Abstract:The catches of the year-class and the mature spawners of the prawn (Penaeusorientalis) in spring are used as indices of the recruitment and the adult stock, and therelation between them is here discussed. It is considered that their relationship can bedescribed with Beverton or Ricker reproductive models in the range of the spawnersrecorded. The values of the parameters in Beverton's and Ricker's models area = 2.092×10^-4 b = 4. 187×10^-2 (r= 0 .60, p0.05) and a= 24.43 b = 3. 565×10^-3(r= 0.58, p0.05) respectively. By the use of mathematical analysis, it seems thatBeverton's models is more suitable to deseribe thier relationship than that of Ricker's. According to the values of the A_max (number of mature spawners needed for themaximum recruilment), R_(max) (maximum recruitment) Msy (maximum sustamableyicld) and the sizes of the maximum recruitment and adult stock recorded by the prawnfishery, it is certain that the number of the mature spawners is too scarce, If the valueof the mature spawners is adjusted to be 250--300 from being 112 (the average valueof 16--year classes) the yield of year-class will be increased approximately 50--70% andthe value will be increased from 1700 (the average value of 16--year-classes) to 2500-3000. The maximum yicld of year-class would attain to 4000, if the conditions shouldbe satisfied.

Abstract:That paper deals with the studies on the distributiou of fucose in the frond of cul-tivated Laminaria japonica on the methods for isolating fucoidan from the alkali--coagu-lants--the waste residue from the comprehenesive utilization of Laminaria. The content of fucose in Laminaria frond is higher in the marginal portion than inthe middle portion, and longitudinally it increases from 0. 3% in the basal part to morethan 1% in the distal part. (Fig. 1 and Table 1) Two methods of isolating fucidan from the alkali-coagulants were tested, i. e., thecetyl pyrimidium chlorid (CPC) precipitation method and the alcohol arecipitationmethod. (Fig. 2, b) The yields of fucoidan obtained by the two methods are 5.6% and4.4% (to the alkalicoagulants at dry state), and the fucose content are 24.7% and28.7% re,spectively. (Table 4, 5, 6) The content of fucose in alkali--coagalants amounts to 1.4--3.5%. (Table, 3) On acid hydrolysis of the crude fucoidan and subscquent treatment including deioni-zation, evaporation, etc. were applied, the fucose crylals settled out in absolute alcoholafter several days with a trace amount of galactose detected by paper chromatograph andwere further purified by dissolving with methanol--acetone mixture and thus rearystal-lization occurred with only a single spot of fucose shown on paper chromatograpgh.

Abstract:The culturo of free-living filaments for direct sopre-collecting, is an improvedmethod in the cultivation of Porphyra haitanensis Customarily, shells of mollusca suchas Meretrix, oyster etc. had been used for clinging of the filaments. Glass bottles havebeen used to substitute the shells in the new method, carpospores are cultivated in thesea water with sufficient nutrient salts, and then filaments germinate from thecarpospores and grow in suspension in sea water or clinging to the bottle wall. They areready for direct spore--collccting in the Autumn. Results of the experiments are concluded as follow:1. Thallus sclected for carposporc--collecting must be thoroughly cleaned to eliminateall injurious ultachments on it. The most simple and effective way to eliminate injurious algae is to bask the thallus in the sun for 1--2 hrs. and then to rinse it in the disinfectedsea water.2. For the purpose to prolong the growth period of the free--living filaments, thecarpospore-collecting should be taken place before the March.3. The production of the free-living filaments in each 800 ml. bottle is about 2--2. 5g.(wet wt.), under the conditions of sufficeent nutrient salts in the sea water and theintensity of illumination is above 1000 Lux.. By approximate estimation 20 bottlesof filaments are sufficient to meet the need for spore--coll ecting of the area l mu. net.4. In the night, by using running water to promoto the formation of binary branenedcells and the rate of spore-releasing of the filaments is a reliable way to obtainsufficient spores for cultivation5. The suitable date for spore--collecting is at the beginning till middle of Oclober.The optimum time for spore-collecting in a day is 9--11 a. m.

