Abstract:Methyl farnesoate ( MF) biosynthesized and secreted by mandibular organ( MO) in Chinese mitten crab ( Eriocheir sinensis) , including precocious and normal crabs, was investigated by using in vitro radiochemical method. It was found that MF biosynthesis rates of precocious crabs ( female and male) in September were about two times higher normal juvenile crabs, and reached the peak levels in October or November( 1st autumn) . After that, it decreased signif icantly , but GSI continued to increase during the winter. In normal crabs, MF biosynthetic rates maintained much lower levels from September( 1st year) to April ( 2nd year) w ith undeveloped gonads. Since June ( 2nd year) , MF biosynthetic rate increased rapidly. In October ( 2nd year) , MF biosynthet ic rates in both female and male were beyond the peak levels of precocious crab. In November, MF decreased signif icant ly, while gonads reached the end of stage .. The results indicated that MO development in advance in the precocious crabs( female and male) , made large amount of MF to be biosynthesized and secreted and then stimulated ovaries and testes development and maturation. That is the endocrine factor for causing precociousness of crab.

Abstract:The specimen used in this study was 42 f ish of seven groups of ayu, Plecoglossus altivelis, and they should be one clone induced art ificially or samples obtained from the eggs of amphidromous form inseminated by the sperm of the individuals of the same clone. The genomic DNA were extracted from caudal fin of adult or all f ish of larva and microsatellite DNA were amplified by PCR. The genotypes of individuals were identif ied according to electrophoretic patterns of the products of PCR. The results suggest 22 fish of ò, ó, . and × groups be one clone, because they have the same genotypes at two loci of Pal- 1* and Pal- 2* respectively. 10 f ish of × group were gynogenet ic diploids induced successfully and one clone. 1 f ish of . is other type fish. 19 f ish of . and . groups were offspring of ., ò or ó and amphidromous form.

Abstract:This paper report s the feeding habits of Mystus guttatus in the Pearl River with natural resources investigation. The reports include feed fullness, feed composition, frequency of feed occurrence and variation of feed composition in dif ferent seasons was also studied. The investigation result shows that the feed of Mystus guttatus in the Pearl River are crustaceans, insect, annelida, f ish and pieces of plant . Among them, the crustaceans and insect s are the main feed, the emergence frequency is 78. 6% and 45. 8% respectively. In different seasons, the variety of feed composition is markedly different , and no pause of feeding. The feed of Mystus guttatus changed with the different body length of the fish. The first feed change period was at about 170mm body length and the second at about 240mm body length. It is getting simpler as Mystus guttatus grows up.

Abstract:The food item were identified using percentage f requency of occurrence. By analysis of food composition, 6 species of eels in East China Sea and Yellow Sea are bottom fishes and belong to 3 types of food habit: Dysomma anguillaris, Rhynchocymba ectenura and Rhynchocymba nystromi are benthophagous fishes; Astroconger myriaste and Pisoodonophis cancrivorus are benthophagous-nektivorous f ishes; Alloconger anagoides is nektivorous f ish. The result s suggested that there is not food competition between Dysomma anguillaris, Rhynchocymba ectenura and Astroconger myriaste. It is suggested that percentage of energetic composition of diets be employed to analyze feeding habits. However, further collection of basic data is required.

