Abstract
The pelagic fish larvae and juveniles were collected in the East China Sea and its adjacent regions from May 16 to June 2, 1968 (R/V Hakuh-maru Cruise KH-68-2, East China Sea and its adjacents) This report deals with the areal characteristics in the species composition of the samples and the similarity of composition between them.
Juveniles and larvae were collected mainly at night by surface towing, the former was taken with juvenile net (1.6m diameter, mesh size 6 × 6 mm, 5 knots for 30 min.), and the latter with larva net (1.6m diameter, mesh size in rear part 0.5×0.5 mm, 2 knots for 10 min.) Since the sampling of larvae was made only once in the East China Sea, the present results are mainly based on the collection of juveniles The results obtained are as follows:
1. On the basis of distribution of dominant species, namely, Engraulis japonica and Myctophum spp., sampling area was tentatively divided into the following 3 sub-areas, among which the characteristics of samples are different The southern Kyushu area (A): neritic species and oceanic species are mixed, with intermediate values between other two sub-areas in number of species and of individuals per haul, and in diversity of species composition The East China Sea area (B): neritic species are dominant, with the least values in number of species and in diversity, but the largest in number of individuals per haul. The oceanic area off the Kuroshio current (C): Oceanic species are dominant, with the reverse values of sub-area B in respect to three items 2 The similarity of species composition among samples was estimated with Morishita's index of similarity The samples of juvenile in sub-areas B and C had no similarity, but those both in sub-areas A and B, and in sub-areas A and C showed an appreciable similarity In the samples of larvae in sub-areas A and C, the same similarity was obtained when Engraulis japonica was excluded from the samples, but when it was included there was no similarity Six species of the genus Myctophum are dominant in sub-areas A and C Although the number of individuals per haul in sub-area A is larger than that in C, no difference in the distribution and the composition of the fishes belonging to the genus Myctophum exists between the subareas
3. Judging from the above results, the association of larva and juvenile faunas among 3 sub-areas can be assumed as follows The association between the East China Sea and the oceanic areas was scarcely appreciable The fauna of the southern Kyushu area might be mixing one of the other two, but seems to be more intimately associated with the oceanic fauna.
