Oxynotus japonicus sp.nov. is described on the basis of a specimen collected by a bottom trawl at depths between 225 m and 270 m in Suruga Bay, Japan. It differs from other species of the genus in having the following combination of characters: spines of 1st and 2nd dorsal fins sloping slightly backward; length from tip of 1st dorsal spine to apex of 1st dorsal fin 2 .6 times vertical height from tip of spine to fin base; length from tip of 2nd dorsal spine to apex of 2nd dorsal fin 1.9 times vertical height from tip of spine to fin base; and 2nd dorsal base 1.3 in interspace between 1st and 2nd dorsal fins.

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Specimens of a new genus and species of the stichaeid fish, Leptostichaeus pumilus, were collected from the Okhotsk Sea off Hokkaido in Japan.The present new genus and species clearly differs from all the other genera and species of the stichaeid fishes in the following characters: 3 or 4 pectoral fin rays;10 or fewer caudal principal rays;79-82 dorsal spines;no pelvic fin; last interneural spine supporting a single dorsal spine;infraorbital, occipital and lateral line canals absent;moderate size of dorsal spine shorter than eye diameter;membranes of dorsal and anal fins widely connected with caudal fin;a large black spot divided by a yellow band present just above gill cover.

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Two new species of the skates, Bathyraja hubbsi and B.pseudoisotrachys are described from the North Pacific.Among the North Pacific Bathyraja, B.hubbsi most closely resembles B.violacea Suvorov in possessing a disc without thorns, a median tail thorns irregularly spaced, and minute fine prickles covering the entire dorsal surface.The two species are distinguished from each other by their dorsal color pattern, proportional measurement of tail in relation to total length, clasper components, and number of precaudal vertebrae.Bathyraja pseudoisotrachys has long been confused with B.isotrachys (Günther) by many Japanese authors, but is distinguished from other North Pacific Bathyraja by dorsal squamation and unique clasper components such as two clefts, terminal bridge and ridge.Bathyraja kincaidii Garman is synonymized with the validspecies B.interrupta Gill et Townsend.Bathyraja abyssicola Gilbert and B.trachura Gilbert are redescribed in detail.Provisionally, 21 species of the genus Bathyraja are recognized in the present study from this region, and a revised key is given to the North Pacific species of the genus .

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The pharyngeal teeth and the masticatory process of the basioccipital bone were compared in fifteen species and subspecies of Japanese bitterlings.Acheilognathus lanceolata, A. limbata and two subspecies of Rhodeus ocellatus, which are characterized by the absence of serrations on the side of the pharyngeal teeth, have reduced occlusal grooves on the pharyngeal teeth. In the larvae of these species, the occlusal grooves are fairly developed.The occlusal grooves of the adult pharyngeal teeth in herbivorous species are more developed than those in omnivorous species.The occlusal grooves seem to have developed in relation to the feeding habits.
On the basis of the combination of developmental degrees of the anterior part of the masticatory process, the occlusal grooves and the chewing area on the pharyngeal first tooth, Japanese bitterlings were classified into two groups and two types and/or five subtypes, suggesting phylogenetic relationships among them.

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The eggs, larvae and pelagic juveniles of Ostracion meleagris, Lactoria fornasini and Lactoria diaphana were identified from reared and field collected specimens from Hawaii, Japan, Australia and the eastern Pacific.Eggs are large and pelagic with limited chorion ornamentation and a cluster of oil droplets.At hatching, larvae are well developed, rotund, and enclosed in a dermal sac.The sac disappears and dermal plates form prior to notochord flexion.Larvae of the three species can be distinguished by their pigment patterns and development of the carapace of ossified dermal plates.Eggs of the three species could not be distinguished.The larval stage ends at a small size (<6mm) but the juveniles may grow to a substantial size while remaining pelagic.L.diaphana matures and spawns while pelagic in the eastern Pacific.

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Seasonal distribution and migration patterns of the steelhead trout and the Kamchatkan trout in the North Pacific were examined based on allelic variations of enzymes from specimens which were collected by Japanese research operations from 1976 through 1983.The western segment of the population mainly consisted of the Kamchatkan trout originating in the Kamchatka Peninsula in all months.As the fish extended to the west from spring through summer, the distribution of the steelhead trout extended to the western North Pacific.The westward extension of the steelhead was more evident in the immature population than in adults.As two major geographic units divided at the crest of Cascade Mountains, namely coastal and inland populations of the steelhead are defined in North America based on the differences of allelic frequencies, the immatures of the inland population exhibited a remarkable westward extension which reaches as far as 160°E longitude in summer.The distribution of the steelhead is distinguished by its extreme westward extension compared to the general distribution of Pacific salmon originating in North America.

