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Yasuhiko TAGO
2002 Volume 50 Issue 2 Pages
137-142
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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Red spotted masu salmon, which is called amago or satsuki masu,
Oncorhynchus masou ishikawae, caught mixed together in the catch with masu salmon,
O. masou masou, in the Jinzu River, one of main fishing rivers of masu salmon in Japan, was investigated from 1991 to 1995. The body size (range 21.5-44.0 cm) of red spotted masu salmon caught in the Jinzu River was markedly smaller than that (range 43.5-70.0 cm) of masu salmon. This means that the period and area of ocean migration of red spotted masu salmon was shorter and smaller, respectively, than that of masu salmon. A red spotted masu salmon caught in the Jinzu River weighed 3.2 kg (FL 62.0 cm), which equaled the mean body weight of masu salmon. This suggests the possibility of cross mating occurring between red spotted masu salmon and masu salmon. The rate of red spotted masu salmon caught with masu salmon in the coatal waters near the mouth of the Jinzu River ranged from 6.9% to 14.6% during five years. The fork length of red spotted masu salmon caught in the sea ranged significantly less (16.0-46.0 cm) than that (13.0-72.0 cm) of masu salmon. It is considered that red spotted masu salmon should be excluded from the Jinzu River, and we should defend the intrusion of juveniles of red spotted masu salmon in order to keep masu salmon body size large and propagate masu salmon resources effectively in the Jinzu River.
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Tatsuo HAMANO, Ryosuke KATSUMATA, Yasuhiko MIYA, Youichi YASUDA
2002 Volume 50 Issue 2 Pages
143-148
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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Basic conditions of fishways for juveniles of the edible catadromous crab
Eyiocheir japonica to migrate to upstream habitats from estuary by walking, were studied using an experimental waterway with V-shaped floor. Crabs actively walked at the water's edge, splash zone, and in the central submerged area in the stream and successfully passed through the waterway at slopes of 20 and 50°, water temperatures of 20 and 25°C and surface current velocities of 50, 100, and 150 cm/s during the nighttime. In 15°C, crabs frequently climbed out of the water. No current flow (0 cm/s) caused a delayed migration at 20 and 25°C. Crabs also were found to migrate up the waterway at various light intensities, 0-103, 080 lx under the best conditions for its upstream migration of 20° slope, 25°C water temperature, and 100 cm/s surface current velocity. The crab shows the positive rheotaxis and its locomotory ability is larger than those of diadromous freshwater shrimps.
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Hideyuki IMAI, Yasuhiro OBATA, Sachio SEKIYA, Tomohito SHIMIZU, Ken-ic ...
2002 Volume 50 Issue 2 Pages
149-156
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The effectiveness of stocking artificially propagated mud crab,
Scylla paramamosain juveniles was measured by releasing the juveniles tagged by variation of mitochondrial DNA (mtDNA) D-loop region. One hundred and forty nine females were collected to use for artificial propagation, at Urado Bay, Kochi Prefecture, Japan. The fourth leg of each was removed by autotomy, then one haplotype, #2 was selected for propagation. Only one female of 23 females showing this haplotype spawned about 3.35 million larvae. Thereafter, about 100, 000 juveniles grown up to 9.6 mm in average carapace width were released at 25 fishing grounds in Urado Bay during May, 1997. A total of 653 crabs were then collected at these sites by seven times of sampling made between Aug. 1997 and Dec. 1998. The frequency of haplotype #2 used as a genetic tag increased significantly after stocking from 15.4% to 29.6%. Thus, the ratio of released juveniles to all the mud crabs in Urado Bay was estimated to be 16.8%. The composition of the haplotype in the samples collected at the end of 1998 suggested that the fecundity of stocked crabs are the very same with those of natural stock. The relevance of mtDNA markers for stocking project and the problem of genetic management of aquatic organisms are discussed.
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Kazumi NIMURA, Hiroyuki MIZUTA
2002 Volume 50 Issue 2 Pages
157-162
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The pattern of sori of
Laminaria japonica Areschoug was investigated by using several blade segments from the sporophytes. Sori formed mostly vertically long patterns on the basal side or on the transition zone between median and marginal regions of the blade, or on both the basal side. The first sori were formed on the basal side of each median region, but on the marginal regions the first sori were formed on the basal and median side of each region. These regions that form sori correspond to the sink area where nutrients first accumulate. These sores formation patterns might be probably based on the source-sink relationship of nutrient between regions of the sporophyte.
