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To elucidate the post-release movement and emigration of juvenile spotted halibut Verasper variegatus, ten hatchery-reared age-0 individuals (10 months old, 17.0-19.7 cm total length) surgically implanted with acoustic transmitters were released near the center of Matsukawa-ura, a shallow brackish lagoon, on 25 November 2009 (water temperature 13.8 °C). They were monitored by ten acoustic receivers for 5 months. Of ten individuals, eight left the release site during December-March. Three of these emigrated to the outer ocean on 17 and 29 January and 30 March 2010, respectively. Juveniles probably started wintering migration in December and January when water temperatures decreased considerably in the lagoon (mean 9.5 and 6.0 °C, respectively). They stopped their migration in the coldest month, February (mean 5.7 °C), and restarted it in March when water temperatures frequently exceeded a plausible threshold for movement (≥6 °C). Statistical analyses revealed that the fish started migration significantly more frequently at nighttime. The migration track of an individual recorded from 11 to 30 March showed gradual nocturnal movements and a slow migration speed (estimated maximum speed 2.2 m/min). Our results revealed that water temperature primarily governed the seasonal timing of nocturnal migratory movements of juvenile spotted halibut. [ABSTRACT FROM AUTHOR]

The objective of this study is to establish a method for acquiring large quantities of high-quality eggs for artificial fertilization from hatchery-reared broodstock of spotted halibut Verasper variegatus. We estimated the optimum conditions for implantation of luteinizing hormone-releasing hormone analog (LHRHa) cholesterol pellet (LHRHa-CP) to induce ovulation from two experiments which focused on the dose and the timing combined with monitoring of oocyte development by ovarian cannulation. From the results of cannulation, vitellogenesis of hatchery-reared broodstock was suggested to occur normally, although final oocyte maturation was not initiated in the first clutch of oocytes. In late December, oocytes in the most advanced clutch still underwent vitellogenesis, having diameter of about 0.82 mm. LHRHa-CP implantation during this period had no remarkable effects, except for administration at high dose (100 μg/kg). In contrast, in mid January, when oocyte diameter reached about 0.95 mm, ovulation occurred in most individuals, even at low dose (20 μg/kg). In mid February atretic oocytes became remarkable and LHRHa-CP implantation showed much lower performance in terms of egg quality. The diameter of growing oocytes converged to about 0.95 mm, which was that of fully grown postvitellogenic oocytes. Thus, oocyte diameter is suggested to be an effective indicator to estimate the timing of LHRHa-CP implantation. [ABSTRACT FROM AUTHOR]

The occurrence and distribution of settling and settled spotted halibut Verasper variegatus were compared with those of Japanese flounder Paralichthys olivaceus in shallow habitats around Shimabara Peninsula, western Japan, to elucidate the settlement and recruitment characteristics of spotted halibut, a rare pleuronectid flatfish in Japan. Push-net sampling conducted at nine sites in March and April 2003 collected spotted halibut from four nurseries located at eastern areas of Shimabara Peninsula in Ariake Bay; Japanese flounder were sampled from eight nurseries. Comparison of microhabitat distributions in a tidal-flat nursery during February-April in 2003-2007 revealed that metamorphosing larvae and juveniles of spotted halibut, which showed the drastic body coloration (black to brown) and behavioral changes (frequent swimming to settlement), were distributed mainly in the lower edge of the intertidal area, whereas Japanese flounder inhabited both intertidal and subtidal areas. Metamorphosing larvae of spotted halibut (12.6-16.5 mm standard length; n = 24) were collected in March when the highest densities were observed, whereas metamorphosing larvae of Japanese flounder (10.0-15.9 mm, n = 55) were observed during March-April. Our results suggest that spotted halibut has a narrower time/space window for recruitment to the specific nurseries compared with Japanese flounder. [ABSTRACT FROM AUTHOR]

