Effect of timing of count events on estimates of sea lice abundance and interpretation of effectiveness following bath treatments

Effectiveness of sea lice bath treatment is often assessed by comparing pre‐ and post‐treatment counts. However, in practice, the post‐treatment counting window varies from the day of treatment to several days after treatment. In this study, we assess the effect of post‐treatment lag time on sea lice abundance estimates after chemical bath treatment using data from the sea lice data management program (Fish‐iTrends) between 2010 and 2014. Data on two life stages, (i) adult female (AF) and (ii) pre‐adult and adult male (PAAM), were aggregated at the cage level and log‐transformed. Average sea lice counts by post‐treatment lag time were computed for AF and PAAM and compared relative to treatment day, using linear mixed models. There were 720 observations (treatment events) that uniquely matched pre‐ and post‐treatment counts from 53 farms. Lag time had a significant effect on the estimated sea lice abundance, which was influenced by season and pre‐treatment sea lice levels. During summer, sea lice were at a minimum when counted 1 day post‐treatment irrespective of pre‐treatment sea lice levels, whereas in the spring and autumn, low levels were observed for PAAM over a longer interval of time, provided the pre‐treatment sea lice levels were >5–10.     

Application of Compensatory Growth to Enhance Production in Channel Catfish Ictalurus punctatus

Four treatment groups that received repeating cycles of fixed feed deprivation for either 0, 1, 2, or 3 d (control, treatment 1, treatment 2, and treatment 3, respectively), followed by periods of refeeding with a 36% protein commercial catfish feed once daily as long as the active phase of compensatory growth (CG) persisted, were assessed in flow-through aquaria. No-feed periods elicited the CG state and were immediately followed by days of ad libatum refeeding. At the end of 10 wk, average growth rate (AGR) of fish was higher ( P < 0.05) than the control by 40%, 180%, and 191% for treatment 1, treatment 2, and treatment 3, respectively. The average weight of fish in treatment 3 was heavier ( P < 0.05) than the average control group at the end of the study period. Mean daily feed consumption was 3.91%, 5.03%, 5.36%, and 5.98% for control, treatment 1, treatment 2, and treatment 3, respectively. Mean feed consumption per fish per day was 24%, 71.3%, and 70.7% higher than the control in treatment 1, treatment 2, and treatment 3, respectively. Restricted feeding is one of the effective methods to contain ESC-related losses in commercial channel catfish fingerling operations. The mean cumulative survival of treatment groups registered higher ( P < 0.05) survival to Edwardsiella ictaluri infection compared to the daily fed control fish. Results from this study show that compensatory growth response triggered by periodic non-feeding days can improve growth rate, feed consumption, and improved survival to ESC infections in channel catfish fingerlings.     

复合生物过滤技术在水产养殖废水处理中的应用研究进展

介绍了复合生物过滤技术的概念、原理、特点,以及植物滤器与微生物滤器复合生物过滤技术、动物滤器与植物滤器或微生物滤器过滤等主要几种复合生物过滤技术在实际生产中的应用,探讨了复合生物过滤技术在养殖废水处理中的发展趋势。     

Preliminary report of histological studies on the grey mullet gonad related to hormone treatment

Hormone treatment is an important and necessary step in the induced breeding of grey mullet. A histological study was made of the grey mullet gonad in relation to hormone treatment. It was found that hormone treatment usually had a favorable effect in inducing the maturation of females. No significant histological change was found in the males, however, after hormone treatment.     

Evaluating bath treatment effectiveness in the control of sea lice burdens on Atlantic salmon in New Brunswick,Canada