Abstract:In April 1998 and May 1999, two survey cruises were carried out in seven coral reef waters of the Nansha Islands-Zhubi, Nanxun, Dongmen, Meiji, Chigua, Yongshu and Huayang reef by handlining, longlining and gillnetting. For total f ishing efforts input in the survey, handlining was 357 hook#h, longlining 4 220 hooks, and gillnetting 1 9750m. For f ishing efforts per operation, handlining was 6- 18 hook#h, longlining 40- 480 hooks, and gillnetting 40- 2 400m. A total of 180 species were caught and their catch was 1 860 ind 1 540. 4kg, among which, handlining caught 102 species 1 225 ind 196. 8kg, longlining 36 species 82 ind 1234. 7 kg, and gillnetting 70 species 553 ind 108. 9kg. For mean catch rates and CPUEs per reef , handlining was 351. 0 ind# (100 hook# h) - 1 and 51. 9kg#( 100 hook #h) - 1, longlining 2. 6 ind# ( 100 hooks) - 1 and 39. 0kg# ( 100 hooks) - 1, and gillnetting 51. 4 ind #( 1000m) - 1 and 7. 5kg #( 1000m) - 1. Both catch rate and CPUE of gillnetting in reef f lat were higher than shallows and depths of reef margin, with 170. 3 ind#( 1000m) - 1 and 23. 1kg# (1000m) - 1. Major commercial species caught included sharks, morays, groupers, snappers, pigface breams, parrotind and wrasseses et al. Huayang and Yongshu reef are abundant in reef fish resources and have higher exploitation potential. Dongmen, Meiji and Nanxun reef are lower than Huayang and Yongshu reef in usable abundance of reef ind, but also have production value. Chigua and Zhubi reef basically have no fishing value.

Abstract:Based on the basic biological survey on captured hairtail, Trichiurus haumela in the East China Sea and the Southern Yellow Sea from 1986 to 2000, the hairtail resource in the East China Sea was assessed by using generation analysis and the variation of its productivity and recruitment was discussed. A relationship between environment and recruitment was given through selected environmental factors. Results showed that the minimum body length of maturation, the average body length and the body weight of spawning parents declined, so did the egg diameter; while individual productivity increased, with the ever-developing f ishing power. After the implementation of Summer No-Fishing Season system, the quantity of recruiting co lony increased a lot , and the recruiting quantity per unit of parent s increased by 45% - 60% . That clinched that the Summer No-Fishing Season system had a very good ecological effects. The recruiting quantity was directly proportional to the number of parents, water temperature and most importantly the period of the season. The parent fish in the East China Sea is still insufficient, so it is imperative to further decease fishing power.

Abstract:Based on the data f rom four trips surveyed, the paper made analysis on the stock of pelagic sharks in the tropical Atlantic Ocean. Fishery data on pelagic sharks are obtained from International Commission for Conservation on Atlantic Tunas( ICCAT) . Results shows that there are 13 pelagic sharks occurring in the Atlant ic longline catch and dominant species are short mako ( Isurus oxyrinchus ) and blue shark( Prionace glauca ) . The shortfin mako catch per unit of ef fort( CPUE) of the first , second and fourth trips tend to decline, with the values of 0. 3502, 0. 1754 and 0. 0642 per thousand hooks respectively. The blue shark catch per unit of effort( CPUE) of preceding three trips fluctuated between 5- 7 per thousand hooks. The blue shark CPUE( 0. 8 per thousand hooks) of the fourth trip declines dramatically. The paper reported the catches of shortf in mako and blue shark caught by China tuna f leet since 1993. The paper also estimates the yearly average biomass of two dominant sharks based on the f ishing mortality and catch data, and discusses affecting factors for shark CPUE and stock status.

Abstract:After the spatial and temporal distributions of squid, Ommastrephe bartrami catch and f ishing ground in North Pacific Ocean f rom 1995 to 2001 are analyzed by use of the methods of related coef ficient and gray relationship assessment , the paper indicates that the main f ishing ground is distributed in the waters of 145bE- 148bE and 153bE- 161bE, which occupy 70- 85 percent of total catch. From the point of latitude, the f ishing ground is mainly located in the waters of 40bN- 43bN before 1999, while in the waters of 39bN- 41bN and 43bN - 45bN in 2000 and 2001 respectively. Based on the related coefficient, the fishing ground and its catch distribution in 2000 and 2001 changed greatly , especially in the waters west of 160bE and east of 170bE, but they had not changed before 1999. On the basis of gray relationship assessment , the squid resources in 1998 were in the best level, the resources in 2000, 2001 and 1996 were in the lower level, those in 1999, 1995 and 1997 were middle, which comply with actual production and ocean environment. The fall of squid resources in 2000 and 2001 may be related with the reduction of population distributed in the waters of 150bE- 160bE.

