• Volume 9,Issue 3,1985 Table of Contents
    Select All
    Display Type: |
    • >PAPERS
    • STUDIES ON THE PATHOGENIC BACTERIA OF THE "ROTTEN--SKIN" DISEASES OF THE NILE TILAPIA (TILAPIA NILOTICA)

      1985, 9(3):217-221.

      Abstract (1844) HTML (0) PDF 746.16 K (1514) Comment (0) Favorites

      Abstract:"Rotten skin" is one of the bacterial fish diseases, its infection rate reaches to80%, which causes great loss of Nile--tilapia in the wintering ponds in some districtsof China. The major symptom of the diseased fish is that, the shape of erosion on the skinis either circular or elliptic. Most of the erosions appear on both sides of the dorsalfin, sometimes scatter on all parts of the body. In its early stages, the surface of thebody appears to be filled with blood, the scales around them begin to loosen and erectup, gradually it rots to a hole, at last causes the death of the fish. The bacterium wasisolated from the liver and focus of diseased fish, and artificial infection with pure cul-tures shows positive. The bacterium is a short rod 0.5--0.6×0.7--1.4 μm long, withrounded ends, with a polar motile flagellum, nonsporulating, and Gram-negative inits stain reactions. Products gas from glucose, glycerol, galactose and mannitol;Veges--Proskauer reaction positive; oxidizcs gluconic acid. According to morphology,cultural character as well as physiology and biochemisty reactions fit well to character-isties of Aeromonas hydrophila subsp. hydrophila biotype I, which is presented inBergey's Manual of Determinative Bacteriology 8th ed. Aeromonas hydrophila subsp.hydrophila biotype I should be considered as a agent for the "Rotten--skin" disease ofNile-tilapia.

    • THE TOXICITY OF PHENOL ON FISH UNDER DIFFERENT TEMPERATURES

      1985, 9(3):223-230.

      Abstract (1885) HTML (0) PDF 744.94 K (1440) Comment (0) Favorites

      Abstract:Experiments were carried out to detect the toxic effects of phenol on some fishes(silver carp, grass carp and common carp etc.) under the different temperatures. The experments included acute toxicity, avoidance reaction, taste and odor thre-shold determination, uptake and loss of phenol and histophathological examination offish livers. The results indicated that 48-h LC50 values of fish were at 20.0℃,23.0℃ and25.0℃ being 22.5--64.8, 25.20--70.10 and 27.10--75.61 mg/l respectively. Theexperiments also show that the fish did not avoid from phenol-polluted water. The tasteor odor concentration threshold for phenol was detected to be as low as 0.01mg/l. Theuptake of phenol into fish body tissue was found to be rapid and the discharge of it wasrapid as wall, by exposing to clean water, within 8h an equilibrium concentration at-tained. Histological examinations indicated that samples of fishes were treated with phenolat concentrations ranging from 1.0 to 5.0mg/l for at least 9 days, the followingchanges were observed in the liver tissue: formation of a number of vacuoles; enlar-gement of nuclei of some cells; and contraction and deformation of the nuclear mem-brane of some cells. After the studies on the toxicity of phenol to fish, it is suggested that phenolcontent in the water for fish culture should not exceed 0.001mg/l in order to ensurethe good quality of fish meat.

    • THE GRVWTH MATHEMATICAL MODEL OF "SEA RABBIT"

      1985, 9(3):231-238.

      Abstract (1940) HTML (0) PDF 483.34 K (1545) Comment (0) Favorites

      Abstract:Accordmg to the data coilectd from the experiments of different growth stages the seedling of Nortcachus(Bxcrsatella) leachu cirrosus Stimpson which was fed in Fisheries Institute of Fujian Province from December 24 to May 20,a regression ana-lysis ws,s mode by means of TRS-80 microcomputer and models were established.The sea rabbit, the reproductive seedling in winter ana its growth in the next spring as well as its spawn in nature period,is popularly called "Ghun Mu" (Spring mother)by the Amoy people.It has au important place in tha production. The math-ematieal models offered by this article have been discussed connection with tha repx-oduction of the sea rabbit. These scientific principle once applied to the production will surely promote the culturing techniqu) and theory to,new high level.

