Studies on the marine cladocerans-I. : A biological note on Penilia

　瀬戸内海備後灘に面する2定点において， 1966-1967年の1年間海産枝角類の調査を行なった.出現した5種のうちウスカワミジンコ，Penilia schmackeri RICHARD，について若干の観察を行ない，次のような結果を得た. 1) Penilia の出現は6月中句にはじまり，その後急激に増加して7月初旬に最高25，000f個体/m3 の密度に達した.以後急速に減少してゆき9月にはみられなくなった(Table 2). 2) 体長の分布は0.38-0.93 mm にわたるが，大別して大小の2群にわかれ，大型群は主として抱卵側体群より成る(Text-fig. 3). 3) Penilia の体長は出現初期から順次僅かながら小さくなるようであるが，雌1尾あたりの抱卵数は出現初期の平均7.5個より時日の経過とともにきわめて顕著に減少する傾向が認められ， 8月末には平均2.0個となった(Text-fig. 4). 4) いわゆる夏卵を有する個体の占める割合は，出現初期にすでに25％を示し，7月初旬に最高69%に達し，以後次第に低下して40%前後に至るが，途中6月末頃より，すなわち群集密度が最高に達する直前に雄個体とともに耐久卵をもっ雌個体が現われ，それら有性生殖{間体群の出現率は群集の消滅前に最高に達し10%に及んだ(Table 3，Text-figg.6).The population of the marine cladocerans was followed up at the two stations in Bingo-Nada, the Inland Sea of Japan, during the period from November 1966 through October 1967. By the observations made on Penilia schmackeri RICHARD, one of the five species of cladocerans occurred, the following results were obtained: 1) Penilia first appeared in the middle of June; then a sharp increase in number was observed, reaching the maximum value of about 25,000 individuals per cubic meter in early July. After that, the numbers decreased rapidly to zero towards September. 2) Standard length varied within the range of 0.38 to 0.93 mm. There was a general tendency that groups of two sizes seemed to be seen. The larger group was mainly composed of egg-bearing females. 3) The standard length of females with eggs seemed to become gradually smaller from the time of its appearance to the later period, while the fertility as expressed in quantity of eggs or embryos per brood was highest (7.5) at first, followed by a drastic decrease thereafter. 4) Females with summer eggs took up about 25% of the population in the middle of June just after its first appearance. They attained their maximum (69%) in early July, then gradually decreased in number to about 40%. Sexual individuals, namely females bearing a resting egg and males, occurred already in late June, shortly before the highest population density, and continued to be seen until the end of August when Penilia was going to disappear

福山港付近における管棲端脚類，アリアケドロクダムシ，に関する二・三の観察

　アリアケドロクダムシ (Corphium acherusicum COSTA) はヨコエビ亜目 (Gammaridea) ， ドロクダムシ科(Corophiidae)に属する端脚類であって， 内湾などに多くみられる.本種はいわゆる管棲端脚類の一種で，海中の浮泥などを用いて棲管を形成し，その中に棲息するという特異な生活様式を有する. 　福山港付近において，本種の極めて高密度な群衆が認められたので，連続的採集，観察を行った結果，次のような生態的知見が得られた. 1) 棲管の乾燥重量1g当りの個体数をもって示した群衆密度には，季節的変動が認められ，6月に顕著なピークを形成する.この時期には1g当り1,000個以上という極めて高い密度を示す. 2) 雌雄とも，体長は冬期に大きく夏季に小さい. このことから年間を通じてみると，体長が大きく寿命の長い越冬世代(大型長期世代)と， 体長が小さく寿命の短い夏世代(小型短期世代)の二者に大別することができる. 3) 産卵は周年ひき続いてみられる. しかし産卵活動は3月-7月中旬に最も活発で10月-11月がこれに次ぎ高く，盛夏および厳寒期時には，かなり低くなる傾向がみられる. 4) 抱卵雌の体長(L，mm) と抱卵数(N) との関係はN= 0.28L2.98なる指数式で示される. 5) 性比は年間を通じて平均すると雌1. 6:雄1の割合であり，雌の方が常にやや多い. 6) 管棲端脚類の生態的意義について，主として汚染生物及び飼料動物としての重要性を中心に，述べた.Observations were made on the population of a marine tubicolous amphipod, Corophium acherusicum COSTA, which was found in greatest abundance in Fukuyama Harbor, Inland Sea of Japan. The results obtained are summarized as follows : 1) Abundance in population density, as expressed in terms of the number of individuals per unit weight of dried mud-tubes of C. acherusicum, fluctuates seasonally, showing a single prominent peak in June. 2) There is a remarkable seasonal variation in size of both male and female, being larger in colder season than in summer season. This fact suggests the presence of large-sized over-wintering generations and small-sized summer generations. In general, the females are larger in size than the males. 3) Breeding continues throughout the year. But, there is an indication that the breeding seems most active in March-mid-July and next, October- November. Both in the coldest and the warmest seasons breeding activity may be suppressed. 4) The relationship between the number of eggs incubated in brood pouch (N) and the standard length of mother animal (L, mm) can be expressed as N = 0.28L2. 98. 5) The females are commoner than the males. The average sex-ratio is 1.6 (females) : 1 (male). 6) Importance of the amphipod as the member of fouling community and the prey for some littoral young fishes is described

