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Volume 63, Issue 3
Displaying 1-17 of 17 articles from this issue
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Original Paper
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Takashi Tani, Chikara Kawagoe, Setsuko Matsumoto, Hiroyuki Mizuta, Haj ...2015 Volume 63 Issue 3 Pages 235-244
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSSeasonal variations and accompanying morphological changes of 'Gagome-kombu' (Saccharina sculpera) from Hakodate, Hokkaido Prefecture were observed for three years. The growth, maturation and renewal of first-year, second-year and third-year plants were documented. Between January and July, first-year plants with frond lengths less than 5 cm emerged and grew slowly to 10 cm by October. Although renewal was observed in first-year plants during October and January, no mature plants were observed. Second-year plants grew between January and July into large plants over 2 m in length, withered between August and October and reached maturity between October and November. Although renewal into third-year plants were observed in about 40% of 400 second-year plants, most of these plants withered and died by April of the third-year. Only 2% of the second-year plants continued to grow until July, withering between August and October and maturing in October and November. All the plants withered and died by December of the third-year.View full abstractDownload PDF (1659K) -
Effects of dietary phosphorus restriction on phosphorus balance in rainbow trout Oncorhynchus mykissShozo Sugiura2015 Volume 63 Issue 3 Pages 245-253
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSThe present study examined responses of fish to dietary phosphorus (P) restriction. Two groups of rainbow trout (mean body weight 129 and 115 g) were fed for 32 and 53 days, respectively, with either the low-P (LP) or high-P (HP) diet. Some fish were starved concurrently. Fish fed the LP diet (LP fish) gradually decreased plasma P from 93 (day 0) to 17 mg/l (day 32), whereas those fed the HP diet (HP fish) and the starving fish maintained normal plasma P levels (81-130 mg/l). Plasma P levels decreased markedly after feeding the LP, but not HP, diet. When fish were fed glucose, the plasma glucose level increased markedly for both LP and HP fish. The LP fish apparently absorbed P from water (~0.2 mg P/kg fish/day), whereas starving fish excreted P (1.8 mg P/kg fish/day). Waterborne P (5 and 50 mg P/l) had little effect on fish plasma P levels regardless of the fish P status. The LP fish had lower ash (65%), P (67%) and calcium (39%) contents compared to the HP fish on a whole body basis. Calcium-wasting is most characteristic in dietary P deficiency.View full abstractDownload PDF (260K) -
Shingo Ito, Hisae Kasai2015 Volume 63 Issue 3 Pages 255-259
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSWe observed mortality due to scuticociliate infection in barfin flounder and subsequently identified the causative pathogen and examined its pathogenicity. In addition, we examined the sensitivity of a pathogen isolate and the tolerance of the barfin flounder to vinegar solutions and tea extract solutions to identify scuticociliate infection control measures in this fish species. Species identification of the causative agent was performed using polymerase chain reaction (PCR); the causative agent was identified as Miamiensis avidus. M. avidus was administered to barfin flounder via immersion or intraperitoneal injection. In the intraperitoneal injection experiments, the cumulative mortality rate within one week was 100% at a dose of 105 ciliates/fish. In contrast, immersion challenge experiments were unsuccessful. M. avidus survival fell below the detection limit after exposure to a 0.7% vinegar solution or a 0.01% tea extract solution for 30 min. Exposure to a 0.03% tea extract solution for 1h was toxic to the barfin flounder, whereas exposure to a 0.7% vinegar solution for 1h exhibited low toxicity. In conclusion, we suggest that exposure to a 0.7% vinegar solution for 30 min is an effective M. avidus infection treatment and control method in vitro.View full abstractDownload PDF (425K) -
Yukihiko Serisawa, Kohei Kimbara, Kazuyo Matsuyama-Serisawa2015 Volume 63 Issue 3 Pages 261-271
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSIn order to clarify the seasonal changes in morphology of Undaria pinnatifida at Omaezaki (southern type population growing), ca. 15 sporophytes were collected and morphometric measurements were carried out monthly in 2006. Small sporophytes were observed in January, which already had several bladelets, a narrow midrib and short sporophyll. In April plants grew to a maximum plant length (primary blade length + stipe length), 232 cm; plant width (primary blade width + longest bladelet length×2), 120 cm; plant weight (without holdfast), 945 g f.w. All plants disappeared in August and oval juveniles without a midrib or bladelets were observed again in December. In order to compare their morphology, sporophytes of the Choshi population (southern limit of the northern type population growing) were also collected in May to July and the same morphological measurements were done. In the Choshi population, plant length and width was maximal in May with 206 cm and 110 cm, respectively, and plant weight was maximal in June for 777 g f.w. In both populations, sporophytes grew to over 2 m in length, morphological characteristics were almost the same, and conspicuous differences were not recognized in the ratio of several measured parts vs. plant length.View full abstractDownload PDF (1144K) -