Abstract:In desiging the magnitude of current velocity at the inlet of a fishway, the currentovercoming ability of fishes should be considered at first. A series of experiments wereconducted in the flume of a hydraulic laboratory. Various kinds of fishes were selectedfor experiments, such as carps (Cyprinus cxrpio); Crucian carps (Carassius auratus);silver carps (Hypophthalmichys molitrix); grass carps (Ctenopharyngodon idellus);mullets (Liza soiuy); whitefish (Erythroculter erythropterus); snake head (Ophiocephalusargus); catfishes(Parasilurusasotus); blunt--headed bream(Megalobrama amblycephala)etc. At the water temperature 10--27℃, and water depth 25--50 cm., the starting velocityfor various kinds of fishes is about 0.2m/sec. The optimum velocity ranges from thelower limit of 0. 3--0. 4 m/sec. to the upper limit of 0. 5--0. 8 m/sec., But the limitingvelocity for different kinds of fishes varies comparatively large. The upper limit of optimum velocity is generally considered as the preferable veloci-ty for fishway inlet. The value is about 15--30% less than the limiting velocity. The experiments denots denote that the current overcoming ability of fishes concernsmainly with their body shapes, body length and the variation of the water temperature. By analyzing the resllts of the experimentsand the observed date from some existingfishways, it indirates that the current overcoming ability of a fish is closely related to itsbody length. so that an empirical formula is proposed for estimation.

Abstract:A rapid method for the radioimmunoassay of carp gonadotropin is developed by us-ing (1) PEG to separate the free and antibodybound antigen and (2) crystalline celluloseto purify the labelled gonadotropin. In comparison with the double antibody method, thenew procedure is much less time-consuming

Abstract:Recently, reproductive mechanism have been widely used in studying fish population dynamies,In this report, the reproduction curve is plotted by the formula R=1525Ac on the hairtails in the Dong Hai, although numbers, parent and offspring, described here are in relative index instead of absolute number, The theoretical value of the reproductive relation obtained from the formula of the reproduction curve is treated by the mathematical model in stationary state from the known parameter of hairtails mentioned above.

Abstract:The hairtails centtal fishing ground of Shengshan is situated at Lat. 30°00'-31°10'N, and Long. 122°30--123°40'E, under the proper water temprature of 17-22℃ in winter. The shift of the fishing ground seems to be closely related with the changeof the nearby front of a high salt water tongue. The hairtails central fishing ground islocated on the north side of the front. In ordinary years, the front of the tongue changesvery little at the beginning and at the middle of the fishing season, but it moves south-ward at the end of the season. The changes usually appear in three types. 1. During the fishing season, While the actions of the wind and the sea current arerelative balanced, the front of the tongue is stable, but it gradually retreats southward atthe end of the season. 2. During the fishing season, the turbulence of the gale disturbs the balance, itmakes the front to retrcat southward earlier than ordinary. 3. During the fishing season, the wind force is weak, and the sea current for thefishing-ground is obvious, so that the front retreats at first and advances then. The central fishing ground shifts coincident with the change of the above types andthe fish schools correspondingly appear stable, and moving near south or north. After all, the movement of the front of the tongue is regarded as the index ofhairtails contral fishing--ground shifting and the marine enviroments changes. Practicallysometimes the index appears in effectual, in caso of: (A) When the front is in thesouth of Lat. 30°N; (B) When the axis of the front is in the east of Long. 123°30'E. In such abnormal cases, other factors should be considered.

Abstract:1. The Crucian carps (Carassius auratus) obtained in Qinpu and Songjiang districtsof Shanghai Municipality are usually heavily infected by the parasitic Isopod- Ichthyoxenus japonensis. 2. The parasites, in pairs dwell in a pouch occupying nearly one-third or half ofthe body cavity of the host, and an opening is situated near the base of the pectoral fins. 3. The fishes bearing the parasites have the gonads poorly developed. nearly 97%of them have the gonads remained at stages Ⅰ--Ⅱ, seldomly at Ⅲ. 4. The body size of the female parasite. attains a longth of 1. 4--2. 1 cm, while themale has only half the length. In the breeding season. the female moults and form a broodpouch by the flat projections of the five pairs of thoracic legs. The abdominal append-ages function as gills. 5. In Shanghai and its vicinity, the breeding season of Ichthyoxenus begins fromAprill to October. The fertilized eggs are released into the brooding pouch and developinto first stage larvae. After a moult the larvae enter to the second stage. They possessthe ability of free swimming, and than larvae the pouch to find hosts. 6. There are great difficulties in eliminating the adult Ichthyoxenus from the hostby chemical treatments, so that the preferable way is to kill the larvae in their free swim-ming stage. During the breeding season, by spraying 0. 1 p. p. m. sodium pantachloro-phenate along the littoral zone once a month seems avilable.

