Thamnaconus Modestus Research Articles

Mycobacterium stephanolepidis sp. nov., a rapidly growing species related to Mycobacterium chelonae, isolated from marine teleost fish, Stephanolepis cirrhifer.

A previously undescribed rapidly growing, non-pigmented mycobacterium was identified based on biochemical and nucleic acid analyses, as well as growth characteristics. Seven isolates were cultured from samples collected from five thread-sail filefish (Stephanolepis cirrhifer) and two farmed black scraper (Thamnaconus modestus). Bacterial growth occurred at 15-35 °C on Middlebrook 7H11 agar. The bacteria were positive for catalase activity at 68 °C and urease activity, intermediate for iron uptake, and negative for Tween 80 hydrolysis, nitrate reduction, semi-quantitative catalase activity and arylsulfatase activity at day 3. No growth was observed on Middlebrook 7H11 agar supplemented with picric acid, and very little growth was observed in the presence of 5 % NaCl. α- and α'-mycolates were identified in the cell walls, and a unique profile of the fatty acid methyl esters and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiles of the protein and cell-wall lipids were acquired. Sequence analysis revealed that the seven isolates shared identical sequences for the 16S rRNA, rpoB, hsp65, recA and sodA genes. Phylogenetic analysis of the five gene sequences confirmed that the isolates were unique, but closely related to Mycobacterium chelonae. Antibiotic susceptibility testing revealed the minimum inhibitory concentration (MIC) of clarithromycin against this novel species was <0.25 µg ml-1, which was lower than that for Mycobacterium salmoniphilum. The hsp65 PCR restriction enzyme analysis pattern differed from those of M. chelonae and M. salmoniphilum. Based on these findings, the name Mycobacterium stephanolepidis sp. nov. is proposed for this novel species, with the type strain being NJB0901T (=JCM 31611T=KCTC 39843T).

Protease Hydrolysates of Filefish (Thamnaconus modestus) Byproducts Effectively Inhibit Foodborne Pathogens.

In this study, novel antimicrobial peptides had been derived by enzymatic hydrolysis of filefish (Thamnaconus modestus) byproduct (HFBP). Different proteases, (papain [P], trypsin [T], neutrase [N], pepsin [PE], and the mixture I [PN] and mixture II [PT]) and different hydrolysis time (60, 120, 180, and 240 min), have been used to generate peptides with different lengths and amino acid sequences. The antimicrobial properties of HFBPs were tested, against Gram-positive and Gram-negative strains, using disc diffusion method. HFBP prepared after 120 min of the enzymatic hydrolysis by trypsin (HFBP-T) exhibited greatest antibacterial activities. Bacillus cereus 10451 (BC) and Salmonella enteritidis 10982 (SE) strains were most sensitive to HFBP-T with an inhibitory zone of 24.68 and 29.67 mm diameter and minimum inhibitory concentration of 1.25 and 2.5 mg/mL, respectively. Moreover, the antimicrobial activities of tested HFBPs increased significantly at low pH and temperature. The amino acid analysis showed that HFBP-T protein hydrolysate is high in an amino acid of proline, which probably contributes to the antimicrobial activity. The results obtained from scanning electron microscopy suggested that HFBPs might kill bacteria by acting on the cell wall of bacteria. Conclusively, the HFBP derived from filefish byproduct with biological activates is an interesting alternative to the use of waste from the fishing industry as natural antimicrobials in food stuff.

Age and growth of filefish, Thamnaconus modestus (Günther, 1877) off the Jeju Island of Korea

The age and growth of filefish, Thamnaconus modestus (Gunther 1877) in the southern waters of Korea were investigated. Samples were collected with commercial trawl catches during the period from May 2009 to December 2011. Of the 2,626 specimens collected, the sex ratio was not significantly different from 1:1 (P > 0.05). The total length ranged from 11.3 to 42.1 cm. The gonadosomatic index for both sexes was the highest in May to June, indicating that May to June is the main spawning period. The length of females at sexual maturity was 25.92 cm. The length-weight relationship of the filefish was TW = 0.0121TL3.0536 (n = 1,692, r2 = 0.9034, P < 0.001). The age of the sampled individuals was estimated by counting growth rings recorded on the 5th vertebrae; ages ranged from 0 to 9 years. The filefish of the same age displayed a high individual variation in total length. Length-at-age data were fitted by using the Von Bertalanffy growth model. The estimated Von Bertalanffy growth parameters were L∞ = 42.04 cm, k = 0.21 year−1 and t0 = −1.56 for females, L∞ = 41.20 cm, k = 0.18 year−1 and t0 = −2.36 for males, and L∞ = 43.16 cm, k = 0.17 year−1 and t0 = −2.18 for the combination of both male and female. These data can be used as useful biological information for the future fishery management of filefish resources in Korean waters.

