Abstract:This paper is the second of a series of studies on the intraspecific variation offecundity of the Large Yellow Croaker, and is concerned with the peculiarities ofthe individual fecundity of the spawning population of Kuanching-yang, Fukian. The material for the present study was collected during the period from March-June, 1959 in the spawning ground. Based upon 173 samples studied, the results aresummarized as follows: 1. The individual absolute fecundity (r) varied between 39.9 and 900.6(×1000) (average, 256. 8 ); the individual relative fecundity r/l varied between1, 410 and 18, 610 (eggs/cm) (average, 7,540) and r/q between 125 and 907(eggs/g)(average, 548). The variability is shown diagrammatically as scatter diagrams offecundity and standard-length, body-weight, age, growth coefficient of condition,standard-length×body-weight (l·q) and (l·q)~(1/2) in Figs. 1-3, 8-11. 2. The dynamical peculiarities of individual fecundity (r and r/l) of theKuanching-yang spawning population, like the Taichu-yang spawning population,increase with increase in weight, length and age. The relations of individual absolutefecundity (r) and individual relative fecundity r/l to length and age are curved,but differently sloped, and to weight are linear. The individual relative fecundity r/qdoes not increase or decrease markedly with length, weight and age. 3. The relations of individual fecundity (r,r/l, r/q) to coeffecient of condition(K =W/L~3 × 100) and to relative condition coefficient (K=W/W ×100) are not quiteobvious, i .e. ) they do not increase or decrease regularly with K and K. 4. The fecundity coefficient (C=(l·q)/r) varied between 0.22 and 1.912,mostly between 0.42 and 0.82.The individual absolute fecundity (r) was found to be related to "l·q" and "(l·q)~(1/2)" linearly, it was like the relation between individualfecundity (r, r/l) and body-weight. Thus the fecundity coefficient is still a goodindex for determining the peculiarity of individual fecundity of fish. 5. The individual fecundity (r, r/l) not only increases with increase of lengthand weight, but also relates to peculiarity of sexual maturity, i .e. , the individualsof first maturity have a lower mean individual fecundity than individuals of repeatedsexual maturity. 6. The fast-growing individuals have a higher mean individual fecundity (r,r/l) than slow-growing individuals in the same age-group. Therefore growth is oneof the main influential factors.

Abstract:The results of eight experiments on the effects of soil extract and its micro-elements as well as of the different concentrations of vitamin B₁₂and cobalt on thegrowth of Nitzschia closterium, in natural and artificial sea water, are presented.The influences of different temperatures and light intensities are also studied. 1. The growth of Nitzschia closterium in natural sea water, enriched with N(NO₃) 4 p.p.m., P (PO₄) 0.4 p.p.m. and Fe (citrate) 0.04 p.p.m., is greatlyimproved (Table 1, 2nd column) by the addition of asbed soil extract) and furtherimproved by the addition of the organic contents of soil extract as well (Table.1,lst column). This shows that the natural sea water used is deficient in microelementsand organic substances, both of which can be supplemented by proper soil extract. 2. The addition of vitamin B₁₂ 5mμg/L [Table 3, (1)] to enriched naturalsea water gives better growths than the addition of ashed soil extract [Table 3, (2)].In different B₁₂ concentrations in enriched natural sea water, best growth occurs inB₁₂ 5mμg/L (Fig. 1 2), noticeable deficiency appears in lower concentrationsand inhibitory effect increased in higher concentrations. 3. Optimum growth is obtained in cobalt concentrations 0.5-5μg/L (Fig. 3-5)in enriched natural sea water, while deficiency is observed in lower concentrationsand inhibitory effect in higher concentrations. 4. In artificial sea water without Al, Li, Ba, Cu, Mo Zn, only slightgrowth can be obtained in various cobalt concentrations and growth is comparativelybetter in Co 500μg/L, being less in lower as well as in higher concentrations [Fig.5 6. (A)]. The addition of 0. 1% soil extract makes a remarkable difference[Fig. 5 6, cf. (A) with (B)], and here best growth occurs in Co 0.5-5μg/L(Fig. 5, A; Fig. 6, A B). 5. Inhibitory effect is very remarkable in cobalt concentrations 2,500-5,000μg/L (Fig. 7 8); but with the addition of microelements (Al, Li, Ba, Cu, Mo Zn) the inhibitory effect is greatly lessened (cf. Fig 5 6, A B with Fig.7 8, A, B, C). and may disappear under certain conditions (Fig. 8, A). Thusthe presence of various microelements, such as in artificial sea water "A", may havean effect of neutralizing the inhibitory or harmful effects due to high concentrationsof cobalt, or of other metals as well.At the same time, the presence of various micro-elements in sufficient quantitics may also relief, in one way or another, the demandor the effect of deficiency of Co (Fig. 7-10), or of some other metals as well. 6. At the presence of sufficient various microelements (such as in artificialsea water "A"), the optimum concentration of B₁₂, 5mμg/L (Fig. 1) may have aninhibitory effect (cf. Fig. 11, A with Fig. 9, A) on growths in all The cobaltconcentrations tested (Fig. 11) and the inhibitory effect is greater in higher cobaltconcentrations (5-500μg/L). 7. In natural sea water, the eontents of B₁₂ and Co vary from very deficientquantities to within the optimum range shown by these experiments. The presenceof various microelements and organic substances in various quantities may havevarious influences on the effect of B₁₂, Co or some other substances on the growthof phytoplanktonic organisms. All these substances are continuously enriched innatural sea water, in the form of natural soil extract washed to rivers and hence tothe sea, as land drainage. They are also continuously produced in the sea by livingorganisms and chemical activities using substances contained in this natural soilextract. Thus the mechanism controlling the growth of marine phytoplankton is verycomplicated and further research in this field is urgently needed.

