Effects of soy protein ratio,lipid content and minimum level of krill meal in plant‐based diets over the growth and digestibility of the white shrimp,Litopenaeus vannamei

This study evaluated the effects of soy protein ratio, lipid content and the minimum dietary level of krill meal in plant‐based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant‐based diets varied the soybean meal (SBM) and soy protein concentrate (SPC) inclusion ratio at 1 : 2.3, 1 : 1 and 2.5 : 1, and their dietary lipid content at 121.4 ± 9.4, 102.3 ± 1.2, and 79.9 ± 1.2 g kg^?1 (in a dry matter basis). An additional diet containing 120 g kg^?1 of fish meal (salmon by‐product) was used as a control. Krill meal was included at 0, 5, 10, 20 and 30 g kg^?1 in a new set of plant‐based diets. After 10 weeks in clear‐water tanks of 0.5 m³, no effect of SBM:SPC ratio and dietary lipid content was detected on shrimp survival. However, dietary lipid levels of 80 and 121 g kg^?1 combined with a high SPC to SBM resulted in the lowest final body weight and the poorest apparent crude protein digestibility, respectively. Krill meal increased feed intake at only 10 g kg^?1, while at 20 g kg^?1, it accelerated shrimp growth, increased yield and reduced food conversion ratio.     

南极磷虾形态特性对虾肉质量的影响

通过研究影响南极磷虾虾肉质量的主要形态特性,丰富南极磷虾生物学资料,同时为南极磷虾脱壳设备的设计提供理论基础。随机选取南极磷虾100尾,测定体长(X₁)、头胸甲长(X₂)、腹部长(X₃)、尾扇长(X₄)、头胸甲宽(X₅)、腹部宽(X₆)及虾肉质量(Y)7个形态特征,采用相关分析和通径分析方法分析形态特征对虾肉质量的影响效应。相关分析结果表明南极磷虾的形态特征与虾肉质量的相关系数均达到极显著水平(P<0.01);经通径分析和回归显著性检验,建立腹部长(X₃)、腹部宽(X₆)对虾肉质量(Y)的多元回归方程Y=-0.187+0.008X₃+0.032X₆,回归系数达到极显著水平(P<0.01)。通径分析显示,腹部长与腹部宽对虾肉质量的通径系数达到（极）显著水平,是影响虾肉质量的重要形态特征指标,其中腹部长对虾肉质量的直接作用最大;头胸甲长和头胸甲宽通过间接作用影响虾肉质量。     

Astaxanthin krill oil enhances the growth performance and fatty acid composition of the Pacific whiteleg shrimp,Litopenaeus vannamei,reared under hypersaline conditions

Hypersalinity culture of marine shrimp can lead to poor growth and feed efficiency. This study evaluated the effect of dietary supplementation of three oil sources (krill, fish and soybean) on the growth of Litopenaeus vannamei reared under high salinity. Shrimp of 2.79 ± 0.60 g were reared for 64 days under isosmotic (ISO, 23 ± 1.2 g/L) and hyperosmotic (HOS, 44 ± 2.0 g/L) conditions. Diets varied in their fatty acid composition: Control, 35 g/kg of the diet (as fed basis) soybean oil; Fish, 27 g/kg fish oil and 10 g/kg soybean oil; Krill, 48 g/kg krill oil and 4 g/kg soybean oil; Krill‐, 15 g/kg krill oil and 21 g/kg soybean oil; Krill+, 55 g/kg krill oil and 4 g/kg soybean oil. At harvest, Krill diet promoted the fastest shrimp growth (1.01 ± 0.01 g/week) and body weight (11.97 ± 2.01 g), regardless of water salinity. There were no significant differences in shrimp survival (93.4 ± 5.07%) and yield (554 ± 68.5 g/m²) among different diets. Shrimp fed Fish, Krill and Krill+ had higher concentrations of PUFA compared to those fed Control and Krill‐ diets.     

