Abstract:In the neurosecretory cells of the caudal neurosecretory system of Megalorama amblycephala, the mitachandria, Golgi compieg, rough endaplasmic reticulum and free ribosomB are weli-developed. The caudal neurosecretary cells and theix axons contain three major types of granules, namely electron-lucent granules,electron-dense and leas eiectron-dense granules.The desmosome can be found occasiorally between unmyeiin.ated nerve fibres in the urophysis. As the gonads develop from stage III to VI，the changes of organellas are not distinct morphologically. But there are significant differences in number and distribution of three Binds of granules. The ultrastuctural changes of caudal neurosectrory sells and neurohemal regions show that the artificially induced spawning can accelerate releasing the secretory materials of electron-dense granolas into the blood capillary.

Abstract:The present paper deals ivit.h the composition of food organisms, the seasonal variations of feeding intensity, and the relationships between the digostive organs and feeding habits of lizard fishes (Saurida tumbil,Saurida wadosquamis and Trachinocephadus myops) collected from South Fujian and Taiwan Bank fishing ground.'The results show thst the three species of lizard fishes bolong to demersal fishes,whioh are carnivorous with cannibalism. The compositions of food organisms of these fishes are rather Simple, whereas they feed chiefly on fish a.nd Cephalopods, and less amount of Macrura, lgrachyura and Stomatopoda. In general, the size of the prey( fishes) increases with the fork lenghh of the predator(Saurida tumbil or S.wadosquamis) It has been shown that those Jizard fishes are feeding throughout the year, and the feeding intensities of Saurida tumbil and S.wadosquamis become higher during the spawning season from March to April. The structures of digestive organs arty adapted to their carnivorous habits w hich Saurida tumbil and S.wadosquamis are similar to each other, and their feeding habits axe more ferocious than that of Trachinocephadus myops.

Abstract:The base-Iine data of the tagging-and-recapture prawns, the statistics from fishing grounds, the relative amounts of catching young prawns caperimentally in the three hays of the Eohai Sea ( Eohai, Laizhou and Liaodoxzg ) and hydrologic investigation in Iarge areas were used to analyze the pexzaeus prawn's regular migration and distribution in the three bays and other fishing gxoungs as well as the forming of the central fishing grounds. The results are as follows: 1.According to the data of the tagging-and-recapture prawns in the autumn fishing, the prawns migratory speed and recapture rate in each Iife is ascertained. 2， According to the annual change of the prawn shoal density in the distributive maps charted by the telegraphic records in the autumn fishing, it seemed that the prawn fishing grounds Iosely related to the cold water masses in September, and to deeper and relatively high temperature areas in Octoher. 3.Early in Autumn to the end. of September of the young prawns in the three hays and the Laihe Estuarine migrated from the shallow waters of low salinity and high temperature (salinity 22-28‰ and bottom temperature 2fi-28℃) to the central-eastern Bohai Sea and central Liaodong Bay of high salinity and. low temperatore(salinity 34-31‰ and. bottom temperature 20-23℃), It revealed that the site and stability of the central fishing ground and the density of the prawn shoals had a close relation to the distributive form of the isotherm (longitude or latitude) with botom temperature 20℃ and. bottom salinity 30.5‰. 4. The investigation data of the relative amounts of the young prawns in the bays during the past fifteen years showed that the prawn abundance in the Laizhou Bay and the Bohai Eay kept a higher level from 1972 to 1981, except 1976. That could be regarded as the basis of forming the fishing grounds in,th.e sea of Yantai-Weihai from the Iast ten days of August to the first and second ten days of September，and in the Liaodong Bay from the last ten days of September to the first ten days of October.

Abstract:This paper is an attemption studing fish synecology in waters of islands off the Zhejiang. The data of catch composition collected from the setrnet was applied to analyse tlxe ragionat, monthly yearly changas of dvminaut species. The connection in the temporal and spatial distributions of the dazninant species were discussedas well as the trophic relationships in fish commezuitiasr.

Abstract:The hermorrago disease of grass carp (Ctenaopharygodon idellla)is an actue infection caused by Reavirus. The symtoms of the disease is that the whole body and alI organs of the fish appears bleeding. The number of erythrocyte, Ieucocyte and. hemoglobin of the diseased fish are obviously Teas than the healthy one, ands that of artifically irzfeeted fish are much less than that of naturally dissesed fish. The bassphils is fixst found in the fish bland. The small blood vessels are extemsively damaged. and the microthrombi are formed. The muscle, intestines, livers, spleen，kidneys and gills of the fish appear bleeding， degenerated and necrotic. There are acidophilic inclusive bodies in the cytoplasm of liver cells.