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Abstract:How to obtain proper and sufficient fish-fry and juvenile prawns used for stock-ing in blackish-water pisciculture in the province of Kwangtung, China, is a keyproblem in pisciculture. To solve these problems it is necessary primarily to knowthe exact time, the maximum number and species components of fish-fry and juveni-le prawns entering the pond in the year. Steps are therefore taken to make quanti-tative investigations in two ponds of embanked sea-water at Changsha-wan of Hai-fong district in Kwangtung from March of 1960 to March of 1961 and from Aprilof 1962 to May of 1963, and the result of the investigation is given as followings. A hemp-twine net of oblong shape was used to collect the samples. Its mouth is 1.8m×1. 38m and its length, 11 m., Its mesh in anterior portion is 2.8 cm and in posteri-or portion, 0.5 cm. The sluice of each pond was equipped with one such net to workone to four hours for each day during the flood-tide period, only the first hourcollection was taken as sample. When the sluice was opened, the sea water carry-ing with itself the fish-fry and juvenile prawns, rushed into the pond. Average mon-thly quantitative catches of fish-fry and juvenile prawns made by the net were com-puted for comparison. 71 species of fishes attributed to 33 families and 7 species of prawns were col-lected in ponds, their names were listed, and there were 4 species of mullets, 15species of miscellaneous fishes, and 6 species of prawns as predominant fry and ju-venile forms. The time of presence and entering of fish-fry and juvenile prawns in the pondswas found in different periods of the year for each species or groups. Among mul-lets: Mugil cephalus, January-April, highest frequency found in February (69.2-71.4%); Liza dussumieri, September-February, highest frequency found in Decemb- er (82.4-100 %); Liza Carinatus, February-June, highest frequency found in Ap-ril (92.3%) or March (100%); Mugil sp., September-December, (82-100%).Among Prawns: Penaeus merguiensis, May-February, highest frequency in July-November (80-100 % ); Metapenaeus joyneri, June-December, high frequencyin June, September and November (100 %); Metapenaeus monoceros and Acetesjaponicus, nearly all year with high frequency. Miscellaneous fishes consisted chieflyof Gobiidae, Tetradontidae and Sparidae. According to fry collections made fromMarch to Aprii, 1960, Gobiidae formed (43.9%). Tetradontidae formed (49.9%) andSparidae formed (2.5 %) of the total miscellaneous fishes entering the ponds.Theyappeared in major parts of year with in continually high frequency. The seasonal variations in components of fish-fry and juvenile prawns werevery marked. Mullets formed the dominant group in winter of 1961, but were repla-ced by miscellaneous fishes in winter of 1963. Miscellaneous fishes formed thedominant group in spring of 1960, but were replaced by Mullets in 1962. Theremaining half year was dominated by prawns, of which Acetes japonicus consistedchiefly of adult individual played the leading role. The authors have used the indexof diversity of Magaref to demonstrate status of the species component of fish-fryand juvenile prawns. Assuming the total number of species taken by month as a com-munty, the following values of indices were obtained, smallest value: 1.45 (Febru-ary, 1961) and 2. 07 (April, 1962); largest value: 3.80 (June, 1960) and 3. 86(August, 1962).It indicated that the dominancy of species composition would be observedin February or April, whereas the reverse situation would observed in June or August.The heterogeneity index of Motomura was also used. The maximum value of thisindex was found corresponding with the minimum value of diversity index. The total catches of fry and juvenile prawns were found to be minimal in win-ter, increased in spring, then attained maximal in summer, and decreased in autu-mn.The patterns of curves for the two observation years do not seem to coincide en-tirely. In 1960, the fry of mullets increased gradually in numbers from January toApril, decreased in the following month,with an another new peak in October.