New host records of monacanthid fish for three Kudoa spp. (K. septempunctata, K. thyrsites, and K. shiomitsui) prevalent in the olive flounder (Paralichthys olivaceus), with the description of K. parathyrsites n. sp. from a black scraper (Thamnaconus modestus).

Kudoa septempunctata (Myxosporean: Multivalvulida) is known as a cause of foodborne disease associated with consumption of raw flesh of the olive flounder (Paralichthys olivaceus). Knowledge of its life cycle, particularly alternate annelid hosts and reservoirs or susceptible fish hosts in natural waters, may facilitate disease control in aquaculture farms. Our recent survey of myxosporean infection in monacanthid fish in natural waters around Japan revealed infection with three kudoid species prevalent in the olive flounder, i.e., K. septempunctata, Kudoa thyrsites, and Kudoa shiomitsui. Of the 51 black scrapers (Thamnaconus modestus) examined, five fish were infected: two fish with K. septempunctata and three with K. thyrsites. One of the fish infected with K. septempunctata was also infected with a K. thyrsites-like species. One of the 17 threadsail filefish (Stephanolepis cirrhifer) and two of four unicorn leatherjackets (Aluterus monoceros) were parasitized with K. shiomitsui. Three modest filefish (Thamnaconus modestoides) had no kudoid infection. K. septempunctata from a black scraper fished in the Inland Sea of Japan off Yamaguchi had 6-8 (predominantly 7) shell valves/polar capsules, whereas K. septempunctata found in another black scraper from the Sea of Japan off Tottori had 5 or 6 (predominantly 6). However, the two isolates displayed identical 18S and 28S ribosomal RNA gene (rDNA) nucleotide sequences, which were also identical to the isolates from the olive flounder. K. thyrsites from the Inland Sea of Japan off Yamaguchi and Sea of Japan off Tottori and K. shiomitsui from the Sea of Japan off Shimane and western Pacific Ocean off Kochi were also morphologically and genetically characterized. They were found to be coincident with the previous reports from olive flounders. Furthermore, the K. thyrsites-like species found in a black scraper from the Inland Sea of Japan off Yamaguchi was morphologically and genetically characterized; a new species, Kudoa parathyrsites n. sp., is erected for this species. The relationships of the new species with K. thyrsites and related species as well as those of K. shiomitsui with Kudoa pericardialis and related species parasitizing the pericardium are briefly discussed.

Ontogenetic changes in the predator–prey interactions between threadsail filefish and moon jellyfish

Although jellyfish are important predators of fish larvae, many fish species also feed on jellyfish. Therefore, the predator–prey role of jellyfish and fish may switch during the course of their life histories. Here, we investigated such interactions by examining (1) the avoidance behaviour of threadsail filefish Stephanolepis cirrhifer to moon jellyfish Aurelia sp. and (2) the feeding behaviour of filefish on moon jellyfish medusae and polyps. The efficiency of filefish as jellyfish predators was examined by comparing their behaviour with that of black scraper Thamnaconus modestus and red sea bream Pagrus major. Filefish and black scraper were able to avoid medusae and obtain tolerance against nematocysts at a smaller body size compared to red sea bream. Filefish initiated feeding on medusae when they became juveniles of 21.8 mm SL. Feeding trials of yearling filefish on polyps at different temperatures (range 10–30°C) indicated that the highest feeding rate was 3.1 individuals s−1 at 26.8°C. We suggest that the feeding pressure of filefish on jellyfish polyps may have an impact on medusa biomass.

Seasonal changes in infection with trematode species utilizing jellyfish as hosts: evidence of transmission to definitive host fish via medusivory.

