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Volume 58, Issue 2
Displaying 1-19 of 19 articles from this issue
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Original Papers
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Yoshihiro Suzuki, Yuji Sagisu, Takahiko Suzuki, Thoru Mekata, Tomoya K ...2010 Volume 58 Issue 2 Pages 161-166
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSUsing a closed recirculating aquaculture system including foam separation and nitrification units for kuruma shrimp Marsupenaeus japonicus, a spawning test was carried out in the limited space of the culturing tank (area, 1 m2). The female shrimp (average body weight 65 g) used in the test were unqualified for seedling production in the actual shrimp farm because they had a spermatophore but immaturity of their ovary. The nine females were treated with unilateral eyestalk ablation using a rubber tag and cultured in the individual cages set in the culturing tank. Ovarian development was visualized by employing a flashlight to distinguish the development ratio of ovary in the dorsal exoskeleton. All individuals in the system survived throughout the test period (15 days). Five individuals within 9 females spawned within 15 days. There were two individuals which spawned two to three times during the period. The average number of eggs in spawning was 5.1×104/individual. After the spawning test, the females reared in the system were judged white spot disease virus (WSDV) free by the method of loop-mediated isothermal amplification (LAMP). In the small-scale of closed recirculating system, it was verified that female shrimps could be spawned under virus-free conditions.View full abstractDownload PDF (434K) -
Shigeaki Gorie, Kazuya Nagasawa2010 Volume 58 Issue 2 Pages 167-179
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSFrom 2003 to 2008, we tried to collect newly settled juvenile whitespotted conger in four areas of the northeastern Harima Nada Sea, eastern part of the Seto Inland Sea, Japan. We also investigated the relation between the stomach contents of juveniles (78-259 mm TL) and benthos composition at the sampling sites. No juveniles were taken from the sand bottom area, but they were collected from the gravel bottom and sand-mud bottom areas. Main stomach contents of the juveniles were crustaceans, polychaetes and teleosts. Crustaceans were strongly preferred being the most common and numerically important prey. Juveniles first fed on amphipods and, with growth, shifted their prey to decapods, polychaetes and teleosts. CPUEs (catch per unit effort) of the juveniles from the sand-mud bottom were significantly higher than those from the gravel bottom, although the crustacean biomass on the gravel bottom was more abundant than those on the other bottoms. These results suggest that, when the juveniles settle, they prefer the sand-mud bottom to the gravel bottom and choose their habitat not by the food environment but by the sediment type. We consider that the sand-mud bottom area is a nursery ground of the juveniles.View full abstractDownload PDF (392K) -
Kohsuke Adachi, Keitaro Kato2010 Volume 58 Issue 2 Pages 181-187
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSIn order to test the effects of shielding from sunlight on the body color of red sea bream, we characterized three phases. In phase 1, juvenile red sea bream (50 days after hatching) were bred with/without a black curtain for 50 days. In phase 2, each group was further subdivided into two groups which were bred with/without a black curtain for 1 year. Finally, all groups were shielded with a black curtain for 3 months (phase 3). No significant difference in L* value (used as a criteria for body color) was observed between the shaded and unshaded groups after phase 1. The results after phase 2 indicate that shielding in phase 1 also had little effect on the later body color. In phase 3, the L* value significantly increased within 2 months in all body sites examined in all groups. We also tested the effects of shielding suntanned red sea bream which had been bred without shielding for 2 years. After 2-4 weeks of shielding, the color in various body sites was significantly improved. We conclude that shielding of juvenile fish is unnecessary because the sun-tanning that occurs during juvenile stages can be improved later by shielding.View full abstractDownload PDF (438K) -
Kengo Ohta, Yasuhiro Shima, Ken-ichi Watanabe2010 Volume 58 Issue 2 Pages 189-194
