魚類学雑誌
検索
OR
閲覧
検索
56 巻 , 2 号
選択された号の論文の12件中1~12を表示しています
    • |<
    • <
    • 1
    • >
    • >|
総説
本論文
  • 柳生 将之
    56 巻 (2009) 2 号 p. 111-118
    公開日: 2014/03/05
    ジャーナル フリー
    To clarify the foraging microhabitat of the Japanese charr, Salvelinus leucomaenis, I investigated focal point depths and velocities in a 730-m reach of a typical mountain stream in central Japan in the spring and summer of 2004. The water depths and velocities of focal points used by 123 fish (>9-cm fork length) were compared to data for random points in the stream. The charr utilized focal points with depths>10 cm and velocities<60 cm/s. The preferred habitat was comparatively deeper (21-60 cm) and moving at a slower velocity (11-20 cm/s). The proportion of favorable foraging habitat in the study reach was calculated to be 15% in July and 18% in August based on focal points. This habitat was dispersed in small patches and distributed randomly throughout the reach. In small mountain streams such as the one studied here, there are repeated small steps and pools. Most of the favorable foraging habitat was in the pools. Therefore, charr density may be affected by river morphology, such as the number of pools or steps in a reach.
    抄録全体を表示
  • 原 政子
    56 巻 (2009) 2 号 p. 119-133
    公開日: 2014/03/05
    ジャーナル フリー
    The fine structures of mature spermatozoa of 13 Japanese osmerid and salmonid species (and subspecies) were studied with TEM and SEM. Three types were recognized, based on combinations of morphological characters, such as nucleus shape, number, size and arrangement of mitochondria, and numbers of flagella, as follows: Osmeridae type (7 species, including Osmerus eperlanus mordax, Hypomesus nipponensis, Hypomesus japonicus, Spirinchus lanceolatus, Mallotus villosus, Plecoglossus altivelis altivelis and Plecoglossu altivelis ryukyuensis), characterized by an elongated ovoid nucleus with a deep cylindrical basal fossa, a single mitochondrion, located along the base of the flagellum, and a single finned flagellum; Salangidae type (4 species, including Salangichthys microdon, Salangichthys ishikawae, Salanx ariakensis and Neosalanx reganius), characterized by a spherical nucleus with a partly invaginated, moderately deep conical basal fossa, multiple mitochondria surrounding the flagellum; and a single finned flagellum; Salmonidae type (2 species, including Oncorhynchus masou masou and Oncorhynchus mykiss) being characterized by a depressed ovoid nucleus with a shallow cylindrical basal fossa, a single mitochondrion, annular around the base of the flagellum; and a single finned flagellum. A comparison between these types and currently-recognized osmerid and salmonid systematics revealed the following: (1) The Osmeridae type variously included Hypomesinae, Osmerini (Osmerinae) and Precoglossinae sperm morphs; (2) the present grouping of sperm morphs is less supportive of some recently proposed systematics of relevant taxa, although concurring with a recent molecular phylogenetic study. It is suggested that spermatozoa are potentially useful in evaluating generic relationships within Osmeridae.
    抄録全体を表示
  • 中島 淳, 鬼倉 徳雄
    56 巻 (2009) 2 号 p. 135-143
    公開日: 2014/03/05
    ジャーナル フリー
    The natural growth and habitat selection of the green chub, Aphyocypris chinensis, an endangered species in Japan, was investigated in an agricultural waterway located in northern Kyushu Island, Japan. From April 2007 to March 2008, green chub were captured by hand net and 5 physical environmental variables measured (water temperature, water depth, water current velocity, connection to paddy field, and presence or absence of tunnel-like cover) at 10 survey sites every month. After obtaining an image of the captured fish with a digital camera, all individuals were released alive at their capture location. The standard lengths of 823 individuals were later determined from the images. Monthly changes in the standard length distribution showed that green chub had a life-span of 1 year, the spawning season occurring from mid-June to August. Multiple linear regression analysis applied to the 5 environmental variables separately in the irrigation (from June to September) and non-irrigation seasons (from October to May), showed water depth to be most significant in the former and absence of water movement in the latter. Fish occurrence patterns indicated that temporary waters were utilized as spawning sites and permanent waters for overwintering. Accordingly, continued ease of movement between temporary and permanent waters is essential for future conservation of the species.
    抄録全体を表示
短報
シリーズ
    • |<
    • <
    • 1
    • >
    • >|
feedback
Top