between the carapace length (X) and the body weight (Y) is: $$Y=5.56008X^{2.25503}$$ in female. $$Y=5.09541X^{2.28875}$$ in male. 9. The relationship between the carapace length (X) and the body length (Y) is: Y= 5.07540+3.36057X in female. Y=4.90514+3.47791X in male.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.1
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• pp.14-16
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• 1983

The present paper deals with seasonal variation of ovary weight, number of eggs spawned and carapace width (CW) of Orithyia sinica (Calappidae, Brachyura) based on the samples monthly collected from May to November 1981. Ovary weight of the prematured crabs (CW, 50 mm) was less than 0.5g. Biological minimum size of the female was approximately 55 mm in carapace width. Ovary weight was 0.01-0.5g in the premature stage, 3.0-15.9g in the virgin stage, and 0.2-1.5g in the ovigerous stage. Number of eggs spawned depended on the size of the females, and it ranged from $240{\times}10^2\;to\;1073{\times}10^2(mean\;ca.542{\times}10^2)$. The diameter of eggs spawned was in the range of 547-913 ${\mu}m(mean ca.712{\mu}m).$

• Journal of Aquaculture
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• v.20 no.3
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• pp.194-198
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• 2007

Reproductive traits of Palaemon gravieri such as embryo size, number of embryo (fecundity), incubation period, larval development mode, larval development period, larval survival and larval growth were described and compared to analyze the correlation among those traits. Embryo volume is a primary factor determining other ensuing reproductive features. Egg volume was $0.042mm^3$ in the first developmental stage. Embryo volume in P. gravieri was comparatively small which is indicative of great number of embryo (y = 3.0161x + 0.0185 $R^2$ = 0.74 positive isometric relationship) and relatively long incubation period. Larvae survived from zoea 1 to post-larvae and it took 45 days at $22^{\circ}C$. Survival rate of the larvae was rather great in the early stage and thereafter steadily decreased. Daily growth rate of larvae in P. gravieri at $22^{\circ}C$ was 0.0195 mm on average. They grew steadily as time went by. Incubation period was between 10-14 days at $22^{\circ}C$. Larval development mode was almost complete planktotrophic. PNR (point of no return) appeared to be the third day on average. Survival rate of larvae without feeding declined rapidly between 3 and 4 days. Larval development period and stage frequency were 23-30 days and 11 stages which imply prolonged larval period and high mortality. The pattern of brood production followed fast successive parturial pattern. Most ovigerous female had mature ovary when they performed parturial molt soon after hatching (larval release).

• Journal of Species Research
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• v.13 no.3
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• pp.340-351
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• 2024

A new species of the canuellid genus Brianola Monard, 1926 (Copepoda: Harpacticoida) was collected during a meiofauna survey in July 2021 at the intertidal muddy sand of Phuket Island, Thailand. Currently, there are only eight known species of Brianola: B. stebleri, B. exigua, B. curvirostris, B. elegans, B. sydneyensis, B. vangoethemi, B. hamondi, and B. haliensis. Thus, the Brianola rawaiensis sp. nov. from Thailand is the ninth species of the genus. The new species, Brianola rawaiensis is most closely related to B. haliensis by sharing a four-segmented antennule in females and five-segmented antennule in males, eight-segmented antennary exopod and three-segmented antennary endopod, and P1 exp-3 with 5 spines/setae. However, B. rawaiensis sp. nov. is different from B. haliensis by having: 1) P1 exp-1 with 1 outer pinnate spine, 2) P1 exp-2 with inner plumose seta, 3) P2 exp-3 with 3 setae/spines, 4) P2 enp-1 with one inner plumose seta, 5) P4 enp-1 with inner seta. Sexual dimorphism is expressed in the antennule and segmentation of the urosome. Ovigerous female bearing one egg sac with 20 eggs.

