Papers Published in Japanese Journal of Ichthyology
Vol. 65, No. 2, November 5, 2018
CONTENTS
Original Papers
A record of Tylerius spinosissimus (Tetraodontidae) from Okinawa-jima Island, Japan
Keiichi Matsuura, Eri Katayama and Tetsuo Yoshino
Migration history of masu salmon Oncorhynchus masou in the Naka River, Tochigi,
Japan, estimated from otolith Sr:Ca ratio analysis
Takatoshi Tsunagawa and Kotaro Shirai
Ichthyofaunal changes in Lake Kitaura, eastern Japan, over the past 50 years
Kensaku Omori, Kouki Kanou, Seiji Usui, Katsuo Mashiko, Gento Shinohara, Takayoshi
Tsuzuki and Ken-ichi Yokoi
First Japanese records of the Redtail Scad Decapterus kurroides (Carangiformes:
Carangidae), from Kumano-nada (Pacific coast of Mie Prefecture) and the East
China Sea
Yumeka Takahashi, Makoto Okada, Daichi Sasaki, Hiroyuki Motomura and Seishi Kimura

Notes
Geographical variation in vertebral numbers of white-sppotted charr on Hokkaido
Island, Japan
Masanori Oda
Spawning nests of six goby species in a newly-established fish-way on the Onga Riverestuary barrage
Akihiko Koyama, Seiya Matsunaga, Tomonori Kawamoto, Kazuki Kanno, Kaito Sawa andNorio OnikuraFirst record of Gymnogobius macrognathos on Akkeshi mud flat, Hokkaido, Japan andutilization of Upogebia major burrows
Yumi Henmi, Ryutei Inui, Ryutaro Goto and Gyo Itani
Height and horizontal distance of territorial attacks by ayu (Plecoglossus altivelis

altivelis) were observed in aquaria
Haruo Honda and Ryosuke Yamamoto
Increasing gill raker numbers in juvenile and young skipjack tuna (Katsuwonus pelamis)
Shinpei Ohashi, Satoru N. Chiba and Hidetada KiyofujiOriginal Papers
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 145–150

A record of Tylerius spinosissimus (Tetraodontidae) from Okinawa-jima Island, Japan
Keiichi Matsuura*, Eri Katayama and Tetsuo Yoshino
Abstract Seven specimens of Tylerius spinosissimus (Regan, 1908) were washed up by atyphoon onto a beach at Nakagusuku in Okinawa-jima Island on 17 August 1997. This
species has been rarely collected, being known from only a few localities in the tropicalIndo-West Pacific. In addition to the seven specimens from Okinawa-jima Island, eightspecimens collected off northwestern Borneo in the South China Sea by TV Oshoro-maru in
November 1973 were found in the fish collection of the Hokkaido University Museum,
Hakodate. Examination of the 15 specimens have revealed that the species is distinguishedfrom other pufferfishes by the following characters: dorsal-fin rays 9–11, anal-fin rays 6–7,
pectoral-fin rays 15–17, body somewhat squarish in cross-section, snout short with dorsal
surface dropping abruptly anterior to eye, nasal organ a short papilla with two nostrils, eyedorsally adnate only, ventrolateral skin fold absent, body anterior to anal-fin base densely
covered by small spinules, dorsal and ventral lateral lines running on lateral surface of body;
frontals broad across interorbit, almost completely covering dorsal surface of ethmoid;
prefrontal strongly down-curved. A juvenile of Tylerius spinosissimus ca. 10 mm in total
length was photographed at 1 m depth in Suruga Bay, on the west coast of the Izu Peninsula,
Honshu, Japan, in November 2008. This small specimen was similar in color to adults of T.
spinosissimus: the dorsal half of the body being brown with a dark brown blotch just behindthe dorsal corner of the eye, the ventral half of body white, and all fins pale.
(*Corresponding author: National Museum of Nature and Science, 4–1–1 Amakubo,
Tsukuba, Ibaraki 305–0005, Japan; e-mail: matsuura@kahaku.go.jp)
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 151–163

Migration history of masu salmon Oncorhynchus masou in the Naka River, Tochigi,
Japan, estimated from otolith Sr:Ca ratio analysis
Takatoshi Tsunagawa* and Kotaro Shirai
Abstract
The migratory histories of individual masu salmon Oncorhynchus
masou collected from the Naka River, Tochigi, Japan were clarified from otolith strontium(Sr) and calcium (Ca) concentrations using X-ray electron microprobe analysis. Mapping andline analysis indicated three migratory types of the species. In addition to the conventional
types, such as freshwater resident and typical anadromous (spending one year in marine
waters), a new migratory pattern of short marine term anadromous (remaining in marine
waters for several months) was apparent. Detailed life histories of short marine term
anadromous individuals were estimated from otolith Sr fluctuations and ageing, from bothscale and otolith daily increments. Consequently, more than half of the Naka River populationwas estimated to migrate to a marine environment upon reaching a total length of 178–252
mm (one year old) in December–January, thereafter staying in marine waters forapproximately five months, before returning to the river in May–July at 345–463 mm total
length. These findings may help establish an enhancement method for this species as arecreational fishery stock. Future investigations, including tagging, verification of age
evaluation methods, and gene analysis are necessary to confirm the existence of the shortmarine term anadromous form.
(*Corresponding author: Tochigi Prefectural Fisheries Experimental Station, 2599 Sarado,
Ootawara, Tochigi, 324–0404, Japan; e-mail: tsunagawat01@pref.tochigi.lg.jp)
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 165–179

