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Volume 51, Issue 4
Displaying 1-14 of 14 articles from this issue
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Hideaki ACHIHA2003 Volume 51 Issue 4 Pages 367-374
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThis paper assesses the relationship between the number of released juveniles of ocellate puffer and the commercial landings at some fish markets in Aichi Prefecture. Since 1985, hatchery-reared juveniles of ocellate puffer have been released in Ise Bay, Mikawa Bay, Kumano Nada, Enshu Nada, and Suruga Bay to propagate fishery resources. After juveniles release, the mean annual catch of ocellate puffer landed by bottom trawl at the Toyohama Fish Market was increased 1.9 times, from 8.8 t (1971-1984) to 17.0 t (1985-2002) . Mean annual catch of ocellate puffer by longline in Aichi Prefecture after release was increased 3.3 times, from 13.2 t (1971-1985) to 43.2 t (1986-2002) . The correlation between the number of released juveniles (mean TL, 30 mm≤) in Ensyu Nada, Kumano Nada, and Suruga Bay and the annual catch in terms of weight landed at Toyohama, Katana, and Isshiki Fish Markets (October-March) by bottom trawl was positively significant (P<0.05) . Correlation between the number of released juveniles in Ise Bay and Mikawa Bay of ocellate puffer and the annual catch in terms of weight (the next year of release, October-February) of ocellate puffer by longline in Aichi Prefecture was also positively significant (P<0.01) . Based on these results, the commercial landings of ocellate puffer in Aichi Prefecture was considerd to be propagated by the juveniles release in the study areas.View full abstractDownload PDF (1331K) -
Susumu CHIBA, Seiji GOSHIMA2003 Volume 51 Issue 4 Pages 375-383
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSHokkai-shrimp, Pandalus latirostris, is one of the most important commercial species of shrimp in Hokkaido and eastern Russia, but its biology in only a few aquatic areas has been documented. We examined the population structure and seasonal growth of this shrimp in Notoro Lagoon, Hokkaido. The population consisted of three or four cohorts regarded as age groups. This shrimp generally matures as male at age-1 and then changes sex to female at age-2. In each age group, however, small proportions had sexual phases different from that of the majority, and their frequencies varied with age group. This shrimp grows from late-April to late-November, and the growth period is consistent with changes in water temperature in the lagoon. The critical water temperature for its growth was estimated at 4°C. We suspect that size-selective fishing potentially affects not only its growth rate but also its life history variation because it increases fitness of only small individuals.View full abstractDownload PDF (1129K) -
Shinji KIRIHARA, Yoshikazu FUJIKAWA, Masahiro NOTOYA2003 Volume 51 Issue 4 Pages 385-390
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSIn order to obtain mature sporophytes of Laminaria japonica for seeding, effect of seawater temperature (5, 10, 15, 20, 25°C) and day length (15 : 9, 12 : 12, 9 : 15h LD) on the growth and zoosporangial sorus formation were investigated in 150 litres culture tank with flowing filtered seawater, and compare with natural seawater temperature and day length as a control experiment. The sporophytes could not survive at 25°C. At 10-20°C, the sporophytes died early with increasing higher temperature or shorter day length. Many sporophytes produced a zoosporangial sorus at 5-20°C and 9 D : 15 L in a short culture period. Zoosporangial sorus was produced earlier more than three weeks at 5-20°C and 9 L : 15 D and at 15°C and 12 L : 12 D in contrast to control experiment tank. We can get mature sporophytes within a month from natural young 1st year sporophytes under these culture conditions. It is considered that the suitable conditions for the growth and maturation of Sporophytes are at lower temperature in the long day conditions.View full abstractDownload PDF (2962K) -
Yuzuru IKEDA, Ikuko SAKURAZAWA, Yasunori SAKURAI, Gen MATSUMOTO2003 Volume 51 Issue 4 Pages 391-400
