著者

佐藤 真央 井上 裕太 溝脇 一輝 小林 大純 松尾 怜 外山 太一郎 日比野 友亮

出版者

一般社団法人 日本魚類学会

雑誌

魚類学雑誌 (ISSN:00215090)

巻号頁・発行日

pp.20-036, (Released:2021-03-22)

参考文献数

14

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Twelve specimens (71.5–89.9 mm standard length) of the genus Lutjanus (Lutjanidae), collected from Ishigaki-jima Island, Ryukyu Archipelago, southern Japan, were identified as Lutjanus biguttatus (Valenciennes in Cuvier and Valenciennes, 1830), being characterized by the following combination of characters: dorsal fin XI, 12; anal fin III, 8; pectoral rays 15–16; body depth 3.5–3.8 in standard length; preorbital depth 10.8– 16.3 in head length; tongue smooth, without patch of fine granular teeth; a dark longitudinal band from snout to caudal fin base; and two white spots above the lateral line. Dentition of the premaxilla and dentary, including several canine-like (one being long and curved) and many small conical teeth, is illustrated. The collected specimens were determined to be juveniles, due to their coloration matching that of juveniles previously described, in addition to their small body size. Although the coloration of L. biguttatus is similar to that of L. vitta during the juvenile stage, the latter species is distinguished by greater body and preorbital depths. The specimens of the former had been caught in a significantly localized area (in ca. 4 m depth) over several days, indicating the likelihood of their having been schooling, as observed in previous studies of the species. Lutjanus biguttatus is distributed in the Indo-western Pacific, from the Maldives to the Solomon Islands, but had not previously been recorded from Japanese waters. The new standard Japanese name “Futahoshi-fuedai”, given in reference to the two white spots above the lateral line in the collected specimens, is proposed.

著者

中山 聖子 木村 将士 金子 誠也 山崎 和哉 外山 太一郎 池澤 広美 加納 光樹

出版者

アクオス研究所

雑誌

水生動物 (ISSN:24348643)

巻号頁・発行日

vol.2024, pp.AA2024-2, 2024-01-11 (Released:2024-01-11)

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東南アジア諸国の水産上重要種であるウシエビPenaeus monodonは、インド・西太平洋の熱帯から温帯地域で生息が確認されており、その分布の北限は東京湾もしくは房総半島沿岸とされてきた。しかしながら、2021年9月から2023年11月にかけて両海域よりも北に位置する茨城県の江戸上川・久慈川・那珂川・利根川河口域と汽水湖涸沼において本種の稚エビ計20個体(頭胸甲長4.8–28.3 mm)が採集されるとともに、江戸上川産の標本に基づいて本種の北限記録を更新した。これらの採集年については、黒潮からの暖水波及と部分的に関連付けられる20 °C以上の高水温の期間が平年と比べて長かった。本種は低水温への耐性がないため茨城県沿岸海域で越冬する可能性は低いものの、今後、海水温の上昇によって稚エビの加入が増えていく可能性がある。

著者

渡邊 美如々 木村 将士 碓井 星二 根本 隆夫 外山 太一郎 宮崎 淳一 加納 光樹

出版者

アクオス研究所

雑誌

水生動物 (ISSN:24348643)

巻号頁・発行日

vol.2022, pp.AA2022-16, 2022-08-23 (Released:2022-08-23)

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The fish fauna in the middle and lower reaches of Sakura River flowing into Lake Kasumigaura was investigated with casting nets, hand nets and scoop nets in May, July, and October 2020 and from April to October 2021, and compared with data from previous studies conducted in 1984–1987, 1996–2002 and 2010–2015. A total of 36 fish species in 11 families, including 20 introduced exotic and Japanese species and 16 native species, were collected in 2020–2021. The analyses of long-term changes in presence/absence of fish species from the 1980s to the 2020s demonstrated the disappearance of four threatened species (three native bitterling species and the crucian carp Carassius buergeri subsp. 2) by various artificial environmental changes and a gradual increase in introduced exotic and Japanese species spreading mainly from Lake Kasumigaura.

著者

山川 宇宙 内田 大貴 外山 太一郎 津田 吉晃

出版者

アクオス研究所

雑誌

水生動物 (ISSN:24348643)

巻号頁・発行日

vol.2023, pp.AA2023-14, 2023-08-02 (Released:2023-08-02)

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Two warm-water fish species, Eleotris fusca (Bloch and Schneider, 1801) and Sicyopterus japonicus (Tanaka, 1909), and three warm-water decapod crustacean species, Macrobrachium formosense Bate, 1868, M. japonicum (De Haan, 1849), and Varuna sp., were collected from a river in Iwaki, Fukushima Prefecture, Japan. The occurrence of E. fusca represents a new record from the prefecture and the northernmost record for the species. It is likely that M. japonicum overwintered, but the other four species probably dispersed from the south via ocean currents. In recent years, the range of many species has been extending northward due to global warming and thermal discharge. To understand changes in the distribution and habitat of these aquatic animal species, it is necessary to continue monitoring the occurrence of warm-water aquatic animals in coastal areas and rivers in the prefecture.

著者

小林 大純 山川 宇宙 内田 大貴 碧木 健人 外山 太一郎

出版者

国立大学法人 鹿児島大学総合研究博物館

雑誌

Ichthy, Natural History of Fishes of Japan

巻号頁・発行日

vol.16, pp.5-10, 2022

著者

佐藤 真央 井上 裕太 溝脇 一輝 小林 大純 松尾 怜 外山 太一郎 日比野 友亮

出版者

一般社団法人 日本魚類学会

雑誌

魚類学雑誌 (ISSN:00215090)

巻号頁・発行日

vol.68, no.1, pp.17-22, 2021

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<p>Twelve specimens (71.5–89.9 mm standard length) of the genus <i>Lutjanus</i> (Lutjanidae), collected from Ishigaki-jima Island, Ryukyu Archipelago, southern Japan, were identified as <i>Lutjanus biguttatus</i> (Valenciennes in Cuvier and Valenciennes, 1830), being characterized by the following combination of characters: dorsal fin XI, 12; anal fin III, 8; pectoral rays 15–16; body depth 3.5–3.8 in standard length; preorbital depth 10.8– 16.3 in head length; tongue smooth, without patch of fine granular teeth; a dark longitudinal band from snout to caudal fin base; and two white spots above the lateral line. Dentition of the premaxilla and dentary, including several canine-like (one being long and curved) and many small conical teeth, is illustrated. The collected specimens were determined to be juveniles, due to their coloration matching that of juveniles previously described, in addition to their small body size. Although the coloration of <i>L. biguttatus</i> is similar to that of <i>L. vitta</i> during the juvenile stage, the latter species is distinguished by greater body and preorbital depths. The specimens of the former had been caught in a significantly localized area (in ca. 4 m depth) over several days, indicating the likelihood of their having been schooling, as observed in previous studies of the species. <i>Lutjanus biguttatus</i> is distributed in the Indo-western Pacific, from the Maldives to the Solomon Islands, but had not previously been recorded from Japanese waters. The new standard Japanese name "Futahoshi-fuedai", given in reference to the two white spots above the lateral line in the collected specimens, is proposed.</p>

著者

外山 太一郎 福地 伊芙映 山崎 和哉

出版者

国立大学法人 鹿児島大学総合研究博物館

雑誌

Ichthy, Natural History of Fishes of Japan

巻号頁・発行日

vol.6, pp.54-65, 2021