著者

Umezawa Ryuhei Urushibata Hirotaro Takahashi Eisuke Arai Katsutoshi Yamaha Etsuro

出版者

北海道大学大学院水産科学研究院

雑誌

北海道大学水産科学研究彙報 (ISSN:24353353)

巻号頁・発行日

vol.70, no.2, pp.133-144, 2020-12-23

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Production of sterile individuals is the key technique for surrogate propagation in teleosts. Sterile hybrids may be the ideal surrogate host when they do not generate their own germ cells in their gonads. Here, we attempted hybridization experiments between zebrafish (Danio rerio) and six closely related species (Danio albolineatus, Aphycypris chinensis, Hemigrammocypris rasborella, Opsariichthys platypus, Nipponocypris temminckii, N. sieboldii) and one remotely related species (Tanichthys albonubes). Intersubfamilial hybridizations in the family Cyprinidae resulted in the occurrence of inviable abnormal larvae with the two parental genomes, except for the T. albonubes x A. chinensis hybridization, in which normal larvae survived. Allotetraploidy and spontaneous gynogenetic diploidy were infrequently detected in T. albonubes x A. chinensis and D. albolineatus x A. chinensis, respectively

著者

Fujimoto Takafumi Fujimoto Suzu Murakami Masaru Yamaha Etsuro Arai Katsutoshi

出版者

北海道大学大学院水産科学研究院

雑誌

北海道大学水産科学研究彙報 (ISSN:24353353)

巻号頁・発行日

vol.70, no.1, pp.103-111, 2020-08-24

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Tetraploid strains are important sources of diploid gametes available for further expansion of ploidy manipulation. Although artificial induction of tetraploid strains has been attempted by inhibition of a mitotic cell division of zygotes using hydrostatic pressure or temperature treatments at the early developmental stage, successful examples of viable and fertile tetraploid fish were very rare. Because most resultant tetraploid progeny exhibited extremely high mortality. Natural tetraploid variants are considered another source of diploid gametes. In the present study, we tried to induce new strains of tetraploid, triploid and androgenetic diploid using diploid sperm of a tetraploid ginbuna (Japanese silver crucian carp Carassius auratus langsdorfii), which caught at the Jounuma lake, Gunma Prefecture, Japan. New tetraploids, i.e., neo-tetraploids were induced by fertilizing eggs of a diploid goldfish Carassius auratus auratus with diploid sperm of the tetraploid ginbuna, followed by heatshock (40°C for 45, 60 and 75 s) to inhibit the second polar body release at 5 min after fertilization. Although a small number of neo-tetraploid fish survived, we could not obtain any fertile gametes from them in the present study. Triploids were successfully induced by fertilizing eggs of a diploid goldfish with diploid sperm of the tetraploid ginbuna. Some resultant triploid males produced aneuploid sperm at the age of maturation. Androgenetic diploids were induced by fertilizing UV-irradiated eggs of diploid goldfish with diploid sperm of the tetraploid ginbuna. A mature androgenetic diploid produced fertile haploid sperm.

著者

浅野 竜太 磯田 豊 小林 直人 中村 知裕 伊藤 薫

出版者

北海道大学大学院水産科学研究院

雑誌

北海道大学水産科学研究彙報 (ISSN:24353353)

巻号頁・発行日

vol.70, no.1, pp.63-76, 2020-08-24

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A new type of mechanism for the generation of vertical circulation is revealed with the use of numerical experiments for the bended channel model. In the steady passage-flow experiment with a flat bottom and no bottom friction, a remarkable vertical circulation is formed only at the downside of bended corner where a negative horizontal shear flow dominates. Specifically, we call this type circulation “Negative Shear induced Vertical Circulation (NSVC)”, which is caused through the dynamical unbalance of gradient flow and the vorticity balance between the lateral vorticity advection and the sea surface divergence. A field observation was carried out around the Ooma-zaki area in the eastern Tsugaru Strait to confirm an enhanced downward flow expected by the realistic experiment including the bottom slope and friction. The spatial istributions of water temperature support the existence of this downward motion.

