NIPPON SUISAN GAKKAISHI
Online ISSN : 1349-998X
Print ISSN : 0021-5392
ISSN-L : 0021-5392
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Volume 76, Issue 5
Displaying 1-50 of 56 articles from this issue
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Technical Achievement Award in Fisheries Science 2009
Originals
  • Growth and age-length key of the tiger puffer Takifugu rubripes in the East China Sea, Sea of Japan, and Seto Inland Sea, Japan
    YUKIO UETA, JIRO SANO, HIDEKAZU UCHIDA, CHIE AMANO, YASUJI MATSUMURA, ...
    Article type: Original
    2010 Volume 76 Issue 5 Pages 803-811
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.803
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      The age and growth of wild and hatchery-reared tiger puffer Takifugu rubripes caught in the East China Sea, Sea of Japan, and Seto Inland Sea, Japan were studied by observing the age-ring of the vertebra centrum of 1,071 individuals. The total length of the collected T. rubripes ranged from 261 to 592 mm in males and from 268 to 632 mm in females. Monthly changes of the occurrence ratio of the marginal transparency at the vertebra centrum showed that the ring was formed once a year from May to June. The ages of T. rubripes captured in these waters were from 0 to 9 years old. Females grew faster than males in the population above 3 years old, and the wild population grew faster than the hatchery-reared one. The relationships between age and total length in the population above 1 year old showed wide variations of total length in the same year class. As these results suggest that the age composition of T. rubripes cannot be accurately estimated based on length-frequency analysis only without age determination, we suggest using the age-length key for converting the length frequencies of T. rubripes into age frequencies.
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  • Vertical distribution of ayu Plecoglossus altivelis altivelis larvae during seaward migration in Kuji River, Ibaraki Prefecture, Japan
    KAZUNORI ARAYAMA, NORIYUKI SUNOH, YUKIO YAMAZAKI
    Article type: Original
    2010 Volume 76 Issue 5 Pages 812-823
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.812
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      Seasonal and nocturnal changes in the vertical distribution of ayu, Plecoglossus altivelis altivelis larvae during seaward migration in the lower Kuji River were examined in 2006 and 2007. Sampling was performed at a site, approximately 3 m deep, using 0.3-mm mesh ring nets (45 cm in diameter). Ayu larvae were caught mainly from late October to early November in 2006 and from late October to early December in 2007. In both years, nocturnal vertical larvae distributions were different in late October and from early November onward; the larvae were evenly distributed throughout the water column in late October, but mainly in the middle and bottom layers from early November onward. Body and quantity of yolk sizes of larvae were not different between layers. No marked differences were observed in water velocity within the water column. Seasonal changes in water temperature showed a gradual decrease from 24°C to 6°C from September to December, while in late October and early November, it was 15°C-16°C in both years. These results show that ayu larvae do not always drift at the same depth and that their distribution in the water column changes seasonally as the water temperature decreases.
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  • Effect of square mesh window on codend selectivity for blackthroat seaperch and white-spotted conger in offshore trawl net
    YUSUKE HAMABE, SEIICHIROU HARADA, HIDEYUKI YAMASHITA, TADASHI TOKAI
    Article type: Original
    2010 Volume 76 Issue 5 Pages 824-840
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.824
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      Covered-codend fishing experiments were conducted to assess the selectivity of a 33-mm diamond mesh codend with square mesh window in offshore pair trawlers. Six types of square mesh window were tested: two mesh sizes of 72 mm and 81 mm mesh openings; and three window positions of top, both-sides, and top & both-sides attached at the anterior half of the codend. Logistic parameters to express the selection curve of each haul for blackthroat seaperch Doederleinia berycoides and white-spotted conger Conger myriaster were estimated by the maximum likelihood method with the SELECT process considering sampling fraction. There were large variations in selectivity parameters between hauls in each type of codend, but no effect of catch size in the codend on the selectivity. The square mesh window had a larger 50% selection length in mean selection curves than the 33-mm diamond mesh codend. The top & both-sides window was most effective to allow fish to escape. For white-spotted conger, the both-sides window was equivalent to the top & both-sides window in selectivity. For blackthroat seaperch, the 50% selection length was larger in the top window than in the both-sides one. The effectiveness of the square mesh window to reduce the bycatch of young blackthroat seaperch while retaining marketable white-spotted conger was also discussed.