Abstract:Surveys of filefish spawning ground and in combination with the strength anal the position variation of the eddy off Diavyu Tsland in Spring (April) from 19$1 to 1984 were carried out. Marine conditions such as temperature,salinity, density б_t specific volume anomaly 10⁵δ and Geostrophic current, were analysed in order to find out the reason of the formation of spawning ground and the variation of catches，and It is expected to provide a basis for fishing forecast, The principal results are as fellows: 1.There exists a cyclonic eddy in the sea area at the northeast of Diaeyu Island(26°-27°N, 124°-125°E)，that is the area of Kuroshio and its branched region.The velocity ef the upwelling in the center of the eddy is in the order of about 10^-4cm/s, and around it is downwelling area. Besides rotation, the Eddy moves horizontally towards northeast，and the velocity is about 0.8km a day. On the northern and western edges of the eddy，the velocity is comparatively slow, where is the passing and spawning greunds of filefiish. 2.In spring, the spawning grounds of filefish generally concentrated in the near bottom stratum of the eddy region and its edge off Diaoyu Island (26°N section ),of which the seatva#er temperature was 17-18℃, the salinity was 3.4.6-34.8‰ and the specific volume anomaly 10⁵δ of 270-290. 3.The eddy characteristics off Diaoyu Island in 1982 and 1983 were obviously different that the yield fluctuation of these two years was influenced to a certain extent. 4.The strength and the position of the eddy off Diaoyu Tsland ( 26°N section )have variation each year during 1981-1984. Supposed. the specific volume anomaly 10⁵δ on the bottom of the eddy is taken as an index to n3easure the strength of the ocean water, the correlational coefficient between it and the filefish production of Shanghai a ud Zhoushan Marine Fishing Compaxiies in April and May could reach 0.9i3，and that between the index and the total annual production was 0.812. So this hydrographio factor can be offered as an index for fishing prealiction. 5.Tha larvae ef filefish basically drift along the current around the eddy towards northeast gradually.

Abstract:Effect of partial freesing on keeping freshness of tila,pia was investigated. Changes in K value, an index for estimating freshness, bacteria number and. pH value were fallawed during storage at一3±0.55℃. The results were compared with that ire storaged. The out sections of muscle tzssus were observed. under microseope and conpared with fresh and the fish frozen at一18℃. The results obtained were summarised as follows: 1.Though. the temperature of ps.rtial fxeezing was only three degrees lower than ice storage, the preservation effect was shown much better. In the case storage period could be prolonged to one month. 2. There was no definite intercorrelation between pH and freshness. 3.The fce crystal farmed in fish muscle storaged at 3±0.55℃ was the type of slow freezing，frozen water percentage was lower than that of storaged at 一18℃ and muscle tissue of non-frozen part seemed no differencfl from fresh muscle.

Abstract:Radioimmunoassay (RIA) has been applied for 17β-oestradiol (17β-E₂) in fish serum. Synthetic analogue of hypothalamic luteinizing hormone(LRH-A) has been used as a stimulant for induced spawning in blunt snout bream.Both serum gonadotropin (GTH) and 17β-E₂ levels have been measured by means of RIA. For 17β-E₂ RIA, the accuracy (recovery, 92.8±8.16%)，specificity (crossreactions with oestrone and oestriol < 3.20 and 2.99%)and sensitivity ( Minimum measurement，2.36-2.50pg) have been determined. The standard curve, г=一0.998, s= 0.023-0.051，measurement range was from 10 to 400pg/tube. After injection of LR,H-A, serum GTH level rose to about 17 times of prespawning, while only 3-5 times in unspawning fish. This showed changes in serum GTH were similar to that of grass carp and silver carp during induced spawning. Serum 17β-E₂ levels and gonado-somatic index (GSI) rose synchronally during the development of ovary. At stage IY of ovary, serum 17β-E₂ reached to a peak level of 2004.11±1136pg/ml. That peak level may be supposed as a sign of quick accumulation of yolk in the oocytes. It was found that 17β-E₂ level slightly declined to 13 92. 71±399.09 and 1219.29±420.51pg/ml just before induced injection. Postspacaning, 17β-E₂ sharply decreased to 346.7±129.51 and 324.28±228.00pg/ml. In contrast to male fish, 17β-E₂ levels progressively decreased during the development of testis, and kept in low levels.

Abstract:An opizootio, which is locally called "blind disease"，occurred among the penaeid shying ponds at Fengxian county in Shanghai during July to October 1983. Eight strains were isolated from the eyebulls and hemolymph of moribund shrimp (Pesaaeus orientalis Kishinouye). It was demonstrated by injecting the bacterial isolates to the eyestalk and by infecting in immersion cultured that the strayins were tha cause of the epizootic. The bacterial isolates were all gram-negative,short rods axis curved. Mortility was by a singlo polar flagellum. Oxidase was positiva. The isolates were non-pigmented,non-lunixzed. Glucose was fermented without the production of gas. Hydrogen sulfide was not formed (TSI). Sucrose was fermented. Arabinose and inosit.ol were not fernented.Fermentation test of mannose was not obvious.Lysine was decarhoxylated in the MΦeller medium but neither arginine nor ornithine was. Growth took place in the peptone water without NaCl. All strains were sensitive to the vibriostatic agent 0/129(10μg)，and were not agglutinated by 0-1 antiserum of cholera vibrio.Thus the present isolates were identified as Vibrio cholerav (non-O1)，