Abstract:The operating performance of beamtrawls has been carried out in offshore watersof the Jiangsu and zhejiang provinces, during March 1982 through July 1983. Basedon fishing survey, a series tests for four kinds of model beamtrawls have been done instill water tank of Nanjing Forestry College in Apr. 1983. Model nets and actualtrawls were calculated according to the criterion of M.Tauti. The large scale ratio is1/10 and the small scale ratio is 1. Moreover,beamtrawling tests were actually takenin July 7--8, 1983, The power of vessel engine is 120 hp. Towing speed and the warptension are measured. the reading is taken with scale lupe (×10). The tension is lookedup from calculated line. The height of trawl mouth is measured with normal dista-nce meter. The meter is tied on centre of the beam and its gas bag is towed behindfootrope with a short wire. The declination angle of the warp is also measured.The results are concluded as follows:1. Current beamtrawls of Jiansu and Zhejiang are divided into three kinds. Theyare small mesh with twin bags, small mesh with multi--bag all for catching shrimpsand big mesh one with twin bags for catching both shrimps and crabs.2. The common similarities of these beamtrawls is with wider horizontal spread. smaller vertical opening, low towing speed and closely touching to sea bottom. Thesebeamtrawls fully touch to bototm and hence they can effectively catch both shrimpsand crabs, and protect fish resources from harm as well.3. Among these trawls, in the operating performance the big mesh beamtrawlwith twin bags obtains the best result, it can catch not only shrimps but also crabs,and so it is more efficient. But the mesh size is too big that a certain rate of shrimpswill be lost. as to the small mesh beamtrawls that with multi-bag is better than that oftwo bags. The weak point of the small mesh beamtrawls with twin bags is that itshanding ratio is too smaller the net could not spread widely as the trawl was towing.Its belly was attached to sand bottom easily.4. The spent power for operation of all these beamtrawls is less than 1/10. Butall length of the beam almost reaches the limit of operation allowed. In order to getlarge horizontal spread further, it is suggested that to adopt the operation method ofthe veesel with two or three nets. It's necessary to keep the beamtrawl balance intowed period. Finally, this fishing gear and fishing method should be developed offthe shallow waters, and avoid in making any harmness to the resource of fish.

Abstract:A study of food and feeding habits of spats and larva of the clam (Ruditapesphilippinarum) was carried out by feeding with planktonic and benthic uni-cellularalage. Results of the experiment are as follows:1. The spare feeding on unicellular algae used in the experiment grew normally.Among them, those feeding on mixed food of benthic diatom and Chaetocerous sp. grewfaster (33.7 micron per day) with higher suvrival rate (ca. 80%) than-the spatsfeeding on other kinds of food.Another mixed food of Dicxateria zhanjingensis and Chaetoceros sp.also gaveideal results with spat growth rate of 29.2 micron per day and survival rate about80%.2. The density of food organism is an importat factor to the growth of spats.Experments show a food density of 25,000--50,000 individuals per millilitre is com-paratively suitable for culturing of spats no matter the food is single or mixed.3. Platymonas sp. is very active whan lives and is not easy for the bottom-livingspats to catch. So, that frozen and heated Platymonus sp. were used in our experi-ment. The results show frozen Platymonus gave better result.4. Although suitable food might increase the survival rate of spats of the clam,yet there are another factors affecting its survival rate such as temperature and salin-ity and the effects of bottom soil should also be considered.

Abstract:The sinergiliosis of grass carp is a common gill disease caused by parasiting ofSinergasilus major (Mark 1940) which mainly make harms to fish than two years ofmore. The histopathological changes of the damaged gill cells and blood were observedand examined. In the damaged gill, the epithelial, mucous and maesenchymal cellsmass-multiplied and the eosinophils mass-infiltrated, lamellae fused and capillariesatrophied. The ends of gill filaments appear pale and swoller. The other parts of gillfilaments and the lamellae are deformed.As to the blood indices of diseased fish, the quantity of erythrocytes per unitvolume, specific volume of erythrocytes, hemoglobin content, plasma glucose contentand total plasma protein content were all lower than of the healthy fish, but thesubsidence rate of erythrocytes and the quantity of leukocytes per unit volume werehigher than that of the healthy ones. The percentage of lymphocytes and eosinophilsreduce in leukocytes, while the monocytes and neutrophils raised.