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSYoung devil stinger Inimicus japonicus (60.7 mm in total length, TL) were individually marked by extracting the fourth, fifth, or the fourth, fifth, ninth, tenth and eleventh spines of the dorsal fin using tweezers and the effectiveness and period that individuals can be distinguished were investigated. As a result, it was confirmed that the extracted spines do not regenerate and could be readily distinguished from control (no fin marking) individuals until the end of the experiment (twenty-four months after marking). Mortality due to marking was not observed. The mean rate at which young (61.6 mm TL) could be marked by extracting the fourth and fifth dorsal fin spines was 298 individuals / hour / person. Advantages of the present new marking method for young fish (ca.60 mm TL) is that it is cheap, easily done and suitable for long term marking.View full abstractDownload PDF (476K) -
Manabu Hibino, Mitsuo Kawane, Munehiko Uemura, Yoshiaki Miyake, Kouji ...2010 Volume 58 Issue 2 Pages 195-202
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSWe assayed the genetic characteristics of hatchery-reared and wild Ayu Plecoglossus altivelis altivelis populations in Aichi Prefecture using microsatellite DNA analysis. No statistical differences were detected in pairwise Fst values among different populations and life stages of wild fish. Wild fish populations from the rivers flowing into Ise and Mikawa bays were thought to constitute the same genetic population. Genetic characteristics of a hatchery stock F1 from wild population, medium in size selection was similar to that of wild populations in terms of both allele number and heterozygosity, and pairwise Fst values. A marked reduction in genetic variability and/or considerable genetic drift was observed in some of hatchery stocks, domesticated stock and artificially selected stock. However, an increase in genetic variability was observed in a cross-breeding stock that had wild fish and domesticated stock as parents. We propose that F1 hatchery stocks originating from wild, amphidromous parents that are not under any strong selection are well suited for release and stock enhancement. In conclusion, in order to reduce the risk of genetic disturbance to wild ayu population, production management initiatives related to managing the genetic aspects of ayu hatchery stocks need to be implemented.View full abstractDownload PDF (404K) -
Masahiko Koiso, Hiroshi Kuwada, Atsushi Hagiwara2010 Volume 58 Issue 2 Pages 203-210
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSWe aimed at developing a technique for practical mass transportation of the rotifer Brachionus plicatilis (S-type), based on the existing method used in transporting L-type rotifer. Among the two S-type strains used in Japanese public hatcheries, Yaeyama strain showed significantly higher tolerance to low temperature (5°C) than Okayama strain, thus, we used Yaeyama strain in this study. For high density transportation of rotifers cultured at 25°C, pretreatment cooling at 15°C, is effective. Rotifers were packaged at 30,000 ind./ml in 300-1,000 ml seawater. Thereafter, the rotifers were refrigerated at 5°C. The recovery rate of rotifers after these treatments was about 70% after 2 days of storage. Refrigerated rotifers were less viable, and at least one day recovery period at 25°C is necessary before the rotifers can be used as starter of mass culture or food for fish larvae. Based on these results, we conducted a high-density rotifer transportation at 5°C, and 3×108 rotifers were transported to other hatcheries in 48 hours using a commercial delivery service. The recovery rates of rotifers at arrival were more than 70%. These results showed that high-density transportation of using Yaeyama S-type rotifer strain is possible by optimizing the processes we established.View full abstractDownload PDF (340K) -
Takayuki Mine, Shigemitsu Tanaka, Yoshio Kawamura, Genta Kobayashi, Ko ...2010 Volume 58 Issue 2 Pages 211-217
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSThree types of bacteriophages that infected suminori pathogenic bacterium, Gaetbulibacter sp., were isolated from seawater and tideland mud of the Ariake Sea. These bacteriophages were classified into two groups according to their morphology and restriction analysis of their genomes. Their virulence against the pathogen was investigated as the length of their latent periods and burst sizes based on a one-step growth experiment. Suminori disease control was also attempted using one isolated bacteriophage selected by its virulence and the storage stability. The incidence of the disease was apparently repressed in phage-treated laver thalli of Porphyra yezoensis immediately after bacterial infection. Furthermore, phage treatment was effective even after 24 h of bacterial infection. The results obtained in this study suggest the possibility of using bacteriophages for suminori disease control in laver cultivation.View full abstractDownload PDF (355K) -