2009/2010-2011/2012渔季中国南极磷虾渔业渔场时空变动

掌握南极磷虾渔业行为及渔场变动信息可为模拟渔业与生态系统相互作用提供非常重要的支撑。基于渔业科学观察员收集的2009/2010-2011/2012渔季中国南极磷虾渔业数据,利用渔场重心指标,分析了中国南极磷虾渔业渔场变动及渔船的行为模式。结果表明,从作业网次上来讲,2009/2010-2011/2012渔季期间,中国南极磷虾渔业主要渔场由48.1小区转向48.2小区,但产量变化却呈相反的趋势。尽管作业位置分布于6个精细管理单元中,但旬别渔场重心集中在4个精细管理单元中（APDPW,APDPE,APBSE和SOW）。中国南极磷虾渔业渔场选择不仅受到本地磷虾丰度的影响,同时还受到预定的决策,渔船条件及市场因素等的影响。     

Use of chitin and krill in aquaculture – the effect on gut microbiota and the immune system: a review

Chitin consists of β‐1,4‐linked N‐acetylglucosamine residues and is estimated as the second most abundant biomass in the world after cellulose. However, relatively little chitin is utilized as a material for industrial, agricultural and medical applications and aquacultural purposes. Chitin may be useful as a constitutive material in formulated fish feed, and the interesting effects in fish merit further evaluation. There is evidence that fish and aquatic animals harbour a gut bacterial community that is distinctly different from that reported in the surrounding habitat or in the diet. Thus, the gut environment provides a specific niche, and bacterial activity in the gut is not merely a continuum of that observed in the environment. Today, it is well accepted that the gut microbiota in fish are modulated by dietary manipulations. But to what extent can dietary chitin and krill (chitin‐rich) modulate the intestinal microbiota of fish and how do these dietary components affect the immune system? These questions will be discussed in the present review.     

The effect of vertical migration strategy on retention and dispersion in the Irish Sea during spring–summer

A biophysical model of the Irish Sea was produced to predict net horizontal movement of key taxa including small copepods (Acartia, Pseudocalanus), large copepod species (Calanus finmarchicus and C. helgolandicus), the euphausiid Meganyctiphanes norvegica, and the larval stages of commercially important fish and Nephrops. The model coupled biological information on the vertical distribution and diel vertical migration (DVM) of these taxa with temporally resolved flow fields generated by a baroclinic hydrodynamic model. The DVM of Calanus spp. and Meganyctiphanes was parameterized empirically from data provided by a biophysical campaign carried out in the nearby Clyde Sea. Small copepods and larvae remained within the layers above the thermocline. Model organisms, programmed with particular behavioural patterns, were spaced at regular intervals (1/20° longitude × 1/30° latitude) in the model grid, which extended from 53 to 54.5°N and 4.5 to 6.4°W. The model was run over the months of April, May and June. Model simulations showed that the movement of model organisms followed one of four characteristic patterns: containment along the coast, advection to the north or south, stagnation in the centre of the gyre or circulation around the periphery of the gyre. The latter pattern was apparent even in April, when gyral circulation was not expected because of a lack of stratification in the water column. Thirty‐day model runs in April, May and June showed that the number of organisms retained within the model grid varied between 23 and 49%. Those seeded close to the Irish coast had the highest probability of being retained within the model grid at the end of 90 days. DVM increased the probability of retention through improving the chances of organisms becoming entrained within the gyre circulation. This was especially true for Calanus spp., with those performing midnight sinking being the most likely to be retained out of any model organism. Meganyctiphanes showed comparatively lower levels of retention in deep regions, which suggests that they may have to swim against currents during certain phases of their DVM to avoid displacement. Overall, model results supported a number of hypotheses on the origin and fate of various taxa in the Irish Sea, as well as revealing some less expected distribution patterns.     

Predicting early life connectivity of Antarctic silverfish,an important forage species along the Antarctic Peninsula

The early life stages of the Antarctic silverfish (Pleuragramma antarctica), an important prey species for higher predators in the Southern Ocean ecosystem, dominate the larval fish assemblages of the Bransfield Strait, one of the most important areas for larval retention off the Antarctic Peninsula. Nevertheless, the spatial location of areas where they were spawned and the timing of larval hatching remain unknown. By linking Lagrangian particle tracking simulations with age data obtained using otolith microincrements from fish caught north of Joinville Island in a pelagic survey, we estimated the distribution of hatch dates and subsequent growth rates of silverfish reaching the Bransfield Strait, and predicted the areas where they were spawned. Larval hatching peaked during the last week of December, and the inner shelf and shelf break, east of the Larsen Ice shelf, were the dominant areas predicted to contribute to larval assemblages in the Bransfield Strait. Over simulated periods of 600–630 days, 35–40% of particles remained within the Bransfield Strait, suggesting an important source of supply to higher predators feeding off the northern Antarctic Peninsula. The daily growth rate at the mean size of 22.3 mm was 0.18 mm, corresponding to a daily change in size of approximately 0.82% standard length (SL), and large variability in growth rate suggested a wide range of environmental conditions experienced during the period of advection from the spawning areas. These results provide spatial predictions that can be tested empirically in future studies, using the simulated trajectories to inform sampling design and spatial coverage.     

