Abstract:Based on the fishing records of bull trawlers operated in the Gulf of North Part(Tonkiu Gulf) by the Nanhai Fisheries Company during the years 1957-1960,seasonal and annual changes of species composition in the catches for differentregions of the gulf were examined in present studies. Thirteen subregions are adoptedin this paper corresponding to the customary boundaries of principle fishing groundsgenerally used. Their numbers and extents are tabulated in a table accompanied with achart. The percentages of species are derived from the average catch per haul ineach subregion or whole region over the whole period of 1957-1960. Rank correalationcoefficients, known as Spearmen's ρ, are calculated for the pairs of subregions, seasonsand years of species compositions, with which the status of changes is discussed. Quantitative data for twenty-two species or groups of fishes and one group ofsquid are available in fishing records. The calculation of the percentages in speciescomposition for the whole region after the following figures: Nemipterus spp. 18. 6,Lujianus erythropterus 10. 7, Upeneus spp. 9. 6, Priacanthus spp. 9.0, Saurida spp.8.1, Caranx malabaricus 4. 0, Arius sp. 3. 4, Squid 2.4, Parargyrops edita 2. 4,Pentaprion Longimanus 1. 5, Therapon theraps 1. 3, Pomadasys hasta 1. 1, Wak spp.0. 9, dogfishes 0.8, Psenes indicus 0. 6, Taius tumifrons 0. 4, Epinephelus spp.0. 4, Trichiurus haumala 0. 2, Pagrosomus major 0. 1, Muraenesox cinerus 0. 1, andother species including unclassified fishes 22. 8. In gerenal, the percentages of speciescomposition for subregions are not similar to those of the gulf as a whole, butmost of them have considerable identifical trends. They are shown in the histograms(Fig. 2(1) (2)]. The rank correlation coefficients of species composition between subregions over four years have been calculated. They show that positive correlations are presentedbetween most subregions. Most significant-levels of correlation coefficient ρ≥0. 66are found between nine subregions with either subregion Ⅳ or Ⅸ, while subregion Ⅴwith only one subregion bears such level of significance correalation.There is no sig-nificant correlaion found between subregion Ⅱ-Ⅶ, Ⅱ-Ⅷ, Ⅱ-Ⅻ, Ⅵ-2-Ⅴ orⅥ-2-Ⅶ, their coefficient ρ'is 0.40. The dissimilarities of the seasonal and annual changes in relative indices of abun-dance of species composition for different subregion are noticeable. They are illus-trated by diagrams. with the help of a number of text-figures to show the curves ofrank correlation coefficients plotted by coefficient values between seasons as wellas between years reciprocally, the variations are found to be more conspicuous whenthe seasons turning from March to April and from September to October, and to beless conspicous when the season turning from December to January and from June toJuly. According to the figure of curves mentioned above, four types of trends inseasonal variations of species composition for different subregion and the gulf asa whole have been recognized. Subregiou Ⅷ, Ⅸ and Ⅺ and whole region are denotedas type 1, subregion Ⅱ, Ⅲ, Ⅴand Ⅵ-1 as type 2, subregion Ⅶ,Ⅹ and Ⅻ as type3, and subregion Ⅳ as type 4. their characteristics are described. The classificationof seasonal variation trends mentioned above is found to be applicable to those ofannual variation with minor differences, In contradiction to subregion Ⅷ belongto type 2, subregion Ⅹ belong to type 3 in seasonal variation, they are consideredas type 4 and type 2 of annual vatiation respectively. It seems probable that relationship of geographical positions of the subregionis one of the essential factor which makes the seasonal and annual variations ofspecies composition much alike among some subregion or differing among the others.In general, the neighboring regions usually maintein their trends is a similar fashionin these variations than the remote ones. The index of diversity after Magalef(1960) has been applied to demonstrate the status of the demersal fish communityof the regions investigated.

