西北太平洋公海秋刀鱼渔场浮游动物数量分布的初步研究

根据2005年7—10月在北太平洋E 150°~158°56′、N 42°34′~46°25′进行秋刀鱼资源探捕所获得的15个站点浮游动物样本资料,测得甲壳纲的桡足类、端足类、糠虾类、磷虾类,毛颚类、腔肠动物以及被囊动物等的代表种。其中桡足类占绝对优势,隶属于1目4科5属8种。浮游动物生物量4~699 mg/m3,均值168.6 mg/m3。根据浮游动物的种类、分布状况及优势种类的强弱,判断和分析黑潮暖流的强弱趋势,对确定秋刀鱼渔场的南北位置具有重要参考价值。     

A comparison among differently enriched rotifers (Brachionus plicatilis) and their effect on Atlantic cod (Gadus morhua) larvae early growth, survival and lipid composition

We evaluated the effect of differently enriched rotifers on the early growth, survival and lipid composition of Atlantic cod larvae (Gadus morhua). The enrichments tested were: (i) AlgaMac 2000^®; (ii) AquaGrow^® Advantage; and (iii) a combination of Pavlova sp. paste and AlgaMac 2000^®. Larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw) and 7.10 ± 0.14 dw specific growth rate (SGR)] were heavier (P = 0.006) and grew faster (P = 0.004) than larvae from treatment 2 (1.03 ± 0.04 mg dw and 6.29 ± 0.04 dw SGR). No significant differences were found in the final weight and SGR among larvae from treatment 1 (1.21 ± 0.07 mg dw and 6.58 ± 0.20 dw SGR) and larvae from treatments 2 and 3. The treatment 3 also resulted in the best survival at the end of the experimental period, estimated to be 3 on a scale from 1 to 5, whereas the survival estimates for the two other groups were 1–2. Larvae from the treatment 3 reached 37 days posthatch with levels of ω6DPA 32‐fold higher than newly hatched larvae. Differences in the larval enrichment of ω6DPA may explain the differences in growth and survival of the Atlantic cod larvae.     

Artemia enriched with high n-3 HUFA may give a large improvement in performance of Atlantic halibut (Hippoglossus hippoglossus L.) larvae

Atlantic halibut larvae were fed Artemia enriched with two different oil emulsions (cod liver oil and 2050TG) from first feeding to 70 days after first-feeding (dpff). Larvae fed 2050TG enriched Artemia had better growth, survival and eye migration than larvae fed the cod liver oil enriched Artemia, while pigmentation rate was similar in the two groups. In addition to the difference in fatty acids, the two emulsions differed in lipid class composition, since 2050TG is a synthetic oil and a mixture of mono-, di- and tri-acylglycerol, while cod liver oil is a tri-acylglycerol. Total lipid level, estimated as fatty acid methyl esters (FAME) was similar in the two Artemia types, but sum of n-6 and n-3 fatty acids, arachidonic acid (20:4n-6, ARA), docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) were higher in Artemia enriched with 2050TG than in the cod liver oil enriched Artemia. However, the main difference in fatty acid composition in the larvae, was a higher DHA (% of total fatty acids) in 2050TG larvae than in cod liver oil larvae. The lipid level measured as FAME was up to four times higher in the 2050TG larvae than in the cod liver oil larvae, and the reason for this may have been a better bioavailability of the partly digested lipid in the 2050TG emulsion. The correlation between a high level of lipid in the larval tissues (e.g. high energy status) and improved eye migration in larvae fed the 2050TG enriched Artemia supports the hypothesis that energy limitation on the larval stage may be a cause of the impaired eye migration commonly observed in farmed Atlantic halibut juveniles.     