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  • Occurrence and feeding habits of Japanese sea bass Lateolabrax japonicus larvae and juveniles around the Ohta River estuary, upper Hiroshima Bay, Seto Inland Sea
    YUJI IWAMOTO, TAKUMA MORITA, JUN SHOJI
    Article type: Original
    2010 Volume 76 Issue 5 Pages 841-848
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.841
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      The occurrence and feeding habits of Japanese sea bass Lateolabrax japonicus larvae and juveniles were investigated in Hiroshima Bay and the Ohta River estuary (Ohta River Diversion Channel and Tenma River) in order to compare the early life history of the species and environmental conditions of the larval and juvenile habitats with those of the Chikugo River estuary, southwestern Japan, where larvae and juveniles occur in the low-salinity water of the river. Larval and juvenile density was significantly higher in the river area than in the sea area with the highest density at 4.7-8.0 km upriver from the river mouth (salinity<12). Major prey organisms of the larvae and juveniles were Podon leuckarti, Oithona spp., Paracalanus parvus and Pseudodiaptomus inopius. The low-salinity waters of the two rivers were considered to be important habitats for Japanese sea bass larvae and juveniles with the zooplankton species as important prey resources during the early life stages, while an estuarine copepod, Sinocalanus sinensis, contributes as a single major prey organism for the Japanese sea bass larvae and juveniles in Chikugo River, southwestern Japan.
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  • Dynamics of dissolved inorganic nitrogen and its effect on the discoloration of Porphyra yezoensis cultured along the eastern coast of Hiroshima Prefecture, the Seto Inland Sea
    OSAMU KAWAGUCHI, HIDEYUKI TAKATSUJI
    Article type: Original
    2010 Volume 76 Issue 5 Pages 849-854
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.849
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      The dynamics of dissolved inorganic nitrogen (DIN) were investigated along the eastern coast of Hiroshima Prefecture facing the Seto Inland Sea from April 2004 to March 2007 to find the reason for the discoloration (January to March) of cultivated Porphyra yezoensis. Along the coast, salinity gradually increased from west to east from December. Low-salinity water appeared in the east but never reached the west. The salinity pattern (inverse to DIN pattern, except in 2007) and evaluation of thallus color suggested that the discoloration of P. yezoensis was caused by the decrease of river flow and migration of water mass from west to east, which disturb the extension of DIN to the culture field.
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  • Upriver spawning migration of shishamo smelt Spirinchus lanceolatus assessed by radio telemetry
    HISAYA NII, YUYA MAKIGUCHI, MAKOTO FUJII, HIROSHI UEDA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 855-869
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.855
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      The upriver spawning migration of shishamo smelt Spirinchus lanceolatus tagged with nano-tag radio transmitters was investigated for both the effects of surgically implanted radio transmitters on swimming and spawning behavior in an experimental water tank and during the upriver spawning migration in the Mukawa River, Hokkaido, Japan. There was no significant effect on the cruising and burst speed, spawning behavior or the physiological status between the tagged and control fish in the experimental water tank. Average swimming speed of the tagged fish during the upriver migration ranged from 3.8 to 17.8 cm/sec. The tagged fish tended to migrate around the center of the stream and predominantly used an area where the water velocity was less than 60 cm/sec with woody debris as a holding habitat. The present study reports on the upriver migration of small-sized shishamo smelt for the first time.
