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Volume 74, Issue 1
Displaying 1-12 of 12 articles from this issue
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Originals
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MINORU TANDA, SHIGEAKI GORIE, YUKINOBU NAKAMURA, SHIGEYOSHI OKAMOTO2008 Volume 74 Issue 1 Pages 1-7
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSAge and growth were estimated for marbled sole, Pleuronectes yokohamae, in Harima Nada and Osaka Bay, the Seto Inland Sea, Japan, in the study periods of 1986-1989 and 1998-2001, based on otolith ring analyses. Translucent otolith rings were formed once a year from May to January or February. Ages were determined from the number of annual growth rings on the otoliths, and growth was estimated by von Bertalanffy's growth equations using Walford's and the least squares methods. The body lengths estimated by Walford's method in each age were smaller than those estimated by the least squares method and it was concluded that the growth estimated from Walford's method was underestimated.
The growth model estimated by the least squares method showed that females grew faster than males in 1986-1989 and 1998-2001. The growth parameters of both sexes significantly differed between those periods, suggesting that marbled sole in 1998-2001 grew faster than in 1986-1989. Also, the growth parameters of both sexes significantly differed between Harima Nanda and Osaka Bay sampled in 1986-1989 and the northern Kii Channel in 1986-1988.
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SATOSHI OHATA, NAOYA IKEGAMI, FUMIO NAKAMURA, KAORU FUJITA, YOSHIKI MA ...2008 Volume 74 Issue 1 Pages 8-13
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSSelectivity of a grid separator for marbled flounder Pleuronectes yokohamae and white-spotted conger Conger myriaster was estimated to reduce bycatch of juvenile marbled flounder while retaining commercial sizes of white-spotted conger. Four different grids made of horizontal bars (13, 15, 20 and 24 mm bar spaces) fixed on the belly of the codend were tested at sea from 2002 to 2004 to develop a measure for redecing bycatch. An external cover-net was attached behind the grid to catch all fish that escaped through the grid. We used three different models (logistic, Richards, and contact-logistic models) to describe grid selectivity. The contact-logistic model was chosen as the best-fit model for marbled flounder and white-spotted conger. Grid selectivity was expressed as the ratio of vertical size of the fish body to bar space for both species. Under the test conditions, we considered that a grid of 15 mm bar space reduced juvenile discards of marbled flounder by 40% and caught most of the white-spotted conger.
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OSAMU KATANO, HIROYUKI SAKANO, BORIS VERKOV2008 Volume 74 Issue 1 Pages 14-19
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSAn automatic bluegill trap (130 cm×80 cm×80 cm high) was developed to cull the number of bluegill in ponds. The trap has four entrances 10 or 15 cm in diameter for fish and has a space (50 cm×20 cm×80 cm high) in the frontal part of the trap to contain attractants for bluegill. A set of the traps placed in an experimental pond with bluegill and a native Japanese fish Pseudorasbora parva showed that bluegill were attracted to the trap significantly more than Pseudorasbora parva. As an attractant for bluegill into the frontal part, middle- and large-sized bluegill and dead branches were examined, and consequently only dead branches were found to have a positive significant effect. By housing a Far Eastern catfish Silurus asotus, a predator of bluegill in the trap, the predator showed an increase in its body weight. Therefore, the introduction of the trap with dead branches in the frontal part and Far Eastern catfish inside the trap into ponds and lakes is considered as a potential method to cull the number of bluegill efficiently and automatically with little labor effort.
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KOMEI HOTTA, TAKAYUKI WATANABE, CHIHO KISHIDA, YUKIO NAKAMURA, SHIGEHO ...2008 Volume 74 Issue 1 Pages 20-25
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSTo investigate the potential effects of female presence upon serum levels of vitellogenin (Vg) in male fish, we held male Japanese whiting Sillago japonica in the presence (Group FM) or absence (Group M) of females for three weeks. Fish were first reared for three weeks after the grouping and then sampled from each group at four-hourly intervals. Analyses were performed on serum vitellogenin levels, gonad somatic index (GSI: gonad weight/body weight ×100), and testicular histology. Serum levels of Vg in males from Group FM were higher than those of males from Group M. Moreover, GSI of Group FM males was also higher than males in Group M, although histological analysis demonstrated active spermatogenesis in the testes of males from both groups. These results suggest that the presence of females causes an increase in the serum levels of Vg and GSI in male fish.
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NORIYUKI HORIE, TOMOKO UTOH, NAOMI MIKAWA, YOSHIAKI YAMADA, AKIHIRO OK ...2008 Volume 74 Issue 1 Pages 26-35
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSTo improve techniques for artificial seed production of the Japanese eel Anguilla japonica, we evaluated two types of artificial fertilization methods: i) the spontaneous spawning method of paired specimens and ii) the stripping-insemination method, by comparing the quality of eggs and larvae obtained. Females artificially matured by the injection of salmon pituitary extract were kept at 20°C before final treatment with 17α,20β-dihydroxy-4-pregnen-3-one. Afterwards, each female for i) the spontaneous spawning method was kept in an individual tank with three males and water temperature was raised to 22°C. For ii) the stripping-insemination method, ovulated fish kept at 20°C for about 15 hrs were stripped and eggs obtained were inseminated. Eggs and larvae obtained by i) the spontaneous spawning method (n=12) showed significantly higher fertility (80±14%), hatching rate (62±23%), survival rate at 5 days after hatching (54±22%), and lower deformity at 5 days after hatching (60±23%) than those obtained by ii) the stripping-insemination method (n=14, 41±32%, 31±29%, 27±25%, 79±19%, respectively). These results show that the spontaneous spawning method at 22°C is better than the stripping-insemination method at 20°C for the fish quality in artificial eel seed production.