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Yukihiko SERISAWA, Toshiyuki UESHIMA, Kazuyo MATSUYAMA, Seiya TAINO, Z ...
2002 Volume 50 Issue 2 Pages
163-169
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The relationship between age and morphology of
Ecklonia cava Kjellman (Laminariales, Phaeophyta) sporophytes were studied seasonally in 1996 in a population off the Tei coast in Tosa Bay, southern Japan. Based on measurement of the growth rings, a small number of 3-year-old sporophytes were confirmed. The mean values of stipe length and diameter of each age group during the investigation period was follows; 7.2-18.4 cm and 4.6-7.5 mm in the 0-year-olds; 3.4-12.6 cm and 7.7-10.2 mm in the 1-year-olds; 5.9-13.7 cm and 10.3-13.4 mm in the 2-year-olds. Primary blade length, primary blade width, number of bladelets and longest bladelet length of each age group was as follows; 18.5-32.8 cm, 4.6-6.2cm, 9-21 pieces and 10.6-23.8 cm, respectively in the 0-year-olds; 22.0-39.1 cm, 5.5-6.9 cm, 14-27 pieces and 20.1-34.9 cm, respectively in the 1-year-olds; 9.6-25.6 cm, 5.8-8.1 cm, 17-30 pieces and 32.5-40.3 cm, respectively in the 2-year-olds. Thus, all biometric parameters except for primary blade length increased with age, but these values overlapped with each age group and they did not separate clearly.
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Katsuaki FUJINAGA, Anthony S. ILANO, Shigeru NAKAO
2002 Volume 50 Issue 2 Pages
171-176
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The extent and influence of imposex in the neptune whelk,
Neptunea arthritica, in Saroma Lagoon, northeastern Hokkaido, were investigated from 1997 until 2001 (excluding 2000), based on three criteria: relative penis size index (RPSI), frequency of imposex, and sex ratio (male/female) . The condition of imposex in female whelks in the lagoon turned into better year by year. The RPSI value of 13.7 in 1997, declined every year, and dropped very low to 0.1 in 2001. The frequency of imposex in adult whelks was 100% in both 1997 and 1998, but lowered to 76.9% in 1999 and 50.0% in 2001. The sex ratio in the adults was very high with values of more than 2.0 in 1997 and 1998. However, subsequently it sharply decreased to 1.62 in 1999, and furthermore to 0.81 in 2001. From these results, it was considered that the neptune whelks in Saroma Lagoon have recovered from imposex. In addition, based on the yearly change in penis index (PI) distribution, the relation between shell height and penis weight, and simple anatomical observations on reproductive organs and digestive gland in female whelks, it was supposed that individuals suffered from imposex might recover at a very slow rate.
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Ken-ichi YAMAMOTO, Takeshi HANDA
2002 Volume 50 Issue 2 Pages
177-181
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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In the sea urchin,
Hemicentrotus pulcherimus, the amount of oxygen uptake (Vo
2) was almost constant from September to June (9.6-24.2°C), except in February and March. In February and March, the ratio of organic matter weight to total body weight was the lowest in the year, but in other months the ratio was almost constant. However, Vo
2 increased with 3°C rise in the water temperature per hour interval and decreased with lowering of the water temperature. Under hypoxic conditions, until the oxygen saturation in water fell to 70.5% at 9.9°C, 62.0% at 15.3°C, 58.1% at 19.9°C, 54.7% at 24.2°C and 29.0% at 28.0°C, Vo
2 remained at the levels of the normoxic condition.
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Ken-ichi YAMAMOTO, Takeshi HANDA, Masahiro KAYANO, Kenji FUJIMOTO, Hir ...