著者

堀尾 一樹 磯田 豊 小林 直人 千葉 彩

出版者

北海道大学大学院水産科学研究院

雑誌

北海道大学水産科学研究彙報 (ISSN:24353353)

巻号頁・発行日

vol.70, no.1, pp.41-62, 2020-08-24

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If there is the coastal upwelling, it is common to think that the upward advection of cold deep water will make the coastal side cooler than the offshore side. Shelf slope upwelling (SSU) presented in this study, however, occurs only when the shallow coastal side is rather warm due to a continuous sea surface heating in summer. The present study investigated the formation process of such SSU using a numerical model driven by surface heating. From the results of examining unsteady state of heat budget and dynamic balance, SSU was found to be a kind of compensation flow, not the bottom Ekman flow. That is, to satisfy continuity in a vertical section, the offshore flow caused by the horizontal density/temperature gradient was supplemented by the shoreward flow strongly confined to the sloping seabed. This SSU will probably be one of the important flows contributing to material transport, e.g., unused nutrients and anoxic water etc., from deep to near coast in summer, while it is difficult to prove the existence of SSU even indirectly from the observed water temperature.

著者

Fang Xiaorong Isoda Yutaka

出版者

北海道大学大学院水産科学研究院

雑誌

北海道大学水産科学研究彙報 (ISSN:24353353)

巻号頁・発行日

vol.70, no.1, pp.25-40, 2020-08-24

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A multi-layered numerical model driven by seasonal change in sea surface heat flux with excess cooling was used to investigate the dynamics of a cooling induced current (CIC) in the Japan Sea. The original idea of the CIC was proposed by Isoda (1999) (Journal of Oceanography, 55, 585-596) as follows : eastward thermal flow in the interior region, i.e., Tsushima Warm Current (TWC), accompanied with meridional thermal gradient on the planetary-β plane would be determined by the heat balance between net heat loss at the sea surface and lateral heat transport from the southern entrance into the Japan Sea. The CIC model produced a significant meandering TWC with an east-west wave number of three, based on the property of a standing Rossby wave, only under the model condition that coexisted with seasonal disturbances of heat. A positive heat supply from the southern entrance to the Japan Sea occurred in late winter, extended slowly to the TWC region as the offshore advection of meandering patchiness in summer, and then contributed to the heat loss by sea surface cooling in the following winter. The whole TWC region was cooled not only at the sea surface in winter, but also by eastward advection of upwelled cold waters originating from the western boundary area in summer to autumn. The meandering flow was stably confined to the southern part because of the dominant southward eddy momentum fluxes, which were caused by the northwest-southeast inclinations of meandering ridge-axes. Owing to such seasonal change in the lateral transports of momentum and heat, the meandering TWC (or CIC) flow pattern was maintained as a “dynamic equilibrium state”.

著者

Matsuura Hiromi Isoda Yutaka

出版者

北海道大学大学院水産科学研究院

雑誌

北海道大学水産科学研究彙報 (ISSN:24353353)

巻号頁・発行日

vol.70, no.1, pp.13-23, 2020-08-24

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We examine the reason why non-equilibrium response of lunar fortnightly tide, i.e., Mf tide with 13.7-day period, dominates in the Japan/East Sea including the Tsugaru Strait. In the present study, tides combining with passage-flow through the (Tsugaru) Strait are numerically simulated with a two-dimensional form of hydrodynamic model. It has been known that nonlinear interaction of dominant diurnal constituents K1 and O1 results in new oscillation with the same period of Mf tide. Analysis of computed sea level and currents is aimed primarily at describing the enhanced currents and patterns of energy flow in the Strait. Next, the focus of our model study is investigation of mechanisms of pseudo-fortnightly current enhancement where passage-flow interacts with diurnal current variations, resulting in temporal change in the friction due to “form drag”. Thus, we combine the study for form drag of passage-flow with the hydrodynamic interactions of diurnal tidal currents to provide some insight into the locally generated fortnightly tidal forcing within the Strait.

著者

大橋 慎平 永野 優季 加藤 克 河合 俊郎 矢部 衞

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.64, no.2, pp.55-69, 2014-07-31

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Approximately 3,500 fish specimens were transferred from the Faculty of Agriculture, Hokkaido University to the Fisheries Science Center, Hokkaido University Museum (HUMZ). The authors identified fishes from at least 16 orders, 57 families, 109 genera and 145 species. Although most specimens were collected around Japanese waters, several species were collected from other areas, e.g., Eleginops maclovinus (Eleginopsidae) from Chile and Luciocephalus pulcher (Osphronemidae) from India.

