NIPPON SUISAN GAKKAISHI
Online ISSN : 1349-998X
Print ISSN : 0021-5392
ISSN-L : 0021-5392
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Volume 78, Issue 2
Displaying 1-50 of 55 articles from this issue
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Originals
  • Stock assessment and release strategy of red sea bream Pagrus major in Kagoshima Bay, Japan
    HIROTOSHI SHISHIDOU, AYUKO TAKIMOTO, YASUHIRO OBATA, KATSUYUKI HAMASAK ...
    Article type: Original
    2012 Volume 78 Issue 2 Pages 161-170
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.161
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      Population sizes of red sea bream (RSB) Pagrus major in Kagoshima Bay were estimated both for wild and released fish by cohort analysis from 1990 to 2002 to consider its fishery management and release strategies. The analysis showed that the population size of released fish had decreased while that of wild fish remained stable. The commercial catch of wild fish tended to decrease as that of released fish increased over 50 tons. The results suggested that the RSB enhancement program with the scale of 700-800 thousand seeds released and 50 tons recaptured was appropriate. Predictions of red sea bream catch in 2017 by a simple population dynamics model under various scenarios of fishing regulation and seed release showed that the catch increases under the enhancement program with improved stocking efficiency.
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  • Estimation of the spatial distribution of a Sargassum bed in Kuruminose, Yamaguchi, Japan, using an acoustic method
    KENJI MINAMI, AKIRA HAMANO, NAOKI TOJO, TAKESHI NAKAMURA, HIROKI YASUM ...
    Article type: Original
    2012 Volume 78 Issue 2 Pages 171-179
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.171
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      Sargassum beds play important ecological roles as nursery grounds, feeding grounds and hiding grounds for coastal fauna in Kuruminose, Yamaguchi, Japan (12 km2). In this study, we tried to estimate the spatial distribution of a Sargassum bed using an acoustic method. For this purpose, binarization and geostatistical methods were used. The binarization provided the optimum thresholds to separate the bottom and head of the Sargassum bed. The bottom threshold and the head threshold were −22.4 dB, and −56.4 dB, respectively. The horizontal distribution was interpolated every 1 m2 using kriging. The area of the Sargassum bed was estimated to be 1.94 km2, with thickness of 0.50 to 2.24 m. The Sargassum bed in the south-southeast of Kuruminose was thicker and larger than that near Kuruminose, suggesting that the south-southeast Sargassum bed is important for the coastal ecosystem in Kuruminose. The estimated thickness and distribution corresponded with those by direct observation by diving and underwater TV camera, suggesting that acoustic measurement is adequate for estimating the spatial distribution of Sargassum beds.
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  • Hydrodynamic characteristics of plane minnow netting made of high-strength polyethylene (Dyneema)
    TAISEI KUMAZAWA, FUXIANG HU, HIROMI KINOSHITA, TADASHI TOKAI
    Article type: Original
    2012 Volume 78 Issue 2 Pages 180-188
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.180
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      The hydrodynamic characteristics of minnow netting composed of high-strength polyethylene (Dyneema) with different types of twine diameter and mesh size were evaluated through experiments conducted in a flume tank. The drag coefficient CD90 of Dyneema minnow netting set normal to the water flow was 8% and 25% smaller than that of minnow netting made of the conventional materials of polyamide and polyvinyl alcohol, respectively. The drag coefficient CD0 of minnow netting set parallel to the water flow showed a slight difference between the materials. Additionally, CD90 and CD0 were expressed as functions of Reynolds number and mesh factor α. Furthermore, the drag and lift coefficients of minnow netting set at various angles to the water flow were estimated by empirical equations as functions of CD90, CD0 and attack angle θ.
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  • Photosynthetic and temperature characteristics of five Sargassum species (Fucales), S. piluliferum, S. patens, S. fusiforme, S. crispifolium, and S. alternato-pinnatum from Kagoshima, Japan, using dissolved oxygen sensor and pulse-amplitude-modulated (PAM) fluorometer
    YUTARO TSUCHIYA, GREGORY N. NISHIHARA, RYUTA TERADA
    Article type: Original
    2012 Volume 78 Issue 2 Pages 189-197
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.189
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      The photosynthetic characteristics of five Sargassum species (Fucales): S. piluliferum, S. patens, S. fusiforme, S. crispifolium and S. alternato-pinnatum, were determined over a range of temperatures (10-36℃) by a dissolved oxygen meter and a pulse amplitude modulation chlorophyll fluorometer. Samples for the experiments were collected during April to June 2010 at Sakurajima, Kagoshima Prefecture, Japan, located within Kagoshima Bay. The net photosynthetic rate of each species was highest from 20℃ to 24℃. An ANOVA analysis indicated that there were no significant differences from 16℃ to 28℃ for temperate species (S. piluliferum, S. patens and S. fusiforme) and from 16℃ to 24℃ for subtropical species (S. crispifolium and S. alternato-pinnatum). The relative electron transport rate (rETR) of photosystem II (water/plastoquinone oxido-reductase) of each species increased with increasing temperature, was greatest between 28℃ to 30℃, and decreased at temperatures above 32℃. Summer seawater temperature is around 29℃ at Sakurajima, suggesting that the electron transport might not be damaged under natural conditions. However, temperatures above 30℃ might influence its photosynthetic activity.
