Abstract:All the lakes of the Huang Gong District of Hu--bei Province had, prior to the time of the liberation of China, been improperly used in fish production, and nothing had been done for fish management. This led to a gradual depletion of the fish resource. At that time, the annual production of those most productive lakes never exceeded ten eattres Per mow, Since the time of lihcratioai, the prvviucial fishery bureau changed its policy, and adopted some fish management programme, suvlt as fish docking, the protection of spawners and spawning ground of some desirable fish populations, introduction of fiah fries and fingerlings fro m Yangtze Piver into the lakes. These operativns have cffcrtively raised ilre fish production of the lakes.Far example,Lakc Zhu Lin with a surface area of 6,600 maw, in 1963 the annual yield reached 124.5 vatties per mow, and Lake Zhang Du with a surface area of 110,000 mows, produced 29.2 eatties per mow in 1961. For yeaxs of experience and practice, same conditions arc recognised to be importans in increasing fish production in the lakes. (1) The composition of species and density of fish populations should be suitable to the feeding capacity of the lakes. (2)The size of fingerlings of the deairablc species (Mylophugodon piccus,Ctenophyryngodon idcllus,Hypophthalmiehthys molitrix,Aristriehthys nobilis,etc.)to be planted in the lakes must be as large as pvssibie. (3)To those lakes with favorable conditivns,it is desirable to slock the fingerlings in the bays or coves of the lakes for a short lime, and then release them into the lakes wilhin the months of January to March. This process is beneficial both to the survival and the growth of the fingerlins. (4)It is of great significance that the yield of native stacks in the lakes attain 37.5% of the total production. Therefore, pravtical regulations concerning the restriction of the catchahle sixe,creel limits, protection of the spawners and the apxwning ground axe necessary to be set up in order to protect the native stacks in the lakes. (5)Inflow and outflow through the locks between the lakes and the river will draw a certain amount of fishes into the lakes to increase the production o, the lakes. Prohlema concerned, with controlling and utilizing the predstaxy fishes, xeformotion of the lakes,and the efficiency of fishing effort are also briefly discussed.

Abstract:Since 1957，an experiment on utilizing domestic setvagr water for fish culture has been carried on by the municipality of irhang Sha,A total surface area of 7，235 mows are used, which utilise completely or partially savage pollution for fish culture.The average amount of sewage water used daily is about 51,000 tans, and up to the present, more than 3 million tattles of pond fishes have been produced. The productivity of so me ponds has exceeded 1,000 tattles per mow. The desirable shape and size of the fish pond should be rectangular and slightly curved with a surface area of 100一300 mows. The inlet and outlet openings of the pon d should not be located an a straight course, an d the elevation of the inlet must be slightly higher than that of the outlet, and the depth of the water is preferably 2 meters. The irrigation of the sewage wafer into the ponds must be frequent and in small flow and long duration. To handling the sewage flow, situations of seasonal climate,water temperature, quality of water, eic.，should also be considered. The species of fish for culture are mainly plankton feeders,they are Hypophthalmichthys molitrix and Aristichthys nobilis and some supplemental species are the Mylopharyngodon piceus,Ctenopharyngodon idellus,Cyprinus carpio,Carussiua auratus,Parabramis pekinensis,Xenocypris argentea, and Meyalobrama termindis. The density of the fingerlings planted is generally 1,000一1,200 individuals of body length 13一16 cm.，or 500一600 individuals of body weight 250 g. per mow.Density may be iu-creased to 15-20%，if the process of planting and catching are alternately applied. It is of importance to treat the ponds regularly with unalaked lime, which will help to increase the productivity of the pond. The benefits of using sewagr water for fish culture are; the increase of the productivity of the fish pond; iha less cost and more profit; easy transportation and the freshness of the fish gvvdsa and at same time the polluted vrater gets to be purified.

Abstract:On the basis of experim ental atudies on the spat rot disease of the fronds of the haidai, Laminaria jnponive, the following results had been obtained. 1.The disease developed more seriously in shallow water regions where water circulation waa slow, and the spread more rapidly with increase of water transparency. 2.No bacteria were iaolated from the healthy parts of the diseaaed frvuda.Bacteria isolated from the diseased parts were found to be Cram-negative bacilli without spores, and inoculation of these bacteria into healthy fronds did not produce similar diseases. 3.Anatomy of the diseased fronds showed no bacteria in tissues in the early stages of the disease; in later stages, the cells last all their pigments, only the protoplasm being left, but the epidermal cells of the ether shadowed side of the fronds remaining healthy; when the white spots developed further and eventually merged with the neighboring spots into large a hole, often a pigmentrd ring was found around the hole. On the basis of these observations, it was concluded that the spot rot disease is physiological in nature and is not caused by pathogenes, although the bacterial growth which eventually followed does worsen the disease. Therefvre the authors suggest that to prevent the disease, means must be taken to make better water circulation in the cultivation regions and to lower the cultivation depth of the haidai at the time when the Laminaria is moat easily infected with this disease.

