2006 Vol. 2 No. 1
Based on the theory of fishery resources assessment and the characteristics of fishery stock enhancement and releasing, the method was put forward to assess the enhancement effect of fishery stock by calculating the biological statistics amount of population. The growth parameters and natural mortality coefficients of the enhancement species that hadn′t been built the growth equations were estimated and the suitable enhancement amounts of all enhancement species were estimated by choosing the suitable model of fishery stock assessment. The method to confirm the recapture amount from the enhancement seedlings of the total catch was pointed out. The formulas to estimate the fishing mortality coefficient, and the surplus amount, the recapture amount, the recapture rate as well as the recapture benefit from the enhancement population by the time series were developed.
The ulcer disease of marine cage-cultured large yellow croakers, Pseudosciaena crocea (Richardson) in Zhejiang Province was investigated in this paper. A bacterial strains (824-1), isolated from diseased large yellow croakers, was proved to be the pathogenic bacterium by artificial infection experiments, and identified to be Vibrio alginolyticus by the morphological and cultural features, physiological and biochemical characteristics. The extracellular products of strain 824-1 were studied by cylinde-plate method. The results showed that the extracellular products included amylase, gelatinase, lipase, casease, haemolysin, lecithinase and chitinase, but didn′t contain urease. The sensitivity of the bacterial isolate to 35 antibacterial agents (20 chemotherapeutants and 15 Chinese herbal medicines) was evaluated. It revealed that 3 chemotherapeutants (Co. SMZ, Sulfarmehoxazole/Trimethoprim and Gentamycinum) and 4 Chinese herbal medicines (Pericarpium granati, Rhizoma sanguisorbae, Fructus schizandrae, Rheum officinale) were examined as the most effective antibacterial agents.
By means of the vertical polyacrylamide gel gradient electrophoresis, four isozymes (EST, LDH, MDH and SOD) from five tissues (kidney, liver, eye, muscle and heart) of hybrid Tilapia were studied. And their locis and phenotypes were also analyzed. The results showed that four isozymes presented obvious tissue specificity. EST isozymes coded by seven locis′s genes; the protein bands of LDH isozymes were more than 5 which LDH phenotypes of most of the typical teleosts have; the phenotypes of both SOD and MDH had two types, mitochondria type and supernatant type, in hybrid Tilapia.
Random amplified polymorphic DNA (RAPD) technique was employed in analyzing the specific genetic markers of seven pearl oysters including Pinctada maxima, P.margaritifera, P.nigra, P.albina, P.fucata, P.chemnitzi in the genus Pinctada and Pteria penguin in the genus Pteria. Twenty one primers of S series and OPM series were screened. Four primers produce 57 loci. The average number of loci amplified by each primer is 14.3. The mean number of fingerprints per species amplified by each primer is 4.9 with length varying from 250 to 2 000 bp. Primer S10 generate diagnostic markers for each species and can distinguish the seven species studied simultaneously. The other primers screened in this study can discriminate two or more species from the others.
Field experiments were carried out from June to October of 2003 and March of 2004 to monitor some environmental factors such as water velocity, pH, dissolved oxygen inside and outside scallop culture lantern net and long-line culture area by using YSI6600 water quality monitoring instrument, SD6000 automatic water velocity and gypsum in Sungo Bay. The results showed: (1) the average seawater velocity inside the lease area were decreased from 7.50±5.29 to 5.28±3.23 cm · s-1, decreased by 29.6%. And the average chlorophyll a concentration was decreased from 2.48 to 1.19 μg · L-1, decreased by 52%. (2) The average chlorophyll a concentration was 4.13 and 4.60 μg · L-1 respectively for the water samples inside and outside the lantern nets at the beginning, but decreased to 1.57 and 4.20 μg · L-1 respectively in the end. pH kept stabile outside the lantern nets, but it declined continuously inside, and reached the lowest value (7.46) in September. During the blooming period of fouling organisms, there was significant difference of dissolved oxygen outside and inside the nets. Compare to 7.04 mg · L-1 outside the lantern nets, the dissolved oxygen inside is only 5.13 mg · L-1, decreased by 27.1%.