Shiela Villamor, Tomoko Yamamoto2015 Volume 63 Issue 3 Pages 273-282
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSThe aim of this study was to describe the population characteristics of Monetaria annulus (Linnaeus, 1758), including the density, abundance of different developmental stages, sex ratio, and size dimorphism between sexes, which are significant factors for resource management. We surveyed populations in the Philippines (tropical area) for comparison with populations in Japan (subtropical and temperate areas). The population density in the tropical area was intermediate between that in the sub-tropical and temperate areas, although density varied among stations in the same geographical area. There was a low proportion or absence of immature cowries in the habitat shared with adults, except for Nogas Island in the Philippines. Because marine protected areas (MPAs) include a nursery area, which is a protective area for immature cowries, further study was required to determine where juveniles are recruited and grow. We detected the sex of adult cowries by histological analysis and measured the length of each shell to distinguish sexual dimorphism. Females were larger than males in some sampling sites. When formulating fisheries guidelines, including controlling the collection of larger individuals, we should investigate the sex ratio and size dimorphism in each resource population to avoid a sex ratio that is biased toward males.View full abstractDownload PDF (510K) -
Masato Sato, Katsuji Shibuya2015 Volume 63 Issue 3 Pages 283-290
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSTo investigate the migration route, growth, and natal-river selectivity of masu salmon Oncorhynchus masou, a total of 323,620 smolts were released in the Yoneshiro River between 1996 and 2010 (except 2007). A total of 501 fish were recaptured by November of the second year after release. Based on recapture data, we estimated that masu salmon migrated to the Okhotsk Sea for the summer and to the eastern area of the Tsugaru Strait for overwintering. Subsequently, the salmon ran up the river by the summer of the second year after release. The mean fork length of recaptured fish steadily increased between April of the first year after release and June of the second year after release. The mean growth rate in the sea was 0.09±0.03 cm/day. Increases in mean fork length were not observed after July of the second year after release. These results indicate that masu salmon grow during the ocean stage. Of the 36 fish recaptured in the rivers, four individuals were recaptured in rivers other than the Yoneshiro, suggesting that these fish had not imprinted on the natal river.View full abstractDownload PDF (901K) -
Shozo Sugiura, Yasuhiro Tonoyama, Hiroyuki Kawachi, Masaki Tsukada, Go ...2015 Volume 63 Issue 3 Pages 291-297
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSSoy sauce oil (SSO) is a byproduct of soy sauce manufacturing. SSO is uncommon as an ingredient for fish or animal feeds. The present study evaluated the dietary effects of SSO on fish growth performance, fillet fat content, and sensory characteristics of the fillets. Biwa salmon Oncorhynchus masou rhodurus (initial mean body weight of 176 g) were fed in commercial aquaculture ponds with either the SSO-supplemented diet or the soybean oil (SBO)-supplemented diet (as a control) for 94 days. Dietary supplementation of SSO at 5% did not cause any adverse effects on fish performance, morphometric measurement, or sensory traits compared with the control fish. Dietary SSO supplementation resulted in significant improvements in some organoleptic properties of fish fillets, which were favored by certain groups of people. The present results indicate that dietary SSO can be used as an alternative ingredient replacing SBO in fish feeds. This is the first study to sensorially evaluate SSO-fed fish.View full abstractDownload PDF (189K) -
Keisuke Kimoto, Tohru Mekata, Hiroshi Takahashi, Kazuya Nagasawa2015 Volume 63 Issue 3 Pages 299-309
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSThe genetic structure of two fluvial forms of the red-spotted masu salmon, amago (ordinary form) and iwame (markless form), collected from two headwater streams, the Kohbaru Stream and the Hakiai Stream, of the Ono River, Oita Prefecture, was examined using mtDNA to identify whether they were indigenous to the streams. The Hakiai Stream consists of two tributaries, Mennotsura-dani and Manryo-dani. The iwame population occurs only in Mennotsura-dani, and since 1970, fishing has been prohibited for the iwame and amago populations in most locations of Mennotsura-dani and Manryo-dani, respectively. One haplotype (Hap-1) was shared by three isolated populations examined: it was fixed (100%) in the iwame population from Mennotsura-dani and dominant (90.5%) in the amago population from the upper Kohbaru Stream, but was infrequent (10.0%) in the amago population from Manryo-dani. Hap-1 was also frequent in the samples of amago fry caught in the Kohbaru Stream. Based on these results and the long persistence of the iwame population in Mennotsura-dani, both the iwame population in Mennotsura-dani and the amago population in the upper Kohbaru Stream are considered to be indigenous, whereas the amago population in Manryo-dani appears to have been mostly replaced by hatchery-reared fish informally stocked in the upper location.View full abstractDownload PDF (653K) -