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  • The growth of baleen plates in Antarctic minke whales, with special reference to the V-shape notch appearing at the outer edge of the plates
    RYOKO ZENITANI, HIDEHIRO KATO
    Article type: Original
    2010 Volume 76 Issue 5 Pages 870-876
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.870
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      The present study examined the growth of baleen plates with interpretation of the V-shape notch that appears on the baleen plate among Antarctic minke whales Balaenoptera bonaerensis. A total of 1,654 baleen plates including those from foetuses collected by the Japanese whale research program under special permit in the Antarctic (JARPA; 1,218 individuals) and commercial whaling (436 individuals) in Area IV were used for the present analysis, with relevant biological information. The total baleen plate length increased with body length and reached the maximum of 261.8 mm at larger than 7.9 m and 278.3 mm at larger than 8.4 m in males and females, respectively. The V-shape notch was found in all animals smaller than 5.5 m but not in the foetal stage, suggesting that the notch might form in the neonate. It seemed that the V-shape notch completely disappeared due to wear at the body length of around 6.4 m.
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  • Diel vertical migration of the toxic dinofragellate Alexandrium tamarense, temporal changes of associated environmental factors and cell toxin content during the course of a large-scale bloom
    KEIGO YAMAMOTO, YUKIHIKO MATSUYAMA, HIROAKI OHMI, HIROYUKI ARIYAMA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 877-885
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.877
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      In late April 2007, a large-scale bloom (>104 cells mL−1) of the toxic dinoflagellate Alexandrium tamarense Balech occurred in Osaka Bay, Seto Inland Sea, Japan. In order to elucidate the ecological profile of the A. tamarense occurrence, we carried out an intensive investigation on diel vertical migration of A. tamarense, associated environmental factors, and cell toxin content from 29 to 30 April 2007, in Sakai Dejima fishing port, Osaka Bay, Japan. Vertical profiles of cell density showed that A. tamarense was distributed in the surface during the day, then dispersed and increased in density on the bottom at night. Before dawn, A. tamarense cells accumulated at the surface, probably due to phototaxis. There was no change in toxin composition, however, toxin content increased from sunset to sunrise. On the other hand, the rate of chain-forming cells decreased. These results suggest that cell toxicity is stored at night and subsequent migration to the bottom increases the risk of shellfish poisoning for edible bivalves.
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  • Effects on nutrient load of removing sediments by maintenance dredging in the Port of Osaka
    TAKAYUKI NISHIO, MASANAO SHINYA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 886-893
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.886
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      The contents of nitrogen, phosphorus, and organic matter were 2-3 times higher in the sediments collected from a sampling point located at the river end than in the sediments collected in and outside the Port of Osaka. Further, the concentrations of these elements were 9-20 times higher in the interstitial water in the sediments collected from the river end than in the sediments collected from the port area and the estimated fluxes of ammonium and phosphate ions were 2-10 times higher in the former case than in the latter case. These potential fluxes from sediments in the river end were high even in winter when the activities of microorganisms were low. The sediment in this area is very loose and can be resuspended easily by turbulence, which causes the nutrients in the interstitial water to drift away. Therefore, dredging sediments in this area is expected to be effective in reducing the pollution loads in the stagnant water area inside the port.
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  • Morphological development, organogenesis and somatic growth of hatchery-reared nigorobuna Carassius auratus grandoculis
    KOH-ICHI FUJIWARA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 894-904
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.894
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      The morphological development, organogenesis and somatic growth of hatchery-reared nigorobuna Carassius auratus grandoculis from newly-hatched larvae to early stage of juveniles were investigated in order to obtain basic data for determining the effective size at release for the stock enhancement program in Lake Biwa. As a result, generally the completion of the fin rays, scales and skeleton, and rapid development of the skeletal muscles and organs for digestion, respiration, circulation, hematogenesis, excretion and sensory perception were observed at the juvenile stage of approximately 16 mm in standard length (SL), leading to an improved ability to survive under natural environmental conditions. It was concluded that this developmental stage (ca. 16 mm SL) is a criterion for determining the effective size at release.