A study was undertaken to evaluate the effect of the densities on the energy conversion efficiency of Litopenaeus vannamei in June~July, 2004. The experimental juvenile shrimps of 5.0 to 6.0 cm per individual and 2.75 to 3.20 g per individual were reared in 9 tanks (0.10 m3) for three weeks with three different densities, 50, 150 and 400 ind · m-3, respectively. Each treatment was triplicate. The feed ratio was 4% to 7%. The results showed that the energy conversion efficiency were 19.31%±1.01%, 22.56%±2.69% and 15.31%±2.49% in 50 ind · m-3 group, 150 ind · m-3 group and in 400 ind · m-3 group, respectively. The highest energy conversion efficiency was observed in shrimp reared in 150 ind · m-3 group. It indicated that the energy conversion efficiency was significantly affected by density.
The experimental effects of accrete organisms of artificial reef material were put up. The results showed there were 20 species of 17 families with dominated by Balanus reticulates on the artificial reef material after 3.5 months of immersion, and 36 species of 31 families with dominated by Perna viridis after 20.5 months of immersion. The accrete effects of concrete slab, wood board, iron plate and plastic board were better than other material. The accrete effects of rough concrete slab, wood board with rustproof paint, iron plate with green paint and gray plastic board were the best among the same material.As being made from iron-wood or ferroconcrete, the most fishing vessels are suitable used for artificial reef material.
Artifical reproduction of Babylonia areolata and B.formosae were taken in this study. The egg capsules of this two Babylonia were held in water temperature 23.6±1.1℃, the hatching time for B.areolata was 7 d and the shell length of firstborn larvae was 482.7±10.6 μm, while the hatching time for B.formosae was 8 d and the shell height of newly hatching larvae was 398.2±10.3 μm. The larvae were reared at 0.1~0.2 ind · mL-1 in water temperature 25.2±0.9, the growth rate of larval shell height for B.areolata was 33.6 μm · d-1 and larvae began metamorphosis when the larval shell height reached 1 323.9±118.6 μm after rearing 18 d, while the growth rate of larval shell height for B.formosae was 25.3 μm · d-1 and larvae began metamorphosis when the larval shell height reached 955.5±174.4 μm after rearing 16 d. The juveniles were reared at 2 100 ind · m-2 in water temperature 26.5±0.7℃, the growth rate of shell height for B.areolata and B.formosae were 0.21 and 0.20 mm · d-1, respective.
The effect of temperature on digestive enzymes activity of yellow fin black porgy (stomach, hepatopancreas and intestinal) was studied in this experiment. The results of specific activity of protease at different temperature (15, 20, 25, 30, 35, 40, 45, 50, 55, 65℃) indicated that the optimum temperature for protease in yellow fin black porgy were 45℃ in stomach, 40℃ in hepatopancreas and 45℃ in intestinal canal; the optimum temperature for amylase were 40℃ in stomach, 35℃ in hepatopancreas and 30℃ in intestinal canal; the optimum temperature for lipase were 40℃ in stomach, 45℃ in hepatopancreas and 40℃ in intestinal canal. In range of 35 to 45℃, the activity of digestive enzymes (protease, amylase, lipase)in stomach, hepatopancreas and intestinal canal of yellow fin black porgy are in a higher level.
To find out a way to process a large number of offal of tilapia, preparation of seafood condiment with offal of tilapia by enzymolysis was studied. Through the orthogonal experiment, the optimum conditions for the hydrolysis by addition of bromelain and flavourzyme were determined to be natural pH, 50℃, the ratio of solid to liquid was 1∶ 1. Bromelain was added first with concentration 2 250 U · g-1 and duration of hydrolysis 3 h; then flavourzyme was added with concentration 750 U · g-1 and duration of hydrolysis 2 h. The degree of hydrolysis was 80%. The hydrolysate solution (30%) as main material, and starch (6.5%), xanthan gum (0.2%), sauce (8%) as supplement materials, under the scientific mix to produce nutritious and good taste condiment. The produces were qualified to the national sanitation standard.
