Abstract:The effects of food, salinity and other factoro on the survival rate and growth ofjuvenile prawns under high density cultivation in lab. were observed. Through ortho-gonal design of multi--factors, the additinal single--factors experiments and productiveexperiment, several key technical measures were explored.The results of the experiments as follows: 1. The fow limit of suitable and optimum salinities for juvenile prawns are 16‰and 22‰ respectively. The optimum cultivation value is 25%.2. Nauplius of Artemia salina were used to fed the post larvae of prawn in thefirst four days. The feeding ration from the first-day larvae was 125 individuals perjuvenile prawn. Latter on. the appropraite daily increasing of food was 90 individualsper prawn. The Tubifex sp, the ground Venerupis philippinarum meat or the brineshrimps could be fed to the post larvae of prawn during the period from the 5th day tothe 20th day. The feeding ration could be calculated as following:Wg×1^(-2)(P) = 0.2482e^(0.2064t)t: days of culture of juvenile prawn3. By keeping the Platymonas spp. a density of 0.5--1.0×10⁴ cell/ml couldremarkably decrease the amount of NH₃--N in culture seawater.4. By keeping terramycin a concentration at 0. 5--1. 0 ppm in culture seawatercould not only prevent diseases, but also accelerate the growth of juvenile prawn.5. In the productive experimental 1.41 million juvenile prawns with an averagelength of 0.95mm were harvested from 13 ponds of 23m³ seawater. The yeild was 61thousand prawns per cubic meter of seawater. The survival rate was up to 83.3%.

Abstract:The ripe eggs and spermatozoa of the pearl oyster Pinctada chemnitzi (Philippi)were fertilized in ammoniated seawater. The maximum fertilizing rate was 65%. Thefertilizing rate depends on the maturity of tho genital products. Although by raisingNH₄OH in seawater can increase fertilizing rate but it will affect the normal develop-ment and the hatching rate. The concentration of NH₄OH in ammoniated seawaterabout 0.14‰ seems suitable.Yeast is not suitable for feeding the straight-hinge stage larvae ofP. chemnitzi.The sperm of P. fucada or a mixture of sperm with Dicrateria zhanjiangensi sp. aremost suitable for the larvae of the stage nd the growth rate is higher than that usesDicrateria zhanjiangensis sp. as food alone. The larvae of the umbo stage are able tofeed with Platymonas sp. and then the growth becomes fast. The growth rates of juvenile mollusk of each food group of yeast, sperm, Dicrateria zhanjiangensis sp. anda mixture of sperm with Dicrateria zhanjiangensis sp. are 0. 03%, 10.22%, 14.73%and 17. 41% respectively.

Abstract:1) Studies on the food habit of abalone, tho only species in northern China,were carried out during 1980 to 1982 in Qingdao's shallow water.2) There ware two main feeding peaks of the abalone in a year, one appreared inlate spring to early summer and the another at late autumn, the temperature rang was8--24℃.The feeding rate of abalones decreased, when the water temperature reachedabove 26℃, or below 7℃. They stopped ingesting at the temperature below 3.0℃ inwinter.3) Abalones had the preference to different kind and the tenderness of algae. They most liked Macrocystis pyrifera,Undaria pinnatifida and Laminaria japonica,specially their tender leaves, arid unliked Sargassum pallidum, S. thunbergii and Gelidium amansii.4) The growth rate of both experimental groups, 6.6--8.5 and 9.1--11.0cm,were rather slow, the mean values of shell lengh increase in a year were 0.3cm, butweight increases were 22.4% and 21.9% respectively. Feeding on Laminaria and Ulva in two months alternatelly, the efficiency of food conversion at temperature18. 8--7. 4℃ for abalones of 6. 6--8.5cm group was found to be 9.2%, containingLaminaria 952.7gm and Ulva 799.7gm, and for 9.1--11.0cm group was 9.8%,containing Larminaria 1706. 8gm and Ulva 1299 .6gm.5) Abalones usually feed at night, sometimes, they could also take food in daywhile they are seriously hungry or present of preferable food.

Abstract:The relation between light intensity and photosynthesis activity of four mainspecies of Gracilaria (i. e. G. tenusitipitata, G. sp.-Hainan. G. verrucosa,and G.sp.--Haifeng), in Guangdong province, were measured in May and December of 1983and in February of 1984. The results of the experiment as in the following:1. In the early summer, the common light compensation point of the four speciesof Gracilaria is 1,000 Lux. From December to February of the second year. while thelight saturation point of G.verrucosa and G. tenunistipitata is 12,000 Lux and 14,000Lux respectively. The difference between two seasons is so wide. That is because fromApril, to June it is the time for spores scattering and germinating while in winter itis the best time for growing. So that need for ligh intensity was different in differentgrowing season.2. The net photosynthetic rate of Gracilaria was comparatively low in the earlysummer,but was very high in December and February of second year.3. The net photosynthetic rate of the sub--branches were higher than that of themain branches. This characteristic was found in G. sp-Hainan in early summer 1983,and in G. tenuistioitata and G. verrucosa in February 1984.4. The net photosynthotic rate on the apical part of the sporophyte of G. tenuisti-pitata was higher than that on the middle and lower parts of which show the samerate. The results will provide a scientific basis for "cutting for increasing production"technique of Gracilaria.From the experiment, the results could be concluded: In expecting to get a goodharvest, the culturing-raft should be set in the upper layer of seawater during theirfast growing period so that the algae can receive strong light to strengthen photosyn-thesis. while the algae grow to late stage the raft should be set in the lower layer inorder to avoid the strong light and to minimize the adherence of miscellaneous algae.