Abstract:The experiments were carried on the coastal region of Putou Island from December.18.1963 to the middle of May 1964. For every 15 days or one month we put down inthe sea one net or two to which the natural spores would attach, then we observedthe appearance, growth and reproduction of the buds. At the same time, we put thethallus on the glass slide in the vessels to liberate the spores. After two days wesurveyed the germinating condition and form of the liberated spores. The experimental results are as follows: 1. The life history of Porphyra yezoensis Ueda cosists two stages, sexual repro-duction and asexual reproduction. The sexual reproduction begins from December to late March or early April. Theneutral spores begin to appear in the plant which is more than one cm to 10 cm inlength, but not in the plant less than 0.7 cm. The sexual reproduction begins from late December to June are early July. The car-pospores are liberated continuously until the plants disappear. The results correspondwith Kurogis (1961) report. 2. The period which the spores adhere to the nets is long. According to tableI, it is from December to early April in general.But we put down the nets earlier,the plants will grow longer and the products will be richer. Therefore the suitabletime for the spores to adhere to the nets is December or January. 3. At the first crop, according to the table 3, every square metre produced an average of 0.5 catty in dry weight.If we put down the nets in the middle ofDecember, and begin to cut in the early April then we may have 3-4 harvests andthe production will be increased greatly. Therefore this method for cultivating Porphyra yezoensis Ueda has an economic significance in the Chekiang region. 4. The time of the appearance of the neutral spores is comparatively long. Inthe course of our research on the reproduction of Porphyra yezoensis Ueda, it isknown that they play an important role in increasing the young buds in cultivation.This problem is worthy to be considered and must be settled, and thus we shouldutilize the neutral spores in the cultivation of the Porphyra yezoensis Ueda to theutmost.

Abstract:The trawl winch is an important equipment for trawlers.Data for theortical ana-lysis for its pull load have not been published as yet.In this paper, various fact-ors affecting pull load of trawl winch are being analysed completely. Derived calcu-lation method of pull load for various steps of hauling the trawl net was based onstatic balance and D'Alembert's principle in calm water and rough-sed. Finally, re-sult of actual ship experiment had been re-calculated by this method. The result ofthis paper was confirmed and may be designed for practical use and for productionof trawl winch.

Abstract:The spawning of Sinonovacula constricta can be induced by lowering the temperature ofsea water from about 20℃ to 10℃--1℃ for 1--36 hours and then raising the temperatureto about 20℃. This method gave positive results in efficiency of 15-70.9 per cent. Withinthe limits of these conditions (10--1℃ and 1--36 h.), the lower the temperature ofthe water and the longer the time treated the higher will be the efficiency. The spawning is also dependent on the presence of certain amounts of oxygen in thewater. When the animals are spawning, there are not any motions of the shells.

