著者

川瀬 成吾 中江 雅典 篠原 現人

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.22-028, (Released:2023-05-15)

参考文献数

61

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The fish collection built up by Chiyomatsu Ishikawa (1860–1935), a Japanese zoologist who investigated the fish fauna of Lake Biwa in the 1890s, was reassessed for the first time in many years, and found to provide an important insight into the fish fauna of the lake at the end of the 1800’s. Now held in the National Museum of Nature and Science, Tsukuba, Japan, the collection includes 1,795 specimens (110 lots) collected from 12 sites in Lake Biwa and adjacent areas (i.e., Hikone, Imazu, Kaizu, Kaminyu, Lake Yogo, Maebara (= Maibara), Matsubara, Nagahama, Omi-Hachiman, Seta River, Shiotsu and Zeze). Thirty-three species, including 10 endemic species/subspecies, in 11 families were identified, including the type series of Pseudogobio zezera (=Biwia zezera). The majority of specimens were included in the following 7 species: Tanakia lanceolata, Acheilognathus tabira tabira, Candidia sieboldii, Ischikauia steenackeri, Sarcocheilichthys variegatus microoculus, Tachysurus nudiceps, and Plecoglossus altivelis altivelis (landlocked type). Such species are now seen infrequently along the lake foreshore (except for P. a. altivelis), the collection indicating a formerly rich fish fauna before the establishment of artificial influences (e.g., concrete revetments, invasion of alien species such as Micropterus nigricans and Lepomis macrochirus, and artificial control of water levels by the Seta River Weir). Although the occurrence of Acheilognathus longipinnis and Sarcocheilichthys variegatus variegatus in Lake Biwa has been unclear for a long time, examples of those species/subspecies in the collection provided evidence of their past distributions in the lake. Importantly, the collection sets a benchmark for any restoration of the past fish fauna of Lake Biwa.

著者

中尾 遼平 入口 友香 周 翔瀛 上出 櫻子 北川 忠生 小林 牧人

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.64, no.2, pp.131-138, 2017-11-25 (Released:2018-06-19)

参考文献数

28

被引用文献数

2

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Genetic disturbance in Japanese wild medaka populations (Oryzias latipes species complex) has resulted mainly from artificial introductions from geographically distinct populations or of commercial varieties, especially an orange-red body color variety (himedaka). Because the extent of genetic introgression within a single water body has remained unclear, the genetic population structure of wild minami-medaka Oryzias latipes in the Nogawa River, a tributary of the Tamagawa River system in Tokyo, Japan, was surveyed using three DNA markers (cytb and ND2 genes on mitochondrial DNA and b-marker on nuclear DNA) to evaluate the extent of introgression throughout upper and lower reaches. Genotypes originating from himedaka were detected at all sites surveyed. Although different genetic composition of introgressed mitotypes among some sampling sites suggested multiple introductions of non-native populations, high dispersal rates of introgressed genes could not be rejected as a cause of wide-spread introgression. Based on this study, appropriate management strategies for the genetic conservation of wild medaka populations are discussed.

著者

望月 健太郎 伊東 正英 本村 浩之

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.22-009, (Released:2022-06-03)

参考文献数

26

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A single specimen (153.7 mm total length) of large congrid leptocephalus, collected at a depth of 400 m off Kuro-shima Island, Osumi Islands, Kagoshima Prefecture, Japan, was subsequently identified as Congriscus maldivensis (Norman, 1939), having the following combination of characters: 46 lateral-line pores before anus; 149 total vertebrae, including 46 abdominal vertebrae; maximum body depth 27.2% of total length (TL); pectoral fin length 40.6% of head length; highest margin of head profile anterior to pectoralfin base; snout rounded, its tip anterior to tip of lower jaw; maxilla and mandibular teeth conical, uniserial; anterior nostril with short membranous tube, below snout margin; posterior nostril rounded, anterior to eye; posterior end of mouth posterior to vertical through middle of eye; cephalic sensory pores and lateral line developed; anus slightly anterior to middle of body; dorsal, anal, pectoral, and caudal fins present (dorsal-, anal-, and caudal-fin membranes fused); and dorsal fin origin slightly posterior to ventral through pectoral-fin base. A neighbor joining tree based on mtDNA cytochrome c oxidase subunit I (COI) gene sequences placed the specimen within a clade of C. maldivensis, based on previously published sequences, thereby supporting its conspecificity with C. maldivensis. The specimen was tentatively determined as a metamorphic larva, based on the following features: 153.7 mm TL, head length 12.7% of TL, and body opaque, with melanophores around the midline. An Indo-West Pacific species, C. maldivensis has previously been recorded from Tanzania to the Philippines, Wallis and Futuna Islands, and Australia, the present specimen therefore representing the first Japanese record and northernmost record of the species. The new standard Japanese name “Nan’you-okianago” is proposed for the species.