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe Brain Science Institute was established to understand the brain using by cephalopod models and employing both ethological and molecular approaches. A special facility, the Center for Squid Culture and Behavioral Research, was opened in January 1999. The initial work dealt with technical problems such as methods of squid transfer, type of aquaria used, and type of diet. Several types of closed-system aquaria are used: a large circular tank (10, 000 l) ; a small circular tank (1, 700 l) ; and cylindrical tanks (eight 20 l or eight of 50 l) . Two species of squids (Heterololigo bleekeri, Sepioteuthis lessoniana) and cuttlefishes (Sepiella japonica, Euprymna morsei) were hatched and cultured from eggs, and wild-caught adult H. bleekeri, S. lessoniana, Todarodes pacifiacus and Idiosepius paradoxus were also maintained. Hatchlings of S. lessoniana and S. japonica were successfully cultured in cylindrical tanks for multiple generations. Heterololigo bleekeri hatchlings survived beyond 2 months in cylindrical tanks. Adult squids were successfully maintained in the large tank for the following durations: H. bleekeri, 78 days; T. pacifacus, 21 days; S. lessoniana, 5 months; I. paradoxus, 54 days. A wide variety of experiments can now be undertaken using live squid and cuttlefish at this facility, but some modifications are still needed for culturing more delicate species such as H. bleekeri.View full abstractDownload PDF (1710K) -
Munehiko KITSUKAWA, Motoo OHBA, Hitomi HIROSE, Keiji HIROSE2003 Volume 51 Issue 4 Pages 401-405
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSHand stripping method is generally used to obtain the fertilized eggs of the Japanese smelt Hypomesus nipponensis. However, the method is laborious and takes much time, so the efficient improvement for egg collection and labor saving were needed for the mass production of fertilized eggs and larvae. We have recently developed the spontaneous spawning method in a tank. This method is very efficient to obtain a large number of fertilized eggs when compared to the hand stripping. Mature male and female smelts were caught by the setting nets in Lake Ashinoko. They were kept in 1.5 t spawning tank with running water through a night. On the following day the broodstocks spawned spontaneously in the tank, and the fertilized eggs were efficiently collected. In an example, 71, 018×104 fertilized eggs from 3, 427 kg broodstock were obtained by the spontaneous spawning method for 37 days in 2002. The rate of eyed eggs were 86.7-96.1%, indicating almost maximum value in the mass production level. By this newly developed method, number of collected egg per hour was about double when compared to the usual stripping method. Therefore, this spontaneous spawning in the tank of Japanese smelt is very efficient to obtain the fertilized eggs, and labor saving method. Also, this is expected to be applied for other fishes.View full abstractDownload PDF (818K) -
Arun Prasad BAIDYA, Shigeharu SENOO2003 Volume 51 Issue 4 Pages 407-415
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThis study observed the fertilization and hatching rates of patin, Pangasius hypophthalmus eggs stripped at different times after ovulation in three females (1.8-2.5 kg) . Ovulation was induced by two human chorionic gonadotropin injections (500 and 1500 IU/kg with a 14-h interval) . Ovulation occurred between 8-10 h after the second hormone treatment at 26.5-28.6°C. The fertilization and hatching rates decreased with time after ovulation (AO) at 26.2-28.5°C. The mean fertilization rates were 95.9% at 0 h AO and 24.6% at 8 h AO. The mean hatching rate was 83.8% at 0 h AO; this finally decreased to 0% at 6 h AO. This study concludes that P. hypophthalmus eggs should be stripped and fertilized within 2 h AO in order to achieve good quality eggs (more than 50% hatching rate on average) .View full abstractDownload PDF (6535K) -
Tadashi IMAI, Yoshimasa TOYOTA, Hiroshi SAITO, Nobuhiko AKIYAMA2003 Volume 51 Issue 4 Pages 417-422