    • PRELIMINARY STUDY ON THE BREEDING HABITS OF EDIBLE JELLYFISH IN HANGZHOU WAN BAY

      1985, 9(3):239-246.

      Abstract (1806) HTML (0) PDF 857.81 K (1489) Comment (0) Favorites

      Abstract:This paper deals with the study of breeding habits of the edible jellyfish (Rhopi-lema esculenta) in Hangzhou Wan Bay from 1978 to 1981. The results are sammarizedas follows: The edible jillyfish is a large coelenterate. its reproductive organ is gonochoristic.The gonads attach inside the membrane of stomach cavity which locates under theumbrella. The ripe egg is roundish, the sperm is triangular with a long-tail. Thecourso of maturity may be divided into four stages: the early stage, developing stage,apawning stage and post-spawning stage. The developing character of the egg mothereells is unsynchronous. The fecundity of this jellyfish is very high. The egg amountranges from 220×104 to 6,700×104 (3,000×104 in average) when the umbrella dia-meter of the jillyfish reached 23--53cm. The egg amount increases along with theincrease of umbella diameter. The spawning period of the jillyfish is quite long inHangzhou Wan Bay. It may be taken three months from Sept. to Nov., but thepeak period of spawing is in Sept. and Oct. when the water temperature reaches to22--26℃.

    • ON THE FORMATION OF PEARL SAC IN FRESHWATER MUSSEL

      1985, 9(3):247-253.

      Abstract (3095) HTML (0) PDF 1.67 M (2140) Comment (0) Favorites

      Abstract:In this paper the preliminary studies on the formation of pearl sac in freshwater mussel (Hyriopsis cumingii) are reported. A paraffia nucleus and a piece of graftmentle are inserted into the mantle of freshwater mussel. During the course of pearlsac formation, samples were taken and histological sections are prepared observed.The following changes occurred. At tbe outset a layer of primordial pearl sac epithelialcells is formed by the graft mentle piece. But the cells of this piece are heterogeneous,they are repeled by cells of the mussel on account of the "cell recognition". The primor-dial pearl sac epithelial cells detached from basel cells, died and dissolved. Then theinner cells of connective tissue of the mussrl transform themselves into epothelial cells.Hence a layer of secondery pearl sac epithelial cells is formed. The pearl sac formationtakes thirty days at 20℃. The pearl sac forms more quickly when the nucleus aretransplanted at the tail part of the mussel than at the middle part. The transplantationis better taking place in May than in October.

    • A PRELIMINARY EXPERIMENT ON PREPARED FEED FOR EARLY LARVAE OF COMMON CARP

      1985, 9(3):255-263.

      Abstract (1987) HTML (0) PDF 677.48 K (1402) Comment (0) Favorites

      Abstract:A series of studies on prepared feed for fry of common carp had been proceededsince the winter of 1981. For the purpose to raise carp larvae and fry in winter, anavailable prepared feed Larvstart-5 had been developed in 1983. This prepared feedenhanced the growth and survival rate of common carp during the early larval stage.At the densities of 200,000 larvae/m~3 and 100,000 larvae/m~3 rearing for 15 days, thefry can grow to 11--13 mm in length and 15--22 mg in weight respectively, solelyrelying on Larvstart-5 in complete absence of nature food. The survival rate of larvaewas 77--97%. The composition of prepared feed Larvstart--5 is as follows: crudeprotein 36.7%, crude fat 5.5%, fiber 1.8%, ash 19%, water 8% and carbohydrate19%.

    • INVESTIGATION ON SEXUAL DIFFERENCE COMPOSITION OF SERUM PROTEIN OF TWO TILAPIA AND THEIR HYBRID

      1985, 9(3):265-273.