Ichthyofaunal changes in Lake Kitaura, eastern Japan, over the past 50 years
Kensaku Omori*, Kouki Kanou, Seiji Usui, Katsuo Mashiko, Gento Shinohara, Takayoshi
Tsuzuki and Ken-ichi Yokoi
Abstract Large-scale Japanese lakes support many fish species and abundant fisheries
resources. However, long-term changes in the fish fauna of such lakes have not been fully
investigated, despite recent significant anthropogenic impacts on associated ecosystems.
Accordingly, the extensive native and non-native fish fauna of Lake Kitaura, a typical large
inland-sea lake (36 km2) in eastern Japan, was investigated based on specimens collected by
the staff of Itako Hydrobiological Station, Ibaraki University from 1977 to 1997, plus datafrom previous studies conducted since the 1950s. In total, 83 species in 35 families have beenrecorded from the lake from the 1950s to the present decade. The analyses of long-termchanges in fish species data since the 1960s demonstrated a sharp decrease in marine,
estuarine and diadromous species due to an estuarine barrage (Hitachi River floodgate)
established in 1973, the disappearance of nine red-list species (e.g., threatened and nearthreatened species) following various artificial environmental changes from the 1960s to
1980s, and an increase in introduced exotic and Japanese species after the 1980s.
(*Center for Water Environment Studies, Ibaraki University, 1375 Ohu, Itako, Ibaraki 311–
2402, Japan; e-mail: kensaku.oomori.0903@gmail.com)
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 181–185

First Japanese records of the Redtail Scad Decapterus kurroides (Carangiformes:
Carangidae), from Kumano-nada (Pacific coast of Mie Prefecture) and the East China
Sea
Yumeka Takahashi, Makoto Okada, Daichi Sasaki, Hiroyuki Motomura and Seishi Kimura*
Abstract The carangid genus Decapterus Bleeker, 1851 is characterized by single finlets
behind both the second dorsal and anal fins, no scutes along the anterior curved part of thelateral line, two low papillae on the shoulder girdle, and a well-developed adipose eyelid.
Members of the genus are distributed in tropical to temperate areas of the Pacific, Indian andAtlantic oceans, and are commercially important food fishes. Four species (D. akaadsi Abe,
1958, D. kurroides Bleeker, 1855, D. smithvanizi Kimura, Katahira and Kuriiwa, 2013 and D.
tabl Berry, 1968), characterized by a red caudal fin, are included in the
red-fin Decapterus group. In 2016 and 2018, three specimens [216–304 mm in standard
length (SL)] of D. kurroides, previously recorded from the Red Sea and east coast of Africa tothe east coast of Australia and the Philippines, were collected from Kumano-nada, Pacificcoast of Mie Prefecture, Japan. Additionally, a single specimen (191 mm SL) collected fromJapanese waters in the East China Sea (west of Kyushu) in 2006 was also identified as D.
kurroides. The specimens represent the first records of the species from Japanese waters, theKumano-nada specimens being the northernmost record for the species. Decapterus
kurroides is the most similar to D. akaadsi, but differs from the latter in the following
characters: scutes more numerous on the straight part of the lateral line (30–32 vs. 26–29 in D.
akaadsi), longer head (head length 29.9–33.0% SL vs. 26.7–30.1%) and longer snout-anus
distance (55.8–60.4% SL vs. 51.2–54.6%) [measurements for both species modified from
Kimura et al., (2013)]. Decapterus kurroides is also distinguishable from D.
smithvanizi and D. tabl by having fewer cycloid scales on the curved part of the lateral line
(45–52 vs. 54–62 in D. smithvanizi, 61–72 in D. tabl) and a deeper body (body depth 23.4–
27.2% SL vs. 19.4–22.5%, 16.6–23.0%). A new standard Japanese name “Kitsune-akaaji” isproposed for D. kurroides.
(*Corresponding author: Fisheries Research Laboratory, Mie University, 4190–172 Wagu,
Shima-cho, Shima, Mie 517–0703, Japan; e-mail: kimura-s@bio.mie-u.ac.jp)