The use of medicinal bath treatment for sea lice is becoming more common, due to increasing resistance to in‐feed treatments with emamectin benzoate. Common treatment modalities in New Brunswick, Canada, include Salmosan administered by tarpaulin or wellboat, and Paramove administered by wellboat. In this study, we assessed the effectiveness of these treatment modalities in the field between 2010 and 2015 using a web‐based sea lice data management system (Fish‐iTrends^©). Effectiveness was evaluated for adult female (AF) and for pre‐adult and adult male (PAAM) life stages separately. We also investigated the impact of variability in pretreatment lead and post‐treatment lag time on effectiveness measures. There were 1185 treatment events at 57 farms that uniquely matched our pre‐ and post‐treatment count criteria. The effectiveness of treatment modality was significantly influenced by season, pretreatment level of sea lice and by lead and lag times. In summer, Salmosan administered by tarpaulin had the greatest effectiveness on both AF and PAAM, when pretreatment levels were above 10 sea lice; whereas in autumn, the performance of treatment modalities varied significantly, depending on the pretreatment levels for the life stages. Ignoring the lead or lag time effect generally resulted in an underestimation of treatment effectiveness.     

Effects of ultrasonic treatment on collagen extraction from skins of the sea bass Lateolabrax japonicus

In this study we investigated the effects of ultrasonic wave treatment on the extraction yield of acid-soluble collagen from sea bass skins. Two extraction methods were compared: a 24 h acid treatment using 0.5 M acetic acid (1:200 sample/acid, w/v) and an extraction using ultrasonic treatment after the addition of a 0.5 M acetic acid solution. The results indicated that the extraction yield of collagen increased with the ultrasonic treatment, with the extraction rate increasing rapidly at higher amplitudes of ultrasonic treatment. The subunit compositions of the collagen extracted by ultrasonic treatment were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which revealed that the α1(α3), α2, and β chains of collagen were present early in the ultrasonic treatment. An unknown component, believed to be a product of collagen degradation induced by the ultrasonic treatment, was detected only after a longer treatment time. The component extracted by the ultrasonic treatment was determined to be collagen based on the finding that there were no changes in the main components of collagen, specifically, the α1(α3), α2, and β chains, following pepsin treatment.     

Improved Utilization of Pond Carrying Capacity by Increasing Initial Stocking Rates and Subsequent Stock Division1

Fingerling channel catfish Ictaturus punctarus were stocked into eight 0.04-ha ponds at 12,500 fishlha (treatment 1) and 50,000 fish/ha (treatment 2) with four ponds per treatment. At the end of of phase I (59 d) 50% of the fish were removed from each of the ponds in treatment 2 and divided equally into two ponds, forming treatment 3 (eight ponds at a density of 12,500 fish/ha). The remaining fish in treatment 2 (25,000 fish/ha) were maintained in the original ponds until the end of phase II (36 d). At this time, the fish were removed and equally divided at a density of 12,500 fish/ha into separate ponds. These ponds were continued to be denoted as treatment 2. All fish were grown for a total of 188 d. Production characteristics between treatments were compared at phases and at the end of the 188 d. There was no significant difference in feed conversion ratios due to treatment. The individual weights of the fish were higher in treatment I, but the difference occurred only in phase I. Size variabilities in treatments 2 and 3 were also higher than in treatment 1, which may cause a decrease in the percentage of marketable fish. Although there were some adverse effects due to the initial high stocking densities, overall pond production was higher in treatments 2 and 3. Treatment 2 had a daily net production of 49.9 ± 3.43 kg/ha and treatment 3 had 44.6 ± 3.81 kg/ha per d, compared to treatment 1 with only 32.4 ± 1.06 kg/ha per d (mean ± SD).     

尖紫蛤壳顶幼虫适宜饵料的研究

为了研究尖紫蛤壳顶幼虫适宜饵料种类和投喂浓度,选用5组微藻做为饵料,研究其对尖紫蛤(Soletellina acuta Cai et Zhuang)壳顶幼虫生长和存活的影响。5组微藻分别是A组微绿球藻(Nannochloropsis oculata sp.),B组亚心形扁藻(Platymonas subcordiformi),C组湛江等鞭金藻(Isochrysis zhanjiangensis)+亚心形扁藻,D组绿色巴夫藻(Pavlova viridis)+亚心形扁藻,E组小球藻(Chlorella sp.)+亚心形扁藻。单因素方差分析表明:A组饵料效果为最好;B组和C组的饵料效果次之,E组和D组的饵料效果较差;不同饵料种类下,A组壳顶幼虫有最大生长和存活率;不同饵料浓度下,A组的最适投喂浓度是12 000个/(mL.d),C组的最适投喂浓度是5 000+5 000个/(mL.d)。A组和C组获得了较高的生长速率和成活率,可做为尖紫蛤壳顶幼虫适宜的饵料。     