Abstract:According to the biological data of 1146 snails R . borneensis which were collected every month f rom May 2001 to May 2002, their biological observation data were comprehensively analyzed in the open country . The resulst indicate that this kind of snail Retusa borneensis , is of quantitative superiority in interval region of tidal zone with distinctive difference in vertical distribution. Preferring sun light, it always appears and disappears at the surface of arid sea-tidal flat. It s habitats are regulated by the distribution of tidal, sunshine and bait. It is evident collective reproduction w ith breeding period from May to September. Especially it teems in June and July and lives only one year and dies after reproduction. The young snails first appear at the late June. It s growth rate reaches the peak during July to September and April to June of next year. From November to January of next year, it almost stops growing. It is the stoutandest and strongest in the July of next year. The height and the width of the snails are linear interrelated, with equation: B = 0. 3224+ 0. 4916H ( r = 0. 9770) . The height of the snails and their fresh and dry weight are functional related, with equation: Wwet= 2. 1 @ 10 - 4 L2. 8352( r = 0. 8448) , Wdry= 2. 97 @ 10- 4L 2. 2803( r = 0. 8939) . In the end, the matter of the opportune moment to kill the snails is also discussed.

Abstract:Though the Chinese fishing fleets had successfully harvested flying squid in the North Pacific in recent years, they met the great problem in 2001. In order to illustrate the reason of severer reduction in harvest, the environment structure, the dorsal mant le length compositions of flying squid and the stomach contents of some harvested squid have been analyzed. The wandering of Kuroshio in south of Japan, the puniness of Kuroshio, and the cooler of the water in the northern part of the ocean are the known disadvantages in hydrologic structure. The reduction in abundance of f lying squid in the western part of the ocean was the important reason for declining of the catch in the area. The poor food abundance happened to be another unfavorable factor. But in the eastern part of the ocean, what worked most on the failure of production was the poor acknowledge of the schools, which caused an earlier withdrawal of f ishing vessels from the waters when there were some difficult ies in searching of the schools.

Abstract:A study has been carried out on growth characters of industrially farmed turbot, Scophthalmus maximus L. The results showed that the maximum growth rate of 13. 52g ..d - 1 appeared on two..year..old f ish and the average growth rate is 6. 84g..d- 1. The body weight could reach more than 500g after 250 days, 1000g af ter one year, and 3000g after 2 years. The relat ionship of the body length and the weight isW= 0. 0314SL3. 0972, and the relationship of total length and body length is TL= 1. 1839SL+ 0. 5012; BD= 0. 8512TL- 1. 0358 showed the relationship between body depth and total length. Von..Bertalanf fy equation is Lt = 49. 2294 ( 1 - e- 0. 7106 ( t 0. 2211) ) , Wt= 6186. 2350( 1- e- 0. 7106 ( t 0. 2211) ) 3. 1609, the growth f lection point of the body weight locates on 1. 3984, the industrially farmed turbot should be harvested after the growth flection point , which matches both economy principle and consumption habit. In addition, growth difference was analyzed between nature and farmed groups by growth character index .... integrated with K and L.. . The result s showed that farmed group grew significantly faster than natural group since there are better conditions under artificial control.

Abstract:The physico-chemical characteristics and seasonal changes of different waters in Heilongjiang system were studied from May to September, 2001. The results are as follows. Heilongjiang system has good water quality, tansparency mean 41cm, pH value 7. 45, dissolved oxygen was rich, and the water type belongs to CCa I and soft water. The contents of major nutrient elements were high, the content of TN in water was 0. 483mg#L- 1, and the content of phosphate was lower. There were hydrobgial and seasonal changes of the physico-chemical characteristics of different waters, but changes did not occur markedly. The water quality changes of different seasons and major physico-chemical factors, nutrient state and the correlation were discussed and assessed. This study provides a theoretical basis for fishery and sustainable use of f ishery resources.