Habitat utilization, feeding, and growth of a rare pleuronectid flatfish, spotted halibut Verasper variegatus, were examined in a brackish lagoon in northeastern Japan: Matsukawa-ura. The distribution and date-length data of spotted halibut collected mainly from beam-trawl samplings during 1983-2008 indicated that age-0 juveniles [ n = 25, 6.0-18.0 cm total length (TL)] and older spotted halibut ( n = 71, 13.8-43.0 cm TL) inhabited almost the entire northern part of Matsukawa-ura. Comparative distribution surveys of spotted halibut, stone flounder, and marbled flounder during 1985-1989 revealed similar distribution patterns of these flatfishes; the highest densities were found around the central part of Matsukawa-ura, although significantly lower abundance was detected for spotted halibut. Linear growth equations of age-0 juveniles demonstrated that spotted halibut were able to achieve high growth after June, probably because abundant prey (e.g., mysids and gammarids) and suitable physical conditions (warmer water temperature and lower salinity) were present. The main prey items shifted from various crustaceans including mysids, caridean shrimps, and anomurans to brachyura Hemigrapsus spp. (≥20 cm TL). Our study shows that spotted halibut use the shallow brackish lagoon as an important nursery for juveniles, and also as a feeding ground for young and adults. [ABSTRACT FROM AUTHOR]

In this study, we determined the color vision and spectral sensitivity of pointhead flounder, slime flounder, and red halibut by recording electrophysiological S-potentials from isolated retinas; this basic data was collected to aid the selection of appropriate colors and effective wavelengths for selective fishing gear for sustainable fisheries. Four kinds of L-response and one C-response were recorded in the pointhead flounder and red halibut. Two kinds of L-response were recorded in the slime flounder. The occurrence of a C-response indicates the possession of color vision. The C-responses show that the pointhead flounder has superior distinction from blue to yellow, and red halibut has superior distinction from blue and green to red. The most frequently recorded L-responses indicate high spectral sensitivity at 544 nm in pointhead flounder and 518 nm in slime flounder and red halibut. All recorded L- and C-responses indicate sensitivity to ultraviolet wavelengths. [ABSTRACT FROM AUTHOR]

Barfin flounder and spotted halibut have been selected as target species for stock enhancement in Japan. Understanding the genetic condition of the wild stock is a principal requirement in any stock enhancement program. The genetic variability of barfin flounder and spotted halibut, and the population structure of spotted halibut were evaluated using microsatellite DNA markers (msDNA) and the control region of the mitocondrial DNA (mtDNA). Barfin flounder and spotted halibut showed high genetic variability at the msDNA level. Barfin flounder A was 16.7 and He was 0.860; spotted halibut An ranged from 7.7 to 10.2 and He ranged from 0.710 to 0.774. At the mtDNA level, high haplotype ( h = 0.922) and low nucleotide (π = 0.002) diversities were observed for barfin flounder; however, low haplotype and nucleotide diversities ( h = 0.603–0.620 and π = 0.001–0.002), and very low haplotype and nucleotide diversities ( h = 0.193 and π = 0.0003) were observed for spotted halibut in the north and south locations, respectively. Slight genetic differentiation among spotted halibut sampling locations was observed from the msDNA. MtDNA analyses showed genetic differentiation between north and south locations, but not within them. The designation of north-specific and south-specific management units in the future stock enhancement activities of spotted halibut is recommended. [ABSTRACT FROM AUTHOR]

To determine the growth performances and habitat characteristics of spotted halibut Verasper variegatus, successive samplings were conducted in the south-eastern coastal area of Shimabara Peninsula in Ariake Bay. The push-net samplings were performed at Kamaga beach from May 2003 to April 2004 to determine the horizontal distribution of larvae and juveniles, while the gill net samplings were done in the coastal waters of Tatsuishi beach from July 2003 to July 2004 to collect the larger juveniles and adults. A total of 478 individuals from metamorphosing larvae to 2-year-old fish (15.2–447.0 mm total length [TL]) were sampled. In particular, the 2003-year class fish were successively collected from May 2003 to June 2004 (15.2–350.0 mm TL; n = 418) and the mean total length in March, June, September, December 2003 and May 2004 was 22.4, 82.5, 172.5, 203.9 and 296.4 mm, respectively. The present study found that metamorphosing larvae migrated into the estuarine tidal flats during March 2003; newly settled juveniles inhabited the shallow intertidal areas; and juveniles had a remarkably high growth in shallow coastal areas. It is suggested that young fish around 300 mm TL migrated from the nursery grounds in Ariake Bay to deeper waters around Tachibana Bay during May–June 2004. [ABSTRACT FROM AUTHOR]