Abstract:The phosphorus compounds in the ovaries of various developmental stages fromthe adult Chinese farm fishes, Hypophthalmichthys molitrix, were analysed accordingto the methods of Schneider 1945 and Schmidt and Thannhauser 1945. At the sametime, the contents of water, protein and fat of the ovaries were also estimated withthe usual biochemical methods. In the ovaries of young developmental stages Ⅱ and Ⅲ, the acid solublephosphorus compound (A) and ribonucleic acid (RNA) are significantly higher thanthe other phosphorus compounds-the phospholipid (L), phosphoprotein (Pp) and deoxyribonucleic acid (DNA). The phosphorus content of the former two compoundsconstitutes more than 85% of the total phosphorus in the young oyaries. As thedevelopment advanced, the phosphorus contents of L and Pp increase promptly duringstage IVa to IVc, while those of the A and RNA decrease during the same stages.The increasing features of the total protein and fat are essentially the same as thoseof L and Pp. Although the contents of these phosphorus compounds manifest differently in aunit weight of various stages of ovaries, the total amount of all these constituentsin one ovary increase in considerable extent during the development here considered.The most prominent feature is the increasing scale of the amounts of L and Pp, whichincrease 980- and 1,333-times respectively within the course of ovarian developmentstudied. These changes seem to bear relation to the formation of yolk in the oocytesand the histological development of the ovary. As the variation in the contents of these phosphorus compounds is considered, itis obvious that the major increase of L and Pp occurs mainly in the stage IV of deve-lopment, which lasts from February to April for Hypophthalmichthys molitrix in ourdistrict. This means that such a vast increment of the ovarian materials may besynthesized in a short period of 2 to 3 months. Therefore, it is obvious that, inpractice, a sufficient food supply in the spring is indispensable for the ovariandevelopment of the brood fishes to be used in the artificial propagation. This mayoffer from the theoretical aspect a technical guidance for the acceleration of thesexual maturity of the brood fishes in the pisciculture. The changes in terms of the percentages of the different phosphorus compounds indifferent stages lead to the conclusion that the developmental process of the fishovary may consist of two phases of synthesis: (1) the early phase, ranging fromstage Ⅱ to stage Ⅳa, is characterized by the synthesis of protoplasm shown as an abun-dance of A and RNA; (2) the late phase including the stage Ⅳ as a whole, ismarked by the synthesis of yolk indicated by an immence increase of L and Pp. The biological significance of the formation of these phosphorus compounds inthe ovarian development of the fishes studied is to incorporate the energy-rich phos-phates into organic constituents in the oocyte as well as to synthesise a large amountof organic substances as reserve materials both for the embryonic development of theeggs after fertilization.

Abstract:1. The bacteria which caused "putrid-skin" disease in Hypophthalmichthys mo-litrix and Aristichthys nobilis are similar to Pseudomonas putida of the common carpsand Salmon fishes. Artificial infection with bacteria isolated from diseased fish causethe same disease in healthy Hypophthalmichthys molitriax and Aristichthys nobilis as wellas in Misgurus fossilis. 2. Symptoms of the disease appeared as follows: at the first stage of the dis-ease, red spots appeared on the skin, then the epidermis putrified and scales felloff, exposing the dermis; the inner margin of the focus was inflamed and the scalessurrounding the focus became loose, displaying a plain mark; as the case progressed,the dermis also putrified and disintegrated, making a deep pit in the skin. In excep-tionally rare cases putrification penetrated deep into the muscle, exposing skeletonand viscera. Observations on the sections of focus showed that the internal organswere not effected. 3. This disease is a menace to fish production. If it occurs during the growthperiod of parent fishes, it will effect the accumulation of nutritive material anddevelopment of gonads, causing great disadvantage to artificial propagation and fryproduction as well as to food fishes. 4. The lowest inhibiting effective concentration of four antibiotics in vitroranges as following: Aureomycin 0.39μg/ml., Chloromycin 0.78μg/ml., Neomycin1.56μg/ml., Streptomycin 3.12μg/ml. 5. The effective lethal concentration of four bactericides (mercurous nitrate,mercurous acetate, mercuric nitrate and bleaching powder) in vitro at 25℃ in 24hours ranges as following: mercurous nitrate, mercurous acetate,mercuric nitrate allat 1/10,000,000; bleaching powder at 1p. p. m. 6. As a measure for prophylaxis, in summer, attention should be paid to thequality of water, prevention of pollution and addition of fresh water. After parturi- fication or infection, Hypoghthalmichthys molitriw and Aristichthys nobilis should betreated with aureomycin or chloromycin in peritoneal or muscular injection with adosage of 5mg./kg. At the same time spraying pond water with bleaching powder,making it containing a concentration at 1 p.p.m. will also be of good help in earlystages of infection.

