Abstract:An analysis of the present abundance of the filofish population(Navodon septentrionalis) and the retional exploitation of the resource are discussedin this paper. The analysis is based on the age date of 1253 filefish examined betweenJan. and Apr. in 1984 as well as the fishing statistical data from 1977 to 1985. Rickerand Schaefer models are edopted, with reference to filefish natural mortality M=0.257,M =0.183. All technical calculation is computer processed. The results show: 1) The present exploitation of the filefish abundance has already reached the fullextent. In 1984 and especially in 1985 there appeared a tendency near over fishing. 2) The maximum sustainable yield in weight of the fish is MSY=205 M_T and thecorresponding fishing efforts is f(may)=47227 haul, according to the present age atfirst capture to=1.5.But the fishing effort on the filefish in 1985 is f₉₅=53869 haul. 3) If the age at first capture increases from tc=1.5to tc=2.5, the filefish fish-ing will be in the better condition, with the fishing level F=0.6-0.8(the fishinglevel in 1985 F₉₅=0.8-1.0).

Abstract:Varicorhinus gertachi (Peters)Is one of the important economical fishesof the Bei Jiang River, Guandong Privince. This paper deals with the characteristics ofmorphology, age and growth, distribution, reproduction and feeding habits of thisfish. The age of the fish was detrmined according to the number of annual rings for-med by the "common" type of ciculi on the scale. The"common"type of circuli is firm-ed between May and September.The relationship between body length(L) and leng-th of scale (S) may be expressed as L=5.63S--0 .912. Specimens include 1-4 years individuals, the largest one is 800 g,which is 4 years old and with a body length of 35cm. The interrelationship between body length(L) and body weight(W) may be exp-ressed as W=4.79×10^-3× L3.3993. The spawning season of the fish is from April toeJune. The age of maturity is two years old. They attained a body length over 15 cmand body weight of over 50 g. The sex ratio of the fish is about 1:1. The fertilizedeggs of V. gertachi are spherical in shape, 2.1-2 .2mm in diameter, and lightly sti-cky. The absolute fecundity of female is 4000-5000 eggs, and relative fecundity is 8-13 eggs per gram of body weight. The fish feeds mainly on algae and benthos. Atlast, the rational exploitation of the resources is also briefly discussed.

Abstract:In this paper, physiogical characteristics and drug sensitivity of vibriocholera (non-01)isolated from the ulcerous eyeballs and hemolyph of disoased penacidshrimp(Penaeus orientalis Kishinouye) are desribcd. Effects of temperature, salinityand pH on the growth of the organism were examined: It grew in 1% peptone waterat temperatures of 20-45℃ (Optimum range 30-42℃), at salinity of 0-5% (Optimum0.5-2%) and a pH from 5 to 10 (Optrium6-9) rspectively. All the isolated strains were highly sensitive to Terramycin, Chloramphenicol,.Tetracycline, Erythromycin, Gentamycin,Kanamycin and Neomycin and also to Co-trimoxazole, Furazolidone and Nitro-furantoin. But they were not sensitive to Penici-llin G, Vancomycin and Bacitracin. In the solution of bleaching powder (contains active chlorine 30%) at 0.2 ppmfor 60 minutes, the bacteria were 95.5% killed. It was successfully treated with blea-ching powder st 1 ppm in the oulture water for controlling this vibrio cholera (non--01)in penaeid shrimp.

Abstract:In 1972, Hung-chia Yang in Taiwan studied the tooth form of the lowerjaw and the articular bones of largehead haitail. He derived the largehead hairtail in theDong Hai Sea into two subspecies. The point-toothed fish were designated Trichiuruslepturus auriga and the barb-toothed fish Trichiurus lepturus lepturus. In 1977,Mr. Sin-che Lee also classified the largehead hailtail into two species further. Onewas thin ribbon fish (T. japonicus with pointed teeth), the other was fat ribbon fish(T. lepturus with barbed teeth). To make clear the question,we collected 586 specimensfrom the Dong Hai Sea and Huang Hai Sea(28-33°N, 123-126°E) during the periodof spring in 1982 to summer in 1984,and repeated Yang and Lee's Work. Some cova-riance analyses for the body admeasurement,the tooth form of lower jew,the shape ofarticular bone and the number of gillrakes of the fish have been studied synthetically.The results show that there is only one species of largehead hairtail Trichiurus leptu- rus Linnaeus (1758) in the Dong Hai Sea and Huang Hai Sea. Yang and Lee classifi-cation are invalid.

Abstract:The Karyotype of Claris fuscus has been determined from Kidney cell by the method of PHA pericardial Cavity injection in vivo. Slides were made by thehypotoic air drying technique with Giemse staining. The diploid number of Chromoso-mes is 56 (that is 2N=56). The total chromosome arm count is 98. They may be clas-sified into three groups: 9 pairs are metacentrie, 12 pairs submetacentric, and 7 pairssubtelo-or telocentric Chromosomes. The resulte are presented in table 1 and Fig 1. It was found that No. 21 was a pairs of homomorphic chromosomes in the fema-le, but it was a pair of heteromorphic chromosomes in the male, therefore the hetero-morphic chromosomes wore sex chrosmes of C. fuscus in all probabillity. They weret?ely designated as XY. The problem of the heteromorphic chromosomes inPisces was thus discussed, but whether the heteromorphic chromosomes were the sexchromosomes or not awaiting for further investigation.