Naturally occurring bacteraemia in American lobsters, Homarus americanus Milne-Edwards, in Long Island Sound

The health status of the American lobster, Homarus americanus Milne-Edwards, in Long Island Sound (LIS) has been in decline, with seasonal mortality events occurring since 1998. In order to assess the potential effects of environmental conditions on lobster health via haemolymph analysis, lobsters collected from various sites in LIS were examined and sampled while concurrent environmental data (water temperature, salinity and dissolved oxygen) were recorded. The pH of the haemolymph of each lobster was tested, followed by a collection of haemolymph for serum biochemistry analysis and bacterial culture. This report focuses on the results of the bacterial sampling. The majority of bacteria cultured were opportunistic pathogens commonly found in the environment, including some that are associated with sewage and pollution. The prevalence of bacteraemia was correlated with the site of collection, the month in which the lobsters were sampled, and water temperature.     

Loggerhead turtle (Caretta caretta) bycatch in Canadian pelagic longline fisheries: Relative importance in the western North Atlantic and opportunities for mitigation

Little is known about the ecology of loggerhead turtles, Caretta caretta, in Canadian waters. However, Canada's eastern waters off the Scotian Shelf, Georges Bank and Grand Banks appear to be seasonal foraging habitats based on dates and locations where they have been captured as fishery bycatch. Estimates derived from data recorded by the international observer program (IOP) and used for this study suggest that thousands of mostly immature loggerheads have been captured in the Canadian pelagic longline fishery (PLF) in the western North Atlantic since 1999. These data suggest that the PLFs for tuna and swordfish are among the most important causes of incidental capture. Although U.S. and Canadian bycatch estimation methods differ and uncertainty associated with the estimates is high, it is clear from the IOP data that bycatch in the Canadian PLF is substantial and roughly within the same magnitude as that reported for the entire U.S. fleet in the North Atlantic for the same period (1999–2005). Analysis of bycatch observer data from the Canadian PLF and other empirical data suggests that fishing at temperatures below 20 °C using fish rather than squid bait and size-18 circle hooks could reduce loggerhead bycatch and mortality. However, research is needed to identify the best options and their commercial viability. Loggerheads that use Canadian Maritime waters are one of the least studied groups of loggerheads in the world, so systematic long-term studies on the ecology of loggerheads in Canada would help fill important information gaps and assist in developing effective recovery plans for this species.     

Variability in conspecific predation among longnose lancetfish Alepisaurus ferox in the western Indian Ocean

ABSTRACT:   Conspecific predation among longnose lancetfish Alepisaurus ferox was investigated in four spatio-temporal strata of the western Indian Ocean. The cannibalism level varied from 0 to 45.5% by frequency of occurrence and was negatively related with abundance of non-evasive prey (such as crustaceans Charybdis smithii and Natosquilla investigatoris ) and foraging success. Predation by lancetfish is often described as a non-selective process, constrained by local prey availability and by its feeding speed during an attack of prey. Our results show that lancetfish may adapt its opportunistic foraging behavior, feeding on non-conspecific abundant prey such as crustaceans when available, and switching to a high level of conspecific predation in poor waters.     

The combined effects of temperature and GnRHa treatment on the final stages of sexual maturation in Atlantic salmon (Salmo salar L.) females

Atlantic salmon (Salmo salar L.) females (2 SW), maturing for the first time, were reared under one of three temperature regimes (high: 14.3 ± 0.5°C; natural: 10.6 ± 1.0°C; and cold: 6.9 ± 1.0°C) in combination with one of two experimental treatments; an injection of GnRH analogue (GnRHa) contained in biodegradable microspheres, or a sham injection (microspheres only). The six experimental groups were then reared under simulated natural photoperiod for 4 weeks. Blood samples were drawn for analysis of plasma steroid levels and the fish were inspected for ovulation weekly. Batches of stripped eggs were incubated in triplicate incubators in raceways until the eyed stage. Treatment with GnRHa resulted in a substantial advancement and synchronization of ovulation at all temperatures, while exposure to cold water also appeared to advance ovulation slightly. While 75% (warm and cold) to 90% (natural) of GnRHa fish ovulated during the 4-week trial, only 30% of sham-treated females exposed to cold water, and none of the sham-treated fish held at higher temperatures, ovulated during this period. Survival rates of embryos to the eyed-stage were significantly higher for broodstock exposed to cold water. Plasma levels of testosterone (T), 17β-oestradiol (E₂), and 17α,20β-dihydroxy-4-pregnen-3-one (17,20βP) were all significantly affected by treatment with GnRHa and, to a lesser extent, temperature. The efficiency of GnRHa in counteracting the negative effects of high temperature on ovulation and the associated changes in circulating sex steroids suggest that temperature inhibition operates at least in part at the brain or pituitary.     