Abstract:Subculture from unialgal culture of Nitaschia closterium,kept in our laboratory for manyyears, was made first in enriched sea water under suitable conditions for a week to gethealthy diatoms for inoculum. These diatoms were then carefully washed by centrifugingand subcultured in sterilized natural sea water,not enriched and very deficient in phosphate,with8 ×10⁶ to 10×10⁶ cells per ml., for ten hours before inoculating the cultures for experi-ments. Dead cells occurred if this starving culture lasted too long or contained too many cells.Experiments were all carried out in 500 ml. conical flasks each containing 200 ml. sterilizednatural sea water enriched with NO_3-N, 4 p.p.m. and P³² 20μc. Cultures of cach serieswere illuminated by a 1,000 W.bulb.Diatoms were washed 5 times by centrifuging to get ridof the P³² adsorbed on the diatom frustules, before P³² absorbed being measured by a Geigercounter. 1. Influences of different temperatures on the absorption of P³². Cultures kept at 0, 5, 10, 15, 20, 25 and 30℃, were arranged obliquely under a 1,000W.bulb at a distance of 53 cm.measured from the surface of the bulb to the center of the bot-tom of the culture flask situated just inside a wall of white glazed paper which was usedto reflect the light. All cultures lasted 12 hours. Diatom cells in cultures at 15℃ absorb largest amount of P³³ (Fig. 1,A), the increase ofdiatom numbers here is also the largest (Fig. 1, B), being up to 44.1%, and the amountof P³² absorbed by a single diatom cell is the largest as well. The next come in order arecultures at 20℃ and 10℃, the smallest absorption occurring in cultures at 5℃ and 0℃. 2. Influence of different illuminating periods on the absorption of P³². Cultures were kept at 15℃ and arranged straight beneath the 1,000 W.bulb with a dis-tance of 33. 5 cm. with light reflecting arrangement; all lasted 26 hours. Three series ofcultures, inoculated respectively with 6×10⁶, 8×10⁶ and 9×10⁶ cells per ml., were made,each consisting of 4 groups, A, B, C and D: A. 26 hours' illumination. The absorption of P³² in 5 minutes gives a count of 100 per minute, increased to morethan 2,000 per minute in 8-9 hours, and then the absorption rate increases rapidly up to 12,800 counts per millute in 17 hours for cultures inoculated with 6×10⁶ cells per ml. (Fig.2a,A), and up to 12,000 and 8,600 counts per minute in 20 and 21.5 hours for culturesinoculated with 8×10⁶ and 9×10⁶ cells per ml.respectively (Figs.2b, A 2c, A).The summitof the absorption curve is higher and reached earlier in cultures with a smaller inoculum. B. 14 hours' illumination followed by 12 hours' darkness. During the period of illumination the absorption curve (Fig. 2, B) follows more or lessthe course of the curve for 26 hours' illumination (Fig. 2,A). When the black-out starts,the absorption curve of cultures inoculated with 6×10⁶ cells per ml. begins to drop im-mediately (Fig. 2a, B), while the curves of cultures inoculated with 8×10⁶ and 9×10⁶cells per ml.still going upward for another three and six hours respectively before dropping(Fig. 2 b, B 2 c, B). C. 12 hours' illumination after 14 hours' darkness. The absorption is very weak during the 14 hours' black-out period, giving only 100-200counts per minute and gradually increases after illumination being started, reaching gteatspeed after 6 hours' illumination (Fig. 2, C). D. 26 hours' black-out. Absorption is very weak throughout the 26 hours, being only 100-200 counts perminute. The following phenomena are worth noticing in the above illumination experiments: 1. Greatest absorption speed of P³² generally occure 8-12 (14) hours after illuminationbeing started. 2. The summit of the absorption curve is reached earlier in the culture with smaller ino-culum, possibly as a result of less sheltering effect and hence more light being received byeach cell. 3. The absorption curve drops after the summit is resched, as a result of P³² being se-creted out into the culture medium.