設置場所の異なる桝網の漁獲物の比較

　内湾に設置された桝網について，その設置場所と漁獲物組成との関係を明らかにするために，瀬戸内海の小内湾である笠岡湾の桝網群の中より，岸に近い網と，同一漁場の沖側の網とを選び，1961年6月から1年間冬期を除いて毎週1回，それらの網の全漁獲物について調査を行ない，次の結果を得た. 1) 桝網の漁獲物は葎類数，尾数，漁獲量の何れにおいても，設置場所により，叉季節によって可成り変動した. 2) 岸の網の漁獲物の種類数は一般に沖の網のそれよりも多く，季節的には夏季が最も多かった. 3) 漁獲物の尾数の点については岸の網より沖の網が多かった.然し，漁獲量では非常に多量のマルアジが沖の網でのみ漁獲された8月と9月を除くと，漁獲尾数と反対に，沖の網より岸の網が多く，両網聞の漁獲尾数についても，叉漁獲量についても相関々係は非常に有意であった. 4) 桝網漁獲物の中では比較的魚体が大きく，重要魚と考えられるクロダイ，ボラ，メナダは主として岸の網によって漁獲された.然しこれらの魚種は一度に多数漁獲されることはなかった. 5) 主として沖の網によって漁獲されたものは，マルアジ，カタクチイワシ，イシモチ，テンジクダィ，ヒイラギ等の魚体の小さい魚，若しくは若年魚群であった.漁獲尾数で第1位に位したマルアジはその99%が沖の網で漁獲された. 6) 湾内に群をなして来治する魚種としてカタクチイワシ， トカゲエソ， トウゴロイワシ，アカカマス，マルアジ，スズキ，イシモチ，メイタガレイ，マコガレイ等が考えられる.The whole daily catches by the two masu-ami (a kind of the pound net) operated in Kasaoka Bay were investigated, with reference to the species and size composition, at about weekly intervals during the one-year period from June, I96I through June, I962, for the purpose of clarifying the difference between the catches. These nets, which were selected as the sample out of the many masu-ami operated in this region, were located off Terama village of Konoshima, one 60 m. and the other 350 m. from the shore. Water depths at the locations of these nets were 3.5 and 5.5 m. below the mean water level respectively. There was no significant difference in such hydrographic conditions as water temperature, chlorinity and dissolved oxygen between the locations of the two nets. From comparison of the catches of the two nets, the following results were obtained: 1) The species composition of the catches of these masu-ami showed considerable seasonal variations and local differences. 2) The catch of the nearshore net was, in general, richer in species, greater in weight and fewer in number of individuals than that of the offshore net. The correlation coefficient between the catches of the two nets either in weight or in number of individuals, was highly significant except in August and September. 3) The number of the captured species was relatively numerous in July and August when water temperature was high. Thereafter, it gradually decreased with the falling water temperature, and remained nearly constant during November and December. The species composition of catches of the two nets, however, always differed from each other. 4) The fishes, larger in size and higher in market value in the catches of masuami, such as Mylio macrocephalus Mugil cephalus and Liza haematocheila except Platycephalus indicus were mainly caught by the nearshore net and seldom came into the offshore net. The number per haul of these fishes was usually small. 5) A large number of young Decapterus maruadsi were caught almost exclusively by the offshore net, practically none of them appeared in the catch of the near shore net. They occurred in Kasaoka Bay in large schools from July through October. 6) There was an indication that small-sized or young fishes are taken more numerously by the offshore net than the nearshore net. 7) The following fishes were presumed to come into Kasaoka Bay in schools. They are Engraulis japonia, Saurida elongata, Allanetta bleekeri, Sphyraena pinguis, Lateolabrax japonicus, Argyrosomus argentatus, Limanda yokohamae and Kareius bicoloratus