2002 Volume 50 Issue 2 Pages
183-188
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The ventilation in the respiratory tree of the Japanese common sea cucumber,
Apostichopus japonicus, was examined under normoxic condition at 16.0±0.1°C using newly developed equipment which continuously measured the ventilation volume. One cycle of ventilation was composed of a large exhalation and several small inhalations. The duration of exhalation per cycle was 10.6±1.3 sec/cycle, the exhalation volume per cycle (Vcy, ex) was 95.5±20.0 m
l/cycle/kg, the exhalation frequency per min was 0.7±0.1 stroke/min and the exhalation volume per min was 67.5±18.8 m
l/min/kg. The period of inhalation per cycle (Tin) was 79.5±26.3 sec/cycle, the inhalation volume per cycle (Vcy, in) was 95.8±26.4 m
l/cycle/kg, the inhalation frequency per the cycle (If) was 10.3±2.9 stroke/cycle, the inhalation volume per stroke of inhalation was 9.8±1.8 m
l/stroke/ kg, and the duration of inhalation per the stroke was 7.8±1.6 sec/stroke. The relationship between Vcy, in and Vcy, ex was Vcy, ex=0.27 Vcy, in+69 [R
2=0.12] or Vcy, in=0.48 Vcy, ex+53 [R
2=0.13] . The relationships between If and Tin, and If and Vcy, in were Tin=8.2 If-4.3 [R
2=0.84] and Vcy, in=7.0 If-27 [R
2=0.61], respectively.
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Tadao JINBO, Nobuhiro TEZUKA, Masahiko KOISO, Katsumi TSURUMAKI, Shuke ...
2002 Volume 50 Issue 2 Pages
189-196
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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Control of spawning was carried out to obtain hatched larvae of Japanese parrotfish,
Oplegnathus fasciatus, from June to September as live food for
Thunnus orientalis (bluefin tuna) larvae. Sixty females and thirty males were divided equally into three groups in mid-March, 2000. The control group (Group C) was reared under natural water temperature and photoperiod conditions. The water temperature-treated group (Group W) was reared at 15°C from late March to late June and at 20-24°C from late June to the end of the spawning season under natural photoperiod conditions. The water temperature and photoperiod-treated group (Group W+P) was reared under the same temperature conditions as Group W, but was treated with photoperiods of 6L/18D to late June, 14L/10D from early July and 16L/8D from late August to the end of the spawning season. The main spawning season of Group C was mid-May to mid-August; that of W was late May to early September; and that of W+P was from late June to late October. These results indicate that both water temperature and photoperiod manipulation is effective in delaying the spawning season of this species.
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Masahiko KOISO, Akinori HINO
2002 Volume 50 Issue 2 Pages
197-204
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The mechanism of growth stagnation is examined in the mass culture of the rotifer in the “batch” mode. Culture tanks are prepared that four phases of batch culture are applied one by one as 3, 6, 9 and 12 days in duration. Carefully designed examinations are executed from three viewpoints of characteristics: (1) population growth; (2) quality of the medium; (3) life-history parameters (time to first spawning, duration of embryonic development, and spawning interval) . The daily growth rate was drastically decreased on the 6th and 9th day contrary to the case on the 3rd day; it turned negative finally on the 12th day. The time required to the first spawning and spawning interval were observed longer on the 6th and 12th day than in the other cases; particularly on the 12th day were also found to occur a considerable decrease of hatchability as well as a higher mortality in both neonate and adult stages. The evidence seems to show that factors given by our investigation have important effects to stagnation in population growth of the rotifer. Some dissolved substance was presumed to be the causative agent, as well as unionized ammonia. Those impediment affected not only on rotifers in the course of culture, but also on life-history parameters of the next generation. In the batch culture, the organism is generally harvested in the stationary growth phase which occurs just after the logarithmic one. This chronological trend may inevitably cause the decline of their own biological activities as well as of their nutritional quality as live food.
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M. Agus SUPRAYUDI, Toshio TAKEUCHI, Katsuyuki HAMASAKI, Jun HIROKAWA
2002 Volume 50 Issue 2 Pages
205-212
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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This experiment was conducted to determine the effect of the nutritional value of rotifers enriched with different kinds of lipids, especially n-3 highly unsaturated fatty acids (n-3HUFA), on the growth and survival of mud crab,
Scylla serrata larvae. Rotifers were enriched with four kinds of materials including corn oil (R-E0, containing 0.3% n-3HUFA), four different levels of EPA28G (R-E10, R-E20, R-E40 and R-E80, containing 0.5%, 0.8%, 1.3% and 3.2% n-3HUFA, respectively), two different levels of single cell algae
Nannochloropsis oculata (R-N18 and R-N42, containing 1.8% and 3.1% n-3HUFA, respectively) and Yugen (R-YG, containing 1.7% n-3HUFA) . Mud crab larvae were reared in one-liter plastic beakers at a stocking density of 30 larvae/L.