Notes
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 187–190

Geographical variation in vertebral numbers of white-sppotted charr on Hokkaido
Island, Japan
Masanori Oda*
Abstract Vertebral numbers in white-spotted charr (Salvelinus leucomaenis), collectedfrom four streams and two lakes on Hokkaido Island, Japan, were significantly higher in fishfrom streams flowing into the Sea of Japan compared with those flowing into the Pacific
Ocean, a result compatible with previous allozyme studies. White-spotted charr in Lake
Shikotsu had the lowest number of vertebrae, possibly resulting from long-term isolation. The
maximum difference in mean vertebral numbers among charr populations was 1.6, twice thatobserved in chum salmon Onchorhynchus keta and a possible reflection of the absence ofhatchery programs that can lead to population mixing. It is likely, therefore, that regional
genetic structures have been maintained in Hokkaido Island whitespotted charr.
(*Tottori Prefectural Fishery Office, 9–20 Showamachi, Sakaiminato, Tottori 684–0034,
Japan; e-mail: malma@sj8.so- net.ne.jp)

Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 191–197

Spawning nests of six goby species in a newly-established fish-way on the Onga Riverestuary barrage
Akihiko Koyama, Seiya Matsunaga, Tomonori Kawamoto, Kazuki Kanno, Kaito Sawa andNorio Onikura*
Abstract A new fish-way, comprising variously-sized bed materials on a gentle slope,established on the Onga River estuary barrage was found to have 69 cobbles and boulders
used as spawning nests of six goby species, including a threatened species, during the period
from June 2013 to May 2014. Male body sizes were positively correlated with spawning
substrate. In addition, wide salinity variations recorded over the fish-way during high tides oneither side of spring tide were also implicated in goby spawning site selection.
(*Corresponding author: Fishery Research Laboratory, Kyushu University, 4–46–24
Tsuyazaki, Fukutsu, Fukuoka 811–3304, Japan; e-mail: onikura@agr.kyushu-u.ac.jp)
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 199–203

First record of Gymnogobius macrognathos on Akkeshi mud flat, Hokkaido, Japan andutilization of Upogebia major burrows
Yumi Henmi*, Ryutei Inui, Ryutaro Goto and Gyo Itani
Abstract Eight specimens of a threatened goby, Gymnogobius macrognathos (30.04–38.87
mm in standard length), were collected on a mudflat characterized by abundant burrowsof Upogebia major, at Akkeshi, Hokkaido, northern Japan in August 2017. Because G.
macrognathos specimens were collected directly from U. majorburrows by suction pump, andwere also collected with U. major by digging sediment exposed at low tide, it was concluded
that G. macrognathos utilized U. major burrows on the tidal flat. Gymnogobius
mororanus and an unidentified species of Gymnogobius also utilized U. major burrows. The
presence of G. macrognathos at Akkeshi represents the northernmost record of the species inJapanese waters, the isolated population being ca. 500 km north of the main distributional
range of the species along the Pacific coast of Japan.
(*Corresponding author: Maizuru Fisheries Research Station, Kyoto University, Nagahama,
Maizuru, Kyoto, 625–0086 Japan; e-mail:henmi.yumi.7c@kyoto-u.ac.jp)
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 205–209

Height and horizontal distance of territorial attacks by ayu (Plecoglossus altivelis
altivelis) were observed in aquaria
Haruo Honda* and Ryosuke Yamamoto
Abstract The height and horizontal distance of territorial attacks by ayu (Plecoglossus
altivelis altivelis) were observed in aquaria. Territory holders responded towards intruders
when approached to within 30–40 cm, chasing them for 40–100 cm. Such chases ceased ca.

30–40 cm from the bottom (in 50–100 cm water depth), indicating that territorial defense
limits in water depths greater than 50 cm were about 30–40 cm (vertical distance) and 40–100
cm (horizontal distance).
(*Corresponding author: Environmental Science Research Laboratory, Central ResearchInstitute of Electric Power Industry, 4–1 Onogawa, Tsukuba, Ibaraki, Japan; e-mail:hnd4864@star.ocn.ne.jp)
Japanese Journal of Ichthyology
Vol. 65, No. 2, pp. 211–216

Increasing gill raker numbers in juvenile and young skipjack tuna (Katsuwonus pelamis)
Shinpei Ohashi*, Satoru N. Chiba and Hidetada Kiyofuji
Abstract An increase in gill raker numbers in skipjack tuna (Katsuwonus pelamis) was
observed during the development of juvenile and young stages (26–187 mm in standard
length (SL)). Examination of 104 individuals showed obvious increments in number withgrowth, until 80–100 mm SL. Subsequently, numbers increased slowly (to 59 in the largest
specimen), indicating that gill raker development in skipjack tuna is slower than in otherscombrid fishes, such as Thunnus. However, gill raker numbers in juvenile and young
skipjack tuna stages remain a useful taxonomic character.
(*Corresponding author: National Research Institute of Far Seas Fisheries, Japan Fisheries
Research and Education Agency, 5–7–1 Orido, Shimizu, Shizuoka 424–8633, Japan; e-mail:shinohashi@affrc.go.jp)