桝網漁獲物より見た笠岡湾における魚類の生態

1) 内湾における魚類の生態を明らかにすることを目的として，瀬戸内海中央部の笠岡湾において，湾内に極めて濃密に設置される桝網の漁獲物を，ほぼ周年にわたって調査した. 2) 桝網漁獲物中に出現した魚類は48科83種に達した.この外，頭足類11種，甲殻類11種，剣尾類1種をえた. 3) 漁獲物の組成では魚類が数量共に首位を占め，個体数，重量はそれぞれ，全漁獲物中の82%および72%に達した.漁獲量には季節的変動があり，夏期に多く，冬期に少ない. 4) 期間中ひきつづいて，かなり大量に漁獲された魚類4種(テンジクダイ，スズキ，マルアジ，イシモチ)について，その出現時期，湾内における成長，その他二，三の生態的事項について述べた. 5) 出現時期および数量から，笠岡湾内に出現する魚類は，昼態的に次の三者に分類することができる. i) 湾内に定住するもの:テンジクダイ，ヒイラギ，アミメハギ，マハゼ，サツパ等. ii) 湾内に一時的に滞留するもの: a. 産卵のため成体が来遊するもの:魚類ではみるべきものが少ないが， トウゴロイワシ，ダツ科の2種(ダツ，テンジクダツ)等がある. b. 幼期にのみ来遊し，湾内で成育するもの:マルアジ，スズキ，イシモチ，マコガレイ，イシガレイ， トカゲエソ，アカカマス等. iii) きわめて稀に出現するもの:クロアナゴ，サンマ，ギンカガミ等.1) Almost year-round investigation was carried out on the catch of masu-ami, a kind of pound net, in Kasaoka Bay located in the central part of Seto Inland Sea. 2) A list of species found in the catch was presented, in which 83 species of fishes belonging to 48 families were contained, with 11 species of cephalopods, 11 species of crustaceans and I species of Xiphosura. 3) Characteristics in the composition of the catch of masu-ami were shown. Among the animals caught fishes dominated in number and weight, comprising 82% and 71% of the total catch, respectively. The catch per haul fluctuated with seasons, being greater in summer and smaller in winter. 4) Growth as deduced from length-weight measurements and weight-length relationships were described on several fishes captured abundantly during the present investigation. 5) On the basis of seasonal occurrence and abundance, the fishes of Kasaoka Bay can be grouped into the following three ecological categories. i. Year-round "residents" : Apogon lineatus, Leiognathus nuchalis, Rudarius ercodes, Harengu/a zunasi, Acanthogobius fiavimanus, Callionymus richardsoni, etc. ii. Temporary "visitors": a) Those coming to spawn: Allanetta bleekeri, Ablennes anastomella, etc. b) Those visiting the area in their young stages only : Decapterus maruadsi, Lateolabrax japonicus, Argyrosomus argentatus, Limanda yokohamae, Kareius bicoloratus, Saurida elongata, Sphyraena pinguis, etc. iii. Infrequent or accidental "visitors": Conger japonicus, Cololabis saira, Mene maculata, Lateolabrax latus, etc

Fisheries in Hashiri-shima : III. Studies on small-sized crabs found in catches of small trawlers part 1.