著者

出羽 優凪 伊東 正英 本村 浩之

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.22-008, (Released:2022-06-24)

参考文献数

22

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A single specimen [411.5 mm total length (TL)] of the Short-tail Brown Moray Gymnothorax pseudoprolatus Smith, Hibino and Ho, 2018 was collected at a depth of 27 m off Kasasa, Minami-satsuma, Kagoshima Prefecture, Japan. The specimen possessed the following characters: 75 pre-anal vertebrae; 175 total vertebrae; maxillary teeth biserial anteriorly and uniserial posteriorly; dentary teeth uniserial; 6 mandibular pores; head length (HL) 11.1% of TL; pre-dorsal length 8.6% of TL; body depth at gill opening 4.1% of TL; body uniformly brown; and lips whitish. Although G. pseudoprolatus is most similar to Gymnothorax prolatus Sasaki and Amaoka, 1991, it differs from the latter in having a longer pre-anal region (pre-anal length 50.0–53.6% of TL vs. 48–51% in G. prolatus), shorter snout (snout length 17.8–20.7% of HL vs. 20.0–23.8%), 6 mandibular pores (vs. 7), 75–78 pre-anal vertebrae (vs. 79–83), and 169–175 total vertebrae (vs. 182–187). In addition, analysis of the mitochondrial cytochrome oxidase I (COI) gene of both species showed them to be separated by 3.2–3.8% average sequence divergence. Gymnothorax pseudoprolatus has been previously known only from the holotype from Taiwan. Therefore the Kagoshima specimen represents the first record from Japanese waters and the northernmost record for the species. The new standard Japanese name “Chairo-utsubo” is proposed for the species.

著者

出羽 優凪 寺井 俊二 本村 浩之

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.21-020, (Released:2021-09-17)

参考文献数

15

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The triplefin genus Ceratobregma Holleman, 1987 includes two valid species, the Spotted Spiny-eye Triplefin C. acanthops (Whitley, 1964) and Helen’s Triplefin C. helenae Holleman, 1987. Both are characterized by the first dorsal fin having 3 spines, the anal fin 2 spines, and the pelvic fin with one spine and 2 rays, in addition to discontinuous lateral lines (upper series of tubular pored scales and lower series of notched scales), well developed lateral ethmoids, 3 or 4 spines on the anterior margin of the orbit in males, and a scaleless opercle and pectoral-fin base. Ceratobregma acanthops is known only from the Coral Sea, whereas C. helenae is widely distributed in the eastern Indian and western Pacific oceans. A single specimen (KAUM–I. 146836, 24.3 mm standard length) of C. helenae collected from Kume-jima Island, Okinawa Islands, Ryukyu Archipelago, Japan in October 2020 possessed the following characters: first spine of 1st dorsal-fin shorter than that of 2nd dorsal-fin; caudal peduncle narrow; sides of body with orange vertical bands; and 2nd dorsal fin with a basal series of orange spots. Previous records of the species from Japan include a single specimen (BPBM 8723, 29.6 mm standard length) collected from Taketomi-jima Island, Yaeyama Islands in 1968, and underwater photographs (as Ceratobregma sp.) taken at Irabu-jima and Miyako-jima Islands, Miyako Islands, in 2002 and 2004, respectively. The two Japanese specimens were examined, that from Kume-jima Island (described in detail) representing the northenmost record for the species. The new standard Japanese name “Mikan-hebigimpo” is proposed for C. helenae on the basis of the Kume-jima specimen, “Mikan-hebigimpo-zoku” serving for the genus Ceratobregma.