Abstract:Undaria plnnatifida (Harv.) Sur, in one of the important economic srawerds of China. So Far it has not yet been brought under cultivation by the artificial metliod,because there is no effective method to cultivate tl;e sparelings. Although the cultivalion of aporelinga was succeasful to a certain extent in the sea, there still exist some handicaps which hinder the growing of the sporelings. The spores of some other aeaweeds and larvae of various invertebrates adhere to the same substratum an which Undaria spares set, and hence they chock the development of the aporea of Undaria. Besides, the artificial substrata are often washed away- by the waves,so the cultivation in the aea is not safe during the aummer. Tseng, Sun and Wu (1955) suggested that cultivation of sporelings of Undaria be made at low temperature. According to our studies the gameiaphytes of Undaria grow well at 25-27℃, and the temperature of sea water seldom rises above 28℃ at Tsingtao. As temperature is oat a limiting factor far cultivating gametophytcs, so loo tempera.Lure method seems not neceasary. We collected the spores of Undaria in July and eulti-vhted them in pools indoors.When temperature dropped to below 25℃, the gametophytea began to develop into aporophytes. Under good light condition the sporelings grew larger and denser. When the temperature of the aea water dropped down to 22--23℃,the sporelings were transfered from the pool to the sea. A month later the sporelings grew to such sizea as 1.8-2.3 cm. There are three advantages in the artificial cultivation of Llndaria spnrelings in pools; (1)The temperature of sea water in pools lowers more quicl.ly than the tcmpersiure of water in the sea after middle autumn. Under lower temperature the young sporophytes grow larger than those in open sea. (2)Filtered sea water is free from various marine invertebrates, an that Undaria sporelings may grow denser. (3)This method of cultivation in pools is safe. sim ple and evono mical along northern China coast.

Abstract:It has long been assumed that the farm fishes [Mylopharyngodon piccus(Richardson),Ctenopharyngodon idellus(Cuv. et Val.),Hypophthalmichthys molitrio (Cuv. et Val.)，Arislichthys nobilis (Richardson)]cannot propagate whear they live in thn environment of the pond. After the study of the development of the gonads of these fishes, this view proves to be wrong. In 1058, Nanhai Fishereis Institue, Ministry of Fisheries succeeded in some experiments on the artificial propagation of the pondxeaxed H.molitris and A. nobilis, and the investigators of Iluzzan and Canton succeeded in the artificial propagation of U. idellus in 1960. With the popularization of technical shill and the development of production,research on fundamental theories has been carried an widely and fruitful results have been acheived in the development and maturation of the oocyte, cytology of fertilization, development of embryo, the mechanism of ovulation and cyto-chemistry. The ovcytea of these pond-reared fishes can only develop to the fourth stage (priwary oocyte),Estrualixation is indispensable for the oocytes to develop from tire fourth to the fifth stage (secondary ooeyte).Oocytes and follicular cclls are of the Same origin, bath derived from the germinal epithelium of the wall of the ovary, The ovaries of farm Fiches st the age of sexual maturation pass the winter in the third stage or from the second to the third. They develop to the fourth stage from April to May, and reach full maturity from May to June. The appearance of physiological death (degeneration) of some oocytes begins in late June, then degeneration exEends to all in August and November. The farm fishes are of the type of spawning vuly once a year. hstrualization prodnccs two rffects upon ovcytes, i. e. maturation and ovulation. The rnaturation and ovulation of oocytes arc two parallel and independent processes and the completion of these two processes requires the action of exogenous hormones in farm fishes. The cytological changes of vvcytea front the fourth stage to the fifth are as fal-ows; (1) nucleus goes under division acrd the first polar body is Given off; (2) follicular cells dissolved and eggs being set free; (3)microgylar cells disappeared;(4) cytoplasm which scatters between the spaces of the yolk floss tvwared the mi-cropyle, Only one sperm penetrates the ovum through the mieropyle, and it is known as monspermic egg. The first diviai.on takes place about 40---45 minutes after fortilixation at the temperature of 24-26℃. The main factors which influence the development of the embryo are the quality.