Spotted halibut Verasper variegatus hatchery juveniles produced in 2002 were genotyped using three microsatellite DNA markers (msDNA) and then released into natural waters. Subsequently, recaptured individuals were examined using msDNA. In order to evaluate the effectiveness of the stock enhancement program, from the genetic point of view, a pairwise FST test was implemented to estimate the genetic divergence between the wild captive broodstock, the hatchery offspring and the recaptured samples. The analysis showed significant differentiation between the broodstock and recaptured samples. Pedigree determination using msDNA was used to calculate the effective population size of the recaptured stock, which was found to be very low ( Ne ≈ 8). Equal family survivability was observed between the two recaptured stocks, but not between the released and recaptured stock. The number of identified families was higher and more equalized in the hatchery offspring compared to the recaptured samples, where the number of families declined. This fact was caused by an unequal family survivability just before or just after release. Separately, the number of contributing parents to the hatchery offspring was lower than the broodstock census number. Consequently, these two facts caused the genetic divergence of the recaptured stock from the broodstock. [ABSTRACT FROM AUTHOR]

Annual changes in testicular development and serum levels of androgen and progestins were investigated using captive male spotted halibut Verasper variegatus in order to obtain basic information on the reproductive physiology of this species. Based on the histological observation of testes, male maturity was divided into the following five stages: spermatogonial proliferation stage (July to September), early spermatogenic stage (October), late spermatogenic stage (November to December), functional maturation stage (January to March) and recovery stage (May). Spermatogenesis rapidly progresses during the autumn from October and December and continues until the functional maturation stage (spawning period of female). Serum levels of 11-ketotestosterone gradually increased from August and rapidly increased to a peak (2.8 ± 0.5 ng/mL) in November, suggesting that this steroid is involved in spermatogenesis in this species. Serum 17,20β-dihydroxy-4-pregnen-3-one levels showed a single small peak (0.55 ± 0.05 ng/mL) in November, suggesting the possibility of the involvement of this steroid hormone in the late spermatogenic period. [ABSTRACT FROM AUTHOR]

The skin of halibut Reinhararditus hippoglossoides hasbeen discarded as a waste product in large quantities by the foodindustry; hence, we examined the biological activity in the skin inorder to make good use of the waste. In the present study, we determinedinduction of hepatocyte growth factor (HGF) from the MRC-5 humanfibroblast cells and inhibition of cell proliferation in tumor cellsusing various components extracted from the fish skin. The glycosaminoglycanfraction was extracted with alkali solution and fractionated byion chromatography. Consequently, dermatan sulfate showed the strongestactivity in HGF induction, as well as commercially available heparinand heparan sulfate. Moreover, the alkali extract of fish skin showedinhibition of proliferation for some tumor cells in vitro .In particular, viable cells determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-tetrazoliumbromide (MTT) assay were significantly decreased by 5% inHL60 and 8% in U937 of leukemia cells in the medium containing5 mg/mL alkali extract. These observations indicatethat the fish skin has significant biological activity and is valuablefor functional foods and drugs. [ABSTRACT FROM AUTHOR]

ABSTRACT: In 1999, spotted halibut Verasper variegatus were experimentally reared at 9, 12, 15, 18, and 21°C from eggs through early juveniles at the Miyako Station of Japan Sea-Farming Association in Iwate Prefecture. Tissue concentrations of thyroxine (T4) increased to maximum levels during metamorphic climax (H-stage) at all the temperatures. The peak T4 levels were higher at lower temperatures, whereas no relationship was observed between tissue 3,5,3′-triiodothyronine levels and rearing temperatures. However, epithelial cell height of thyroid follicles and the number of vacuoles in colloid were not different among rearing temperatures. Although the peak T4 levels were different, thyroid activity to produce T4 might not be so different at all temperatures. Therefore, much T4 observed at low temperatures was possibly due to the accumulation of the unused hormone in blood and tissue. [ABSTRACT FROM AUTHOR]

The article investigates the inheritance of mitochondrial deoxyribonucleic acid (DNA) variable number of tandem repeats in barfin flounder Verasper moseri and spotted halibut in Japan. The investigation has been carried out to test whether mitochondrial variable number of tandem repeats (mtVNTR) analysis is appropriate when used in studying population genetic diversity or pedigree tracing. It uses the hypervariable repeats comprising the mtVNTR for pedigree tracing evaluation of the released stock of both species. The results recommend not to use mtVNTR of the control region in the evaluation for genetic diversity and pedigree tracing of both species.

Examines the effect of waterborne bisphenol A and nonylphenol in seawater on spotted halibut Varaspar variegates. Bioconcentration factors; Ratio of chemical in the fish body to concentration in the seawater; Use of gas chromatography/mass spectrometry analysis.

A correction to the article "Egg collection from hatchery-reared broodstock of spotted halibut Verasper variegatus treated with LHRH analog," by Daisuke Shimizu and colleagues is presented.