Abstract:The authors have made a coast-wise investigation of the fishing ground of Kiangsu from1960 to 1963, and have found out that there is a relation between the variation of fish sch-ool and ammonia content in water. It is shown that the greater the density of fish schoolis, the larger the excretion becomes, and the more the ammonia content in water increases.Results of the investigation on Pseudosciaena polyaotis (Bleeker) , Pseudosciaena orocea(Richardson), Trichiurus haumela (Forskal), Setipinna taty (Cuvier Valenciennea) and Ilisha elongata (Bennett) show that, in the water level or vertical column of water, the am-monia contents are all very high, where the fish schools are crowdy.

Abstract:Tests have been made on the fingerlings of the Cyprinid, Hypophthalmiohthys molitric,to determine the acute toxicity of certain phenolic effluent. The 24-hr TLm. and 48-hr TLm.were found to be 7.75 mg/L and 6.10 mg/L respectively at 6-8℃, and from which a "harm-less concentration" of 1.13 mg/L was computed after the formula of Hart et al. Oxygen con-sumption of the fish remained practically the same in a medium of 3.52 mg/L as in the bl-ank test; marked increase occurred when the concentration of the test solution was raised to6.07 mg/L. On the other hand, concentration up to 1.58 mg/L was sufficient to clicit an avo-iding reaction on the part of the fish. Growth rate of another Cyprinid, Ctenopharyngodonidella, was adversely affected even at a concentration of 0.05 mg/L. In view of these find-ings the authors propose that in evaluating the disposal index of phenolic wastes routine bio-assay method alone seems inadequate and should be supplemented by more refined toxicolog-ical research methods.

Abstract:This paper is written to assure that the water layers in Tsingtao district are suitable forthe growth of Porphyra yezoensis and Porphyra suborbioulata and to present references for abetter development and a higher production of Porphyra cultivation. The experiments werecarried out from December, 1963 to April, 1964, in the Middle Harbour (中港), Tsingtao. The results obtained are as follows: 1) Porphyra yezocnsis can grow extremely well from December to April in the followingyear. Their increase in volume in the course of 91 days, is from 0.54 cm² to 154.12 cm². 2) The water layers fitting them best in the littoral zone are 0.5-1.5 meter over thestandard level. In these layers they do not only show rapid growth but also show good colours.(The volume increase of plants growing two meters above the Standard level is, within 58days, only one-tenth of that growing one meter above the standard level). The growth of Por-phyra yezoensis is hindered. In the layers of two meters or more above the standard level. Th-eir pigments fade, they turn to be quite pale, and they die off in the end. 3) Porphyra yezoensis which have been growing in littoral zone and have been later tran-splanted into the sea water do not suffer any deterimental effect on their growth. And whatis more, they grow very well in an ever changing weather with no sunlight before the Mouthof March. It is the authors' finding that the layer which suits their growth best is the one thatlies between the surface water and 0.5 m. below. 4) The growth of Por phyra suborbiculcata in the littoral zone is the same as that of porphyrayezoensin.Porphyra suborbiculata growing two meters above the standard level is scarcely existing.The migration of Porphyra suborbioulata from the littoral zone into the sea water favours theirgrowth. The speed of growth becomes much faster. Based upon the experimental results, the authors hold that full attention should be paidto the growing layers of Porphyra duriug their cultivation in the littoral zone, and the authorsdeem it necessary that, in the time the cultivation in the littaral zone is going on. attentionshould also be given to the hanging method of their cultivation in a big scale. Although thegrowth of Porphyra in nature is confined in the littoral zone, it is not correct to considerthe surface layer to be unsuitable for their growth. It is shown by the experimental resultsthat Por phyra raised in the water layers from the surface to 0.5 meter below grow fairly well, especially before March and they over-match those cultivated in the littoral zone. This phe-nomenon is perhaps produced by the relatively stable surroundings , viz. appropriate conditionsof temperature and sunlight. The authors consider it to be desirable to raise Porphyra byhanging method at this depth. The cultivation by hanging method is particularly practicableto spread the cultivation areas. It can be practised in shallow waters which are unsuitablefor the cultivation of Laminaria. The cultivation of Porphyra by the hanging method is alsoan easy job.