In the Seto Inland Sea of western Japan, metacercariae of three species of trematodes, Lepotrema clavatum Ozaki, 1932, Cephalolepidapedon saba Yamaguti, 1970, and Opechona olssoni (Yamaguti, 1934), were found in the mesoglea of the jellyfish Aurelia aurita s.l., Chrysaora pacifica, and Cyanea nozakii. Moreover, these jellyfish frequently harbored juveniles of the fish species Psenopsis anomala, Thamnaconus modestus, and Trachurus japonicus. The former two fish species are well-known medusivores. We investigated seasonal changes in the prevalence and intensity of these metacercariae in their host jellyfish from March 2010 to September 2012 and presumed that infection by the trematodes of the definitive host fish occurs through these associations. The mean intensity of metacercariae in A. aurita s.l. clearly showed seasonality, being consistently high in June of each year. The intensity of metacercariae in C. nozakii was highest among all jellyfish hosts and appeared to be enhanced by medusivory of this second intermediate, and/or paratenic host. Trophic interactions between jellyfish and associated fish were verified using both gut content and stable isotope analyses. The detection of trematodes and nematocysts in the guts of P. anomala and T. modestus juveniles, in addition to stable isotope analysis, suggests that transmission of the parasites occurs via prey-predator relationships. In addition, the stable isotope analysis also suggested that P. anomala is more nutritionally dependent on jellyfish than Th. modestus and Tr. japonicus.

Parasitic copepods of marine fish cultured in Japan: a review

This paper reviews aspects of the biology of copepods infecting marine fish commercially cultured at fish farms or held as broodstock at governmental hatcheries in Japan. In total, 20 species of parasitic copepods have been reported from these fish: they are mostly caligids (12 spp.), followed by lernaeopodids (4 spp.), pennellid (1 sp.), chondracanthid (1 sp.), taeniacanthid (1 sp.), and unidentified species (1 sp.). The identified copepods are: Caligus fugu, C. lagocephalus, C. lalandei, C. latigenitalis, C. longipedis, C. macarovi, C. orientalis, C. sclerotinosus, C. spinosus, Lepeophtheirus longiventralis, L. paralichthydis, L. salmonis (Caligidae); Alella macrotrachelus, Clavella parva, Parabrachiella hugu, P. seriolae (Lernaeopodidae); Peniculus minuticaudae (Pennellidae); Acanthochondria priacanthi (Chondracanthidae); and Biacanthus pleuronichthydis (Taeniacanthidae). The fish recorded as hosts include carangids (4 spp.), sparids (2 spp.), monacanthids (2 spp.), salmonids (2 spp.), scombrid (1 sp.), tetraodontid (1 sp.), pleuronectid (1 sp.), paralichthyid (1 sp.), and trichodontid (1 sp.). Only five species (C. orientalis, L. longiventralis, L. salmonis, C. parva and A. priacanthi) parasitize farmed fish in subarctic waters, while all other species (15 spp.) infect farmed fish in temperate waters. No information is yet available on copepods from fish farmed in subtropical waters. Three species of Caligus (C. fugu, C. sclerotinosus and C. longipedis) are serious pests in aquaculture of Japanese pufferfish (Takifugu rubripes), red seabream (Pagrus major), and striped jaw (Pseudocaranx dentex), respectively. Due to its one-host life cycle that is unique among pennellids, P. minuticaudae is considered as a potentially serious pest with further development of aquaculture of its filefish hosts, threadsail filefish (Stephanolepis cirrhifer) and black scraper (Thamnaconus modestus). Infection of farmed salmonids by L. salmonis is not a serious problem in Japan.

Effect of UV-C light on the microbial and sensory quality of seasoned dried seafood

This study investigated the effects of different doses of UV-C light at 253.7 nm (0-18 kJ/m(2)) on the reduction of Escherichia coli,Staphylococcus aureus and Bacillus cereus in contaminated seasoned dried filefish (Thamnaconus modestus) and sliced squid (Todarodes pacificus) surfaces and sensory quality. The counts of all three bacteria were significantly (P < 0.05) reduced by the increase of UV-C dosage.E. coli,S. aureus and B. cereus on filefish with 18 kJ/m(2)of UV-C maximally reduced by 2.70, 2.55 and 2.57 log CFU/g, respectively; however, on the sliced squid using the same UV dose reduced the same bacteria by 1.35, 0.54 and 1.05 log CFU/g, respectively. However, the results suggest that 6 to 9 kJ/m(2)of UV-C could be used for the inactivation of E. coli and B. cereus in these dried fishery products without any changes in sensory quality. However, S. aureus levels on sliced squid will require a combination of UV-C light and chemical treatment.