      Abstract (1991) HTML (0) PDF 617.18 K (1647) Comment (0) Favorites

      Abstract:Serum proteins of Tilapia mossambica. Tilapia nilotica and their hybrid (female T. Mossambica×male T. nilotica) were examined by using 7% polyacrylamide gelelectrophoresis.The T. mossambica serum was isolated into 12--14 protein bands, T. niloticaserum into 12--13 protein bands and the bybrid serum into 13--15 protein bands.Sexual differences in the electrophoretic patterns of serum proteins of the twospecies and their hybrids were compared. The electrophoretic patterns of bandingshowed two new bands in the serum of mature female T. mossombica. They were notobserved in the males. But in the females of T. mossambica and of T. nilotica theprotein bands were broder and darker in colour than those of the males. The eletropho-retic pattern of the hybrids was transient among several components.Various staining methods were used: (a) for total proteins with amide black dyetwo new protein bands appeared; (b) for glycoproteins with the periodic acid-Schiffreaction, the two new protein bands were not visible. However, other protein bandsshowed red colour;(c) for lipoprotein with sudan black B there were two markedprotein bands.For scanning electropherograms on serum of the fish and amins acid compositionof female specific serum protein,ultra-violet-spectro photometer was used. This femalespecific serum protein was characterized by relatively high contents of glycine, pheny-lalanine and amide NH. but the absence of histidine and tyrosine,

    • A PRELIMINARY STUDY ON GROWTH AND FEEDING HABITS OF ICE--FISH IN TAIHU LAKE

      1985, 9(3):275-287.

      Abstract (1926) HTML (0) PDF 756.69 K (1829) Comment (0) Favorites

      Abstract:Ice-fish (Protosalanx hyalocranius Abbott) is an econmically important fish inTaihu Lake. Investigation on its growth and feeding habit was made from Fibrary1981 to Fibrary 1982 in order to understand the potentiality of the ice-fish resourceand the correlation among other fish resources in the lake.The results are summarized as follows:1. Ice--fish is a lake-dweller and has one-year lifespan. The fry grows relatively fastand the average body length may reach to 110 mm in seven months.2. Ice-fish is a predatory fish eating smaller fishes and sbrimps. The main food oflarvae less than 60 mm consists of cladocera tal copepod. 36 genera or species of foodorganism were found in the digestive tract of the fish of 5.4--181 mm in body length.3. The adult individuals feed mainly on lake ancovy (Coilia ectenes taihuensis)andanother ice-fish (Neosalanx tangkahkeii taihuensis) in Taihu and hence it has beenconsidered ss a potential danger to them.4. It is proposed that the catchable size of ice--fish should be increased to 60 mm intotal length (about 52.4 mm in body length).

    • A STUDY ON FEEDING HABITS OF MULLET FRY UNDER CULTURING ENVIRONMENTS

      1985, 9(3):289-296.

      Abstract (1888) HTML (0) PDF 2.66 M (1308) Comment (0) Favorites

      Abstract:Results on feeding habits of mullet fry in brackish water ponds applied withmunures for producing natural feed is obtaind. The mullet fry below 20 mm in totallength feed mainly on zooplanktons, beyond 20 mm, the feeding habit is rapidlydiversified. The palatable starting feed of mullet fry is the nauplius and small cope-pods. There is a diurnal rhythm for feeding intensity of mullet fry. Feeding beginswith sunrise and stops at sunset, maximum fullness is attained before sunset. The fryessentially not take food at night. Therefore. feeding activity of mullet fry may relys,on visual acuity.

    • >RESEARCH NOTES
    • COMPUTER PROGRAMMING OF SYMMETRIC CUTTING SEQUENCE FOR FISHING NET

      1985, 9(3):297-302.

      Abstract (2002) HTML (0) PDF 324.47 K (1561) Comment (0) Favorites

      Abstract:Symmetric cutting technique has been widely used for fishing net cutting in Chinese fishing industry due to its advantages in saving metarial and man-power. Acomputer programme of symmetric cutting sequence has been developed by author in 1983. It can be used in real--time control for making fishing nets or net cutting(CAM)and used in fishing gear design (CAD) as well.Author applied the experience of fishermen and developed a ranging technique of"Mirror group-numeric". The best results of symmetric cutting sequence has beenachieved.

Current Issue


Volume , No.

Table of Contents

Archive

Volume

Issue

Most Read

Most Cited

Most Downloaded