　小型機船底曳網の漁獲物中には，多くの未利用の底棲動物が含まれている.これらは漁獲後直ちに廃棄され全くかえりみられていない. これらの未利用資源の活用を目的として底曳網廃棄物中の小型カニ類と，アサリとを餌料として用いたクルマエビの飼育実験を行なった.実験期間は秋季→冬期の低温時期(10月下旬-12月下旬)の2ヶ月間である. 　アサリ投与群と，アサリ，カニ混合投与群の成長を比較した結果，後者の方がやや成績が良好であった.脱皮個体は何れの群においても水温15℃以上のときにのみ観察された. 　摂餌量の日変動は著るしいが， 10日毎の測定結果よりみると， 日間摂餌率と水温との聞には正の相関が認められた.すなわち，水温12℃ では，日間摂餌李は2%付近の低い値であるが， 16-17℃ を境として，その急激な増加がみられた. 　また，日間摂餌率と増重率とを対比させてみると，同様な正の相関関係が認められた. この関係から，クルマエビの体重維持lこ必要な餌料量は，体重の2-3% にあたることがわかった. 　アサリ，カニ混合投与群におけるクルマエビは，それぞれの餌の混合比率に応じて摂餌することが明らかとなり，この2様類の餌料lこ関する限りでは，摂餌における餌の選択性はあまり認められなかった.Many useless benthic animals are contained in the catches of small trawlers. Small crabs are one of these unutilized resources. Attempt was made to use these animals as food in rearing of the Kuruma prawn, Penaeus japonicus BATE. The experiment was carried out using these small crabs and clam meat during low-temperature season from late October to late December, 1964. Comparison of the growth between the two groups fed on clam meat only and on the mixture of clam and crabs, respectively, clarified that the latter group grew more rapidly than the former. Molting was observed only at temperatures above 15°C. in both groups. A positive correlation was shown between the feeding rate per day and the mean temperature of 10-day period; namely, at 12°C., the feeding rate was as low as about 2%, and with the elevation of temperature, especially above 16-17°C., increased remarkably. Furthermore, the correlation between the feeding rate per day and the growth rate was also positive, revealing that the daily ration necessary for the maintenance of body might be 2-3 % of the body weight. The prawn fed with the mixture of clam and crab meat took the two kinds of food in approximately the same clam/crab ratio as was given. This fact seems to show that in the feeding of the prawn there is no selectivity as to the two kinds of food

Fisheries in Hashiri-shima : II. Spawning of a file-fish, Navodon modestus (GÜNTHER)

　瀬戸内海中央部における重要魚類の産卵生態に関する研究の一環として，備後灘におけるウマヅラハギNavodon modestus (GÜNTHER) の産卵について調査を行なった. 　備後灘では毎年4-6月の3ヶ月間にわたって，主として島嶼部周辺に設置される桝網によって，多量に本種が漁獲される.この時期のウマヅラハギは，発達した卵巣を有するから，産卵群と考えられる. 　3月より5月までにえられた数標本の卵巣を観察すると，時期の推移とともに卵巣の急速な発達がみられる.卵巣卵の卵径頻度分布からみると，本種の産卵はl同で終わるものではないことが推定された. 　ウマヅラハギの漁獲量は岸寄りの網に多く沖合の網lこ少ないこと，またその卵の性質などからみて，本種は島嶼部の沿岸で産卵するものと推定し，島艇部周辺のガラモ場よりガラモおよび底質を採集して産着卵の有無を精査した. 　1963年6月初旬，走島のガラモ中より92個の卵が発見されたが，これらは形態，構造，大きさなどから，ウマヅラハギ卵と同定された.このことから，ウマヅラハキ、は，少なくとも島嶼部沿岸のガラモ場を産卵場として利用していることが明らかとなった. 　なお，ウマヅラハギの卵は，天然では室内で観察されるような強い粘着性を示さない可能性のあることを示唆した.A study was carried out to clarify the spawning of a file-fish, Navodon modestus (GÜNTHER), in the Bingo Nada area, as a serial study on the spawning ecology of the commercially important fishes in the central part of the Inland Sea of Japan. As described in previous paper, the file-fish are caught abundantly by the masu-ami, a kind of pound net, in Bingo Nada, operated during the three months from April until June. Since most of the fish in these months have well developed gonads, they are considered to be spawners. Observations on ovaries of several samples taken at different times from March through May indicated a rapid development of ovaries during the period. From the analysis of the frequency distribution of diameter of ovarian eggs, the spawning of Navodon modestus may occur at least more than once during the spawning season. On the basis of the catch records and from the nature of the eggs of the aluterid fishes in general, it was presumed that the file-fish may spawn somewhere along the coasts of islands in Bingo Nada. Efforts had been devoted to find the eggs spawned in nature, especially in Sargassum zones along several islands. A large amount of Sargassum, together with the bottom sediments nearby, were collected at low water and thoroughly examined. Finally, in early June, 1963, 92 eggs were found among Sargassum serratifolium collected near St. I, located at south-western coast of Hashiri-shima. These eggs were identical in structure and size with the eggs of Navodon modestus obtained by artificial fertilization. It was thus made clear that some of the file-fish may spawn in Sargassum zones. A consideration was given on the possibility that the eggs of Navodon modestus may not so firmly adhere to substrates in nature as in the laboratory