Inter-river, -annual and -seasonal variability in fecundity of Atlantic salmon, Salmo salar L., in rivers in Newfoundland and Labrador, Canada

Abstract  Fecundity is an integral component of the calculation of Atlantic salmon, Salmo salar L., egg depositions in rivers. Fecundity determinations can be time consuming and prohibitively expensive in terms of application on a broad scale. Consequently, where river specific and annual data are not available, default means are used in calculations in Newfoundland and Labrador. It is important therefore to know the extent of variability among rivers, years and seasons and the potential error involved in using default values. Annual fecundity data were available for one river in Labrador and nine rivers in Newfoundland. Fecundity was determined from ovaries collected in the recreational fishery in the summer for all 10 rivers. For three of these rivers, fecundity determined from summer sampling was compared with that obtained from sampling at time of spawning in autumn. There was significant variability in fecundity with length as a covariate among rivers, years and seasons. Mean number of eggs per female decreased between 8.3% and 29.0% from summer to autumn while mean number of eggs per cm decreased from 5.0% to 28.5%. Depending on the measure of relative fecundity used (no. of eggs kg⁻¹ or no. of eggs cm⁻¹), results of simulations showed that estimates of egg deposition incorporating defaults can deviate from those obtained by applying year-specific and river-specific values by 50–75%, without adjusting for the seasonal reduction in fecundity, and by 30–50% with an adjustment. A sensitivity analysis revealed that of three parameters used in the calculation of egg deposition (size, percent female and fecundity), fecundity was the most influential.     

2011年西南大西洋拖网渔获物阿根廷滑柔鱼生物学分析

根据2011年1月～4月双拖网船在西南大两洋作业时采集的901尾阿根廷滑柔鱼（lllex argentinus）样本,对其渔获群体组成、摄食等级、胴长-体质量关系以及性腺发育等进行了分析。结果表明,样本个体大小随采样时间的推移有明显增大趋势;小胴长组阿根廷滑柔鱼的摄食能力较大胴长组弱,摄食等级的高低与其繁殖高峰期有关。阿根廷滑柔鱼雌、雄初次性成熟胴长分别为191．6mm和182．6mm,性腺成熟度为Ⅴ期个体的平均胴长小于处于Ⅲ、Ⅳ期个体的平均胴长。综合分析推测,该研究采集的901尾样本为南部巴塔哥尼亚群体和夏季产卵群体的混合样本,在拖网作业后期,渔场补充了部分大个体的夏季群体。     

全国海洋水产类高校学报被引计量指标的统计与分析

期刊被引计量指标，包括总被引频次、影响因子、即年指标、他引率和被引半衰期等5项计量指标。这些指标主要显示该期刊被读者使用和重视的程度，以及在科学交流中的地位和作用，是评价期刊质量高低的重要依据和客观标准。为了全面、准确、公正、客观地评价和利用全国海洋水产类高校学报，对其被引计量指标中最重要的前3项分别进行统计与分析的结果表明，提高学报的被引计量指标应采取以下措施：(1)努力提高编辑质量：(2)加强组约稿工作；(3)加快编辑流程，尽快缩短出版时滞；(4)重视并增加交叉学科论文的发表。