Teruwo Morita, Chie Suzuki, Michihiko Kumon, Akio Douke2015 Volume 63 Issue 3 Pages 311-316
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSThe growth and vegetative propagation of Sargassum miyabei were examined at four salinities (3, 7, 15 and 30 psu) in outdoor tanks. The plant was collected in Aso Lagoon, Kyoto Prefecture. The optimum salinity for plants growth was 15 and 30 psu. On the other hand, the inhibition of the growth was observed at 3 and 7 psu. Additionally, the number of newly formed stem from old stem was observed at 15 and 30 psu, but there was no difference in both temperatures. The number of newly formed stem from filamentous holdfast was almost the same at 7, 15 and 30 psu. In contrast, the number of newly formed stem from filamentous holdfast was inhibited at 3 psu. The growth of stem from filamentous holdfast was inhibited at 3 and 7 psu. Overall, the growth and vegetative propagation of S. miyabei was inhibited at 3 and 7 psu. So, this finding suggests that the S. miyabei in Aso Lagoon was high resistant plant for low salinity condition.View full abstractDownload PDF (614K) -
Masahiro Nakagawa, Takuro Hotta, Kazunori Yoshida, Tsutomu Noda, Hirot ...2015 Volume 63 Issue 3 Pages 317-324
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSThis study examined the state of formation and formative period of inscribed rings on scales and otoliths using 102 cultured longtooth grouper, Epinephelus bruneus fish of known age (age 2-7 yr). Based on the results, we assessed their validity for age determination. Scales were collected from four body regions regarded as the most suitable positions to determine the ratio of regenerated scale/original scale, the scale length, and the count of rings. Significant differences were found to be greatest for the ratio of regenerated scales / original scales collected from position B, but those collected from position C exhibited the lowest tendency. Significant differences were found in the longest scale length collected from position C. Ring counts of the scale collected from position C were consistent with 74-100% of the age. This value was higher than those of other positions. The ring counts of the otoliths were consistent with 66.7-100% of the age. June was lowest in MGR for scales and otoliths, suggesting that rings of scales and otoliths were formed during May-June. These rings formed once a year. Results show that rings of the scales collected from the C position (head-side abdominal region) and the otoliths were effective for age determination (age 2-7 yr).View full abstractDownload PDF (1981K) -
Alok Kalla, Mohammad Nakib Dad Khan, Toshiyoshi Araki, Takao Yoshima ...2015 Volume 63 Issue 3 Pages 325-332
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSFingerlings of koi carp Cyprinus carpio (mean weight 3.0 g) were randomly distributed with a stocking density of 13 fish per aquarium. Fish were fed thrice daily on each diet containing different levels of Pyropia spheroplasts, (PS: 0, 15, 30, 45 and 78%) for 150 days. The growth performance and nutrient retention values of 15% PS group increased and feed conversion ratio (FCR) decreased compared with control and the other PS groups. A linear regression was fitted where the dietary PS levels over 30% resulted in a reduction of growth parameters. The carcass crude protein content of 15% group was higher than other PS groups. According to the experimental results obtained in the preliminary trials, PS is expected to be a new material as a fish meal substitute for koi carp.View full abstractDownload PDF (281K) -
Kentaro Higuchi, Junpei Konishi, Toshinori Takashi, Yosuke Tanaka, Aya ...2015 Volume 63 Issue 3 Pages 333-341
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSFertilized eggs of Pacific bluefin tuna Thunnus orientalis need to be disinfected to prevent viral nervous necrosis occurring during seed production. Electrolyzed seawater containing residual chlorine is a potential disinfectant, but treatment of eggs with electrolyzed seawater may reduce the hatching rate. To determine suitable conditions for electrolyzed seawater treatment for Pacific bluefin tuna eggs, we investigated the effects on the developmental stages (4-cell stage, morula stage, gastrula stage, 5-somite stage, beginning of heart beat and 1 h before hatching) and the concentration of residual chlorine (0.0, 0.5, 1.0 and 1.5 mg / l) on the hatching rate after the treatment. Treatment with 1.0 mg / l residual chlorine for 1 min had no effect on hatching of eggs at all developmental stages. However, the hatching rate of eggs at 4-cell stage and 1 h before hatching exposed to 1.0 mg / l residual chlorine for 2 min markedly decreased. In addition, treatment with 1.5 mg / l residual chlorine for 1 min reduced the hatching rate. These results indicate that 1.0 mg / l residual chlorine within 2 min, at the morula stage to beginning of heart beat, are acceptable conditions for the electrolyzed seawater treatment.View full abstractDownload PDF (754K) -