Correlation between the Temperature Tolerance of Live Fish and Caudal Fin Cells in Black Scraper Thamnaconus modestus

Correlation between the Temperature Tolerance of Live Fish and Caudal Fin Cells in Black Scraper Thamnaconus modestus

Relationships between Temperature and Growth of Thread-sail Filefish Stephanolepis cirrhifer and Black Scraper Thamnaconus modestus

Relationships between Temperature and Growth of Thread-sail Filefish Stephanolepis cirrhifer and Black Scraper Thamnaconus modestus

A new species of Neolebouria Gibson, 1976 (Opecoelidae: Plagioporinae) from the whitecheek monocle bream, Scolopsis vosmeri (Perciformes: Nemipteridae), from the Panjim coast at Goa, with a checklist of parasites previously reported from this fish.

Neolebouria capoori n. sp. (Opecoelidae: Plagioporinae) is described from the whitecheek monocle bream, Scolopsis vosmeri (Bloch) (Perciformes: Nemipteridae) from the Panjim coast on the central west coast of India at Goa. The new species differs from both Neolebouria cantherhini (Li, Qiu & Zhang, 1988) as originally described from Thamnaconus modestus (Günther) (syn. Cantherines modestus Günther ) and Neolebouria confusum (Overstreet, 1969) as originally described from Ocyurus chrysurus (Bloch) by having the cirrus sac surpassing the ventral sucker posteriorly in N. cantherhini and being entirely preacetabular in N. confusum compared to terminating near the midlevel of the ventral sucker in N. capoori n. sp. The new species is most similar to N. confusum, but it further differs from this species by having the vitelline fields terminating near the level of the esophageal bifurcation compared to terminating near the level of the posterior margin of the pharynx, a larger sucker ratio (1:1.7-1:2.0 compared to 1:1.4-1:1.7), a somewhat shorter cirrus sac relative to body length (160-448, representing 9-18% of the body length compared to about 367, representing 22%), and the egg of the new species has a boss at the anopercular end that is not present in N. confusum. This study represents the first report on an opecoelid from S. vosmeri. A review of the parasites reported from S. vosmeri is included.