Abstract:The genetic structures and variations of 16 enzyme loci in 8 populationsof silver carp,big head and grass carp from Chang Jiang River, Zhu Jiang River andHeilong Jiang River were analyzed by LKB horizontal acrylamide gel electrophoresis. Amarked biochemical genetic differences were found among different populations ofsame specics from different water systems. The mean proportion of polymorphic loci(P) was 13. 3%, 26. 7% and 13. 3%,the average heterozygosity per locus was 0 .0493, 0. 0484 and 0 .0511 for silver carppopulations from Chang Jiang River,Zhu Jiang River and Heilong Jiang River respe-ctively;For big head populations from Chang Jiang River and Zhu Jiang River,the Pwas both 31 .3%, but the H was 0.1375 and 0.0977 respectively;For grass carppopulations from Chang Jiang River,Zhu Jing River and Reilong Jiang River,the Pwas 30. 0%, 38. 0% and 21.3%, the H was 0.1241, 0.0961 and 0.0525 respectively.There was a trend that the mean prpportion of polymorphic loci in southern popula-tion was higher than that in northern population. The genetic similarity (S) of silver carps between Chang Jiang River and Zhu Ji-ang River,Chang Jiang River and Heilong Jiang River,Zhu Jiang River and HeilongJiang River was 0.9957, 0.9955 and 0.9696 successively;The S of big head popula-tions between Chang Jiang River and Zhu Jiang River was 0.9955; The S of grasscarp populations between Chang Jiang River and Zhu Jiang River,Zhu Jiang River andHeilong Jiang River, Chang Jiang Biver and Heilong Jiang River wax 0.9679, 0.9483and 0.9324 respectively. The genetic distance was smaller within the central popula-lions (Chang Jiang River and Zhu Jiang River),but was larger between the marginal populations(Heilong Jiang River) and the central population. The population size ofgrass carp in Heilong jiang River was very small, which should be given enoughaffention tco.

Abstract:This paper describes a new method in producing agar from Gracilariaby treatment with dilute alkali prior to extraction. The raw material was trcated withan AWS solution containing 3-4% sodium hydroxide at a temperature of 78--80℃ for3 hr or at a lower temperature for longer time. The yield and gel strength of the agarproduced were higher than those treated with usual concentration of sodium hydroxidesolution.

Abstract:A few antisera against fish reovirus(FRV) were prepared by our labor-story. An enzyme-linked immunosorhent assay (ELISA) and discounter imnaunoele-ctropharesis (DCTE) were developed to do the serological. diagnosis of FRV infection in grass carp, using these antisera. The DCIE was compared with ELSA for deteo-tion of FRV. The EL1SA was found to be at least 400 times mare sensitive than the DOIE，and as a highly sensitive, rapid and specific method for early diagnosis of FRV.

Abstract:The effects of salmon gonadotrophin (GTH)on production of proges-terone, 17α-hydroxyprogesterone. 17α, 20β-dihydroxy-4-pregnen-3-one(17α 20βP),androstenedione, testostone and estradiol by vitel1ogenic ovarian follicles of Atlanticsalmon (Salmo salar)in vitro were examined. The breakdown of germinal vesicle ofoocyte did not occur in both incubations with 0.1 and lμg/ml GTH, only small a-mount of 17α20βP was produced by lμg/ml GTH incubation at the 10th day. The follic-les with 0. 1μg/ml GTH produced two-fold amount of oestradiol than that with 1μg/mlGTH incubation. Progesterone, 17α--hydroxyprogesterone, androstenedione and testo-sterone were produced by the stimulation of GTR in a dose-dependent manner. Theresults indicate that vitellognic follicles show differnt responss to low or high doseof GTH stimulation. Oesthradiol production is the major biosynthesis pathway of sex ster-oids by late vitellogenic follicles in Atlantic salmon and it is responsible for oocyte vi-tellogenesis. A low dose of GTH is more effective on stimulating oestradiol production.

Abstract:The present paper deals with the organs development of blunt snoutbream (Megalobrama amblycephala).Specimens were collected from Qing Pu Fre-shwater Fishfarm of Shanghai during May to Nov., 1985. The morphogensis of larvaewere observed continuously on living specimens. The total and standard body length,head length, greatest depth, diameter of eye and otic capsule, and intestine lengthwere all measured. In the development of the digestive system, the increase of relative length of in-testine reaches to 228% when standard body length is 59 .8mm. Teeth andgill rakersgradually increase in number. The respiratory organ at first bears a few buds on eachgill arch, then a series of gill filaments formee and divided into feather-like gilllamallae, the lamallae increase rapidly in number. The air bladder has threechambers, at first the midbober grows out from the oesophagus, and afterwardthe anterior and posterior ones develop. Olfactory and otio sense organs complete afterhatching. The morphological characteristies of larval development can be divided into A-Gstages. Stage A: The larva has just hatched, bearing a pear-shaped yolk sac, Totallength is 4.0-6.2mm. Stage B: The yolk sac reduced, air bladder inflated, fin-folddifferentiated, TL 6.2-7.0mm. Stage C: Yolk is assimilated, TL. 7.0-8.8mm. StageD:Finrays appeared in dorsal, eaudal and anal fin, TL 8.8-16.6mm. Stage E: Pelvicfins with unossified rays, TL 16.6-22.0mm. Stage F: Pelvic fins with ossified rays,scales appeared on sides of the body, TL 24.0-35.0mm. Stage G: Body is fully scaled,TL over 35mm.