太平洋牡蛎工厂化育苗技术研究（上）

太平洋牡蛎工厂化育苗技术研究（上）太平洋牡蛎是广盐性、广温性的内湾品种。具有个体大、生长快、产量高、适应性强的特点，现已被世界沿岸国家所普遍养殖，是目前世界上养殖牡蛎优良品种之一。为了改良牡蛎养殖品系，开发利用浅海资源，福建省于１９８２年和１９８３年...     

野生和养牡蛎种群的比较摄食生理研究

１９９５年４￣５月在山东省荣成市桑沟湾用模拟现场流水法对该湾野生和养殖太平洋牡蛎种群不同大小个体的摄食生理进行了比较研究。实验结果表明，野生和养殖太平洋牡蛎种群在滤水率、选择率和吸收率等方面无明显的差异，但在保留率和摄食率等方面有明显的差异。这说明野生种群能比养殖种群更好地过滤下并摄入海水中的颗粒物。根据实验数据，用计算机模拟得出了野生和养殖牡蛎种群的滤水率与个体体重的关系为：ＦＲｗ＝２．８８２３     

外海区吊养褶牡蛎探析

近几年,由于养殖工艺的改进,内海褶牡蛎养殖操作更加简便,生产成本也大大降低,发展十分迅速。目前,内海区养殖显然已密度过大,导致牡蛎生长缓慢而且不肥,产量极低甚至绝收。为了改变这种状况,拓宽褶牡蛎养殖范围,我们在浅海10米等深线以外的海区进行吊蛎养殖试验。现将试验情况简介如下:     

福建沿海牡蛎养殖群体的多重种类特异性PCR分析和形态参数比较

应用多重种类特异性PCR方法对福建沿海养殖牡蛎的6个自然苗群体（福鼎FD、连江LJZ、福清FQ、莆田门、石狮SSZ、厦门XM）和4个人工苗群体（宁德ND、连江LJR、石狮SSR、诏安ZA）进行种类鉴定，并应用方差分析和Tukey多重比较对10个养殖群体的4个壳形态参数进行比较分析。每个群体随机选取30个个体，共分析10个养殖群体300个个体。多重种类特异性PCR分析结果显示，自然苗群体中共发现熊本牡蛎17个，其余为葡萄牙牡蛎；人工苗群体均为葡萄牙牡蛎。福建沿海养殖牡蛎种类为葡萄牙牡蛎和熊本牡蛎，其中葡萄牙牡蛎为优势种类。应用方差分析和Tukey多重比较分析结果表明，葡萄牙牡蛎的壳形态参数明显大于熊本牡蛎；FD和SSZ群体间差异不显著（P〉0．05），SSR和xM群体间差异不显著（P〉0．05）；FD与FQ、ND和LJR群体间差异显著（P〈0．05）。     

世界牡蛎养殖概况

<正> 牡蛎是一种世界性的食物,食用牡蛎已成为人们的传统。无论是高级饭店还是穷苦人家的餐桌都有牡蛎的踪迹。人们对牡蛎的喜爱促进了牡蛎养殖业的发展。除了南极洲外。世界各大洲均养殖牡蛎,养殖规模大小不一,养殖方式多种多样。1988年世界牡蛎总产量为109.4万吨,其中养殖产量为100.9万吨。从品种看,养殖产量最高的是太平洋牡蛎(Crassostrea gigas),产量达     

莱州湾金城海湾扇贝养殖海区防牡蛎附着的研究

１９９９年６￣８月，在莱州湾莱州市金城镇海湾扇贝养殖区，研究了牡蛎幼虫对海湾扇贝的附着规律。在养殖海区，离岸１５００ｍ以外纵向设立了３个定点站，近岸１５００ｍ海区作为一个观察点。结果表明，牡蛎主要为长牡蛎和褶牡蛎，６月下旬水温达到２２￣２３℃时，海水中出现牡蛎幼虫密度最高峰期（９５０个／ｍ＾２），主要为长牡蛎；８月中旬水温降到２７￣２６℃时出现次高峰（３７０个／ｍ＾２），主要为褶牡蛎。水温是监视牡     

6—二甲在氨基嘌呤诱导太平洋牡蛎三倍体—抑制受精卵第一极体释放

于１９９６－１９９７年，用６－二甲基氨基嘌呤抑制受精卵第一体体的释放，诱导太平洋牡蛎产生三倍体。选用Ｌ１６（４＾５）设计，进行三因素四水平的正交试验，６－ＤＭＡＰ肖度，设１５０，３００，４５０和６００μｍｏｌ／Ｌ；诱导时机，设１０，１５，２０和２５ｍｉｎ诱导持续时间，设１０，１５，２０和２５ｍｉｎ。试验平行重复二次。     

