• Journal of fish pathology
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• v.33 no.1
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• pp.71-75
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• 2020

A survey was conducted to investigate viral infections in 184 whiteleg shrimp (Litopenaeus vannamei) collected from nine farms and one wholesale fish vendor during 2018 and 2019. Gill and abdominal muscle of shrimp were tested for the presence of five viruses, viz. infectious hypodermal and haematopoietic necrosis virus, taura syndrome virus, infectious myonecrosis virus, yellow head virus genotype 1, and covert mortality nodavirus by reverse transcription-polymerase chain reaction (RT-PCR) and PCR. These viruses were not detected in any of 184 samples, screened under the study.

• Journal of fish pathology
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• v.25 no.3
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• pp.271-277
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• 2012

The practical monitoring was performed to survey the mortalities in aquaculture farms of olive flounder, rockfish, rainbow trout, Japanese eel, white shrimp and abalone in South Korea from May to November, 2011. The aquatic organism disease inspectors, who have the national licenses for the diagnosis and prevention of aquatic disease and have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. In 70 flounder farms, the cumulative mortalities rate was 27.9%, and the mortalities were caused by scuticociliatosis, streptococcosis, VHS, non-infectious loss, vibriosis and gliding bacterial disease. The moralities rate of 30 rockfish farms was 13.6%, and those were mainly contributed by gill flukes and streptococcosis. Most of mortalities of rainbow trout were caused by non-infectious loss and protozoan white spot disease. The mortalities rate of Japanese eel was 0.6% by edwardsiellosis, protozoan white spot disease and gill flukes. The loss rate of white shrimp was 71.2%, and most of them was related with non-infectious ones, such as carnivalization, transportation loss, and the rest was caused by viral white spot disease. The mortalities rate in the abalone farms was 10.7% and all of them were related with non-infectious loss.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.691-697
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• 2021

Vibrio parahaemolyticus associated with acute hepatopancreatic necrosis disease (Vp_AHPND) and Enterocytozoon hepatopenaei (EHP) are the two most important pathogens in shrimp aquaculture and they have caused enormous losses to the shrimp industry worldwide. In ponds, the major target organ for the two pathogens is the hepatopancreas, and infection with EHP is a known potential risk factor for Vp_AHPND infection. This study aimed to develop a PCR (polymerase chain reaction)-based diagnostic method for simultaneously detecting Vp_AHPND and EHP. The newly developed PCR diagnostic method could be used to test various samples, such as seawater, shrimp, and feces. The diagnostic method exhibited high sensitivity and specificity for both pathogens. This will help reduce the potential economic losses that may have been caused by the two major shrimp pathogens, Vp_AHPND and EHP, and will allow for the efforts and time spent combatting them to be dedicated elsewhere.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.287-292
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• 2021

This study was conducted to evaluate the effects of dietary supplementation with shrimp soluble extract (SSE) on growth performance, feed utilization, innate immunity and digestibility of Pacific white shrimp Litopenaeus vannamei. A basal diet (Con) was formulated and three other diets were prepared with SSE supplementation at different levels of 1, 2 and 4% (designated as SSE1, SSE2 and SSE4, respectively). Triplicate groups of shrimp (1.20±0.01 g) were fed one of the experimental diets for 6 weeks. At the end of the feeding trial, growth performance and feed utilization of the shrimp were significantly improved by dietary supplementation of SSE4 compared to those of shrimp fed the Con diet. Shrimp fed SSE4 diet had significantly higher phagocytic activity than shrimp fed the Con diet. Dietary supplementation of SSE improved the protein and dry matter digestibility of shrimp. These results indicate that SSE can be used as a functional additive in the diets for Pacific white shrimp.

• Journal of fish pathology
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• v.25 no.3
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• pp.231-241
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• 2012

Diagnostic monitoring in fish farms with land-based tanks and netpen cases were conducted in eastern, western, southern and Jeju island of Korea during summer of 2007~2011. In total, 2413-fish samples of 4 marine fish species were tested for the detection of bacteria and parasite. Fish species tested were olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), red sea bream (Pagrus major), pacific white shrimp (Litopenaeus vannamei). During the diagnostic monitoring from 2007 to 2011, the infection rates by single infection of bacterial or parasitic pathogens were relatively higher than the mixed infections. The main bacterial pathogens in olive flounder, black rockfish and pacific white shrimp were Vibrio spp. (V. harveyi, V. ichthyoenteri, Vibrio sp.). The main bacterial pathogens in red sea bream were also Vibrio sp. and Photobacterium damselae subsp. damselae. The main parasitic pathogens were both Miamiensis avidus and Trichodina sp. in olive flounder, Microcotyle sebastes in black rockfish, Microcotyle tai in red sea bream and Zoothamnium sp. in pacific white shrimp.