著者

永江 栞奈 高橋 弘明 遠藤 広光

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.21-007, (Released:2021-07-30)

参考文献数

23

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Mating behavior and early development of Cobitis sp. (BIWAE type D, TosaShima-dojo) were observed in the laboratory by inducing spawning of females with human chorionic gonadotropin (HCG). Subsequently, laboratory bred individuals were compared with spawned eggs and larvae obtained from the field. Mature adults, naturally spawned eggs, and larvae were collected from a river in eastern Kochi Prefecture, Shikoku Island, Japan, and a natural spawning ground adjacent to the river. Mating behavior was observed 15 times at night, and distinguished into four stages: phase 1, tracking; phase 2, approaching; phase 3, amplexus; and phase 4, spawning. Egg diameters after water absorption were 2.1–2.3 mm, the spherical, demersal eggs having a light-yellow yolk, no oil droplets, and slight viscosity. Newly hatched larvae [3.3–4.9 mm in total length (TL)] had 46 (32 + 14) myomeres, two pairs of outer gill filaments on the cheek, and melanophores on the head. Notochord flexion started at 6.0–7.2 mm TL (wild individuals at 6.0–6.3 mm TL) and was completed at 8.8 mm TL (6.6 mm TL). The formation of membranous fins and full fin-ray complements were attained in the fin order pectoral, caudal, dorsal, anal, and pelvic, and caudal, dorsal, anal, pectoral, and pelvic, respectively. Some individuals (7.0–8.0 mm TL at the flexion stage) had free neuromasts, each with a short cupula, laterally on the caudal region. In addition, following the postflexion stage, some morphological differences between artificially bred and wild individuals were observed but could not be quantified due to the small sample size.

著者

村﨑 謙太 甲斐 嘉晃 遠藤 広光 福井 篤

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.20-044, (Released:2021-05-10)

参考文献数

23

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Snailfishes (Cottoidei: Liparidae) are a large, morphologically diverse group of marine fishes, comprising about 32 genera with over 430 species worldwide. Among them, Osteodiscus Stein, 1978 is primarily distinguished from other genera in having a unique skeletal pelvic disk covered only by thin skin. Three species of the genus are currently known: Osteodiscus cascadiae Stein, 1978 from the eastern North Pacific; Osteodiscus andriashevi Pitruk and Fedorov, 1990 from southern Sea of Okhotsk; and Osteodiscus rhepostomias Stein, 2012 from southeast of New Zealand. During a taxonomic study of snailfishes, a single female specimen of Osteodiscus (150.3 mm in standard length) collected off Iwate in a depth of 1,997–2,108 m, was discovered in the fish collection of the National Museum of Nature and Science, Japan (NSMT). The specimen, characterized by 60 vertebrae (total), 54 dorsal- and 49 anal-fin rays, a horizontal mouth, simple blunt teeth on both jaws, some teeth with lateral cusps on the tip, an unnotched pectoral fin, and the presence of epipleural ribs and a reduced epural, was identified as O. andriashevi, previously known only from the holotype and three paratypes. The present specimen represents the first record of Osteodiscus from Japanese waters and the southernmost record of O. andriashevi. The new standard Japanese names “Hariban-kusauo-zoku” and “Choja-hariban-kusauo” are proposed for the genus and species, respectively. Based on the present specimen, the species diagnosis was partly revised.

著者

中野 寛 小針 統 山口 敦子 久米 元

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.20-030, (Released:2020-10-02)

参考文献数

28

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The diet of the critically endangered Ryukyu-ayu Plecoglossus altivelis ryukyuensis in the middle reaches of the Kawauchi, Sumiyo, and Yakugachi Rivers, Amami-oshima Island, southern Japan was examined by gut content analysis and inferred from stable isotope signatures. No clear differences in diet composition were apparent among the rivers. Microalgae, such as diatoms and cyanobacteria, generally considered as important food, were only rarely observed in gut contents, whereas detritus was almost exclusively found. However, stable isotope signatures indicated that detritus was not directly utilized as a nutritional source, indicating that food availability was an issue for P. a.ryukyuensis.