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SATOSHI KATAYAMA, SATOSHI WATANABE, MASAAKI FUKUDA2008 Volume 74 Issue 1 Pages 36-44
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSSeasonal changes in the structure and composition of the demersal fish assemblages along the coastal area of Sagami Bay, Japan, were examined based on data collected from bottom trawl surveys in 2002-2004. Species diversity and abundance of fish assemblages increased in spring and summer compared to other seasons. Cluster analysis indicated that samples belonging to clusters, which infauna feeding Sasaushinoshita, Heteromycteris japonica, dominated and in which the number of species and abundance were low, occupied over 80% of all lots. Another commonly observed cluster was dominated by the nekton and epifauna feeding Sabihaze, Sagamia genetonema, and was observed primarily in May-June. The feeding habits of fish assemblages were compared with data for the same area from 30 years ago, and similarities in seasonal patterns of production structure were examined.
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YOSHIHIRO YONEDA, TANEMI FUJITA, HIROYUKI NAKAHARA, KENJI KANEKO, TETS ...2008 Volume 74 Issue 1 Pages 45-54
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSSeaweed production rates were estimated at an intact and two manipulated urchin-dominated seawall communities in Osaka Bay for three years from 2002 to 2005. Three experimental sections were made at a depth of 2 m, in which the densities of sea urchins were kept at three levels: ‘removal’ (1.3-4.8 ind./m2), ‘control (intact)’ (11.7-22.3 ind./m2), and ’double density’ (30.0-59.6 ind./m2). Monthly feeding rates of sea urchins were estimated to be 5 to 20 g-dry weight/m2/month at ‘removal’, 40 to 80 g-dry weight/m2/month at ‘control’, 100 to 250 g-dry weight/m2/month at ‘double density’.
On the other hand, the biomass of seaweed community was maintained at a stable level within the range of 300 to 800 g-dry weight/m2 regardless of density of sea urchins. The amount of seaweeds grazed by sea urchins could be regenerated by the remaining thalli immediately, because the growth rates of seaweeds were much higher. Thus, seaweed production rates were larger where there was a higher density of sea urchins, resulting in the maintenance of seaweed community even at 2000 g-wet weight /m2 (60 ind./m2). The major reason for the coexistence of high density of sea urchins and seaweed community is supposed to be the eutrophicated nature of the area.
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MASAHIKO KITAGAWA, TOSHIYUKI IIDA, SHIGEHARU NOBUTA, HIDEKI KISHIMURA, ...2008 Volume 74 Issue 1 Pages 55-60
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSChum salmon and skipjack tuna meats containing skin and bone were frozen and pulverized at below -130°C and the frozen powdery fish meats thus obtained were applied to extrusion cooking. The raw materials were mixed with defatted soy protein concentrate at the mixing weight ratio of 70:30, adjusted their moisture to 63%, and then applied to a twin-screw extruder. The extrudates showed a strong fibrous structure along with the direction of the extrusion, when the extruder was operated at 50 rpm of the screw speed and 170°C in the final barrel. There is no difference in the proximate composition between the raw materials and the extrudates. Although taurine, methionine and histidine decreased slightly during the extrusion cooking, no significant change was observed in other amino acid contents. In addition, the extrusion cooking has no effect on the fatty acid compositions of total lipid. These results indicate that fish meat containing skin and bone at the intrinsic level would be utilized for extrusion cooking without significant loss of nutrition.
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REIKO NAGASAKA, AKIRA SHINODA, HIDEKI USHIO, TOSHIAKI OHSHIMA2008 Volume 74 Issue 1 Pages 61-65
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSWe investigated the hydroxycinnamic acid derivatives in laminarian seaweeds. The total lipid was extracted from commercially available and dried laminarian seaweed according to the Bligh & Dyer method, and subjected to HPLC analysis for the determination of hydroxycinnamic acid derivatives. The structures were analyzed with EI-MS. Laminarian seaweeds contained relatively high amounts of γ-oryzanol, one of the hydroxycinnamic acid derivatives. Rishiri laminarian seaweed contained the highest amounts of γ-oryzanol among the analyzed 4 seaweeds. EI-MS fragment analyses of γ-oryzanol suggested that stigmasteryl ferulate was a prominent component in the seaweeds.
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YUJI OMURA, MAYU WATANABE, TAKASHI KIMIYA, YUMIKO YAMASHITA, EMIKO OKA ...2008 Volume 74 Issue 1 Pages 66-74
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESSThe mantle muscle from frozen then thawed specimens of the Japanese common squid Todarodes pacificus was boiled at 80°C for 20 min, freeze-dried, and ground into powder. The squid mantle powder washed with water slightly colored brown during preservation at 35°C, while the mantle powder washed with chloroform-methanol (1:1) mixture solvent became brown remarkably. The 5% perchloric acid extract from the water soluble fraction of the squid mantle powder rapidly turned brown during preparation. Glucose 6-phosphate and ribose remarkably accelerated the browning. In this regard, the squid mantle powder added with ribose, but not with glucose 6-phosphate, exhibited characteristic features of the browning of the dried products made from squid under atmospheric conditions.
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Short Papers
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TOMOAKI GOTO, KYUKICHI NAKAJIMA, TAKASHI YOSHIDA2008 Volume 74 Issue 1 Pages 75-77
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESS -
KUMIYO TAKATA, HIDEYUKI TAKATSUJI, MASATO SENO2008 Volume 74 Issue 1 Pages 78-80
Published: 2008
Released on J-STAGE: January 23, 2008
JOURNAL FREE ACCESS
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