말쥐치, Thamnaconus modestus의 산소소비율과 수온의 관계

말쥐치, Thamnaconus modestus는 우리 연근해에서 1970년대 말부터 1980년대에 걸쳐 대표적인 어획종이였으나 지속적인 남획으로 인해 현재 자원이 급격히 감소한 상황이다. 2000년대에 들어오면서 인공종묘생산이 성공하게 되고 현재에는 새로운 양식 대상어종으로서 그 가능성을 타진하고 있다. 이 연구에서는 성체에 진입하는 단계에 있는 말쥐치(전장 <TEX>$22.6{\pm}0.8$</TEX> cm, 총습중 <TEX>$140.3{\pm}13.9$</TEX> g)의 수온(<TEX>$12{\sim}28^{\circ}C$</TEX>)에 대한 표준대사율을 측정하여 이들 종이 가지는 수온 특성을 파악하고자 하였으며, 각 측정치로부터 그 관련 식을 얻었다. 표준대사율은 수온 <TEX>$23{\sim}26^{\circ}C$</TEX> 부근에서는 수온 상승에 대해 증가 경향이 나타나지 않았으나, <TEX>$12{\sim}28^{\circ}C$</TEX>의 수온 범위 전반에서 단위 체중 당 산소소 비율(SOCR, <TEX>$m/O_2/gWW/h$</TEX>)의 경우, SOCR = 0.0117WT-0.0135 (<TEX>$r^2$</TEX> = 0.9351), 개체 당 산소소비율(IOCR, <TEX>$m/O_2/fish/h$</TEX>)의 경우는, IOCR = 1.8160WT-5.4007 (<TEX>$r^2$</TEX>= 0.9428)로 수온 상승에 따라 직선함수로 증가하는 경향을 나타내었다. 그리고 단위 체중 당 산소소비율을 통해 수온민감도(<TEX>$Q_{10}$</TEX>)를 계산하여 비교한 결과, 수온이 높을수록 낮아지는 경향을 보였는데 외온성 동물의 일반적인 <TEX>$Q_{10}$</TEX> 값인 2~3보다 <TEX>$12{\sim}15^{\circ}C$</TEX>에서는 <TEX>$Q_{10}$</TEX> 값이 6.27로 매우 높았고 <TEX>$23{\sim}28^{\circ}C$</TEX>에서 <TEX>$Q_{10}$</TEX> 값은 1.30으로 다소 낮아서 난류성 어종의 수온 특성을 보였으며, 이로부터 성체에 진입하는 말쥐치에 있어서 <TEX>$15{\sim}28^{\circ}C$</TEX>는 그 적수온대에 속하는 것으로 판단된다. The black scraper Thamnaconus modestus was a commercially important fish species in the 1980s, but suddenly its commercial significance decreased in the 1990s mainly due to continuous overfishing. Recently, in order to reverse the depleted stocks of the black scraper and help the species recover, seed production technology has emerged. This has led to the farming of the black scraper in several parts of the southern coast of Korea. Since detailed research on its metabolism in relation to water temperature has been scanty, this was the investigative focus of the present study. The standard metabolism rates of the black scraper (9-10 months old, total length=<TEX>$22.6{\pm}0.8cm$</TEX>, wet weight=<TEX>$140.3{\pm}13.9g$</TEX>) were measured at seven different water temperature settings (12, 15, 17, 20, 23, 26, <TEX>$28^{\circ}C$</TEX>) to understand the relationship between metabolism and water temperature. Relationships between water temperature (WT) and oxygen consumption rate (OCR) were obtained as SOCR (weight-specific oxygen consumption rate) = 0.0117WT - 0.0135 (<TEX>$r^2=0.9351$</TEX>) and IOCR (oxygen consumption rate per individual) = 1.8160WT - 5.4007 (<TEX>$r^2$</TEX> = 9428). The <TEX>$Q_{10}$</TEX> (temperature sensitivity), an indicator of the sensitivity of biological function to temperature, was analyzed. In our experiment, when the water temperature increased, the <TEX>$Q_{10}$</TEX> value decreased. The <TEX>$Q_{10}$</TEX> value was 6.27 in waters where the temperature ranged from <TEX>$12-15^{\circ}C$</TEX> and this was much higher than the values obtained in waters where temperatures ranged between (1) <TEX>$15-23^{\circ}C$</TEX> and (2) <TEX>$23-28^{\circ}C$</TEX>. Consequently, it was shown that the black scraper is a warm water species and inhabiting waters in the temperature range from <TEX>$15-28^{\circ}C$</TEX> is deemed appropriate.

Fishing vs. Climate Change: An Example of Filefish (Thamnaconus modestus) in the Northern East China Sea

The main cause of annual fluctuations in catch and species composition of fisheries is usually uncertain, but a prevailing view has been that fishing effects are more critical than environmental variability. Filefish is a good anecdote: many Korean fisheries scientists have attributed the sudden collapse of Korean filefish fisheries in the early 1990s to overfishing, especially by trawl fisheries in the northern East China Sea (NECS). However, interdisciplinary researches have revealed that climate-driven, multi-decadal variability in oceanic conditions impacts both fish and fisheries around the world. To test the two alternative hypotheses (i.e., fishing and climate) as the major cause of the sudden decline of filefish, we compared fisheries data of filefish from the adjacent countries of the NECS and analyzed oceanographic conditions in relation to changes in species composition of fish assemblages in the NECS. Results suggested that the basin-wide, 1989 regime shift in the North Pacific and the subsequent shrinkage of habitat range to the southwest were the major cause of the sudden decline of filefish catch in the NECS. Locally, shifts in water temperature and currents were identified in the NECS for the early 1990s, but further physiology-oriented researches are required to understand the detailed mechanism of climate-change effects on filefish stocks in the marginal seas of East Asia.

방류용 수산종묘의 수산생물 병원체 검출 동향 (2009~2012)

Hatchery-reared seeds provides a key source of animal protein for human consumption and restocking for fishery management. For stock enhancement program, we have inspected the hatchery-reared seeds of 33 species in 2009, 44 species in 2010, 43 species in 2011 and 46 species in 2012 for legally designated diseases. Results showed that abalone was the most abundant in the marine species group and then sea cucumber, olive flounder, rockfish and swimming crab were followed. Crucian carp was the most abundant and then mandarin fish, Korean bullhead, melanian snail and Chinese mitten crab were followed in the freshwater species group. The number of inspection for black sea bream, rock bream, scorpionfish, black scraper, and eel has continuously decreased for four years. The inspection for flathead mullet has been carried out only in 2009. The total number of inspection cases for eight pathogens in this study were 8,476 and disqualification cases were 56 (0.67%) by detection of aquatic animals pathogens such as koi herpesvirus, white spot syndrome virus, red sea bream iridovirus or viral haemorrhagic septicemia virus.

