Although much attention has been paid to the fishes accompanying floating algae in the daytime, so far as is known, no study has been made of those at night. This paper is concerned with the relation between the life of fishes and the floating algae during night as well as day.
The authors obtained larvae. and juveniles of fishes accompanying the floating algae at night as well as in the daytime. They also collected fishes under a 1-kilowatt lamp at night, independent of algae. Collections were made during April, 1958 to March, 1959, in the vicinity of Tsuyazaki, Fukuoka Prefecture, by mean of a rectangular scoop net and dip nets. The results are given in Table 1. In the case of day collections, the floating algae drifting near the rectangular route as shown in Fig. 1 were scooped up. In the case of night collections, the authors left port thirty minutes before official sunset, and slowly proceeding searched for the floating algae with the help of lamp. The lamp was held at the bow, light-ing the water surface within about thirty meters. At certain locations the boat stopped with the lamp hung on the side of the boat for collecting about an hour.
Species and size ranges of fishes obtained from the floating algae at night were similar to those obtained in the daytime. In Oplegnathus fasciatus and Dasson trossulus from the night collecting the characteristic yellow coloration of their bodies was not revealed, and the blackish patterns on whitish ground color were clearly seen. Aluterid fishes did not show any noticeable color change. Most of the species collected under the mere lamp light were different from those accompanying the floating algae. In the few species caught both under the mere lamp and under the algae, differences in size and color patterns were observed. The majority of the juveniles appeared under the lamp light were those living near the surface, and some species among them were also obtained with the floating algae. This fact can be understood that those grown juveniles only temporarily used floating algae as their habitat in place of the algal zone in shallow waters where they were to live after the change of habitat in their life history.
Number of individuals as well as of species in the collections varied in seasons. Fish were abundant during spring to early autumn and scarce in winter. The largest number of species, 17, was obtained in early August, and the least number of species, 3, in October and in early February. Sebastes spp. were found in abundance from mid-April to mid-May. Late May yielded large catch according primarily to the abundance of Seriola quinqueradiata and Girella punctata in the collection. Dasson trossulus and aluterid fishes were taken in abun-dance during July to December. The largest number of individuals was collected in early September, represented by but 6 species. Girella punctata and Agrammus agrammus dominated from February to early March, but total number of individuals was rather few.

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1) 海産魚の種苗生産に関する研究の一つとしてイサキの成長ならびに人工受精について報告した。
2) イサキの漁獲量は主要三県 (和歌山, 徳島, 大分) の合計で年間420トンに過ぎず農林統計に選ばれた魚種ではないが地域的にはかなり重要な高級魚である。
3) 大分県地方での産卵は6月下旬頃から始まる。
4) 6月27日に佐賀関沖漁場で人工受精を行ない, 受精ふ化したが, いずれも6日を経て斃死した。
5) 体長測定と鱗の年輪調査から生後3年までの成長については推定できたがそれ以後のものについては資料不足のため不明である。
6) 産卵数は2才魚が5-6万粒, 3才魚が50万粒で, 4才魚では約100万粒と推定された。

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During the months from June to October “Shiira-zuke” fishery is operated off Shimane Prefecture on the Japan Sea coast with help of bamboo rafts serving as floating shelters for the dolphin, Coryphaena hippurus, and other fishes. (For construction of the raft see KOJIMA, 1956. Bull. Jap. Soc. Scien. Fish., 21: 1049 ?? 52). In catching fish gathering around the shelters purse seines are used. The present work deals with relative importance of catches by species and individual size on the basis of the data made available for the 1955-58 seasons.
In Table 1 the amount of landings from four fishing units is indicated by species and month. As the fishing season lasts from early summer till autumn, a majority of catch is represented by warm-water species. Of the total weight of the annual catch, the dolphin occupied 93-96 percent, the rest being composed of such species as Seriola, filefish (Monacanthus cirrhifer), and hardtail (Caranx helvolus). Each of them seems to occur in almost the same months every year under study. As skipjack and tunas can not be caught by purse seine, their catches as in Table 1 must have been made by angling during the trip from one shelter to another.
Numbers of individuals sampled from “shiira-zuke” catches at various ports were identified as to species, and the total length of them measured as in Table 2. In a report by previous workers the size of fish following drifting seaweed was noted. They were smaller in size than those observed in the present work. Differences in the size of fish are attributable to the fact that the former group of fish following drifting substance is too small, while the latter staying with the bamboo shelter kept at a point is large enough, to resist the current.

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In the Seto Inland Sea the conger eel, Astroconger myriaster (Brevoort) is a commercially important species to be caught by small sized trawlers. In the present work, growth of the fish has been studied on the basis of morphometric surveys conducted during 1952-56 for 1, 960 individuals from fishing grounds off Marugame and 1, 892 off Takuma (Table 1 and Fig. 1).
1) Frequency distribution of the anal length composition and seasonal changes in the modes (Figs. 2 and 3) have suggested that the fish under study consist of two major age groups: the young exploited during August to December and the older staying in the areas over the year. The field data indicated the average growth from summer to summer to be about 50mm.
2) Relation between total length (L) and anal length (l) of 400 specimens collected in 1956 may be expressed as
L=14.38+2.45l.
From the anal length composition obtained at Marugame during 1952-56, the mean anal length of the young and the older groups was separately computed for the coordinate months of the years (Table 3). The results revealed that the annual growth averages 50mm. in a close agreement with the one determined from the field data. However, the young group from Marugame was found a little different in the growth trend from that of Takuma (Fig. 4). The difference may be partly attributable to the particular topography of Takuma area where the tidal currents from the outer sea join each other and receed to different directions. According to the least square method, the growth of the conger eel in these areas may be formulated as follows:
For the young group occurring during August to December
l=73.143+2.150a (Marugame),
logl=1.8327+0.1288logl (Takuma);
For the older group occurring in early months of the following year
l=110.464+1.484a (Marugame),
l=105.133+1.851a (Takuma),
where l is anal length and a is age by ten day period.
3) In the conger eel under report, relation between body weight (w) and anal length (l) is indicated as in Fig. 5 and by a formula
log w=-5.8326+3.614 log l.
Assuming that the fish complete their metamorphosis in a year after hatching, it is inferable that the conger eel in the areas are composed of the two-year-old and the three-year-old groups.

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