Abstract:The effect of light intensity, temperature, pH and density of sea water in thephotosynthetic activity of carpores and free-living filaments was studied by usingthe oxygen electrode method. The results obtained are summarized as follows:1. The photosynthetic activity of carpospores depends on the time of exposure tolight; the activity of carpospores those not exposed to light is much lower than thoseexposed to light for 1--3 days.2. The activity of free--living filaments shows periodic alternation when culturedunder 12hr/12hr light-dark cycle, with the peak value in the middle of the lightphase and the valley in the middle of the dark phase.3. The activity is greatly raised when 5mM NaHCO_3 is added to sea water, indi-cating the need for standardizing the measuring condition.4. The activity of both carppores and the filaments shows a linear relationship- to light intensity over the range from 500 to 7000 Lux. While the activity of the fila-ments decreases when the intensity above 8000 Lux, whereas that of carpospores doesnot fall until 12,000 Lux.5. Within the temperature range of 10--25℃, the activity of carpospores andfilaments increases.6. The activity of carpospores and the filaments reaches to the hightest point atpH 8.0, less at 7.5 and 8.5, at 7.0 and 9.0 reaches to the lowest.7. For both stages, the highest activity appears at the sea water density of1.025.The resuls obtained are consistent with the germinating rate of carpospores andthe growth rate of the filaments. as well as the ecological observation.

Abstract:The cluster analysis method to determine the water-masses in the shallow water area can overcome some difficulties which are met in using analysis method of the oceanic water-masses. According to the features of different sea area, this method applied in defining the marginal value and inspectoral value possesses great flexibility.The correlations of the modified water-masses in the shallow water area with the central fishing grounds are discussed in this paper.The results show that the bottom layer cold waters and surface layer waters of Donghai Sea and the coastal waters of continent are important factors effecting the fishery production in this area. Therefore, it is necessary to use this method in research and analysis of the Variation.

Abstract:A study on the feeding habit and food basis of hairtail fish (Trichiurus lepturusLinn.) as well as the relationship between its food organism and fishing grounds hadbeen carried out during the years from 1960 to 1981. Food organisms and stomachcontent samples were collected from some fishing grounds along the coastal waters ofZhejiang Province and off the Chang Jiang estuary during 1963--1965.The results are as follows:1. Hairtail fish is omnivorous mainly feeding on planktonic crustaceans (Eupha-usiacea etc.) and also fishes, Cephalopods, Chaetognaths etc.2. The Euphausiacea resource of the Dong Hai region is very abundant. Thequantitative distribution of the shrimp seems verey closely related to the migration ofhairtail.It obviously manifests in some fishing grounds along the southern coastal waterof Zhejiang province in winter and spring seasons and also occurs at the mouth ofChang Jiang in summer and autumn.3. The present paper deals with the analyse of the structure of plankton com-munities in some fishing grounds and the discussion of the relationship with the move-ment and migration of hairtail fish.