太平洋牡蛎控温育苗及当年养成试验

１９９２年，在５０ｍ＾３水体中，太平洋牡蛎控温育苗量为２０．２万粒／ｍ＾３。当年筏式殖６个月，亩产５６７０ｋｇ，利税６４００元平均亮高８ｃｍ以上，个体重９７．４ｇ，比常温育苗，可缩短养殖周期近１年，专家鉴定认为：本研究属国内首创，居国内领先水平。     

长江口鳗苗时空分布特征及资源利用现状研究↑（*）

１９９５～１９９８年长江河口区鳗苗数量逐旬分布１９９７年呈双峰型，其它３年均呈单峰型。峰值以１９９５年为最高；２４ｈ中２０：００至凌晨０４：００鳗苗数量相对较高。鳗苗主要分布区有从该水域北京（１９９５年）逐渐移向南部（１９９６、１９９７年），再反向北移到中部（１９９８年）的趋势。１９９５年旺发最早，持续时间最长，１９９６年旺发最迟，１９９８年旺汛期最短。水域表层水温５～６℃时仍有部分鳗苗溯河或栖息水域上层，８～１０℃时溯河数量明显增多。鳗苗数量一般大潮多于小潮，涨潮多于落潮。１９９７年和１９９８年鳗苗产量已跌入低谷，建议应合理控制捕捞强度，保证补充群体数量，恢复其资源。     

韩国牡蛎生产与贸易研究

牡蛎养殖在韩国海水养殖业中占有重要地位,韩国是世界上仅次于中国的第二大牡蛎生产国。由于苗种供应不稳定、养殖密度增加造成的环境污染等问题,韩国牡蛎产量近年来呈下降趋势。韩国与中国互为近邻,其牡蛎产业发展面临的问题和采取的对策,对中国牡蛎产业的健康发展具有一定借鉴意义。文章通过分析韩国牡蛎苗种采集、养殖过程与管理制度、流通渠道、价格与养殖生产经营情况、进出口贸易以及存在的问题和政府采取的对策等,为中国牡蛎养殖业的健康发展和管理提供参考。     

Range and diet of Eurasian otters Lutra lutra (L.) in the catchment of the River Lee (south‐east England) since re‐introduction

• 1. After re‐introduction in 1991 of Eurasian otters Lutra lutra (L.) to the River Lee catchment (England), changes in range were assessed from spraint collections in the periods 1991–1994, 1995–1997 and 1998–2000. Diet, assessed from concerted spraint sampling within the first two periods, was compared between 1992–1994 and 1996–1997, with dietary preferences assessed for the initial phase using available fish stock data for that period.
• 2. In 1991–1994, range encompassed much of the catchment, but reduced in 1995–1997 to a small area around the initial release site, when the otters were joined/replaced by natural immigrants presumed to come from a contiguous catchment. Range expanded in 1998–2000 to upper reaches of the catchment's major tributaries.
• 3. Fish, mainly cyprinids, were the major prey taken in 1992–1994 and 1996–1997. In 1996–1997, fish abundant near the initial release site became more prominent, in particular chub Leuciscus cephalus, and (upstream) species characteristic of the initial range decreased in importance.
• 4. Despite confirmed and unconfirmed sightings of females with cubs, it remains unclear whether the presence and apparent expansion of otters in the Lee catchment is the result of the re‐introduction or of natural immigration/recolonization.

Copyright © 2003 John Wiley & Sons, Ltd.     

Histopathological survey of diseases and pathogens present in redclaw crayfish, Cherax quadricarinatus (Von Martens), cultured in Ecuador

A histopathological survey of commercial farms in Ecuador culturing redclaw crayfish, Cherax quadricarinatus (Von Martens), revealed the presence of different viral, bacterial and non‐infectious pathologies. A total of 536 animals from 27 different farms were analysed during a 3‐year period; 25, 154 and 357 specimens in 1995, 1996 and 1997, respectively. From the total sampled, a virus referred to as Cherax quadricarinatus bacilliform virus (CqBV) had a prevalence of 44% in animals examined during 1996 and 33% in 1997. A rickettsia‐like organism (RLO) was detected in five specimens sampled from three different farms in 1995. This RLO was detected in 36 and 12% of samples analysed in 1996 and 1997, respectively, and was the infectious agent most frequently associated with mortalities above 60%. Co‐infection by CqBV and the RLO was observed in 18 and 3% of the crayfish examined in 1997 and 1998, respectively. Five specimens out of 25 examined presented no sign of an infectious agent during 1995. The proportion of specimens testing negative by histopathology to known or suspected infectious agents was 25 and 32% in 1996 and 1997, respectively. Although different infectious agents were present in cultured crayfish, farms in general had overall survivals higher than 50% in most ponds. Other conditions observed included an intracellular prokaryotic organism, iron granules in the R and F cells of the hepatopancreas, different species of epibionts on the surface of the gills and body, and two cases of haemocytic enteritis. Two cases of serious mortality in different farms were associated with the presence of Cowdry type A inclusions, pyknosis, karyorrhexis and haemocytic infiltration in the stomach hypodermis and the antennal gland.     