The growth performances of mud crab larvae were affected by n-3HUFA levels and the ratio of docosahexaenoic acid (DHA; 22: 6n-3) and eicosapentaenoic acid (EPA; 20: 5n-3) contained in rotifers. Mud crab larvae fed rotifers containing 0.8% of n-3HUFA had a highest percentage of reaching the first crab stage. Increasing the n-3HUFA content of rotifers in excess of 0.8% caused a high rate of megalopa molting failure, and most mud crab larvae were failed to molt to megalopa when larvae were fed rotifers containing 3.1% n-3HUFA.
The results suggested that n-3HUFA content in rotifers should be adjusted to 0.8% (containing 0.33% EPA and 0.13% DHA) in terms of growth performance for the mud crab,
Scylla serrata larvae.
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S.M.A. MOBIN, Kinya KANAI, Kazuma YOSHIKOSHI
2002 Volume 50 Issue 2 Pages
213-218
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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Effects of four different feeding levels (L1, L2, L3, and L4) on food ingestion of laboratory-reared larval and juvenile Japanese flounder
Paralichthys olivaceus were studied from 12 to 36 days posthatch. In test 1, the food densities at L1, L2, and L4 were 0.5, 2.5, and 5 times that at L2. Feeding level L2 has conventionally been adopted by some hatcheries located in the western part of Japan for the mass propagation of Japanese flounder larvae and juveniles. The mean number of food organisms in the digestive tracts in L4 feeding level was greatest followed by L3, L2, and L1. The number of brine shrimp nauplii eaten increased for all feeding level with growth, because of selection by the larvae. In test 2, only L2 feeding level was applied in all the four different feeding levels fed-raised flounder groups (L1, L2, L3, and L4) separately. In this test a similar result as test 1 was observed; the obtained results suggest that the application of increased feeding levels does enhance the feeding response of larval and juvenile Japanese flounder. In both tests a few juveniles bigger than 16 mm in total length ate rotifers.
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Koh-ichi SATOH, Yasuhiro SANADA, Etsuhisa HITAKA, Keisuke KIMOTO
2002 Volume 50 Issue 2 Pages
219-226
Published: June 20, 2002
Released on J-STAGE: December 10, 2010
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Eight kinds of experimental meals that contain different revels of hydrolyzed proteins were prepared after several protease treatments of the fish meal (FM), and analyzed their dietary effects on the growth performance and protein digestibility of yellowtail,
Seriola quinqueradiata during low temperature season.
The group of meals containing 25-34% of TCA soluble nitrogen (N) obtained after the middle treatments of proteases showed higher effects on the daily growth rate (DGR; 1.03-1.09 times to the group of the meals without the protease treatments), feed efficiency (FE; 1.04-1.15 times), and apparent protein digestibility (APD; 1.04-1.10 times) of yellowtail than those of FM containing 15-17% of TCA soluble N without the protease treatments. On the other hand, the group of the meals with excessive protease treatments containing 37-40% of TCA soluble N had worse effects on DGR (0.90-1.01 times), FE (0.82-0.95 times), and APD (0.87-0.96 times) comparing with those of FM without the treatments.
These results indicate that, during low temperature season, feeding with the protease treated FM has the beneficial effects on the growth performance and protein digestibility of yellowtail, although the excessive treatments of FM may have the counterproductive effects.
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Toshiharu SHIBATA, Yasuhiro CHIKUSHI, Takasi NAKAMOTO, Kenji WATANABE, ...
2002 Volume 50 Issue 2 Pages
227-232
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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Amyotrophia of juvenile abalones has been a serious impediment in large scale production of
Haliotis discus discus and
H. discus hannai at the Fukuoka Mariculture Corporation since 1984. The efforts to prevent this infectious disease by removal of all the stocks from the facilities, disinfection of the facilities and washing fertilized eggs with U.V. -irradiated sea water were unsuccessful. Since the sea water supply was suspected to be contaminated with the etiological agent, a rearing experiment was conducted using three groups of juvenile
H. discus discus that were previously reared in untreated, anthracite-filtered or U.V. -irradiated sea water, respectively, at their larval stages. Amyotrophia occurred in the former two groups but not in the last group that was reared in U.V.-irradiated sea water. U.V.-irradiation of sea water supply with other measures mentioned above has succeeded to produce healthy juveniles on a large scale in the hatchery for consecutive three years since 1999.