Abstract:Trachidermus fasciatus Heckel is a catadromous fish breeding in the coastal regionof the sea. In May and June the young fish migrates to the river where it grows for se-veral months and attains to maturity. In the later November the adult fishes begin todescend to the sea for spawning. A spawning ground is found in the south of the HuangHai, it is a small island, 5 knots away from the coast where the salinity varies from30‰ to 32‰ and the water temperatur about 4--5℃ in the breeding season. From themiddle of February to the middle of March, the male fish arrives to the spawning groundearlier than the female. Eggs are adhesive and laid in clumps attaching to oyster shellswhich form small caves in the big pile of shells on the oyster reef in the intertidal zone,the female leaves the cave as soon as the eggs being laid and the male fish remains totake care the eggs. The eggs hatch about in 26 days. The yolk sac of the fry absorbs in14 days. The young fishes begin to aggregate in the coastal region at the late April andreach to a peak in the middle of May.

Abstract:A reaonant frequency equation of the unsymmetrical end-plate megnetostrictivetransitting trsnsducer has been derived. From the solution of wave equation by applyingof this equation to five different contructed megnetostrictive transducer after rearrangingand modifing five corresponding formulae have been developed some of which were notreported before. It is proved that this resonant frequency equation can be regarded as ageneral basic equntion of all megnetostrictive transducers of different construtions. For the convenience of calculation, a group of curves showing the relation betweenresonant frequency and dimensions of a T--shaped transducer is plotted. By using the electro--mechanieal analogy and its fundamental definitions, the equa-tions for calculating the acoustical efficiency of the unsymmetrical end-plate megnetos-trictive unidirectional transmitting transducer and its sound radiating power arediscussed.

Abstract:Aseries of experments have been conducted in determining the influences of the totalsalinity, chemical ingredients, water temperature, dissolved oxygen, and food in theartificial sea water, to the copulation, breeding, hatching, and the development of thezoeal larvae of the woolly-handed crab. The result of the experiments manifests that when the optimum total salinify forspawnmg of the crab is 10‰ to 17‰. and the content of calcium is between 144 mg/L to335 mg/l, the zoeal larvae may develop to megalop stage and within this range there is alendency that the rate of survival is increased by the raise of the caleium content. Thepreferable conlents of Mg, K, and Fe are 461 mg/L--935 mg/L, 200 mg/L--400 mg/Land 0. 02 mg/L--0. 05 mg/L respectively. The content of Cu is very slight and negligi- ble. The changes of the water temperature influence greatly to the hatching of the eggs,and the development of the zoeal larvae. The optimum water temperature for the breedingof the crab is above 14℃, and the hatching of the eggs demands 13--27 days at thewater temperture of 21.1--26.9℃. The optimum temperature for the development ofzoeal larvae is slightly higher than that of the hatahing. The tolerant ability of the zoeal larvae in lacking of oxygen is cmparatively muchlower than that of fishes, when the dissolved oxygen is at 2 mg/L, it would cause a largequantity of zoeal larvae to die, and if further reduced to 1. 4 mg/L, Then death occursinstantly. The optimum content of the dissolved oxygen for normal development of thezoeal larvao is above 4 mg/L. The ideal food in cultivating the zoeal larvae of the woolly-handed crab is thenauplius larvae of the brine shrimps.

Abstract:Few empirical formulas have been proposed by means of mathematical inductionmethod, in accordance with the data from the weight and the center of gravity of about30 small fishing boats. These formulas can be used as ready reference for calculating displacement in apreliminary design.

Abstract:This paper points out the importance of classification of fishing gears, and makes ahistorical review on the main classifications existed, the definitions of fishing methodsare emphatically dicussed as well. A new systematic classification of fishing gears basedmainly upon the principles of fish catching is proposed. It is suggested that the fishinggears may be divided into three ranks: Groups, Forms, Kinds. All kinds of fishing gearsshould be included in the following table.