南极半岛邻近海域南极大磷虾(Euphausia superba Dana)的数量组成和分布

根据2010年1月23日?2月13日在南极南设得兰群岛和南奥克尼群岛邻近海域渔场采集的南极大磷虾(Euphausia superba Dana)样品,分析了南极大磷虾数量、个体体长分布和发育期组成等种群结构特点。样品由330 μm和500 μm浮游生物网垂直拖网和表层水平拖网两种采集方式所获。结果显示,采集样中,南奥克尼群岛水域的南极大磷虾平均密度为1.92 ind/m3,高于南设得兰群岛水域的相应值(0.35 ind/m3);出现的南极大磷虾个体发育期包括CI至CIII期原蚤状幼体、FI至FIV期和FVI期蚤状幼体、未成体、成体(包括雌体和雄体);各发育期个体中,原蚤状幼体数量较多;原蚤状幼体、蚤状幼体、未成体及成体的体长范围(平均体长)分别为1.76–4.96 mm (3.48 mm)、3.95–14.80 mm (5.96 mm)、16.87–39.85 mm (36.10 mm)、40.00–58.96 mm (43.94 mm)。CIII期原蚤状幼体和FI期蚤状幼体的生长率较高。推测,南奥克尼群岛水域南极大磷虾生殖季节始于9月末,集中出现在12月中上旬;而南设得兰群岛生殖季节应早于上述水域。比较两种采集方式,南极大磷虾在水平网中的出现频率和个体出现数量均高于垂直网采集样的相应值,建议传统垂直拖网与水平拖网两种采样方式有效结合,可促进更全面了解大磷虾水平分布和种群结构特点。     

基于广义可加模型研究时间和环境因子对南极半岛北部南极磷虾渔场的影响

基于南极海洋生物资源养护委员会(CCAMLR)统计公报(Statistical Bulletin,Volume 23)提供的数据,利用广义可加模型(generalized additive model,GAM),实验对1998-2009年南极半岛北部(CCAMLR 48.1、48.2和48.3小区)内的南极磷虾渔场时空分布及其与环境因子(表温和叶绿素a浓度)之间的关系进行了研究.结果表明,模型对3个小区的单位捕捞努力量渔获量(catch per unit fishing effort,CPUE)总偏差解释率分别为51.11％、69.25％和65.82％,其中各小区贡献最大的因子均为月份.1998-2009年期间,3个小区内各年平均CPUE保持相对稳定.48.1小区各年间平均CPUE值变化最小,而48.3小区则较48.2小区大.3个小区之间及48.2小区和48.3小区内年均CPUE差异不明显,而48.1小区内平均CPUE则存在显著性年份差异.从CPUE月均变化可以看出,3个小区均呈单峰分布,48.1～48.3小区的峰值分别出现在4月、5月和6月.3个小区之间平均CPUE月变化不显著,但各区内平均CPUE则存在显著的月变化.48.1～48.3小区南极磷虾渔场的适宜表温范围分别为-3～2℃、-2～2℃和0～5℃,但CPUE主要分别集中在表温-2～1℃、-1～0℃和1℃左右以及0.8～2.4℃范围内.48.1小区(53％)、48.2小区(39％)和48.3小区(51％)3个小区较大比例的CPUE值处于叶绿素a浓度为0～0.2 mg/m3的范围内.     

南极海洋生物资源养护委员会与中国:第30届年会

以南极海洋生物资源养护委员会第30届年会为例,介绍了南极海洋生物资源养护委员会的基本运作与最近发展趋势以及中国在其中的作用。首先阐述了委员会会议的基本结构以及下设的遵守与执法常委会会议主要内容,如养护措施的执行与修订,非法、不报告与不管制捕捞,渔获文件制度等;接下来分析了南极磷虾与犬牙鱼两种主要渔业的生产与管理情况,围绕与中国相关的三个议题,即两艘渔船、香港适用渔获文件制度以及IMO号等,指出中国的影响和作用,最后对2012年会议进行展望,并提出提高参会能力的有关建议。