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  • Prolonged change of fishing ability in experimentally lost gillnet
    SEIJI AKIYAMA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 905-912
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.905
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      In order to determine the effect of ghost fishing by lost gillnet, the relationship between soak time and number of enmeshed animals in an experimentally lost gillnet was examined by diving observation. The gillnet was deployed in a small trough surrounded by artificial reefs at 13 m depth in Tateyama Bay, Chiba Prefecture, Japan for 2000 days from 16 February 2004 to 8 August 2009. During the experimental period, 8 species of crustaceans including Japanese spiny lobster Panulirus japonicus as the main target species, 3 species of gastropod, and 3 species of bony fish were enmeshed in the gillnet. The number of enmeshed animals in the gillnet increased rapidly within 11 days after deployment, and then declined gradually showing fluctuations caused by the decrease in newly enmeshed animals, and dropping off from the gillnet as the dead animals decomposed. The decrease in the number of enmeshed animals was expressed by an exponential equation, and based on this equation, the duration of capture function for the gillnet was calculated to be 182 days. The duration of capture function for the lost gillnet for non-commercial by-catch species such as small crustaceans and gastropods was longer than for commercial species such as Japanese spiny lobster and bony fish.
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  • Enhancement of the fishing efficiency of the bluegill Lepomis macrochirus by using a trap containing conspecific individuals as decoys
    YASUFUMI FUJIMOTO, KIYOTAKA TAKAHASHI, KENTARO SINDO, HIDENOBU YAMBE, ...
    Article type: Original
    2010 Volume 76 Issue 5 Pages 913-919
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.913
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      The attractiveness of conspecific individuals as decoys was investigated in Lakes Izunuma and Kejonuma in northern Japan to develop a new effective method for extermining the bluegill Lepomis macrochirus on the basis of their aggregation behavior. Two types of trap—empty traps (control) and traps with bluegill individuals as decoys (treatment)—were set up in these lakes, and the catch-per-unit efforts (CPUEs) of the treatment and control traps were compared. The CPUEs of the treatment traps were higher than those of the control traps in Lake Izunuma where bluegill density is low; this finding suggests that the decoys attracted the conspecific fish. In Lake Izunuma, the treatment traps were introduced to eradicate the alien fish and were used for 2 months, resulting in a 1.86 times increase in the total catch of bluegill compared with conventional methods. These results showed the attractive effects of the conspecific bluegill as decoys, which can thus be used for effectively controlling the bluegill population. On the other hand, the decoys did not attract the fish in Lake Kejyonuma where bluegill density is high. Thus, the attractiveness of the decoy is affected by the density of the bluegill.
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  • Seaward migration period and size of Japanese dace Tribolodon hakonensis in the Kamo River, Mie Prefecture
    DAISUKE ISHIZAKI, TAIGA YODO, MOTOI YOSHIOKA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 920-925
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.920
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      The seaward migration period of anadromous Japanese dace Tribolodon hakonensis in the Kamo River was surveyed by periodical changes of occurrence at two stations: their spawning area (freshwater) and lower tidal area (brackish). Except when spawning occurred, only age 0 and 1 fish were collected. Both age 0 and 1 fish appeared in the tidal area from spring to summer and the number of individuals caught per minute in the spawning area concurrently decreased. These results indicate that the seaward migration period of T. hakonensis in the Kamo River is from spring and summer at age 0 and 1. Based on otolith Sr:Ca ratio analysis, specimens initially migrating into the tidal area were estimated to be 12 to 106 mm standard length.
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  • Interrelationships of the freshwater clams Corbicula leana Prime, 1864. and C. fluminea (Müller, 1774) distributed in Japan inferred from shell type and mitochondrial DNA Cyt b region
    MITSUYA YAMADA, RYO ISHIBASHI, KOUICHI KAWAMURA, AKIRA KOMARU
    Article type: Original
    2010 Volume 76 Issue 5 Pages 926-932
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.926
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      The freshwater clams, Corbicula leana Prime, 1864. and C. fluminea (Müller, 1774) are native and exotic androgenetic hermaphrodites in Japan, respectively. Since the early 1980s, C. fluminea has been repeatedly introduced from East Asia throughout Japan. To elucidate the relationship between the two species, we examined their phenotypes, ploidy, and nucleotide sequence of mitochondrial DNA (mtDNA) cytochrome b (Cyt b) gene. Although the clams were classified into three phenotypes (C. leana, and green and yellow types in C. fluminea) by shell morphology, both diploid and triploid were observed in all phenotypes. In the phylogenetic tree based on the Cyt b sequences, two major clades were recognized, which did not correspond to phenotype or ploidy. In addition, the same dominant haplotype was commonly observed in the three phenotypes. These results unambiguously indicate that C. leana and C. fluminea are genetically indistinguishable, casting doubt on the validity of their taxonomic status.