Fatty acid composition of edible marine fish in Zhoushan, Zhejiang province

To analyze the main fatty acids in edible marine fish from Zhoushan, Zhejiang province. From September to October 2011, a total of 186 edible marine fish (31 species,6 individual fishes/species) were collected in local markets. Total lipids of edible part were extracted by Folch's method and fatty acids were separated and quantified by gas chromatographic after the homogenization of edible part. The differences of composition of n-6 polyunsaturated fatty acid (n-6 PUFA), n-3 polyunsaturated fatty acid (n-3 PUFA),saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) among fishes were analyzed. Among the 31 fishes, total lipids were highest in Auxis thazard ((13.2 ± 1.2)g/100 g edible part) and lowest in Thamnaconus modestus ((0.6 ± 0.1)g/100 g edible part). Total n-6 PUFA were highest in Mugil cephalus ((875.7 ± 506.4)mg/100 g edible part) and lowest in Seriola quinqueradiata((2.1 ± 1.9)mg/100 g edible part). Total n-3 PUFA were highest in Auxis thazard ((2623.8 ± 426.1)mg/100 g edible part) and lowest in Scoliodon sorrakowah ((82.0 ± 13.9)mg/100 g edible part). SFA were highest in Trachinotus ovatus((3014.9 ± 379.0)mg/100 g edible part) and lowest in Seriola quinqueradiata ((89.7 ± 5.8)mg/100 g edible part). MUFA were highest in Coilia nasus ((3335.7 ± 383.5)mg/100 g edible part) and lowest in Thamnaconus modestus ((32.1 ± 16.9)mg/100 g edible part). There were significant differences of composition of total lipids and of fatty acids among 31 edible marine fish species from Zhoushan.

Genetic structure of the Korean black scraper Thamnaconus modestus inferred from microsatellite marker analysis

The Korean black scraper, Thamnaconus modestus, is one of the most economically important maricultural fish species in Korea. However, the annual catch of this fish has been continuously declining over the past several decades. In this study, the genetic diversity and relationships among four wild populations and two hatchery stocks of Korean black scraper were assessed based on 16 microsatellite (MS) markers. A total of 319 different alleles were detected over all loci with an average of 19.94 alleles per locus. The hatchery stocks [mean number of alleles (N(A)) = 12, allelic richness (A(R)) = 12, expected heterozygosity (He) = 0.834] showed a slight reduction (P > 0.05) in genetic variability in comparison with wild populations (mean N(A) = 13.86, A(R) = 12.35, He = 0.844), suggesting a sufficient level of genetic variation in the hatchery populations. Similarly low levels of inbreeding and significant Hardy-Weinberg equilibrium deviations were detected in both wild and hatchery populations. The genetic subdivision among all six populations was low but significant (overall F(ST) = 0.008, P < 0.01). Pairwise F(ST), a phylogenetic tree, and multidimensional scaling analysis suggested the existence of three geographically structured populations based on different sea basin origins, although the isolation-by-distance model was rejected. This result was corroborated by an analysis of molecular variance. This genetic differentiation may result from the co-effects of various factors, such as historical dispersal, local environment and ocean currents. These three geographical groups can be considered as independent management units. Our results show that MS markers may be suitable not only for the genetic monitoring of hatchery stocks but also for revealing the population structure of Korean black scraper populations. These results will provide critical information for breeding programs, the management of cultured stocks and the conservation of this species.