Evaluation of large-scale stocking of early stages of brown trout, Salmo trutta, to angler catches in the French–Swiss part of the River Doubs

Around 500 000 brown trout, Salmo trutta L., alevins are stocked annually in the 24‐km section of the River Doubs under study. All the alevins stocked in the period 1994–1996 were identifiable by fluoromarking their otoliths with tetracycline chlorhydrate. Anglers' catches, between June 1997 and September 1998, comprised trout aged 1+ to 7+ , but most (90% +) were 2+ to 3+ or 4+ , with the majority at 2+ and 3+. There was no significant difference in the size for a given age between marked and unmarked angled trout. The contribution of stocked fish in anglers' catches was around 22% for the 1995 cohort. The contribution of stocking (cohorts 1994 to 1995–1996) to the 1998 catches was around 23% (95% confidence limits: 19–27%). The estimated recapture rate was three to four trout per 1000 alevins stocked for the 1995 cohort. The major contribution (78%) of natural recruitment to anglers' catches suggests that the fishery management based on natural recruitment is still realistic in this part of River Doubs.     

The effect of water temperature on habitat use of young Pacific bluefin tuna Thunnus orientalis in the East China Sea

ABSTRACT:   Immature Pacific bluefin tuna Thunnus orientalis , tagged with archival tags, were released near Tsushima Island in the East China Sea (ECS) during the winters of 1995, 1996 and 1997. Geolocations were estimated using the archival tags from recovered fish. These data, together with sea surface temperature (SST) data from satellite remote sensing, are used to describe the habitat used by these bluefin in the ECS from January to June for 3 years (1996, 1997, 1998), and to asses the effect of water temperature on fish distribution and movement. The results indicate that their geolocations ranged from the area north-east of Tsushima Island to the offshore area in the south-west. However, the area of highest density differed among years, being furthest south in 1996 and furthest north in 1998. The differences were probably caused by changes in SST associated with La Niña (1996) and El Niño (1998) events. Another densely populated area was identified in offshore waters of latitude 28–30 °N in 1996 (only), on the cold side of the Kuroshio front. These fish may have been prevented from moving northwards by an intrusion of Kuroshio water of approximately 25°C into the region immediately to the north-east.     

Early- to late-summer population growth and prey consumption by age-0 pollock (Theragra chalcogramma), in two years of contrasting pollock abundance near the Pribilof Islands, Bering Sea

Acoustic survey data were used to estimate the abundance and distribution of age-0 walleye pollock and zooplankton near the Pribilof Islands, Bering Sea, nursery area at two time periods in two consecutive years: the beginning of August, and mid-September, of 1996 and 1997. The 1996 pollock year class ultimately produced a large adult cohort in the eastern Bering Sea, while the 1997 year class produced a below-average adult cohort. Acoustic densities of age-0 pollock were significantly lower in August – and declined more strongly from August to September – in 1997 than in 1996, indicating that the trend to adult cohort strength was already set by August. Diet composition analyses revealed that age-0 pollock ate a much higher proportion of euphausiids in 1997 than in 1996, despite lower acoustic abundance of euphausiids in 1997. We infer that in 1996, age-0 pollock experienced greater feeding success by August, with high concentrations of copepods available for smaller fish to consume, and high concentrations of euphausiids available for larger individuals. In 1997, age-0 pollock had lower body condition in August and may have been limited by the availability of small (<2 mm) copepods. Bioenergetic modeling of prey consumption did not indicate a likelihood that age-0 pollock would begin to deplete euphausiids until late August in 1996, and not at all between August and mid-September in 1997.     