Treatment of flow-through trout aquaculture effluents in a constructed wetland

A study on effluent treatment with sub-surface flow (SF) constructed wetlands was conducted in a small commercial scale Bavarian (Germany) flow-through trout farm. Under limited spatial and financial conditions a most suitable wetland was constructed. The wetland treatment efficiency at high hydraulic loading rates during raceway runoff and cleaning situation in comparison to sedimentation as initial treatment method was examined.

The constructional solution involved the alteration of six existing sedimentation basins (SB) to SF horizontal flow constructed wetlands with a pre-sedimentation area. As constructional materials only local, cheaply available materials were used in order to reduce the costs. The SF wetland had high treatment efficiencies in the two operational modes examined. During cleaning situation at a hydraulic loading rate (HLR) of 13.6 m/day treatment efficiency for total suspended solids (TSS) was highest and reached 68%. While during raceway runoff situation total ammonia nitrogen (TAN) treatment efficiency of 88% overtopped the efficiency of the other nutrients examined at a HLR of 10.6 m/day. In both treatment situations the SF wetland efficiency was significantly higher than the effect of the SB. SF constructed wetlands treating high hydraulic loading rates accompanied with short retention times were effective on dissolved nutrient treatment only for TAN and nitrite nitrogen (NO₂–N), while other dissolved nutrients like nitrate nitrogen (NO₃–N) and phosphate phosphorous (PO₄–P) showed no or even negative treatment effects through the wetland passage. To reduce these nutrients, other treatment conditions or wetland configurations are needed.     

不同脂肪源对罗氏沼虾生长及体组织常见组分的影响

用5种不同脂肪源组合的饲料(Ⅰ.鱼油0.5%+豆油2.5%;Ⅱ.鱼油0.5%+菜籽油2.5%;Ⅲ.鱼油0.5%+花生油2.5%;Ⅳ.鱼油0.5%+亚麻油2.5%;Ⅴ.豆油1.5%+亚麻油1.5%)投喂体重为(2.22±0.04)g的罗氏沼虾(Macrobrachium rosenbergii)40 d,研究不同脂肪源对其生长及全虾和肌肉中水分、粗蛋白、粗脂肪含量的影响。结果显示:在生长方面,第Ⅴ组的罗氏沼虾增重显著高于Ⅱ组和Ⅲ组(P<0.05),Ⅰ组和Ⅳ组增重也显著大于Ⅱ组(P<0.05)。在体成分方面,Ⅰ组全虾总水分含量最低,显著低于Ⅲ组和Ⅳ组(P<0.05),其他各组间无显著差异(P>0.05);Ⅴ组全虾粗脂肪含量最高,显著高于其他各试验组(P<0.05);Ⅲ组全虾粗蛋白含量显著低于Ⅰ组、Ⅱ组及Ⅴ组(P<0.05);Ⅳ组肌肉总水分含量显著高于其他各组;肌肉粗脂肪和粗蛋白含量各试验组之间差异不显著(P>0.05)。     

不同棉酚含量的日粮饲喂伊莎褐生长鸡、产蛋鸡的试验研究

本试验Ⅰ组用１０％脱毒棉仁饼代替部分大豆饼，日粮中含游离棉酚０．００４９８％。试验Ⅱ组用５％棉仁饼代替部分大豆饼，８粮含游离棉酚０．００６％。对照组用低鱼粉大豆日粮，不含棉酚。试验分二个阶段进行。试验１，３种日粮饲喂莎褐生长鸡结果不影响增重，饲料利用率试验组低于对照组，增重成本试验Ⅰ组最低，试验Ⅱ组稍高于对照组。试验２，３种日粮饲喂伊莎褐商品代蛋鸡结果不影响产蛋率，蛋重和饲科利用率对照组高于试验组。鸡蛋成本试验Ⅰ组比对照组低０．０７元。试验证明１０％脱毒棉仁饼代替部分大豆饼合游离棉酚０．００４９８％的日粮经济效益最高。目前缺乏蛋白质饲料，而大豆饼价格上涨的情况下，试验Ⅰ、Ⅱ组日粮均可采用。     