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  • Laboratory studies on oxic and anoxic decomposition of fish food and feces
    TOMOKO SAKAMI, KATSUYUKI ABO, TOSHINORI TAKASHI
    Article type: Original
    2010 Volume 76 Issue 5 Pages 933-937
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.933
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      A laboratory study of the decomposition of fish food and feces in seawater showed that first-order decay constants of the highly reactive particulate organic carbon (k1) of fish food were 0.28 and 0.16 day−1 under oxic and anoxic conditions, respectively. Those of the less reactive one (k2) were 0.008 and 0.005 day−1, respectively. The decay constants of fish feces were similar to those of fish food except the k1 under the oxic condition. Relative contents of the highly reactive particulate organic carbon fraction in fish food were 88 and 80% under oxic and anoxic conditions, respectively. On the other hand, it was 67 and 39% in fish feces, suggesting that the influence of feces might continue longer in the bottom environment.
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  • Heart rate change during exercise and maximum sustained speed of kuruma shrimp Marsupenaeus japonicus
    BU-YEONG KIM, TAKAFUMI ARIMOTO
    Article type: Original
    2010 Volume 76 Issue 5 Pages 938-945
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.938
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      The heart rate of kuruma shrimp Marsupenaeus japonicus during exercise was examined in a flume tank based on swimming endurance trials in a speed range of 17.7-33.9 cm/s, and by electro-cardiogram (ECG) monitoring. With increased swimming speed, endurance time was shown to decrease, showing a sustained speed of 23.9 cm/s by swimming curve analysis. Heart rate in the control phase could be divided into three groups according to the peak mode of beat per minute; the dominant group showed a heart rate of 90-100 beats/min, and the lower level group was 40-50 beats/min. The high level group showed a rate exceeding 100 beats/min. When the shrimp were forced to swim against the flow, heart rate increased to the range of 80-210 beats/min. However, the magnitude of increase was not proportional to the speed. The increment ratio of heart rate for the exercise phase against the control in each individual revealed a trend of higher values for the low control heart rate group, and lower values for the high heart rate group. The variation of increment ratio was observed to be larger at higher speeds than the sustained speed.
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  • Effects of low-temperature preservation of Japanese scallop adductor muscle on rigor mortis
    TADAAKI TAKEDA, MASAKI AKINO, TAKUMA IMAMURA, HISANORI NOZAWA
    Article type: Original
    2010 Volume 76 Issue 5 Pages 946-952
    Published: 2010
    Released on J-STAGE: November 01, 2010
    DOIhttps://doi.org/10.2331/suisan.76.946
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      Rigor mortis of the adductor muscle in the scallop Patinopecten yessoensis is a serious quality control problem for the distribution of scallop products. We aimed to develop technologies to delay the rigor mortis of the adductor muscle in scallops. We investigated what factors were involved in the rigor mortis during the storage period after removal of the adductor muscle from the scallop shell, especially the effects of energy recovery during the process of preserving live individual scallops on the quality of the adductor muscle. We also examined effective conditions for preserving the scallops to recover their energy levels. We found that the arginine phosphate concentration in the adductor muscle was important with respect to rigor mortis but not ATP concentration. We also found that it was necessary to preserve the scallop just after harvesting at low temperature and with sufficient oxygen supply, to recover the arginine phosphate concentration lost during the process of harvesting and then leaving the scallops in air.
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