Abstract:This present paper deals with the xuorphnlogical characteristics of the Bgg,embryonic and larval development of Misgurnus anguillicudatus (Cantor).The materials were obtain from artificial fertilization and hatching. The observations have been carried out from March to May 1983 in Zhuhai city, Guandong Province.The eggs of the fish are adherent, spherical and small with a diameter of 0.72--0.84mm. The fertilised eggs hatched out for 26 hours anal 40 minutes at the watertemperature of 19.5-23.0C. The body of newly hatched larvae is 1.95---2.4mm in total length wish 26---32 pairs of myotomes. Two days after hatching, the external gills appear as long stripes and perform the function of respiration. 5 days after hatch-ing, the yolk sac almost absorb and the larvae start to eat. 15 days after hatching, theexternal gills disappear and the internal gills form. 45 days after hatching, the young fish develop in full and rsSemble to the adults.

Abstract:This paper reports the xesults infrom the fermented marsh-gas pondusing pig farmyard manure and manuxe waterrzs fertilizers for raising phytoplankton.experiment w as carried nut in two same siaed neightouring fish ponds in 1980---1982. Some physical-chemical environment and biological factors had been measured and analysed. The marsh-gas water manifests great effect on change of the constitu-eats of phytoplankton，and it can also regulate and sustain the natural food in different seasons. Consequently, a good harvest wo}xld be expected. The net yield per Mu is 564.5 Kg in 1981，and 655.5 Kg in 1982. Since the marsh gas-manure has long runfertility in compare with pig farmyard manure. So the it is a good fertilizer for high vield fish founds.

Abstract:本文以 PHA 体内注射法制备染色体标本,分析比较了长春鳊（Parabramis pekinensis）、团头鲂（Megalobrama amblycephala）及其杂种F₁的染色体组型与各对对应染色体的相对长度和臂比,探讨了团头鲂×长春鳊两性全育的染色体基础。结果表明,团头鲂×长春鳊是二倍体杂种;上述鱼类二倍体染色体数目均为2n=48,均分为A、B二组,分别由13对中部着丝点染色体和11对亚中部着丝点染色体组成,雌雄个体间均未发现与性别决定有关的异形同源染色体对。团头鲂×长春鳊两性全育的主要原因,很可能在于亲本双方染色体组型完全相同,且各对对应染色体形态很为相近。

Abstract:Sargassum, one of the most prevalent seaweeds in China, is also the only onewith a high content of fucoidan, laminaran and algin among all the marine algae inChina. Therefore, the utilization of the seawed is obviously important for our country.In order to furnish some basic data to the seaweed industries, methods for the extrac-tion and isolation of mucilage have been studied.The samples were collected in Huilai Xian, South China. The algae was analysedon dry basis it contains 5.1% of laminaran, 6.1% of fucoidan and 21% of alginicacid.Methods of extraction and isolation: Dried seaweed was extracted with a dilute HClsolution at a constant temperature for a definite time. The extract was then filtratedand washed. Crude fucoidan was precipitated at 50% alcohol. Crude laminaran wasobtained at 80% alcohol. Alginate was extracted from the residue with alkali.The optimum conditions for extraction, consists of stirring for two hours at 70℃with HCl solution at pH 4.Purification: By dissolving one part of crude fucoidan in ten parts of distilledwater and then one part of 4M CaCl_2 solution was added. After centrifugalized, thesupernatant was fractionally preciptated with 30% and 60% of alcohol pecipitation in30% alcohol was impurilles nd in the 60% fraction was fucoidan.On part of crude laminaran was dissolved in five parts of water, and fractionallyprecipitated in 50% and 80% alcohol and in the 80% fraction was Iaminaran.The yields are fucoidan (containing 44. 7% of fucose) 3.9%; laminaran (contain-ing 91% of glucos) 3.1% and sodium alginate 17.8%.

Abstract:本文报道了杂色鲍标志放养和人工造礁试验的方法和结果,试验表明,杂色鲍的最适放养壳长为2.5—3.0厘米;2 龄的杂色鲍,平均壳长为4.8厘米,这一龄段的鲍生长最快,3 龄的杂色鲍平均壳长为6.3厘米。最大的个体可达7.0厘米;4 龄以后,其生长明显减慢。据此,似可将3一4龄,壳长超过6.0厘米的杂色鲍定为上市规格。此外,本文还对杂色鲍对自然环境的适应、生长、移动,以及人工造礁的方法和效果作了介绍。

Abstract:带裙拖网的两条下纲之间装有一长带形大目网裙。作业时,网裙斜立于海底,鱼类受惊下潜,由网裙边逸出网外;对虾受惊上跳,入网被捕。当网裙高度为0.7—0.8米时,比旧式拖网少捕幼鱼40—70%,增产对虾10%以上,适合于对虾捕捞业。

Abstract:据不完全统计,截至1981年底,日本已对25科52种海产鱼类(不包括降海和溯河鱼类)进行了人工育苗研究。真鲷 Pagrus major、黑鲷 Mylio macrocephalus 等6种已建立年产苗种达100万尾以上的生产技术;年产达几万至几十万尾的种类有褐菖鲉 ,Sebastisus marmoratus 等 10—20种。育苗方式以室内水槽高密度育苗为主。日本人工育苗技术开发的要点:1.开发了与多数海产鱼分批产卵型的繁殖特性相适应的自然产卵的采卵技术;2.开发了适口优质的生物饵料和人工配合饵料并建立饵料系列;3.建立生物饵料大量培养技术。文中着重探讨和讨论了我国和日本海产鱼类人工育苗生产和科研几个方面的异同点,并就我国海产鱼人工育苗工作提出了几点探讨性的看法。