Prasatporn Borisutpeth, Pithai Kanbutra, Chutima Hanjavanit, Emi Ho ...2010 Volume 58 Issue 2 Pages 219-224
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSChlorine dioxide possesses antifungal activity against three species, Saprolegnia diclina, Achlya bisexualis and Aphanomyces sp. Chlorine dioxide was more effective against Aphanomyces sp. than S. diclina and A. bisexualis. Three days of immersion in chlorine dioxide >100 ppm inhibited hyphal growth of S. diclina and A. bisexualis, and concentrations >50 ppm inhibited growth of Aphanomyces sp. Immersion in 500μg/ml chlorine dioxide for 1-4 h killed the hyphae and concentrations of 32 to 63μg/ml inhibited germination and killed zoospores of all three strains. The result suggest that treatment of hatchery water with 63μg/ml of chlorine dioxide for 10 min can control the zoospores but does not inhibit the growth of fungal hyphae of these strains. We conclude chlorine dioxide is an effective antifungal agent on both the hyphal and zoospore stages of S. diclina, A. bisexualis and Aphanomyces sp.View full abstractDownload PDF (98K) -
Kengo Ohta, Yasuhiro Shima, Ken-ichi Watanabe2010 Volume 58 Issue 2 Pages 225-231
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSWe investigated the effectiveness and distinguishable period of improved spaghetti anchor tag in young (50 to 80 mm in total length) devil stinger Inimicus japonicus, under artificial rearing conditions. Part of the anchor and tube of a commercial spaghetti tag was cut to make the improved tag. It was clarified that the improved tag could be completely distinguished in the individuals for at least about two years after tagging. Mortality related to tagging was not observed. However, a large portion of the tag was buried in the body of ca. 20% of individuals about 500 days after tagging.View full abstractDownload PDF (378K) -
Shigeaki Gorie, Minoru Tanda, Kazuya Nagasawa2010 Volume 58 Issue 2 Pages 233-242
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSWe conducted a tagging survey to study the movement and growth of whitespotted conger Conger myriaster in the eastern Seto Inland Sea and found that the fish moved to Osaka Bay and the coastal waters of the Kii Channel from the northeastern Harima Nada Sea, the release site, through the Akashi Strait from January to August. Total length and gonadsomatic index of females recaptured in the Osaka Bay-Kii Channel waters were larger and higher, respectively, than those in the Harima Nada Sea-Akashi Strait waters, suggesting that the fish conducted a pre-spawning migration. The fish were recaptured up to 420 days after release and exhibited various growth rates ranging from 0.1 to 2 mm day-1. There was no particular trend in age of recaptured females although the age ranged from 1+ to 3+. Not all the released fish passed through the Akashi Strait, nor they did always move to Osaka Bay even when they were at liberty for a long period. Some large-sized fish remained in the Akashi Strait. These results suggest that there are two types of groups (a locally resident group and a migratory group) and that whitespotted conger have a complicated migratory behavior.View full abstractDownload PDF (1229K) -
Hiroyuki Matsunari, Yasuro Iwashita, Nobuhiro Suzuki, Taro Saito, Atsu ...2010 Volume 58 Issue 2 Pages 243-252
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSThe effects of soybean meal fermentation on the biliary bile status and intestinal and liver morphology of rainbow trout Oncorhynchus mykiss were investigated. A fish meal based diet (FM) and non-fish meal diets, composed mainly of fermented defatted soybean meal (FSBM), and of defatted soybean meal (SBM), fortified with and without essential amino acids (EAA) to simulate the EAA composition of FM diet, were prepared. Each diet was fed to five duplicate groups of rainbow trout (average body weight: 12 g) for 12 weeks. Weight gain and feed efficiency of fish fed FM diet were significantly higher than those of fish fed the non-fish meal diets. Total biliary bile acid content was lowest in fish fed SBM diets, intermediate in fish fed FSBM diets and highest in fish fed FM diet. Morphological changes occurred in the distal intestine and liver of fish fed SBM diets, although morphological features in some fish fed FSBM diets were similar to those of the FM diet. EAA supplementation to FSBM diet tended to improve the performances mentioned above. These results indicate that fermentation of soybean meal has certain effects on normalizing the biliary bile status and intestinal morphology of rainbow trout.View full abstractDownload PDF (416K) -
Takayuki Fujiwara, Hideo Aoki, Takashi Ishikawa, Takashi Atsumi, Hisay ...2010 Volume 58 Issue 2 Pages 253-259