• Journal of fish pathology
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• v.32 no.2
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• pp.123-127
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• 2019

In this study, white spots appearing in carapace of imported white leg shrimp Litopenaeus vannamei were observed by macroscopic and microscopic examination. White spots due to white spot disease showed two types, white spots with a regular circular shape ranging from 0.4 mm to 1.7 mm and white spots with an irregular shape ranging from 0.05 mm to 2 mm. White spots due to other causes showed four types that appeared as crystalized materials in range of 100 ㎛ around the tegumental gland, as polygonal inorganic deposits ranging from 58 ㎛ to 188 ㎛, as Linear inorganic deposits ranging from 0.8 mm to 9 mm, as brownish spots ranging from 0.1 mm to 0.4 mm, and brownish spots containing melanin ranging from 0.1 mm to 2 mm. As a result, white spots occurred in imported white leg shrimp Litopenaeus vannamei were divide two type, due to white spot disease or other causes, for quarantine works.

• Journal of fish pathology
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• v.33 no.1
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• pp.77-81
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• 2020

This study was performed for screening yellow head virus(YHV) complex in 252 including 235 white leg shrimps (Litopenaeus vannamei) and 17 oriental shrimp (Fenneropenaeus chinensis) collected from 18 farms located in southwestern province of Korea. The virus complex was detected by nested reverse-transcriptase polymerase chain reaction (RT-PCR) assay. In the assay, amplicons were resulted in RNAs exracted from 38 shrimps (21 white leg shrimps and 17 oriental shrimps) obtained from 7 farms. In phylogenetic analysis using sequences of ORF1b gene, all 38 sequences obtained in this study formed an independent lineage with YHV-8 genotype firstly isolated in China, belonged to an YHV-8 clade.

• Journal of Aquaculture
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• v.17 no.4
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• pp.246-250
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• 2004

Survival of 12.7 g (average body weight) Litopenaeus vannamei was examined at temperatures of 14, 16, 18, 28, 32, 34 and 36$^{\circ}C$ and salinities of l0, 20, 30 and 40 ppt after 7 days. Hemolymph osmolality was measured at 12 combinations of salinities (l0, 20, 30 and 40 ppt) and temperature levels (18, 28 and 34$^{\circ}C$) after 14 days. The results show that the species have their best survival between temperatures of 18 and 3$0^{\circ}C$ and salinity above 20 ppt. Hemolymph osmolality increased with increased salinity at all temperatures tested. The isosmotic point calculated from the linear relationship between hemolymph osmolality and medium osmolality and recorded as 826, 809 and 1,117 mOsm/kg which is equivalent to 29.4, 28.8 and 40.2 ppt at 18, 28 and 34$^{\circ}C$, respectively. The slopes obtained from the relationship between hemolymph osmolality and medium osmolality were 0.314, 0.276 and 0.541 for L. vannamei at 18, 28 and 34$^{\circ}C$, respectively, suggesting that the shrimp at 34$^{\circ}C$ regulated osmotic concentration much worse than those at 18 and 28$^{\circ}C$. This result also indicated that L. vannamei living at 34$^{\circ}C$, showed more fluctuation in hemolymph osmolality than those at 18 and 28$^{\circ}C$.

• Journal of fish pathology
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• v.35 no.1
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• pp.129-133
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• 2022

The full genome sequence of a Korean white spot syndrome virus (WSSV, isolate: WSSV-GoC18) is presented here. We obtained a total of 12,320,554 reads with 291,172 bases, 170 gene, and 170 coding DNA sequence, which were assembled in 1 contig. Phylogenetic analysis revealed that the WSSV-GoC18 was closely related to Chinese isolate (WSSV-PC) and distinctly different with previously reported a Korean isolate (WSSV K-LV1). The complete genome sequence of WSSV isolates will be of great help in molecular epidemiological studies, contributing to molecular diagnosis and disease prevention in shrimp aquaculture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.960-966
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• 2022

We aimed to determine the dietary myo-inositol (MI) requirements of Pacific white shrimp Litopenaeus vannamei. A basal diet was formulated without myo-inositol (M0) and a negative control diet (M0-) was prepared by adding tetracycline hydrochloride to the basal diet to prevent intestinal inositol synthesis. Five MI diets were prepared by adding MI at 300, 600, 900, 1,200 and 1,500 mg/kg to the basal diet (designated as, M300, M600, M900, M1200 and M1500, respectively). Triplicate groups of shrimp (initial body weight, 0.55±0.01 g) were fed one of the experimental diets for 42 days. The growth performance of shrimp in M0- group was significantly lower when compared to that of shrimp in M0, M1200 and M1500 groups. Feed efficiency was significantly improved in M1200 and M1500 groups when compared to the M0 and M0- groups. GPx activity was significantly higher in M1200 and M1500 groups compared to that in M0 and M0- groups. Therefore, a practical diet (over 240 mg/kg) meets the minimum MI requirements of Pacific white shrimp. However, the optimum dietary MI level would be potentially above 1,200 mg/kg for better feed utilization efficiency and antioxidant capacity of Pacific white shrimp.