• Korean Journal of Environmental Biology
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• v.41 no.3
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• pp.298-307
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• 2023

The annual reproductive cycle of two species, Upogebia major (de Haan 1841) and Austinogebia wuhsienweni (Yu 1931), of the female mud shrimp from the west coast of Korea was investigated using histology. The collected samples were divided into adult and juvenile groups to understand the mature period of age class based on the carapace length(CL). Juvenile Upogebia(CL<25mm) were mostly inactive gonad with early (62%-100%) and late (10%-38%) development stages during the year, whereas the adult shrimp showed a seasonal pattern of gonad maturation(CL≥25 mm). The early and late developmental stages of oocytes were observed in adult Upogebia from November to March and mature eggs appeared from April to October. In adult Ausitnogebia (CL≥15 mm), fully grown oocytes were consistently observed during the study period, in which the ripe stage was found between January and June. On the other hand, most juvenile Austinogebia (CL<15 mm) maintained an immature state in the gonad. Both species of the mud shrimp reproduced from ovigerous females in the adult population and their egg-bearing period was distinguished from January to April for U. major and from July to September for A. wuhsienweni.

• Development and Reproduction
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• v.12 no.3
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• pp.231-241
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• 2008

The present study was designed to clarify aspects of the annual reproductive cycle of the fresh water mitten crab, Eriocheir japonicus inhabiting Sumjin river, and to determine the adequate conditions of temperature, photoperiod and salinity on the gonadal maturation and breeding of adult female crabs. Based on the seasonal changes of GSIs and gonadal histology of adult crabs, the annual reproductive cycle could be divided into 4 periods as follows: previtellogenesis period (from September to October) when GSIs were low value and ovaries had oocytes in previtellogenesis stage and meiotic prophase stage; maturing period (from November to March of the next year) when GSIs increased gradually and ovarian oocytes accumulated yolk globules; spawning period (from April to June) when high value of GSI of female was kept and ovigerous female appeared; resting period (from July to August) when GSIs decreased rapidly, and vitellogenic oocytes degenerated. Gonadal maturation was influenced by water temperature, but not photoperiod and salinity. GSI more increased in experimental regime of $18^{\circ}C$ than that of $10^{\circ}C$ regardless of photoperiod conditions (12L12D and 15L9D). However, in $26^{\circ}C$ regime of both photoperiod conditions, the value of GSI was not changed, and vitellogenic oocytes were not observed. Spawning was considerably influenced by water temperatures and salinities regardless of photoperiods. Vitellogenic female crabs did not spawn at $10^{\circ}C$ in any salinity conditions. However, at $18^{\circ}C$ and $26^{\circ}C$, over a half of rearing female crabs spawned in condition of 30% sea water (salinity 9.6%o) and 60% sea water (salinity 19.2%o), while no female spawned in freshwater condition (salinity 0.0%o).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.1
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• pp.35-43
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• 1996

The appearance of the primordial germ cells (PGC's), early gonadogenesis, sex differentiation and sex ratio of the embryo in the viviparous teleost, Ditrema temmincki were investigated by using photomicroscopy. The PGC's were first observed in the fibrous mesenchymal tissue located between the early alimentary tract and the dorsal body wall in the late embryonic development stage. During the period from the hatching to the individual total length (TL) of 4.0 mm the PGC's were evenly distributed in the fibrous mesenchymal tissue between alimentary tract and body wall. But the period of TL 5.0 mm mesenchymal tissue separated from the dorsal body wall, the PGC's moved to the posterior mesenchymal tissue and formed the primitive gonad. During the early gonadogenesis, differentiation of the testis and ovary were distinguished from the arrangement of the germ cells and somatic cells. Gonad of embryo in TL 10.0 mm can be separated into the ovary and testis by external morphology. The testis had a separated form which was consisted with two lobes, and the ovary had a fused form in half-posterior part. In the testicular differentiation of the embryo, histological pattern of the seminiferous tubule appeared when TL of the embryo was to be 25.0 mm, for the seminal vesicle was formed In the individual TL of 30.0mm. The testis of the embryo with TL of 45.0 mm was similar to that of the adult fish in the external and internal structures. In the ovarian differentiation, formation of the ovigerous folds and the ovarian cavity were clearly observed when the TL reached to 30.0 mm. The ovary from the individual with TL of 60.0 mm was differentiated into a similar ovary as seen in the adult fish in the external and internal structure. Right before parturition the total length of the individual was approximately 63.0 mm of which the individual embryo has an ovary containing the oocytes in the chromatin nucleolus stage, or a testis containing the spermatogonia, respectively. And the embryonic sex ratio of female to male was 1.65 : 1. Ditrema temmincki is dioecism and the pattern of sex differentiation is belonged to a differentiation type.