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Electrophoretic discrimination was carried out on three species of the genus Tribolodon (Cyprinidae), T.hakonensis, T.brandti and T.ezoe, by examining five loci controlling lactate dehydrogenase (LDH), phosphoglucomutase (PGM), phosphoglucose isomerase (PGI), and muscle protein (MP).Consequently, a clear-cut identification of the three species was possible even in 0⁺young which were difficult to distinguish morphologically.Moreover, 1.0-19.9%of fish examined were detected electrophoreticaly as hybrids which had been previously undetected.The existence of such spontaneous hybrids has further complicated the classification of the genus Tribolodon.In spite of imperfect reproductive isolation, the electrophoretic data supports the independent nature of the three species of the genus Tribolodon.

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Aggressive behaviour and dominance relationships of Zacco temmincki were observed by introducing fish into an enclosed pond.Chase (-flee), lateral display, parallel swim and butt were the principal behavioural patterns in aggressive encounters between fish, while chase, resulting in lateral display by the chased fish was the most common behavioural sequence.Initially, mutual behavioural patterns such as parallel swim and mutual lateral display were most evident among the total aggressive acts although chase became dominant three days after introduction into the pond.The dominance matrix constructed from chase-flee interactions during all observation periods contained many reverse attacks (336 out of 2, 740 chases).These reverse attacks did not concentrate upon a specific period and were not site-dependent.Examination of chase-flee interactions and the subsequent behavioural pattern revealed that a chased fish reacted to the chaser either by attacking in turn, or performing lateral display etc.roughly in relation to the dominance rank of the chaser.This result implies that fish recognized each other to a great extent during aggressive encounters.It seems likely that such individual recognition was initiated during the early period when mutual behaviour was most frequent, and that some attacks against the dominance order were caused as a result of revolts rather than mistakes.

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Habitats including depth, diurnal activity patterns, and diets of the two cheilodactylid fishes Cheilodactylus zonatus and C.zebra were studied at Igaya Bay, Miyake-jima, Japan.Both species occurred at nearly equal densities in identical habitats and depths.They preyed on benthonic organisms from early morning to shortly before sunset, when feeding activities decreased remarkably and intraspecific social behavior greatly increased.Gut analyses showed a high degree of dietary overlap, but proportions of food items in their diets differed slightly.C.zonatus was more of a food generalist than C.zebra, showing a higher niche breadth value.C.zebra tends to feed on epifauna, especially gammaridean amphipods and decapods, while C.zonatus takes both epifauna and infauna including polychaetes.

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The breeding of the anemonefish, Amphiprion clarkii, and the settlement of larvae were observed in temperate Japan.Spawning had two peaks near the first and the third quarter of the moon in 1983, but did not in 1984.The clutch size varied greatly during the breeding season, with a peak from the second half of June to the second half of July.Adult fishes inhibited larval settlement. The proportion of disappeared 0-year olds to the total was higher in 1984 than in 1983.This differencemight bemainly due to the difference in the degree of crowding in each sea anemone. The period of larval settlement closely paralleled the breeding season.The larvae settled abundantly around the first quarter and the third quarter of themoon in 1983, and did from the third quarter to the first quarter in 1984.In both years, the number of settled larvae wasmore from the fullmoon to the newmoon than the newmoon to the fullmoon.The daily pattern of larval settlement did not reflect that of breeding.

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Seasonal variations in the concentrations of protein, RNA and DNA, and the RNA/ DNA ratio were studied in the liver of major carps, Catla catla, Labeo rohita and Cirrhina mrigala during their prematurity phase.These biochemical parameters maintained strikingly similar patterns of change in the three species.Alterations in nucleic acids were reciprocal to that of protein.Magnitude of such interrelation, however, varied with the season.Protein level was generally low during winter and high in the summer months, attaining peak value in March and June.Higher concentrations of RNA and DNA were registered in December and June and a sharp decline was evident in January as well as July.During the remaining months, protein, RNA and DNA varied intermittently, but not profoundly.

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[in Japanese]

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[in Japanese]

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