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  • Genetic differentiation of the neon flying squid Ommastrephes bartramii between North Pacific and South Atlantic populations
    TOSHIE WAKABAYASHI, SHIRO WADA, YOUSUKE OCHI, TARO ICHII, MITSUO SAKAI
    Article type: Original
    2012 Volume 78 Issue 2 Pages 198-203
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.198
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      Genetic differentiation between samples of Ommastrephes bartramii collected from the North Pacific (n=50) and the South Atlantic (n=50) was examined using nucleotide sequence variation of 506 bp of the mitochondrial 16S ribosomal RNA gene. Thirteen mtDNA haplotypes were identified: seven in the North Pacific (Ob1-Ob7) and six in the South Atlantic (Ob8-Ob13). No haplotypes were common to the two oceans. An exact test of haplotype frequency showed significant differentiation between the two ocean samples (p>0.001). The genetic distance (the number of net nucleotide substitutions) between the North Pacific and South Atlantic samples was 0.00597, similar to the respective within-ocean values. These findings suggest that the two ocean samples of O. bartramii were genetically differentiated to a lesser degree than the interspecific level.
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  • Genetic differentiation of annual Zostera marina L. growing in Kagoshima Bay, Kagoshima, Japan based on an analysis using microsatellite markers
    HIROMORI SHIMABUKURO, MASAKAZU HORI, SATOSHI YOSHIMITSU, NARIMITSU TOK ...
    Article type: Original
    2012 Volume 78 Issue 2 Pages 204-211
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.204
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      The Zostera marina bed is an important habitat for the biological productivity and diversity of coastal marine organisms including various important fishery species. Seed dispersal is a definitive factor to that regulates the annual Z. marina production and is inportant for maintaining the annual Z. marina beds. This study examined the seed dispersal dynamics of the annual Z. marina based on a molecular analysis using 7 microsatellite markers and measuring the morphological characteristics of thallus in Kagoshima Bay, Japan. Samples for DNA analysis and morphological measurement were collected from five local populations at 10 sites where annual Z. marina was found to be growing. Morphological characteristics of the Z. marina samples differed among local populations with different environmental conditions. Moreover, pairwise Fst values of microsatellite locus calculated from the five populations ranged from 0.112 to 0.415 (mean=0.273), suggesting that the genetic differentiation among local populations was markedly large. The results of this study indicated that the seed dispersal of annual Z. marina among local populations has rarely occurred for a long time.
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  • Population genetic structure of the neon flying squid Ommastrephes bartramii inferred from mitochondrial DNA sequence analysis
    KOHEI KUROSAKA, TAKASHI YANAGIMOTO, TOSHIE WAKABAYASHI, YUYA SHIGENOBU ...
    Article type: Original
    2012 Volume 78 Issue 2 Pages 212-219
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.212
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      Neon flying squid is one of the most important commercial species in the North Pacific. For effective stock management, population genetic structure was examined using nucleotide sequence variation of mtDNA ND1-16S rRNA gene regions in samples widely collected from the North Pacific. Samples from the Indian Ocean were used for comparison. Significant differences among the North Pacific and Indian Ocean samples were observed, but no clear genetic differences were observed among sampling locations in the North Pacific. Further analysis using a region with large variations will be necessary to estimate the population structure of neon flying squid.