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSShell-closing strength (SCS) has been reported to be a useful indicator for selecting pearl oysters with a high survival rate in summer. The objective of the present study was to determine the suitability of near-infrared (NIR) spectroscopy to select pearl oysters with strong SCS. The SCS of Japanese lineage, Vietnamese lineage and a hybrid between Japanese and Chinese lineages showed a positive significant relationship with protein content and a negative significant relationship with moisture of soft tissue. Therefore, protein and moisture contents were found to be indicators of pearl oyster health as well as SCS. The spectra of intact pearl oysters of three lineages collected in 2008 were acquired using a portable NIR spectrophotometer. Second-derivative NIR spectra and multiple regression analysis were used to develop the calibration equations for protein and moisture contents. The predicted protein and moisture contents of pearl oysters collected in 2009 using the calibration equations showed sufficient accuracy for the selection of oysters with strong SCS. In conclusion, we propose that NIR spectroscopy is useful for monitoring SCS for the preliminary selection of pearl oysters in a breeding program.View full abstractDownload PDF (307K) -
Teruwo Morita, Hideki Kokubu, Ami Miyamatsu, Mizuho Fujii, Akira Kuras ...2010 Volume 58 Issue 2 Pages 261-267
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSWe studied the water temperature requirements and desiccation tolerance of the shoots of seagrass Zostera japonica to determine the conditions for its growth and surviving in mesocosm tanks. All shoots were withered on the artificial shallows set at a depth of D. L. + 40 cm (datum line plus 40 cm) and D. L. + 20 cm until 4 and 9 weeks after transplanting of Z. japonica shoots, respectively. On the other hands, there were 18.5±1.7, 13.5±5.8 and 11.8±4.3 shoots of new lateral shoots at a depth of D. L. + 0 cm, D. L. -20 cm and D. L. -40 cm, respectively. At the depth of D. L. + 0 cm, only three shoots developed into reproductive shoots.
The upper temperature was 28.6°C at a depth of D. L. + 0 cm. On the other hands, the upper temperature at a depth of D. L. + 40 cm and D. L. + 20 cm were 40.5°C and 34.2°C, respectively. We deduced that the emergence periods on the artificial shallows set of D. L. + 40 cm, D. L. + 20 cm and D. L. + 0 cm could be 17 hours, 9 hours and 2 hours from the temperature change in bottom sediments, respectively. Thus, the one of the factors affecting the critical upper distribution for Z. japonica were the high water temperature and desiccation of bottom sediments.View full abstractDownload PDF (512K) -
Yu Chai, Ryota Tosaka, Tomoki Abe, Keisuke Sago, Yosuke Sago, Eri Hata ...2010 Volume 58 Issue 2 Pages 269-278
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSFeminized 2-year-old eels were reared in freshwater at 26°C until October, then the water temperature was gradually decreased to 16°C to December, and gradually increased to 26°C from February to April. They received weekly injections of salmon pituitary extract (body weight, 15 or 30 mg/kg) to induce sexual maturation in September, December, or April. The quality of the eggs obtained in each season was evaluated by the resulting fertilization, hatching, and 8-day survival rates. High quality eggs were obtained via high-dose injections in most experimental groups. In the high-dose injection groups, eels were induced to the final maturation phase in all seasons; however, egg quality obtained in April was extremely low in contrast to that obtained in September and December. Histological observation of oocytes just before the process of artificial maturation was commenced indicated that the developmental stages of oocytes varied by season: oil droplet in September, early vitellogenic in December, and regressive from vitellogenesis in April. The extremely low egg quality in April is probably due to the fact that the oocytes had already entered the regressive stage. These results indicated that better quality of eel eggs can be obtained by starting the process of artificial maturation between September and December.View full abstractDownload PDF (772K) -
Kenichi Oyama, Motohide Tochino, Yutaka Ueta, Hiroyuki Takemori, Takeo ...2010 Volume 58 Issue 2 Pages 279-287