The PCR technique was used to analyze the mtDNA control region sequences in 20 individuals of P.monodon in Shenzhen′s sea area. A series of nucleotide fragments with about 650 bp were obtained. The PCR products were purified and sequenced. As a result, a series of 526 bp nucleotide sequences of partial control regions were obtained. The 20 sequences were arranged in counterpoint by Clustal _ X software. And then, comparing the control region fragments with each other by Mega software, 114 sites were variable among all the partial mitochondrial control region sequences including 84 parsimonious message sites and five deletion / insertion sites. The relative genetic distances were calculated among individuals by "Pairwise distance" method of Mega. The results indicated that the differentiation of the 20 sequences ranged from 0.010 to 0.054 and showed 20 kinds of haplotypes among 20 individuals. The UPGMA and NJ phylogenetic trees were established by the cluster analysis. The number of polymorphic sites (S) was 114; the nucleotide diversity (Pi) and the average number of nucleotide differences (K) were 0.05278 and 27.500, respectively. It can be concluded that the variation in mtDNA control region sequences of P.monodon in Shenzhen′s sea area was greater relatively. So the genetic diversity of P.monodon in Shenzhen′s sea area was higher relatively. As a result, mtDNA control region sequences can be used to scan genetic diversity of populations.
Based on experiments done in Tokyo Bay from 1995 to 2000, the results show the mesh size selectivity of pots with mesh size 21.0, 18.1, 15.5, 13.6, 11.6 cm is nearly zero as 0 < l < 25.50 cm, 0 < l < 22.50 cm, 0 < l < 18.50 cm, 0 < l < 18.50 cm, 0 < l < 16.50. The selectivity increases as mesh size gets larger as 25.50 < l < 35.50 cm, 22.50 < l < 32.50 cm, 18.50 < l < 27.50cm, 18.50 < l < 26.50 cm, 16.50 < l < 24.00 cm. As l > 35.50 cm, l > 32.50 cm, l > 27.50 cm, l > 26.50 cm, l > 24.00 cm, the selectivity gets to 1.00. By the theory of AIC, the influence of cover net is notability when the mesh size of cover net is close to that of experimental net and single curve model fits better. The 50% selectivity of is 1.11, the selectivity range is 0.52. As 0 < < 0.55, selectivity is nearly to zero and as 0.55 < < 1.60, selectivity increases as gets larger. As > 1.60, the selectivity is 1.00.
The technology of instant fried fish skin was studied, using the castoff of tilapia fillets, in order to improve the economical efficient and promote the development of aquaculture. Through the tests of seasoning formula, fried temperature and sensory evaluation, the optimal technological condition was determined.
Deep-water net cage culture started relatively late in China. The first set deep-water net cage was introduced from foreign by Hainan province in 1998. After the deep-water net cage culture, coastal provinces and cities took a great upsurge in deep-water net cage industrialization manufacture for its high benefit and well performance. The first set independent intellectual patent "HDPE circular double-float over and under type deep-water anti-storm net cage" was developed in 2001. Its fish yield reached 14 kg per m3 water. According to inadequacy statistic, there were over 2 300 units deep-water net cages, 299 m3 culture water body, 49 140 tons theoretic yield in China by the end of 2004.With the rapid development of deep-water net cage, the problem appeared gradually. The investment of the deep-water net cage culture system was big for the first time. The net cage industry didn′t form a complete set perfectly. Such as auxiliary facility of deep-water net cage, culture technology and main culture breed, culture overall arrangement and culture capacity, feed and disease prevention and cure, product processing and circulation, and so on, restricted the development of deep-water net cage directly and induced the high vacancy rate of deep-water net cage culture facility which was up to more than 1/3.How to settle the existing problem of industrialization development of deep-water net cage? Implement of the high technology integration of deep-water net cage, accomplishment of the culture industry chain link, establishment of the complete newly culture mode, linkage of the policy for fishery industry structure rectify are the important research items of the deep-water net cage industry.
This paper reviews methods and application of feeding behavior following aspects: (a) stomach contents analysis; (b) effects of starvation on feeding behavior; (c) relationship between feeding behavior and the morphological characteristic of the digestion organs; (d) effects of ecological and physiological factors on the feeding selectivity of fish. Consumption, prey speed of starvelling larvae and Ivlev index I were also analyzed.
The aminoglycosides are widely applied in aquaculture as veterinary medicine. It has become increasingly urgent to realize the importance of their residue in food and detection. The major part of this article comprises a comprehensive review of current detection, including microbiological assay, instrumental analytical method, immune analytical method, and predicts the research and development for the future.