合浦珠母贝三倍体的卵诱导四倍体

将合浦珠母贝三倍体的卵与二倍体的精子授精,用０．５μｇ／ｍＬ细胞松弛素Ｂ抑制精卵第一极体的释放诱导四倍体。研究了处理起始时间及持续时间对胚胎孵化率和四倍体诱导率的影响及幼虫的生长及存活。实验结果表明：持续时间与胚胎孵化率呈负相关,而与四倍体诱导率呈正相关,持续时间一般为１５￣１８ｍｉｎ,处理起始时间一般在第一极体出现前３￣５ｍｉｎ。在胚胎期,四倍体诱导率平均为２０％。在幼虫培养阶段,幼虫死亡严重,     

海水工厂化养鱼水处理系统工程的研究——工艺流程、综合气浮、接触氧化池

对海水工厂化养殖牙鲆、大菱鲆的循环水处理系统工程进行了研究，对循环水系统各环节的设备性能及水质指标进行了测试和研究，确定了工艺流程及系统设施设备，对水处理系统各单元分别进行了设计计算。为我国海水工厂化养殖走向产业化打下了良好的基础。     

刺参肠组织蛋白质双向电泳体系的建立及优化

以刺参肠组织为材料,通过蛋白质提取方法、上样前处理方法、上样量以及聚焦条件的优化,建立了刺参肠组织蛋白质双向电泳技术体系.试验结果表明,采用TCA-丙酮沉淀法制备刺参肠组织蛋白质,能够得到高纯度的蛋白质提取液.刺参样品上样前不经过处理,等电聚焦电压1 000V,电流7mA,聚焦时间3h,平衡时间30min,最佳上样量25μg,pH 4～6.5、8.5cm的IPG胶条,银染能获得较好的双向电泳图谱.通过蛋白质双向电泳体系的优化,获得了刺参肠组织的蛋白质表达图谱,为进一步研究刺参差异表达蛋白的筛选及蛋白质组学研究提供技术保障     

低功率密度超声波强化絮凝沉降除藻技术研究

超声波强化絮凝沉降除藻技术能够提高絮凝沉降除藻效率,但以往研究采用的较高超声波功率限制了这一组合技术的应用。通过探究低功率密度超声波(0.5～1.0 W/L)对絮凝沉降技术去除微囊藻的增效作用,比较了增重剂种类及用量、超声波预处理的时间和距离、超声波预处理与絮凝沉降的间隔时长、日光照射时长等因素对除藻率的影响,并通过水池试验验证了低功率密度超声波的增效作用。结果显示:(1)超声波的处理距离对除藻率无显著影响,但增加超声波预处理时长则明显有利于提高除藻率,处理30 s时的除藻率显著高于仅处理10 s时的除藻率;(2)除藻率的日均变幅较大,当日光光照时长为3～9 h时,试验组的除藻率平均比对照组高17%,日光照射时长为0 h和12 h时,试验组与对照组的除藻率则无显著差异;(3)随着超声波预处理与絮凝沉降间隔时长的增加,除藻率会明显下降,仅当间隔时长不超过30 min时,试验组的除藻率才显著高于对照组;(4)水池原位试验中,试验组的除藻率高达70.47%,显著高于对照组的58.12%。研究表明,低功率密度超声波预处理能明显增加絮凝沉降除藻率,且应在日光开始减弱的下午作业。     

Hybrid catfish (♂Ictalurus punctatus X ♀Ictalurus furcatus) production: Does mixed-size production make economic sense?