著者

川路 由人 瀬能 宏 武藤 望生 本村 浩之

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.66, no.2, pp.137-154, 2019

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<p>A comparison of 68 specimens of <i>Plectranthias</i> (Serranidae: Anthiadinae) from Japanese waters with 85 Indo-Pacific specimens, all characterized by the fourth dorsal-fin spine longest, no branched pectoral-fin rays, two antrorse spines on the lower preopercular margin, the lateral line incomplete with fewer than 22 pored scales, and scales absent from the maxilla, revealed the former to include <i>P. longimanus</i> (Weber, 1913) [23 specimens, 8.5–28.4 mm standard length (SL)], <i>P. nanus</i> Randall, 1980 (38, 10.6–32.3 mm SL), and <i>P. winniensis</i> (Tyler, 1966) (7, 24.1–38.6 mm SL). Among the Japanese specimens, <i>P. longimanus</i> was similar to <i>P. nanus</i> in overall body appearance, but differed from the latter in having modally 12 pectoral-fin rays [vs. 13 in <i>P. nanus</i>], 15 gill rakers (vs. 17), 14 pored lateral-line scales (vs. 18), 26 or 27 scale rows in the longitudinal series (vs. 28), 8 scale rows below the lateral line (vs. 9), 3 interopercular spines (vs. spines absent), and 2 or 3 subopercular spines (vs. spines absent), a maximum body depth 34.1% (mean) of SL (vs. 28.6%), and a vertical band absent near the base of the caudal fin (vs. band present in both fresh and preserved specimens). Japanese <i>P. winniensis</i> clearly differed from the other two species, having 16 or 17 soft rays in both the dorsal and pectoral fins (vs. fewer than 15 rays in the latter two species), modally 16 pored lateral-line scales (vs. 14 in <i>P. longimanus</i>, 18 in <i>P. nanus</i>), subopercular spine absent (vs. 1–4 present in <i>P. longimanus</i>), and a greenishred body without dark blotches or bands (vs. reddish-brown body, mottled with dark blotches and bands). In addition, analyses of 12S ribosomal RNA and cytochrome c oxidase subunit I gene sequences indicated that the three species were genetically distinct from each other. In Japanese waters, <i>P. longimanus</i> has been recorded from the Izu Peninsula and the Izu Islands to the Koshiki Islands, mainland Kagoshima, and the Ryukyu Islands, <i>P. winniensis</i> having a similar distribution pattern, i.e., from the Izu Islands south to the Ryukyu Islands. <i>Plectranthias nanus</i> has been recorded only from island groups, including the Ogasawara, Ryukyu, and Daito islands.</p>

著者

松沼 瑞樹 山川 武 星野 和夫

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.19-003, (Released:2019-07-24)

参考文献数

18

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Previous Japanese records of Chelidoperca margaritifera Weber, 1913 (Perciformes: Serranidae) were reviewed, and all available Japanese specimens previously reported as that species found to be either C. santosi Williams and Carpenter, 2015 or C. tosaensis Matsunuma, Yamakawa and Williams, 2017. No evidence was found of C. margaritifera occurring in Japanese waters, the species instead being known solely from the holotype, collected off New Guinea. Chelidoperca santosi is characterized by three scale rows between the lateral line and middle of the spinous dorsal-fin base; two pairs of dark spots on the snout; a pair of dark spots on the lower jaw tip; the interorbital scales just reaching or extending slightly beyond mid-orbit but not reaching level with the posterior nasal pores; scales on the mandibular ventral surface extending anteriorly onto the dentary; and enlarged canine-like teeth on both jaws, thereby being distinguished from all Japanese congeners [C. hirundinacea (Valenciennes in Cuvier and Valenciennes, 1831), C. pleurospilus (Günther, 1880) and C. tosaensis]. The standard Japanese name “Minamihimekodai” should be applied to C. santosi.

著者

藤岡 康弘

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.60, no.1, pp.57-63, 2013-04-25 (Released:2015-05-05)

参考文献数

46

被引用文献数

8

著者

木村 克也 津田 裕一 中山 直英

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.22-019, (Released:2022-11-14)

参考文献数

26

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The stomiid snaggletooth genus Astronesthes Richardson, 1845, including 49 valid species distributed in tropical to temperate waters of all oceans, is characterized by the following combination of characters: anal fin with 11–22 rays; maxillary teeth comblike, closely spaced, and slanting rearward; and photophores in the ventral series arranged in regular intervals. To date, 13 species of the genus have been reported from Japanese waters. A single specimen of Astronesthes (111.9 mm in standard length) was collected in December 2020, during a mid-water trawl survey conducted by R/V Shunyo-Maru in the vicinity of the Ogasawara Islands, Japan. Subsequently identified as Astronesthes gemmifer Goode and Bean, 1896, the specimen clearly differed from all congeners in having the following combination of characters: four premaxillary fangs in the main row (vs. 5–6); the posteroventral part of the terminal bulb of the chin barbel black (vs. usually not black or terminal bulb absent); and the last six VAV (photophores from the inner-pelvic space to the end of the row posterior to the anal-fin origin) located above the anal fin (vs. 1–4). Although A. gemmifer has been often recorded from the North Atlantic, records from the South Atlantic, Indian, and Pacific oceans are sparse. In the Pacific Ocean, the species has been recorded in Hawaiian waters from O‘ahu to the Hancock Seamounts, but not previously reported from Japanese waters, the present specimen representing the first Japanese record of A. gemmifer. The new standard Japanese name “Sumitsuki-tokagehadaka” is proposed for the species.