Abstract:Rearing of Tilapia mosambica in the rice fields and the correlation between the fishes andthe rice plants, has been studied during the years of 1962-1964 in Amoy, Fukien Province.The physical, chemical and biological environments of the rice fields have been observed andmeasured once a month. The physical properties of the rice fields differ greatly with those of fish ponds. ButTilapia adapts itself favorably to these shallow water environments. The chemical properties of the rice fields are basically good for fish stocking. Dissolvedorganic matters are plentiful in the rice fields. The content of inorganic salts (NO₃^一, PO₄^三,SiO₃^二) in the fields stocked with fishes, are much higher than the fields not stocked. It isaffected by the excrement of the fishes. A large number of aquatic organisms inhabits the rice fields. 99 species of plankton,34 species of aquatic plants, and 17 species of bottom dwelled invertebrates and insects havebeen collected and observed. Most of them are directly or indirectly used as food by theTilapia. The average yield of fish from rice fields in four months of rearing, is 170 kg. perhectare. When stable manure is added, the production can be increased to 206-315 kg. perhectare. Besides, an additional production of few ten thousands of Tilapia fries have beenreproduced during the months. Regarding the growth of the rice plants, those in the fields stocked with Tilapia growsmuch better than in the fields without fish. And the yield of rice of the former is 3.0-13.2%greater than the latter. The experiment shows that the rearing of Tilapia mosambica withgrowing rice has a beneficial effect on rice production.

Abstract:The present report deals with the zooplankton of the foodstuff collected along theTaichu-Yang and Dajie-Yang of the Chu-San region duritig 1960-1961. The results are asfollows: The average total biomase of zooplankton is 88 mg/m³ in this region, and the higbestis 140 mg/m³ in July and the lowest is 4 mg/m³ in February. In general, it reaches a maximum in summer and a minimum in winter. Its seasonal va-riation is just the same as the water temperature. There are 100-250 mg/m³ of the total biomass of zooplankton distributed in the southeastof the fishing ground and 250-500mg/m³ distributed outside of it. The dominant zooplanktons are the eurythermic low-saline neritic species and the brackishwater estuarine species. They are the Labidocera cuchacta, L. bipinnata, Contropages dorsispin-atus, Tortanus vermiculus, Schmackeria poplesia, Gastrosacous ko jimacnsis, Acctes ohinensis,etc., and are mainly distributed in the west of the fishing ground and Hangchow-Bay. Thereare also high-saline oceanic species, including Calanus parper, Undinula vulgaris, Eucalanuscrassus, Euchact plana, Sagitta bedoti, S. enflata, etc. They are mainly distributed in thesouth and southeast of the fishing ground.

Abstract:The chief chemical composition of some marine zooplanktonic crustaceans, Acetes, chin-ensis,Euphausia sp, Acanthomysis longirostris and Copepods-mainly Schmakeria poplesia, offAmoy water and its vicinity has been analysed, with special emphasis laid on the proteinand the essential amino-acids contents. The results reported in this paper show that theprotein content of these animals is quite rich, amounting to 50% or over in the dry matterbase and the essential amino acids of the protein are fairly complete. Among the animalspecies analyzed,the copepod is especially prominent in these respects and contains essentialamino acids in higher proportion than the other species. When prepared dry, both the con-tents of protein and the proportion of essential amino acids are without much lost. The content of the lipid in the zooplankton is higher than that in the benthos, but thereverse is true of the ash. The results show that the marine zooplanktonic crustaceans have a relatively high nut-ritive value as the food for human consumption as well as for the marine economic animals,and, therefore are of great importance to the fisheries.