Riho Miyazaki, Ken-Lin Huang, Katsuya Hirasaka, Satoshi Takeshita, Sh ...2015 Volume 63 Issue 3 Pages 343-348
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSTo clarify the mechanism of post-mortem softening in burnt meat of cultured yellowtail Seriola quinqueradiata, we examined the ultrastructural changes of endomysium, which is a connective tissue within the dorsal ordinary muscle. The specimens slaughtered by suffocation in air in summer (S-SA) were used as burnt meat model, while spinal cord destruction in summer (S-SCD) and winter-spinal cord destruction (W-SCD) were used as control specimens. Color L＊ value and expressible water content in S-SA were higher than those in control specimens, while muscle pH was lower. A fine endomysial honeycomb structure was observed in control specimens on scanning electron microscope (SEM), although its structure was disrupted in S-SA after 4 h storage. Consistent with SEM results, the intricately entangled collagen fibers, which were a major component of endomysium, was not observed in S-SA with the transmission electron microscope. These results suggested that post-mortem softening of cultured yellowtail influenced the disruption of collagen fibers, resulting in burnt meat.View full abstractDownload PDF (670K)
Short Paper
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Tadashi Imai, Hiroshi Saito, Nobuhiko Akiyama2015 Volume 63 Issue 3 Pages 349-351
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSLarvae of freshwater prawn Macrobrachium nipponense reared in tap water dechlorinated with sodium thiosulfate (STS) have reduced survival time and retarded development, compared with other dechlorination methods. We examined the effects of STS and sodium tetrathionate (STT), which is produced by residual chlorine and STS, on survival and molts of larvae. STT had the same effect on larvae as the positive control (aerated tap water), however, larvae were susceptible to STS, onset of death was rapid at STS concentrations of >2 mg/l. Therefore, further clarification of appropriate concentration of STS for dechlorination is necessary.View full abstractDownload PDF (294K) -
Satoshi Yamamoto, Masanori Okauchi, Takao Yoshimatsu2015 Volume 63 Issue 3 Pages 353-355
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSA Thoma-zeiss counting chamber is generally used to determine the cell densities of microalgae in laboratory. But, this counting method is a time and labor consuming practice. Therefore, as an easier method to determine cell density of a microalga Rhodomonas sp., the availability of spectrophotometric method of chlorophyll a was investigated. The amount of Chl. a was firstly determined by measuring absorbance at 664nm, 624nm wavelengths. After that regression analysis with the amount of Chl. a and cell density were computed. As a result, a regression equation obtained makes it possible to determine the cell density of Rhodomonas sp. more easily.View full abstractDownload PDF (297K) -
Hiroyuki Doi, Takayuki Sonoyama, Yuko Yamanouchi, Kenta Tamai, Harumi ...2015 Volume 63 Issue 3 Pages 357-359
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSEggs spawned in the Shimonoseki Marine Science Museum Aquarium by eight species of Diodontidae (Allomycterus pilatus, Chilomycterus antennatus, Ch. reticulatus, Ch. schoepfii, Cyclichthys orbicularis, Diodon hystrix, D. holocanthus and D. nicthemerus), representing four genera, were mostly pelagic, only A. pilatus and D. nicthemerus spawning adhesive demersal eggs. The adaptive implications of such demersal eggs require comparative studies on diodontid spawning ecology.View full abstractDownload PDF (246K)
Note
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Ayumi Yoshida, Hideki Yamazaki, Atsushi Ito, Kazutaka Sakiyama, Yoshit ...2015 Volume 63 Issue 3 Pages 361-366
Published: September 20, 2015
Released on J-STAGE: September 20, 2016
JOURNAL FREE ACCESSWe investigated shell-length of short-neck clam Ruditapes philippinarum ingested by kuruma prawn Marsupenaeus japonicus. One hatchery-reared kuruma prawn (23.1-141.2 mm body length, BL) and 5-10 hatchery-reared short-neck clams (1.6-10.4 mm shell-length) were measured and transferred into a container with bottom sand overnight. Next, predation of clams by a prawn was examined by counting and measuring survived clams. Kuruma prawn ingested short-neck clam with shell-length smaller than an average of 6.7% (1.3-9.5%) BL of kuruma prawn. The size of the second maxilliped and the first maxilla of kuruma prawn coincided with the maximum and minimum size of ingested clam, respectively. We conclude that the shell-length of short-neck clam ingested by kuruma prawn is determined by the length of mouth-parts of kuruma prawn. Therefore, kuruma prawn may prey on small size short-neck clam during stock enhancement program in tidal flats. Moreover, kuruma prawn can coexist with short-neck clam larger than 10 mm of shell-length indicating the possibility of polyculture with these 2 species.View full abstractDownload PDF (505K)
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