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  • Role of ocypodid crabs on carbon and nitrogen cycle in a tidal flat
    TAKAHITO OHZONO, TOMOYUKI MIURA
    Article type: Original
    2012 Volume 78 Issue 2 Pages 220-229
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.220
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      Many kinds of benthic organisms in tidal flats are considered to be involved in the purification of organic load. Among them, ocypodid crabs are expected to play an important role due to their high population density in sandy tidal flats. We estimated the organic ingestion of the crabs in Hitotsuba Lagoon within Miyazaki Port in all seasons throughout the year of 2003. Three dominant species, Uca lactea, Ilyoplax pusilla, and Scopimera globosa, and their feeding pellets were collected by quantitative methods. Their habitats were 3500, 1500 and 20750-26750 m2, respectively. The maximum accumulations of their feeding pellets were 944, 486 and 2266 g m−2 d−1, respectively. The original bottom sediments contained organic matter of less than 5.0 mg Cg−1 and 0.5 mg Ng−1, and the loss compared to the feeding pellets was 5-80%. These three species ingested 3.36, 0.18 and 1.67 g Cm−2 d−1, 0.416, 0.024 and 0.086 g Nm−2 d−1 from the bottom sediments, respectively. Their total ingestion was estimated to be about 13 kg Cd−1 and 1.4 kg Nd−1 in this lagoon, which might be equivalent to 7% of the organic load from outside of the lagoon.
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  • Growth of Chionoecetes japonicus females west of the Oki Islands, Sea of Japan
    IKUKO YOSHO, TARO HIROSE, SHIGERU SHIRAI
    Article type: Original
    2012 Volume 78 Issue 2 Pages 230-240
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.230
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      To clarify the growth and bathymetric distribution of Chionoecetes japonicus females, we sampled them by a sledge net from the depth range of 200-2000 m west of the Oki Islands in the Sea of Japan, during every summer for 7 years (2005-2011). In 2005, there were two depth zones at which immature females were abundant at ≤1000 m and ≥1700 m deep, and of which the modes of carapace width were different. The size distribution pattern in following years suggested that the growth rates of these groups were different.
       We detected 5 different instars in immature and 2 instars in adult, and the mean size of each instar was estimated from the carapace width frequency by the Hasselblad method. The smallest instar was regarded as the 6th instar. Compared with the mean size of the same instar by depth, it was smaller at deeper depth in all the instars other than the 6th instar. This suggests that the growth per molt could be smaller at deeper depths in this study area. Moreover, the main instar at maturity molt (9th or 10th) may differ by depth.
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  • Feeding trial of red sea bream with dioxin-reduced fish oil
    TOMOKI HONRYO, HIROSHI YAMAMOTO, ATSUNORI KUMANISHI, HIDEKI HIROSE, YO ...
    Article type: Original
    2012 Volume 78 Issue 2 Pages 241-245
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.241
    JOURNAL FREE ACCESS
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      It is important to produce safe cultured fish by reducing their dioxin content. We investigated the reduction of dioxin content in cultured red sea bream Pargus major by feeding artificial diets containing two sorts of fish oil with different dioxin content: CT (3 pg-TEQ/g) and MD (18 pg-TEQ/g). There was no significant difference in the growth, survival, and feeding indices between the CT and MD fed groups. The content of dioxins in the muscle significantly decreased in the CT fed group (0.07 pg-TEQ/g) compared with the initial content (0.14 pg-TEQ/g), whereas that in the MD fed group increased to 0.30 pg-TEQ/g. This effect was particulary clear in the liver. These results demonstrated the possibility of producing cultured fish with low content of dioxins by feeding low-dioxin fish oil.
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  • Recovery of nori Porphyra color by uptake of nutrients supplied intermittently from rivers
    SHUZO TAKAGI, YASUKO SHIMIZU, KOJI KUSAKA, TOKISHIGE FUJISAWA, MUNEHIR ...
    Article type: Original
    2012 Volume 78 Issue 2 Pages 246-255
    Published: 2012
    Released on J-STAGE: April 20, 2012
    DOIhttps://doi.org/10.2331/suisan.78.246
    JOURNAL FREE ACCESS
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      To elucidate the threshold amount of DIN value for keeping the nori color, nori color (a* value) and variability of fluval DIN concentration were investigated in the Bisan Strait. The results show that even if oceanic DIN is less than 1 μM, nori can keep its color (a* value>6) by taking up the DIN supplied intermittently from rivers. In that time, the standard deviation of DIN was larger than 2 μM. At this farm, the total period when DIN>7 μM was 1.6 hour day−1; this condition coincides with an incubation experiment conducted in a laboratory. The discolored nori transplanted to this place recovered its a* value within 14 days to the same level as that of the nori originally growing at this place.
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Short Papers
Symposia
Present state and the prospect of application of the genome information to aquaculture
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II.
III.
A microbe's-eye view of coastal environments: Toward the preservation and restoration of Ariake Sea
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III.
Damages to fisheries by the Great East Japan Earthquake and tsunami disasters
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Highlights in Fisheries Science Research
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