瀬戸内海中央部におけるトラフグの産卵に関する研究

　トラフクの産卵については従来まったく知られていなかった.われわれは， 1960年および1961年の4-5月，瀬戸内海中央部において，本種の産卵に関する研究を行ない，次の結果をえた. 1) 備讃瀬戸におけるトラフグ漁場は，水深20m以上の比較的潮流の早い場所IL 局在している.漁期は4月中旬-5月中旬であり，産卵群を漁獲の対象としている.従って，これら漁場は同時にトラフグの産卵場である. 2) 産卵群の形態的特徴を明らかにした.タイ縛網に混獲される産卵群の性比は，雄3:雌1の割合であった.全長平均値閣の雌雄差は認められなかったが，体重平均値聞にみられる両者の差は極めて有意であり，雌が大きい. 3) 卵巣内における卵の発達は，一様に進行する.とのζ とから，放卵は一回あるいはきわめて短期間に完了するものと推定される. 4) 字卵数(N) と全長(L，mm) および体重(W， g) との関係は，それぞれ次の指数式で表わすことができる。 N=0.0000312・L3.862; N =0.0120W1.161. 5) トラフグ漁場の底質中より，天然に産着された多量のトラフグ卵の採集に成功し，産卵場を確認することができた. 6) 産着卵数と底質の粒子組成との聞にみられる関係から，産卵床の特徴を明らかにすることができた.卵の最も多く見出された場所は，径2-4mmの粒子の卓越する(重量組成)場所であった.底質が細砂，粗様よりなる場所からは，殆んどあるいは全く産着卵は採集できなかった.1) In order to make clear the fecundity and spawning of a puffer, Fugu rubripes T. et S., investigations were carried out in the central waters of the Inland Sea of Japan in April-May, I960-I961. 2) Distribution of the fishing grounds of Fugu rubripes in Bisan Strait was shown. 3) Morphological characteristics of the spawners of Fugu rubripes were clarified. Sex-ratio (female: male) of the spawners caught by seine-nets was approximately 1: 3. Females were significantly greater in weight than in males, while the difference in total length between both sexes was not significant. 4) Development of ovarian eggs seems to be advanced uniformly within an ovary, which makes reasonable to consider that the spawning may occur at a time or at least in a very short period. 5) Relationships of fecundity with total length and weight of body were clarified. 6) Successful collection of the eggs deposited on natural spawning beds was made. The data obtained in the present investigation show that the spawning beds of Fugu rubripes lie in the bottoms having particle-size of sand 2-4 mm. in diameter

Re-examination of Furuya Cave Site, Naka Town, Tokushima Prefecture

application/pdf徳島県那珂町古屋岩陰遺跡から出土した，土器および自然遺物について再検討を行った。古屋岩陰遺跡から出土した土器群は，押型文土器とそれ以外の土器に区分され，それらのうち，特に無文土器群については，ある程度のまとまりをもったもので，学史的にも「古屋式」と呼称されていたものである。それらを抽出し，これまでの研究を概観し，考察を加えるものである。あわせて，それらの年代として想定される「カワニナ」について，周辺の事例などを含めて考察を行った。 　結果，古屋岩陰遺跡の資料の中に縄文時代草創期と考えられる資料を抽出することができ，それらが今後研究の大きな一点となることを示した。departmental bulletin pape

14C Dating of Charred Materials Excavated from Kaminohara Site, Saeki City, Oita Prefecture

application/pdf大分県佐伯市神ノ原遺跡から出土した縄文時代早期土器に付着した炭化物の年代測定結果を報告し，その結果を踏まえて，これまでの研究を概観し，考察を加えたものである。 　東九州を中心に展開する条痕・無文土器群は長期にわたって存在する土器群であるが，その型式学的特徴が乏しいため，様々な解決すべき問題がある。特に型式理解の齟齬が大きいことは資料の少ない当該時期の研究を進めるうえで，大きな障害となっている。 　神ノ原遺跡の無文土器群の測定値は9600～9400BP であり，実年代で9400～8600calBC 頃に位置づけられる可能性が高く，東九州における研究の一定点となる可能性が高い。departmental bulletin pape