Abstract:The Changjiang (Yangtze) River Estuary in Shanghai Region is covered an areaabout 2,750 thousand mu and lengthened a little over than 100 kilometers. It is famousfor abundance on fisheries resources and is the most important fishing ground of theestuarine fishery in China.As a result of the past few years' investigation, the fishes of the area, as knownat present, are represented by 106 species. According to the ecological features of thespecies, they may be referred to four types, viz. the freshwater, the brackish water,the marine and the diadromous. The freshwater species are 24 in number, about 22.64%of the total;the brackish water species 32 in number, about 30.19%;the marine species44 in number, about 41.51%;the diadromous species, including the anadro mousand the catadromous, 6 in number, about 5.66%. Acute-nosed anchovy Coilia mystus(Linnaeus ), long--tailed anchovy Coilia ectenes Jordan et Seale and ice fish Hemisalanxprognathus Regan are the major commercial species. Besides these, gray mulletMugil cephalus (Linnaeus), red--eyed mullet Liza haematochila (T. et S.), Japanesesea perch Lateolabrax japonicus (C. et V.), long-nosed catfish Leiocassis longirostrisGunther, Chinese paddle-fich Psephurus gladius (Martens), sturgeon Acipenserdabryanus (Dumeril), hilsa herring Macrura reevesii (Richardson ) head-spinedcroacker Colichthys lucidus (Richardson), Japanese eel Anguilla japonica T. et S.,striped puffer Fugu xanthopterus (T. et S.), dusky puffer Fugu obscurus (Abe) and sting ray Dasyatis navarrae (Steindachner), etc are with more commercial signifi-cance.There are a little more than 20 apecies of shrimps and crabs in the same area,among them, Palaemon (Exopalaemon) annandalei(Kremp) and Eriocheir sinensisH. Milne--Edwards are the major species and with most commercial value. As regard tofish fry and megalopa larva of commercial crab, it is noticed that elvers of Anguillajaponica T. et S. and the megalopses of Eriocheir sinensis H. Milne--Edwards areabundant and of commercial importance for inland water stocking.In recent 24 years since 1959 to 1982, the average annual catch of the aquaticanimals mentioned above is 4, 587.68 tons, 4,047.2 tons in 1960s, 5, 089. 9 in 1970s.The highest catch is 7,483 tons in 1971, the lowest catch is 2,921.5 tons in 1962. It isworried that the annual catch of both 1981 and 1982 is less than 4,000 tons. The annualcatch of commercial crustaceans is inereased, but that of all major fisheries fall down.It is obviously caused by the influence of water conservency works, water pollution,and the fish recources damaged by overfishing.The annual catch dynamics of the major commercial aquatic animals are introdu-uced and analysed in the present paper. In addition, some problems concerned to theprotection and propagation of the fisheries resources of the Changjiang Estuary areherewith discussed.

Abstract:The short--snout icefish, Salangichthys (Neosalanx) jordani Wakiya Takahasi,is one of commercial fishes in Tai Hu Lake. Experiments on artifical fertilization ofthe fish were carried out in spring of 1981 and 1983.The ripe egg of the icefish is spherical, on the egg membrance there bear 8--13slender filaments radiating around the margin of micropyle, the filament are dichoto-mously divided directing to the opposite pole of the micropyle and connected each otherto make a network covering almost the entire surface of the egg. The eggs are strongsticky, the spawned eggs attach on the submerged plants and other matrix in thewater. The diameter of swollen egg is 0.59--0.73mm, average 0.64mm. The embryohatched out 149 hours after the fertlization, 865 prelarvae were obtained in the experi-ment. The protection of spawning ground of the icefish, especially the submergedplants is proposed.

Abstract:The fishery of the spanish mackerel (Scomberomorus niphonius Guvier Valen-nes) is one of important fisheries in the areas of the Yellow Sea and Pohai Sea. Wehave adopted the the bioeconomio model which is based on both Scheafer model andFox model, to discuss the problem of profit, energy consumption and employment ofthe fishery. The values of the maximum revenue (U_max),optimum economic effort(f_eop) and optimum energy consumption (O_opt) were estimated. These values are pres-ented in table 2. If the bed economic result is the managemen objective of the fisherywe can get the maximum revenue (U_max)=19.65 millions) and the optimum energyconsumption when the level of the effort is (f_eop=2900). Comparing to the resultobtained from the management objective of maximum sustained yield, the revenuewould increase 15. 5% and the energy consumption would be decreasd 26.8%. But theyield would reduce 7.2% about 2000 tons. If the employment is the management ob-jective of the fisheries, the effort might be controlled to 5400. Comparing to the resultof the best economic result. the employment would be increased 76.8%, but the reveuewould reduce 35.2% and the energy consumption would be increased 78.9%.

Abstract:本文报道了几种植物生长刺激素、微量元素和氮磷等营养盐对细基江蓠(Gracilaria tenu-istipitata)孢子萌发影响的试验情况。结果表明:(1)低浓度乙烯利(10ppm左右)对细基江蓠孢子萌发有积极的作用;(2)β-吲哚乙酸(40ppm)和增产素(1ppm 以下)对细基江蓠孢子的萌发有促进作用;(3)细基江蓠在孢子萌发阶段施用氮肥和磷肥有积极效果。此外,还探讨了两种微量元素——钼和锰分别对细基江蓠孢子萌发的影响。 在进行江蓠采孢子培苗时,如能适宜地使用植物生长刺激素、微量元素及氮、磷等营养盐,可望得到良好的效果,但必须注意控制使用浓度,并与其他方面的因素配合,才能较好地发挥效用。