Preliminary Studies of Artificial Spawning of Channel Catfish as Male-Female Pairs or All-Female Groups in Recirculating Systems

Abstract— Channel catfish Icralurus punctatus are commonly spawned for research purposes by pairing of a hormonally treated female with a male in flow-through aquaria. A technique that allows hormonal induction of ovulation in females without pairing would accelerate genetic improvement and production of hybrid catfish. Over a 3-yr period (1994, 1995, and 1996) we conducted a series of trials to demonstrate the potential for artificial spawning in recirculating systems, and in 1996 we included trials with grouped females in addition to male-female pairs. Females were induced to spawn with injection of synthetic leuteinizing hormone-releasing hormone, and those that ovulated were stripped and the eggs were artificially fertilized. During 1994 and 1995, all fish were spawned by pairing, and in 1996, half of the females were spawned by pairing and half were grouped in tanks without males. Spawning success (percent of females that produced eggs), latency (time between injection and ovulation), and percent fertilization were observed for the paired and grouped trials. Spawning success was 36% in 1994 (N= 36). 22% in 1995 (N= 54). 41% in 1996 (N= 27). and 58% for grouped females (N= 26). The latency period was 113 ± 69 h in 1994, 109 ± 57 h in 1995, 44 ± 8 h in 1996, and 50 ± 9 h for grouped females. Percent fertilization was 16 ± 26% for eggs stripped in 1994, 72 ± 25% in 1995, 43 ± 20% in 1996, and 16 ± 37% for grouped females. In 1995, water quality problems were associated with high mortality of females (24 of 44 females; 4 of 44 males). The metabolic demands of final oocyte maturation in combination with methemoglobinemia caused by high nitrite levels could account for the increased vulnerability of females. These trials indicate that with adequate biofiltration, artificial spawning is possible in recirculating systems and with females grouped rather than paired. Further research on hormone dosage and timing of egg stripping will increase the utility of grouped spawning of channel catfish.     

Comparison of freshwater and marine performances of all‐female diploid and triploid Atlantic salmon (Salmo salar L.)

The performance of all‐female diploid (AF2N) and triploid (AF3N) Atlantic salmon were compared in fresh water, under commercial production conditions in 1995 and 1996 year classes. The performance of the 1996 year class was also assessed for 14 months in a commercial sea farm. Freshwater mortality was higher in the triploid groups. The majority of losses occurred in the early stages of egg development and during the first feeding period, when the incidence of non‐feeding fry was consistently higher. In growth studies, although diploid fry were significantly heavier during first feeding there were no significant differences in weight between groups some 8 months after fertilization or in presmolt growth periods from February to April in 1996 and 1997. Smolting rates were high (range 93.5–95.3%) and the incidence of deformities was low (< 1%) in both groups. Marine survival was lower in the triploid group, largely as a consequence of higher losses sustained during a period of chronic stress, when triploid losses were 9% higher. Growth patterns were similar for the first 11 months in sea water. Although graded triploid salmon were heavier in January 1998 (AF3N 1.62 ± 0.033 kg, AF2N 1.46 ± 0.36 kg, P < 0.05), when the fish were harvested in May 1998 diploid salmon were significantly heavier than triploid salmon although there was no significant difference in weights after evisceration (AF3N 2.40 kg ± 0.04 AF2N 2.49 kg ±0.03). The increase in weight of the diploids between winter and harvest reflects the growth spurt that occurs in maturing fish in the spring. Overall yields of triploid salmon in salt water were lower as a result of inferior survival.     

Growth patterns and plasma levels of testoterone, 11-ketotestosterone, and IGF-1 in male Atlantic halibut (Hippoglossus hippoglossus) from juvenile stages throughout sexual development

This study was initiated to establish basal data on growth patterns, as well as hormonal regulation of growth and maturation in male Atlantic halibut. Weight increase was approximately linear until one year before first sexual maturation, when growth rates decreased. In spawning fish, somatic growth was arrested or slightly negative. Plasma androgen levels reflected sexual maturation. A slight elevation of androgen levels was apparent one year before first maturation. Plasma IGF-1 levels fluctuated throughout the study and were correlated with body weight during the winter/spring of 1995, 1996, and 1997.     

Interannual variability in stock abundance of the neon flying squid, Ommastrephes bartramii, in the North Pacific Ocean during 1979–1998: impact of driftnet fishing and oceanographic conditions

Variability in catch-per-unit-effort (CPUE) was examined for the autumn cohort of Ommastrephes bartramii collected with research driftnets during 1979–1998 along five longitudinal transects passing through the Subarctic, Transitional and Subtropical Domains in the North Pacific. CPUE was generally low during the period of intensive commercial driftnet fishing (1980–1992) and increased following the 1992 moratorium on the use of large-scale driftnets. However, CPUE levels were low for the cohorts hatched in 1992 and 1996 (captured in subsequent years owing to a one-year life of O. bartramii ) that experienced low sea surface temperatures from hatching to recruitment. Among similar-aged squid collected from 180° and 179°30'W in June, mantle lengths were significantly greater in 1997 than during 1995–96. These findings suggest that the driftnet fishery and sea surface temperatures from hatching to recruitment strongly affected stock abundance and possibly growth.