Alternative management strategies will be required to produce hybrid catfish (♂Ictalurus punctatus X ♀Ictalurus furcatus) year-round to provide continuous market supply. Hybrid catfish fingerlings were stocked at 9,880 head/ha singly or in co-culture with sub-marketable (mean weight = 454 ± 16 g) hybrid catfish carried over the winter from a previous year’s multi-size trial. Economic analyses compared cost of production ($/kg of market-size fish produced) and cash flow of single- and multiple-batch production of hybrid catfish for a single- and two-year period. Gross total and marketable yields were significantly greater in the mixed-size treatment as compared to the single-size treatment, in spite of the significantly greater percentage of market-size fish (84%) in the single-size treatment than in the mixed-size treatment (71%). Cost of production ($/kg) was 4% to 10% lower in the multi-size treatment in the single-year analysis, but 18% to 20% lower when the full two-year cycle was assessed. Cash flow and cash flow risk were improved substantially with the multi-size treatment primarily because the overwintered sub-market-size fish from the previous year reached market size three to four months earlier than in the single-size treatment.     

3种常见水产养殖尾水处理技术的研究进展

随着我国水产养殖业的迅速发展,养殖尾水排放问题日益凸显。大量的养殖尾水若未能得到科学处理,会严重污染周围水环境,造成生态环境恶化,最终也会影响水产养殖业的健康发展。文章介绍了物理、化学和生物处理等3种常见水产养殖尾水处理技术,并分类叙述了水产养殖尾水处理技术的进展情况,可为水产养殖尾水处理提供参考。     

罗氏沼虾与三角帆蚌、鲢和鳙混养模式优化

研究了罗氏沼虾、三角帆蚌、鲢和鳙不同混养系统的养殖产量、饲料系数、增长率、总氮(TN)/总磷(TP)利用率和综合养殖效果,以期获得最优养殖模式。采用基于陆基围隔的比较实验方法,设6个实验组,分别为罗氏沼虾单养(G),罗氏沼虾与三角帆蚌二元混养(GH2)、罗氏沼虾、鲢和鳙三元混养(GSB),罗氏沼虾、鲢、鳙和三角帆蚌按照不同密度放养的四元混养(GSBH1、GSBH2和GSBH3),各实验组设置4个重复。结果表明:GSBH2组罗氏沼虾产量最高[(14.71±0.33)kg/32 m2],显著高于G组[(12.44±0.60)kg/32 m2,P0.01];GSBH1组饲料系数最低(1.43±0.04);GSBH1组增重率最高(4.66%±0.12%),G组最低(3.80%±0.23%);TN平均相对利用率在(0.92±0.09)~(1.60±0.23)之间,GSB组最高,G组最低;TP平均相对利用率为(0.23±0.03)~(1.46±0.32),GSBH3组最高,G组最低;综合养殖效果指数在(0.91±0.02)~(1.25±0.05)之间,GSB组最高,GSBH1组次之,G组最低,且三元、四元混养组显著大于G组和GH2组(P0.05)。研究表明,混养组能显著提高罗氏沼虾养殖的经济效益和生态效益。     

Trial of probiotics to prevent the vertebral column compression syndrome in rainbow trout (Oncorhynchus mykiss Walbaum)

Two probiotics were tested as alternative treatment to limit the prevalence of the vertebral column compression syndrome (VCCS) in rainbow trout, compared with a preventive treatment with florfenicol. Either the antibiotic, or a lactic acid bacterium, Pediococcus acidilactici, or a yeast, Saccharomyces cerevisiae var. boulardii, was introduced into experimental diets, which were compared with the control diet without supplementation. The antibiotic caused some mortality during the first week after treatment, likely because of the toxicity of the compound. However, this antibiotic treatment limited the occurrence of VCCS to 3%, vs. 13% of fish affected in the control group. Pediococcus acidilactici provided the same level of protection as the antibiotic, but on condition that the treatment was applied during the 5 months of the experiment, without any adverse effect on survival. A treatment with P. acidilactici only during the first 20 days of feeding was not sufficient to limit VCCS, nor was the treatment with the yeast sufficient. These results were discussed while comparing the microbiota associated with the intestine. The experiment reinforced the hypothesis that pathogenic bacteria are involved in VCCS. The long‐term dietary supplementation with P. acidilactici seemed promising as a preventive treatment against the syndrome, but large‐scale investigation in fish farms will be necessary to confirm its prophylactic relevance.