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSTap water is generally used for the rearing experiment of aquatic animals. Dechlorination of tap water is required to eliminate harmful effect of residual chlorine which is used to control the quality of tap water. In this study, the effects of dechlorination methods of tap water on survival and growth of Macrobrachium nipponense larvae were investigated under feeding and non-feeding conditions. Tap water was dechlorinated by three methods, namely aeration, ion-exchange resin and sodium thiosulfate for rearing larvae. The animals were taken from a freshwater lake, Lake Suwa-ko, a brackish water lake, Lake Sanaru-ko, and a river, River Asahina-gawa which flows into Suruga Bay. Larvae from the Lake Suwa-ko and the Lake Sanaru-ko lived longer and reached more advanced stages in the tap water dechlorinated by aeration and ion-exchange resin than those in the same freshwater dechlorinated by sodium thiosulfate. Survival time of larvae from the River Asahina-gawa in tap water dechlorinated by the three methods showed no distinct difference. Moreover, almost all of the larvae did not molt in the freshwater. Adding seawater to the dechlorinated tap water improved the survival rate of larvae irrespective of the dechlorination methods. These results indicate that neither aeration nor ion-exchange resin for dechlorination of tap water affect larval rearing.View full abstractDownload PDF (817K) -
Hozi IWATANI, Koji INOUE, Tadahisa SEIKAI, Yoshio TAKEI2003 Volume 51 Issue 4 Pages 423-428
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe four-spine sculpin, Cottus kazika, is a catadromous teleost endemic to Japan. In this study, we examined changes in tolerance to fresh water (FW) in developing larvae to establish an efficient culture system of this species. Larvae hatched in the laboratory were reared in 4 separate tanks all containing artificial seawater (SW) . Every 10 days from 40 through 90 days after hatching, 45 fish were randomly selected from each tank and transferred directly into FW. FW survival of these fish was counted 24 h after transfer, and the relationships among age, size (total length; TL) and survival were analyzed. Experiments were replicated in 2002 and 2003. The average age for the achievement of 50% survival at 24 h after the transfer was different between 2002 and 2003 experiments, 49 and 65 days after hatching, respectively. On the other hand, the average size at which 50% surviva124 h after the transfer to FW was almost the same (approximately 15 mm TL) . In addition, all fish over 17.5 mm survived FW transfer in the 2003 experiments, regardless of age. These results indicate that FW adaptability of this species is correlated with the size of fish rather than the age. The critical size of 17.5 mm TL corresponds to the stage of transition from planktonic to benthic habitats.View full abstractDownload PDF (895K) -
Katsutoshi KAWABE2003 Volume 51 Issue 4 Pages 429-434
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe oxygen consumption rate of reared blacktip grouper, Epinephelus fasciatus was investigated under six different water temperature conditions (15.0, 17.5, 20.0, 22.5, 25.0 and 27.5°C) and three body sizes (16, 97 and 645 g in mean body weight) from young to adult. In each body size, the oxygen consumption rate per individual (R: ml/ind./h) increased with an increase in water temperature (T: °C) between 15.0 and 27.5°C following the equation R=AT⋅B, where A and B are constants. In each temperature, the oxygen consumption rate increased with an increase in body weight (W: g), following the equation R=K⋅ Wb, where K and b are constants. To unite the two equations, the quantitative relationship of oxygen consumption rate as it related to body weight and temperature between 15.0 and 27.5°C was expressed by the equation R=M⋅ Wb⋅AT, where M, b and A are constants. The estimated values of these three constants for blacktip grouper were 0.0256, 0.773 and 1.083, respectively.View full abstractDownload PDF (824K) -
Koh-ichi SATOH2003 Volume 51 Issue 4 Pages 435-441
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThree feeding experiments were conducted to establish the optimum feeding regimes of extruded pellet (EP) for young yellowtail, Seriola quinqueradiata during the declining period of water temperature. Fish were fed at frequencies of six or two times per week or every other day during September to December or January. Growth performance and feed utilization in fish under the feeding regimes of six times per week and every other day were similar and better than those two times per week. Therefore, it was assumed that the optimum feeding frequency for EP during this season was once in every two days. The relations between daily growth rate (DGR, %/day) and daily digestible energy intake (DDE, kcal/kg⋅BW/day) in the experiments are indicated by a curved line of DGR=0.721 {1-e-0.137 (DDE-42.848) } (γ2=0.913) . From a point of contact with the tangent to the curved line, the optimum energy requirement for the most efficient growth and feed efficiency of fish fed EP during this season is 58.9 kcal/kg⋅ BW/day.View full abstractDownload PDF (943K) -