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSTo prevent discoloration of dark muscle and improve flesh quality of yellowtail Seriola quinqueradiata, the effects of a diet supplemented with powdered olive Olea europaea leaves on growth, metmyoglobin concentration, and color deterioration were investigated. One-year-old yellowtail (average body weight 3.6 kg) in aquaculture enclosures (10×10×3.5 m, approximately 3200 fish) were fed moist pellets containing an average of 0% or 1.7% olive leaf powder for 4-7 days per week at the same time each day, for 42 days, from October 30 to December 11. Growth performance and proximate muscle composition did not significantly differ between the dietary groups, but serum glucose was significantly higher in the olive leaf-fed yellowtail than in nonsupplemented fish. On and after 14 days, the metmyoglobin concentration in the dark muscle of yellowtail fed the powdered olive leaf supplement was significantly lower than that in the nonsupplemented fish. After 42 days, the color quality r on the surface of the dark muscle of the slices of nonsupplemented yellowtail significantly decreased than that of the olive leaf-supplemented fish. These results suggest that a diet including powdered olive leaves reduces dark muscle discoloration and improves flesh quality without affecting yellowtail growth.View full abstractDownload PDF (463K) -
Atsushi Narita, Makoto Kashiwagura, Hiroshi Saito, Yoshihiro Okada, No ...2010 Volume 58 Issue 2 Pages 289-296
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSThis study investigated the diurnal changes of feeding activity, Daily food consumption (DFC) and growth of hatchery-reared marbled rockfish Sebastiscus marmoratus larvae from 2 to 35-day post-partum reared under different densities of rotifers and photoperiods. Larvae in all stages ingested food organisms only during lighted period, and they ingested about 47-68% of the DFC during the 3 hours before turning off. When the 2 days post-partum larvae were reared in deifferent densities of rotifers, the DFC was higher as the density was higher. When the 7 days post-partum larvae were reared in the diferent densities of rotifers, no difference was found in the DFC. When the larvae were reared under two different lighting conditions: 24 hours of light exposure and 12 hours of light exposure for 9 days, larval growth was better under the 24 hours of light exposure conditions. We confirmed that all of the larvae had ingested rotifers 44 hours post-partum under the 24 hours of light exposure conditions, while under the 12 hours of light exposure conditions, they were confirmed that all of them had ingested rotifers much later, 80 hours post-partum. Therefore, the larval feeding can be infulenced by feeding densities and photoperiods.View full abstractDownload PDF (413K)
Short Papers
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Norio Onikura, Jun Nakajima, Hiromi Kouno, Yoshiko Sugimoto, Jun Kanet ...2010 Volume 58 Issue 2 Pages 297-298
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSMaturation and growth in the wild population of Hemigrammocypris rasborella were investigated from January 2007 to January 2008 by analyzing specimens fixed in formalin. Monthly changes in the gonadosomatic index (GSI) in female and male and oocyte diameter in females were estimated. From the GSI and oocyte diameter measurements, the spawning period of wild H. rasborella was determined to be from June to August. The von Bertalanffy growth curves (VBGCs) indicated that females had higher growth rates than males.View full abstractDownload PDF (136K) -
Emiko Takayama, Hitoshi Abe, Hiroshi Nagaoka2010 Volume 58 Issue 2 Pages 299-300
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSIn this study, we proposed a simple and rapid evaluation method for identifying feeding stimulants of baits for Japanese crucian carp. Sponges soaked with a test liquid were hung in the test tank. The feeding stimulus effect was derived from the pecking counts of the sponges. The pecking counts were measured in six test series for ten min, and the results were analyzed by t-test. The pecking counts for the commercial pellet extract and an extract of baked wheat gluten “Fu” in Japanese, were respectively statistically higher than control by t-test (P<0.01), which suggested the validity of this evaluation method.View full abstractDownload PDF (332K) -
Mitsuhiro Nakaya, Taizo Morioka, Kyohei Fukunaga, Naoto Murakami, Taka ...2010 Volume 58 Issue 2 Pages 301-303
Published: June 20, 2010
Released on J-STAGE: October 05, 2012
JOURNAL FREE ACCESSTo reduce mass mortality of Pacific saury caused by collision with the tank wall, we examined rearing of saury in a tank with a vinyl sheet attached to the tank wall, and no vinyl sheet tank. We compared survival rate and ratio of the lower jaw length to the knob length of those fish. Survival rate of the former was higher than the latter. No significant difference was recognized for the ratio. These results suggest that the vinyl sheet could not reduce the damage to the lower jaw, but it could reduce the mortality caused by collision.View full abstractDownload PDF (62K)
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