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Masanobu MATSUOKA
2002 Volume 50 Issue 2 Pages
233-234
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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From a total of 241 wild fishes of 18 species examined, one specimen with deformed inter-nostril epidermis was found in the finepatterned puffer,
Takifugu poecilonotus. The specimen had a normal inter-nostril epidermis for the right nostril but the left nostril was deformed. Although the deformed nostril had two epidermal membranes, they were not combined. The other 9 specimens of the same species caught had normal epidermis. Deformity of the inter-nostril epidermis very rarely occurs in wild fishes. This finding is only the second one after striped puffer,
Takifugu xanthopterus.
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Hisashi CHUDA, Takahiro NAKAO, Toshihisa ARAKAWA, Michiya MATSUYAMA
2002 Volume 50 Issue 2 Pages
235-236
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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In the present study, induction of maturation and ovulation and subsequent artificial insemination were tried in the cultured two-year-old brood stock of yellowtail,
Seriola quinqueradiata to acquire fertilized eggs from young fish. After confirming the yolk accumulation by monitoring oocyte diameter through ovarian biopsy, fish with oocyte sizes between 700 and 740μm.....were selected. A single injection of HCG (500 IU/kg BW) could induce oocyte maturation and ovulation after 48 hours in all the fish except one. Enough volume (212, 000 eggs/fish) of floating eggs was obtained by the artificial insemination performed just after ovulation.
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Haruo SUGITA, Yosuke MASUO, Tomohiro TAKAGI, Ryutarou TANAKA, Chiyumi ...
2002 Volume 50 Issue 2 Pages
237-238
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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Strain No. 442, which is capable of producing an antibacterial substance against pathogenic vibrios, were isolated from an intestinal tract of Japanese flounder and examined for their taxonomic status. The 16S rDNA of strain No. 442 (corresponding to positions 18-1470 in the
E, coli rDNA sequence) was sequenced and analyzed. Both phenotypic and phylogenetic analyses strongly suggested that strain No. 442 is identical to
Vibrio proteolyticus.
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Shusaku TAKAGI, Kanako TIBA, Taiju KURAMOTO, Masaharu UKAWA, Takanobu ...
2002 Volume 50 Issue 2 Pages
239-240
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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We determined biliary bile salts levels in red sea bream fed on either fish meal or alternative soybean meal for 33 weeks. The feeding of soybean meal showed smaller body weight gain and higher mortality. No significant difference was observed in hematological parameters such as hematocrit value, plasma enzyme activities, and protein level between the groups. However, the biliary bile salts concentration in soybean meal group was significantly decreased following the reduction of plasma cholesterol and taurine levels, when compared to that in fish meal group.
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Hideki YASUNOBU, Kaori FURUTSUKA-UOZUMI, Shinpei WADA, Kishio HATAI
2002 Volume 50 Issue 2 Pages
241-242
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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A disease with mortality was observed in Japanese black abalone (
Nordotis discus discus; 3+ -year old) reared at Kobe city sea-farming center in 1997. The diseased abalone showed a characteristic clinical sign of raising shell and died. There was no parasite in the gill or peduncle tissue. No significant microorganism was isolated from the peduncle tissue by bacteriological media. The disease sign was produced in healthy abalone by cohabitation with diseased abalone, but the disease was not reproduced by immersing 0.45μm-filtered homogenate of disease abalone. Histopathological examinations revealed that abundant heteromorphic cells were scattering in the muscular tissue of diseased abalone. In these heteromorphic cells, a lot of coccus like fine granules, negatively stained with Gram stain were observed. From these findings, it was considered that this case should be an infectious disease and the causative agent might be a kind of intracellular microorganism observed as the fine granules in the heteromorphic cells.
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Shigeaki GORIE
2002 Volume 50 Issue 2 Pages
243-249
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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The Solver program on MS-Excel's worksheet was applied for the estimation of parameters in a mixture of normal distributions and Age-Length key. In the present study, I used the length frequency composition and growth formula of Japanese flounder,
Paralichthys olivaceus, caught in the coastal waters of Hyogo Prefecture located in the Sea of Japan as a sample, and estimated the mixture rate and Age-Length key with the non-linear least squares and maximum likelihood methods. The mixture rates estimated by the two methods were almost the same, but the non-linear least squares method was more stable in obtaining a solution than the maximum likelihood method. If the merits and demerits of MS-Excel's Solver are well understood by users, the worksheet is considered a suitable method for modification to estimate the parameters of other species.
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2002 Volume 50 Issue 2 Pages
252-257
Published: June 20, 2002
Released on J-STAGE: March 09, 2010
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