Takaaki KAYABA, Takashi SUGIMOTO, Taihei MATSUDA2003 Volume 51 Issue 4 Pages 443-450
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSThe present study was conducted to investigate the cause of mass mortality associated with sudden sinking of flexion larvae in barfin flounder, Verasper moseri. Observations on swimming behavior of larvae showed that most of the larvae suddenly sank from the upper layer to the bottom of the tank at 25 days of age, and that mass mortality occurred just after sinking. Coinciding with the sinking of larvae was an obvious increase in body density, especially in larvae from 24 to 28 days after hatching (dah) . In order to investigate the effects of turbulence on sudden sinking and mortality, 10 day-old larvae were reared at various aeration levels, i.e., no aeration, gentle aeration and strong aeration. Larvae in both the no and gentle aeration groups sank suddenly at 24-25 dah and high mortality occurred. On the contrary, in the strong aeration groups, almost all larvae swam in the upper or middle layer throughout the experimental period. The survival rates at 36 dah were 74.3-89.0%, clearly superior to those in other experimental groups. These results suggest that sudden sinking of flexion larvae in this species is caused by a rapid increase in body density during a period of rapid ontogenetic change. It is likely that manipulating aeration to establish an vertical mixing is very successful for preventing flexion larvae from sinking, and hence, to avoid mass mortality.View full abstractDownload PDF (1439K) -
Yuzo IWATA, Isao SUGAHARA, Toshio KIMURA, Kenichi KHOHASHI, Kentarou N ...2003 Volume 51 Issue 4 Pages 451-458
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSA bacterial strain that showed algicidal activity against the Karenia mikimotoi was isolated from Gokasho Bay, Japan, by the modified algal growth potential (AGP) assay method. The bacterial strain, designated 6/6-46, was identified as Alteromonas sp. This strain showed algicidal activity against K. mikimotoi, but did not kill Chattonella antiqua, Chattonella marina, Heterosigma akashiwo, or Skeletonema costatum. We also examined the growth of both K. mikimotoi and the bacterium strain 6/6-46 in the presence of a marine microbial assemblage. The bacterium strain 6/6-46 was inoculated into K. mikimotoi suspension with a marine microbial assemblage consisting predominantly of Vibrio species. Although the bacterium strain 6/6-46 reached a cell density of the order of 107 cfu/ml, which was sufficient to kill K. mikimotoi in the absence of the marine microbial assemblage, this bacterium showed a slight algicidal activity but did not cause its disappearance in the presence of the marine microbial assemblage. These observations suggested that the algicidal activity of the bacterium strain 6/6-46 on the growth of K. mikimotoi was suppressed by the marine microbial assemblage.View full abstractDownload PDF (1081K) -
Naoki NAGANO, Masahiro HAYASHI, Tsugiyo YUKINO, Hisashi MURATA2003 Volume 51 Issue 4 Pages 459-460
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSα-Tocopherol (TOC) and various fatty acids were supplemented into the Chlorella vulgaris strain K-22 culture at 28°C for 24 h, and TOC content of the Chlorella cells was determined. The addition of TOC alone into the Chlorella culture medium did not give an increase of the cellular TOC content. However, the TOC contents in the Chlorella cells supplemented with TOC and various fatty acids were much higher than those supplemented with TOC alone. Moreover, the TOC content in the cells supplemented with a mixture of TOC and oleic acid was higher than those supplemented with a mixture of TOC and docosahexaenoic acid (DHA) . The TOC content of the rotifers fed on the TOC-enriched Chlorella was much higher than rotifers fed on unenriched Chlorella. On the other hand, rotifers could be easily enriched with TOC by feeding the TOC-enriched Chlorella cells.View full abstractDownload PDF (414K) -
2003 Volume 51 Issue 4 Pages 461-480
Published: December 20, 2003
Released on J-STAGE: March 09, 2010
JOURNAL FREE ACCESSDownload PDF (3327K)
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