著者

内藤 大河 山川 武 遠藤 広光

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.64, no.2, pp.139-143, 2017-11-25 (Released:2018-06-19)

参考文献数

12

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A single specimen [226 mm in standard length (SL)] of a haemulid fish collected from Iriomote-jima Island, Okinawa Prefecture, Japan, in 2012, was identified as Diagramma melanacrum Johnson and Randall, 2001, characterized by the following combination of characters: third dorsal-fin spine longest; first dorsal-fin spine length 45 % of second dorsal-fin spine length; pelvic-fin length 23.9 % SL; 57 lateral-line scales; and dorsal 3/4 of caudal fin yellow with many dark spots, and pelvic, anal and remainder of caudal fin black when fresh. The species has been recorded previously from the Philippines, Malaysia, Indonesia (Kalimantan and Bali to West Papua), the Timor Sea and Japan (Miyako-jima and Ishigaki-jima Islands, Okinawa). However, because both Japanese records were based on photographs, the Iriomote-jima Island specimen represents the first reliable, specimen-based record of D. melanacrum from Japan, an extension of its known northernmost range. The new standard Japanese name “Hireguro-korodai” is proposed for the species.

著者

佐藤 真央 長嶋 祐成 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.21-039, (Released:2022-04-28)

参考文献数

30

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A specimen (39.1 mm standard length) of the genus Ostorhinchus Lacepède, 1802, collected from Ishigaki-jima Island, the Ryukyu Archipelago, southern Japan, was identified as Ostorhinchus hartzfeldii (Bleeker, 1852). The specimen showed characteristic coloration of the species, including the following features: four slightly wavy longitudinal silver lines on the head and body, the dorsalmost running along the dorsal body margin to the caudal fin base, and the others terminating on the trunk or caudal peduncle; the entire body base color brown; all fins slightly reddish, transparent; a dark spot on the caudal fin base, of similar size to the pupil. Ostorhinchus hartzfeldii is similar to Ostorhinchus cookii (Macleay, 1881), Ostorhinchus nigrofasciatus (Lachner, 1953), and Ostorhinchus taeniophorus (Regan, 1908), but differs from them by having only the dorsalmost longitudinal silver line reaching the caudal fin base (vs. three or four lines reaching the fin base in the other three species) and absence of a longitudinal silver line on the ventrolateral aspect of the trunk (vs. present). Ostorhinchus hartzfeldii is distributed in the western Pacific, from the South China Sea to Australia, but had not previously been recorded from Japanese waters. A photographic record of the species from Ishigaki-jima Island is also included. The new standard Japanese name “Sazanami-ishimochi” is proposed, a reference to the slightly wavy silver lines that disappear with growth, based on the specimen collected from Ishigaki-jima Island.

著者

荒山 和則 松崎 慎一郎 増子 勝男 萩原 富司 諸澤 崇裕 加納 光樹 渡辺 勝敏

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.59, no.2, pp.141-146, 2012-11-05 (Released:2014-12-02)

参考文献数

29

被引用文献数

2

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Eight specimens (28.2–170.2 mm SL) of the non-indigenous bagrid catfish Pseudobagrus fulvidraco were collected from the Lake Kasumigaura system, Ibaraki Prefecture, central Japan, during December 2008 and November 2011. Three juvenile specimens of this invasive species indicated successful reproductive activity in the lake system. The species is known to have similar morphological and food habits to channel catfish Ictalurus punctatus, which has also invaded Lake Kasumiguara, causing damage to the ecosystem and problems for local fisheries. The establishment and future habitat expansion of P. fulvidraco would also cause serious ecological and economic problems.

