Sebastes schlegeli Hilgendorf is a viviparous scorpaenid fish distributed around Japan.The larvae and juveniles of this fish were reared for 80 days to clarify their development, relative growth, and mouth size in relation to feeding capability and changes in behavior. The development of this fish can be devided into eight stages as shown in Fig.2.The just spawned larvae were 6.89 mm on average in total length.Individuals of 9.5 11.7 mm are regarded to have attained to the juvenile stage, when all the fin rays were brought to completion.The fish reached 30 mm in total length in about 50 70 days. The growth of seven body parts (post-anal length, ante-anal length, head length, trunk length, eye diameter, auditory vesicle diameter, and mouth size) was examined against changes of total length.The growth inflection of each body part occurred at the size of 9.1-12.9 mm in total length, and coincides with the shift period from the larva to juvenile stage or just after this period (Figs.4 and 5).The mouth size and trunk length demonstrated common change showing tachyauxesis before growth inflection and isauxesis after it. The size of food taken is determined by the mouth size.As the results, it is esti-mated that the mouth size of newborn larvae is 836 μ, and the food less than 423-629 μ can be taken easily by these larvae.The mouth size can be roughly estimated by the measurement of the trunk length.
The marine gobiid fish, Luciogobius platycephalus Shiogaki and Dotsu (1976) is ananguilliform in shape and grows to 80 mm in total length.Over three hundred and fifty specimens of the goby were collected from Kawahara and Nomo, both near Nagasaki City on the western coast of Kyushu (Fig.1).The habitats of the goby are restricted to the upper intertidal zone where pebbles and stones are sedimented over the hollows of the rocky bottom and the bottom is exposed to the air for several hours during the ebb tide (Fig.2, A).During the ebb tide the goby was found concealing itself among pebbles and stones.The goby fed on small crustaceans.From the examinations of the specimens collected through all seasons, it seems that the goby grows to about 50 mm long in a year and to about 70 mm in two years (Fig.3). The spawning season at Kawahara seemed to extend from the beginning of October to the end of December.Seven egg masses were collected from the habitat on the coast of Kawahara on October 23, 1972.The eggs were attached in a dense one-layer mass on the underside of a stone lying among pebbles and guarded by a male parent.Number of the eggs in each egg mass ranged from 66 to 528.The eggs are club-shaped, from 2.05 to 2.28 mm in long axis and 0.68 to 0.75 mm in short axis, and provided with a bundle of adhesive filaments at the basal end (Fig.2, B, C).Hatching of the eggs, which were collected at 24 myomere stage, took place 129 hours after collection in an incubator with the temperature varing between 18.7 and 20.5°C (Fig.4).About four hundred hatched larvae, from 3.5 to 3.8 mm in total length, were kept in a 30-liter plastic vessel and fed on the rotifers, Brachionus plicatilis and nauplii of brine shrimp, Artemia sp.They were reared for 42 days after hatching and the biggest one grew to 16.2 mm long in the last planktonic life 35 days after hatching (Fig.5, A-G).A 22.2 mm long young was collected from the habitat on the coast of Kawahara to prove that the fish of this size already performs a benthonic life among pebbles as the adult fish does (Fig.5, H).
Geographical variations of some meristic characters of the Dolly Varden, Salvelinus malma, which were collected in some districts (Nome, Anchorage, Juneau and Seattle) of North America, Bering Sea, Okhotsk Sea and in some rivers of Hokkaido, were investigated with special reference to the systematics of the Miyabe char, S.malma miyabei, in Lake Shikaribetsu in Hokkaido.An obvious “geocline” associated with an increase in the number of vertebrae, gill-rakers, dorsal rays and pored scales of the north American populations was found.Toward the east and toward the uplands, slight increases in the number of vertebrae and pored scale were observed in the land-locked populations of Hokkaido. No significant differences were recognized in the number of anal rays among populations of the Dolly Varden, however, pyloric caeca were slightly fewer in Hokkaido populations than in the others.Meristic characters of the Miyabe char, excepting gill-rakers, were similar to those of Dolly Varden living in Hokkaido.A striking characteristic of the Miyabe char was found in the number of gill-rakers, as well as accessory gill-rakers in the medial surface of the gill arch.Gill-rakers of the Miyabe char were the most numerous among all Dolly Varden investigated.It was discussed that, in relationship to food habitats of the anadromous Dolly Varden, the changes in morphology might be an adaptation to plankton feeding.