The so-called micronekton is an intermediate group between the nekton and the plankton from the view-points of swimming ability as well as of its body size. Most of the micronektonic fishes have been known to undertake diurnal vertical migration and dwell in the meso- and bathypelagic zones of ocean. Fifteen species belonging to four families, Gonostomatidae (A), Sternoptychidae (B), Chauliodontidae (C) and Myctophidae (D), were collected from the surface to about 2000m depths in Sagami and Suruga Bays by ORI-plankton net and Isaacs-Kidd midwater trawl at night.
The lipid contents of the micronektonic fishes on the wet weight basis were 2.1% to 6.0% in A, 1.4% in B, 2.4% in C, and 2.0% to 11.9% in D. The wax esters in their lipids were 13.0% to 69.8% in Gonostomatinae (sub-family of A) and over 50% in most of the genus Cyclothone, 15.3% and 6.1% in Maurolicinae (sub-family of A), 4.2% in B, 7.2% in C, and 1.7% to 67.1% in D, As the representative example of micronektonic fish, Cyclothone atraria was chosen and its various tissue lipids were analyzed. The fat-filled swim-bladder contained the highest amounts of lipids (52.1%), in which 78.3% were the wax esters.
The wax esters consist mainly of C₃₀ to C₄₄ with even carbon chain-lengths. The major esters are C₃₄, C₃₆, C₃₈, C₄₀ and C₄₂, and also a trace amounts of odd numbered esters exist. The acid moiety of wax esters is dominantly monoenoic acids and docosahexaenoic acid, while the alcohol moiety contains mainly C_{16 : 0}, C_{18 : 1}, C_{20 : 1} and C_{22 : 1}, as much as 80% in the sum of four components. Comparing the wax ester distribution of micronektonic fish with that of mullet roe, the former ranges rather longer esters because of major moiety of longer chain alcohols in its esters.
Although the relation between the micronektonic fishes and their wax ester contents in the lipids has not been fully understood yet, the bathypelagic nonmigrants, such as the genus Cyclothone, contain larger quantities of wax esters than the surface and midwater migrants which contain less than 20% and contain a few per cent in most of them.

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スジイルカStenella coeruleoalbaは，世界中の熱帯から温帯の海域にかけて広く分布するハクジラ亜目に属する小型鯨類である．本研究では，本種の食性解明のための基礎的知見を得ることを目的として，2019年1月から2021年5月までに相模湾の神奈川県沿岸に漂着した10個体の胃内容物を調査した．その結果，6個体の胃から頭足類（カギイカ，ホタルイカモドキなど5科3種）の顎板，魚類（ハダカイワシ，オオクチイワシなど2科3種）の耳石が確認された．魚類・頭足類ともに日周鉛直移動を行う中・深層性の種が主体であったことから，漂着したスジイルカ6個体が索餌のため中・深層まで潜水したか，或いは夜間に表層へ浮上した小型遊泳動物を採餌していたことが示唆された．

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The sharksucker, Echeneis naucrates Linnaeus was spawned from June 2nd to August 7th, and from September 18th to December 3rd in a tank of Oita Ecological Aquarium.Embryonic development and metamorphosis after hatching were observed.
Spawning activities were continued for 30 minutes between 18: 20 and 20: 00.Lights for exhibition were put out at 18: 00.The spawning behavior was always repeated 2-5times with-in 30 min in the daily spawning period.The temperature of the breeding aquarium was regulated from 27.5 to 30.5°C.
Fertilized eggs are transparent and free floating.Eggs are rather large, 2.62 mm in diameter, and nearly spherical in shape.One to five yellowish oil globules (2-3 in average) measuring 120 to 170 μ in diameter are found on one side of the vegetal pole.Time intervals of embryonic development after fertilization were summarized in Table 1.
Mouth cleft appeared 2 days after hatching.The mouth and anus were well formed and open, the tail showed a fan-like shape and the yolk mass was completely absorbed on 4th day.On 6th day, the larvae attained 12.0 mm in total length and several pieces of small hooklike projections appeared on the anterior part of each jaw.
When larvae measured up to 15-20.5 mm in total length 9 days after hatching, the epidermal boarding bulge appeared on the median line of the dorsal part of the body above the basal part of the pectoral fin.The caudal fin was twice as long as the head.The number of fin rays reached the fixed number of the species.
Larvae grew to 29 30 mm in total length 12 days after hatching, and the epidermal bulging shifted to the upper part of the posterior margin of the eyes, forming a sucking disk in an oval shape.When larvae reached 34.0 mm in total length (14th day), the anterior margin of sucking disk extended above the middle of the eyes.On 15th to 20th day, the anterior margin of the sucking disk reached above the anterior margin of the eyes.
Young fish grew to 41.0 55.0 mm in total length 20 N 27 days after hatching, and the anterior margin of the sucking disk reached the anterior margin of the upper jaw.In young fish, 80 mm in total length on.50th day, the sucking disk enlarged to a length longer than the head.The length of the tail reduced.
|The first small scales appeared scattering on the lateral side of the young fish when they attained the size of 75.5 mm in total length.

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新しい世紀の初頭に当り, 前世紀において行われた魚類および他の水生生物の脂質に関する研究を著者らの研究を中心にして総説した。魚類における高度不飽和脂肪酸の起源に関し, リノール酸からアラキドン酸へ, またα-リノレン酸からエイコサペンタエン酸を経てドコサヘキサエン酸への代謝経路を明らかにし, さらに水界食物連鎖のモデル実験を行った。それらの結果をもとに, 魚類での血液栓球におけるプロスタグランジン生合成と血液凝集, 鯉の鰓でのリポキシゲナーゼ産生物等についても研究した。また水産脂質の不けん化物および非グリセリド脂質に関する研究として, 炭化水素スクアレン, キミルアルコール等のグリセリルエーテルおよびワックスエステルについても総述した。

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A previous checklist of the fishes of Sagami Bay, Japan, which included 1517 species belonging to 249 families (45 orders) recorded up to 2006, was revised using the following resources: fish collections of the Kanagawa Prefectural Museum of National History (KPM), the fish image database in KPM and literature records. The survey revealed 1934 species belonging to 284 families (43 orders) in the study area. Many of the species newly recorded in Sagami Bay are distributed mainly in waters south of the bay, which is likely to be closely linked to the transport of fishes by the Kuroshio Current. In addition, the recent rise in seawater temperatures in and around Sagami Bay due to global warming and other factors, may have allowed normally southern fish species to overwinter in Sagami Bay, thus leading to the significant increase in the number of species recorded over a relatively short period.

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