著者

森 誠一 小北 智之 松田 征也

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.63, no.2, pp.148-152, 2016-11-05 (Released:2018-06-01)

参考文献数

17

著者

長谷川 稜太 山田 寛之 石原 千晶 和田 哲

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.19-021, (Released:2020-02-28)

参考文献数

56

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Animal personality, defined as consistent individual differences in behavior across time and/or context, has been associated with individual dispersal tendencies in some species. White-spotted char (Salvelinus leucomaenis) populations, often found in above-dam watersheds in Japanese mountain streams, the dams preventing continuous distribution with lower stream reaches, were subject of a behavioral study comparing above-dam and open-stream behavior of fry. Fries were collected from an above-dam area and two open-stream areas within the Kame River system (southern Hokkaido), and personality quantified by measuring a suite of behaviors, such being repeated two-month later. Above-dam fry showed a shorter swimming duration against a novel object and mirror than open-stream fry. The latency time to catch food in above-dam fry tended to be longer than that of the latter. Swimming duration against a novel object and mirror were significantly correlated when data for both groups combined, but not so when data for each group were analyzed independently. These results suggest that personality traits in whitespotted char fry would be shaped by natural selection acting on each habitat, resulting in differing adaptive personality traits.

著者

矢頭 卓児 中山 直英 遠藤 広光

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.19-040, (Released:2020-03-24)

参考文献数

14

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The original description of Pterygotrigla cajorarori Richards and Yato, 2012, based on eight specimens from the western Pacific Ocean, including one Japanese specimen, indicated hyperostosis in the rostral projection, head bones (infraorbital, frontal, and parietal), post temporal spine, humeral spine, and the 2nd–4th first dorsal-fin spines, although variations in these characters were poorly documented. Thirteen specimens (including two paratypes) of P. cajorarori collected from southern Japan, the South China Sea, and Indonesia were found to vary individually in the degree of hyperostosis in the rostral projection, mesethmoid, lateral ethmoid, frontal, sphenotic, pterotic, and infraorbital bones, whereas the condition was not prominent in the parietal and posttemporal bones, or the humeral spines. However, hyperostosis was newly found in the 5th and 6th dorsal-fin spines and pelvic-fin spine. A detailed description of fresh coloration (previously unknown) in P. cajorarori is also given.

著者

平田 智法 小栗 聡介 平田 しおり 深見 裕伸 中村 洋平 山岡 耕作

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.58, no.1, pp.49-64, 2011 (Released:2014-03-07)

参考文献数

24

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A monthly underwater visual census was conducted in the coral-dominated habitat of Yokonami, Tosa Bay, Japan, from June 2006 to January 2009. A total of 12,586 individuals belonging to 168 species in 43 families were recorded during the study period. The number of species and individuals increased from June-August (summer), the highest numbers occurring in September-December (autumn), thereafter decreasing from January (winter) to the lowest point in May (spring). Labridae was the most dominant family in terms of species numbers (28 species), followed by Chaetodontidae (21 species) and Pomacentridae (18 species). In terms of individual numbers, Chaetodontidae was the most abundant (56.3% of total individual numbers), followed by Labridae (15%) and Pomacentridae (12.5%). The most dominant species were Chaetodon speculum (33.4%), Pomacentrus coelestis (11.1%), and C. lunulatus (8.2%). The fish assemblage was divided into 4 groups: (1) temperate fishes (1877 individuals in 26 species), (2) (sub-)tropical fishes (10,648 individuals in 136 species), (3) temperate-tropical fishes (28 individuals in 2 species), (4) unknown fishes (33 individuals in 4 species). Species and individual numbers of temperate fishes were high in summer and low in winter, whereas those of tropical fishes were high in summer and autumn and low in spring, suggesting that typhoons in summer and autumn, and low water temperatures in winter might affect fish recruitment and community density. Moreover, at least 44 tropical species were observed throughout the year during the study period.

著者

藤本 泰文 福田 亘佑

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.70, no.1, pp.111-118, 2023-04-25 (Released:2023-04-30)

参考文献数

38

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Although overfishing has been recognized as a major factor threatening the existence of rare freshwater fishes, no case studies exist on the impact of collection pressure by fish enthusiasts and traders. In 2021, a habitat of reintroduced Acheilognathus typus, a species rarely seen the previous year, was visited every day by such enthusiasts. A monitoring survey indicated subsequently that the mean number of captured A. typus had decreased from 25.0 individuals/day in July 2021 to 1.6 individuals/day in October, the October 2021 figure being about one-tenth of that for September-October 2020. In addition, the standard length of A. typus in 2021 (56.8–59.5 mm) was greater than in 2020 (47.2 mm), possibly due to a thinning effect caused by the reduced fish numbers. During the period surveyed, some 50 to 100 fish enthusiasts and traders visited the habitat, apparently collecting thousands of A. typus by fishing or in bait traps. Such collecting pressure has clearly driven the reintroduced population of these rare fish to significantly low levels within a short period.