著者

田村 亮輔 中川 宙飛 五嶋 聖治

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.64, no.2, pp.37-44, 2014-07-31

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Shell growth of the short-necked clam Ruditapes philippinarum at Hakodate Bay, Hokkaido, Japan, was studied from February 2011 to February 2012. Monthly measurements of shell growth increment from the last ring on the shells revealed that a ring was formed annually from February to March. The Gompertz growth equation was fitted to the relationship between number of rings and shell length, and the equation, LR = 38.41exp (-exp (-0.892 (R-2.029))) was obtained, where LR is the shell length (mm) at the number of ring R. This equation shows highly depressed growth rate after 30 mm in shell length, and maximum shell length was attained about 40 mm that is smaller than those of the other localities. The estimated growth pattern was in accordance with the results of analyses of the size frequency distributions. The observed depressed growth was not explained by a shortage of food supply or seawater temperatures, but may be due to sediment character of including many cobbles and pebbles with sand which disturbs shell growth of the short-necked clam.

著者

HO Ju-shey NAGASAWA Kazuya TAKATSU Tetsuya

出版者

北海道大学大学院水産科学研究科 = GRADUATE SCHOOL OF FISHERIES SCIENCES, HOKKAIDO UNIVERSITY

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.52, no.1, pp.1-3, 2001-03

著者

清藤 秀理 米田 国三郎 甫喜本 司 齊藤 誠一

出版者

北海道大学大学院水産科学研究科 = GRADUATE SCHOOL OF FISHERIES SCIENCES, HOKKAIDO UNIVERSITY

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.52, no.3, pp.139-144, 2001-12

著者

木村 友紀 宮下 和夫

出版者

北海道大学大学院水産科学研究科 = GRADUATE SCHOOL OF FISHERIES SCIENCES, HOKKAIDO UNIVERSITY

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.54, no.3, pp.53-57, 2003-12

著者

津村 良祐 木村 暢夫 藤森 康澄 岩森 利弘

出版者

北海道大学大学院水産科学研究院 = RESEARCH FACULTY OF FISHERIES SCIENCES, HOKKAIDO UNIVERSITY

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.57, no.1-2, pp.19-24, 2006-11

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Ship motions on the small fishing boats for scallop cultivation in Funka-Bay, Hokkaido, are usually influenced by the dynamic force of large scale cultivation facilities. On the rough sea condition, it would generate fatal ship motions like large amplitude rolling motion. To reduce such ship motions under fishing conditions, we designed a new type of mooring device with buffer materials used as absorber for ship motions. We carried out the tank experiment used the model in the wave conditions corresponded to the actual fishing operation to confirm the effect of reducing ship motion. For the waves in the long-period frequently generated under rough sea, the damping effect of the absorber was effective to reduce rolling motion, and accounting for nothing less than 10.0% compared with the normal mooring device without the absorber. As a result, the mooring device with absorber is effective for the improvement of seakeeping qualities of the fishing boats for scallop cultivation.

著者

清水 茂雅 堀口 明日香 山崎 浩司 川合 祐史

出版者

北海道大学大学院水産科学研究院 = Research Faculty of Fisheries Sciences, Hokkaido University

雑誌

北海道大学水産科学研究彙報 (ISSN:13461842)

巻号頁・発行日

vol.59, no.2, pp.37-42, 2009-08-03

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Recovery of heat-injured vegetative cells and spores of Clostridium perfringens was evaluated on selective media, CW Egg-yolk agar with kanamycin (ECW+A), Tryptose sulfite cycloserine agar(TSC+A)and modified Handford agar (mHFA). As a result of heat treatment at 54℃ for 15 min, viable counts of C. perfringens vegetative cells on a selective medium (ECW+A)was significantly less than those on non-selective media. This means C. perfringens vegetative cells should be in an injured state. Comparing of the three selective media, TSC+A was the best growth and recovery of heat-injured C. perfringens vegetative cells. Recovery on ECW+A was 1 log CFU/ml less than that on TSC+A. Supplementation of TSC+A with sodium pyruvate (0.1-0.5%) further enhanced recovery and detection of heat-injured C. perfringens vegetative cells, and its efficacy was the highest on TSC+A supplemented with 0.3% sodium pyruvate. Supplementation of TSC+A with sodium pyruvate did not affect recovery of heat-injured (95℃, 2 or 60 min) C. perfringens spores. These findings suggest that TSC+A is the most favorable medium for enumeration of C. perfringens and supplementation with sodium pyruvate improves recovery and detection of heat-injured C. perfringens.