New polymorphic microsatellite loci of threadsail filefish, Stephanolepis cirrhifer (Teleostei, Monacanthidae), from Korean waters

The threadsail filefish, Stephanolepis cirrhifer (Monacanthidae), is found mainly in the western Pacific. It is intensively caught in Korea and is a highly appreciated seafood delicacy. Consequently, the natural population of this species has drastically decreased, despite introductions from hatcheries. To provide information necessary for its conservation and management, we developed 24 polymorphic microsatellite markers using a combination of a total enriched genomic library and a small-scale 454 pyrosequencing. A total of 90,847 raw reads were obtained, and 75,128 unique sequences were generated, with an average length of 477 bp; 5350 (7.12%) sequences contained a minimum of 5 di- to tetranucleotide repeat motifs. Seventy-four sequences were used for microsatellite primer design. They all amplified successfully; 24 were polymorphic, with 8 containing trinucleotide repeats and 3 containing tetranucleotide repeats. The genetic variations based on 15 primer sets were investigated using 45 wild individuals from the coastal waters of Geomun Island. The number of alleles per locus varied from 4 to 15, with an average of 7.47. The observed and expected heterozygosities ranged from 0.333 to 0.956 and from 0.316 to 0.870, with averages of 0.692 and 0.701, respectively. No linkage disequilibrium was found between any pair of loci, indicating their independence. One locus significantly deviated from Hardy-Weinberg equilibrium after Bonferroni's correction; this may be due to the existence of a null allele. Cross-amplification was also tested for all 24 polymorphic loci in another monacanthid species, Thamnaconus modestus; 7 loci were effectively amplified. The high degree of polymorphism that was exhibited by the 15 newly developed microsatellites will be useful for assessing genetic variation and for conservation genetic studies of these 2 monacanthid species.

短波長域用および長波長域用の携帯型近赤外分光計によるマダイの背肉およびウマヅラハギの肝臓の脂質測定

短波長域用および長波長域用の携帯型近赤外分光計によるマダイの背肉およびウマヅラハギの肝臓の脂質測定

Breeding and Larval Rearing of Bluefin Leatherjacket, &lt;i&gt;Thamnaconus modestus&lt;/i&gt; (Günther, 1877) Under Commercial Scales

The spawning of wild caught broodstocks bluefin leatherjacket ( Thamnaconus modestus ) as well as the development of egg and larvae were studied under commercial scales. Spawning period was lasted 55 days from 15th June to 9th August, 2010. Total 4.3 million eggs were collected during the spawning period, and 65.5% of eggs were subjected to be properly hatched and developed. The diameter of the eggs was in range from 0.59mm to 0.63mm. Total 1.8 million newly hatched larva were obtained in present study with a hatching rate of 41.7%. First feeding was observed on 3 days post hatching (dph), and the yolk sac was completely exhausted on 4 dph. Metamorphosis occurred between 29 dph and 33 dph, at the total length (TL) of (11.93±2.18) mm. The growth in terms of TL can be expressed as a polynomial equation TL=3.30394-0.31862(dph)+0.02222(dph) 2 (r 2 =0.90362, n=427). After 70 days rearing, 0.3 million juveniles (TL>40 mm) were obtained and the ratio of seedling/newly hatched larvae was 5.62%. The results in this study demonstrated that bluefin leatherjacket was feasible breeding under artificial environment, and our results might provide some technical guidance for the further application in breeding this species.

Redescription of two Pennellids (Copepoda, Siphonostomatoida) from Korea with a key to species of Peniculus von Nordmann, 1832

Redescriptions of two pennellid copepods, Peniculus minuticaudae Shiino, 1956 and Peniculus truncatus Shiino, 1956, are provided, based on postmetamorphic adult females collected from marine ranched fishes captured at Tongyeong marine living resources research & conservation center, Korea. Peniculus minuticaudae was collected from the soft fin rays of black scraper Thamnaconus modestus. It can be distinguished from the other two closely related congeners Peniculus ostraciontis Yamaguti, 1939 and Peniculus truncatus by having a well developed triangular-shaped abdomen; the abdomen is rudimentary in other two species. This is thefirst report of the occurrence of Peniculus minuticaudae in Korea. Peniculus truncatus was collected from the dorsal fin of Korean rockfish Sebastes schlegelii. It can be distinguished from Peniculus minuticaudae by the combination of a rudimentary abdomen, long neck and setae on leg 1 and from Peniculus ostraciontis by the long neck, slender trunk, and setae on leg 1. It is also shown that Peniculus truncatus captured from the same host in Korea was misidentified as Peniculus ostraciontis and hence, this is thesecond record of the occurrence of Peniculus truncatus in Korea. A key is provided for the 14 nominal species of Peniculus.