Abstract:With normal regulat ions method, the digestive tube indices of Mystus macropterus such as ratio of intestine gut length to body length was 0. 531 ? 0. 006 while the ratio of stomach, intestine gut, hepatopanceras or viscera weight to body weight were 0. 014 ? 0. 006, 0. 017 ? 0. 003, 0. 0084 ? 0. 0029 and 0. 070 ? 0. 011, respectively . The regression of body weight with body length was Y= 0. 1238X2. 8388( r = 0. 9949, P < 0. 01) . The pH value of stomach, anterior intestine, middle instestine, posterior intestine and hepatopancreas were 3. 0- 3. 8, 6. 6- 7. 4, 7. 2- 8. 2 and 7. 2- 7. 9, respectively. At the same time, the activities of protease were middle instestine> anterior intestine > hepatopancreas > posterior intestine> stomach; the activities of amylase were anterior intestine> posterior intest ine> middle instestine> hepatopancreas> stomach. The crude protein of muscle and whole body were 62. 09 ? 3. 8% and 68. 28 ? 4. 6, repectively ; the crude fat were 15. 33 ? 1. 7 and 21. 87 ? 2. 9, repectively. The essential amino acids accounted for 40. 76% of total amino acids and the delicious amino acid accounted for 29. 70% of total amino acids. It was indicated that the nutritive value of Mystus macropterus is higher than that of the common carp and grass carp.

Abstract:The observation indicates the head length of sperm 6. 5..m, the top of broad-head 1..m, the lower part of head 1..m, neck 0. 5..m and tail length 16..m under scanning electron micro scope ( SEM) . The sperm.. s tail has axle and two wings. There are 6- 9 micropyles on the animal pole of the mature egg of Acipenser schrenckii , all of which are able to accept sperm. The micropyle.. s outer diameter is 18..m and inner 6..m. There are micropyle cells f illing in micropyle. The micropyle cells disappear after fert ilization 10s. The micropyles are sealed with membrane after sperms penetrating. The fertilization is got through about in two minutes. The sperms not penetrating egg are blocked on the way. Amur sturgeon.. s sperm and mature egg are different from those of other sturgeons.

Abstract:Nitric oxide ( NO) is a highly reactive, labile gas produced by the enzymatic conversion of L - arginine by nitric oxide synthases NOS. In mammals, NO mediates multiple physiological processes from cardiovascular control to neural transmission. Three NOS isoforms neuronal, inducible and endothelial have been cloned, sequenced and characterized from several mammalian species. nNOS isoforms were characterized from adult grouper ( Epinephelus coioides ) by using RT- PCR with degenerate oligonucleotide primers designed against a portion of the mammalian NOS gene that codes for the calmodulin - binding region, this region was chosen because it is highly conserved among NOS sequences to date and is a functionally important region of NOS proteins. A partial gene sequence of 377 bp corresponding to mammalian nNOS is obtained. This sequence showed 82% - 83%, 85% - 93% homogeneity with that of mammalian and the other f ish respectively. The deduced amino acid of E . coioides show s high identity with that of mammalian ( 92% - 93%) , and the other fish ( 93%- 99% ) . Phylogenetic analysis of these sequences conf irms the conserved nature of NOS, particularly of the calmodulin- binding domains.

Abstract:The effect were examined in vitro of the ionic composition of the incubation medium on the acquisition and loss of the potent ial for motility were exammined by the spermatozoa of the Japanese eel ( Anguilla japonica) . Milt was obtained from male eels that had been artif icially matured by repeated injections of HCG. The percent motility increased with increasing concentrations of Na+ 、K 、Ca2 and Mg2 ions ( 0- 400mmol#L- 1 ) and decreased with concentrations of those ions( 500- 1000 mmol#L- 1) , eel sperm was collected and then incubated w ith nitric oxide donor-sodium nitroprusside in different doses. Eel sperm motility was accelerated or maintained at low dose of sodium nitroprusside ( SNP) ( 10- 10- 10- 6mol#L- 1) , while marked inhibition effects were found at high dose ( SNP> 10- 5mol#L- 1) . Nitric oxide affect s the motility of eel sperm in dose- dependent manner. The eel sperm of maturation by SPN and HCG was used for fertilizing three batches of eggs and hatchability is higher than the sperm of maturation by HCG.