渔船密闭舱室内氨气泄漏数值模拟

渔业船舶舱室内一旦氨气发生泄漏扩散,就会引起严重的环境污染和人员伤亡,为此设置了用以检测氨气泄漏的探测装置。由于安装好的探测装置不易挪动位置,因此需要事先考虑好安装位置。本文基于Fluent软件对渔业船舶冷冻舱室氨气泄漏过程进行数值模拟,研究氨气在不同泄漏方向和不同泄漏位置下的舱内质量浓度变化。研究表明,泄漏方向的变化对舱顶与舱壁附近监测点的氨气检测影响不大,泄漏位置的改变对监测点的氨气检测影响较大,较高位置处的监测点对氨气检测更为精确,氨气泄漏扩散后在舱壁附近和舱室顶部质量浓度较高。因此,氨气泄漏探测装置最好安装在冷冻舱室偏上位置,舱壁与舱顶附近都需要布置探测装置,有利于确定氨气是否泄漏。     

纷散固相萃取—超高效液相色谱—串联质谱法测定水产品中利福平残留

建立一种测定水产品中利福平药物残留的超高效液相色谱—串联质谱检测方法。样品用乙腈—二氯甲烷(6∶4,体积比)提取剂提取,通过100 mg C18+100 mg PSA分散固相萃取净化,以3 mmol/L乙酸铵溶液(含0.05%甲酸)和乙腈为流动相进行梯度洗脱,采用电喷雾离子源正离子多反应监测模式测定,内标法定量分析。检测结果显示,利福平在1~20μg/kg质量浓度内呈良好的线性关系,相关系数r≥0.9986,方法检出限为0.3μg/kg,定量限为1.0μg/kg,对罗非鱼、凡纳滨对虾、中华鳖进行加标回收试验,回收率为90.17%~101.07%,相对标准偏差为3.11%~7.66%,该方法简单、快速、准确,适用于水产品中利福平残留的确证和定量分析,为监管利福平药物的违规使用提供便捷、有效的技术支持。     

大银鱼生物学与渔业生态学研究进展

大银鱼是东亚特有的小型经济鱼类,相关研究工作主要由我国科技工作者开展。本文对大银鱼分类、生长、繁殖、孵化与胚胎发育、移植与产量波动以及对其他鱼类的影响等研究进展进行了归纳和总结。更正后的大银鱼拉丁学名存在尚未被广泛使用的问题。多年的移植增殖使大银鱼产生了大量新的遗传变异,形态上也有所改变,丰富了大银鱼的种质资源。不同纬度地区大银鱼快速生长的月份不同,虽然北方生长季节短,但大银鱼个体却不小于南方。大银鱼能否稳定地转变为食鱼性决定了其生长速率和最终个体大小,其种群内出现个体大小分化的饵料资源条件尚不清楚。种群内是否出现个体大小分化决定了大银鱼的性选择模式,而相关的研究尚未开展。大银鱼为一次性产卵鱼类,其自然受精率高于人工受精率,因此,在增养殖中若能保留合适的繁殖群体量则无需人工投放受精卵。大银鱼的胚胎发育及其影响因素已经比较清楚,足以指导受精卵的生产。大银鱼是耐盐碱鱼类,可用于发展盐碱水域渔业。饵料生物资源的过度消耗被认为是大银鱼产量跌入低谷的原因,但相关的定量生态学研究有待开展,以指导大银鱼的可持续稳产。本研究还针对大银鱼种群爆发对土著鱼类影响的问题,提出了应对策略。     

Fishery indicators during a predictable aggregation of Atlantic sharpnose sharks Rhizoprionodon terraenovae in the southern Gulf of Mexico: An alternative to assess a heterogeneous data‐poor fishery

Small‐scale fisheries in the southern Gulf of Mexico that catch Rhizoprionodon terraenovae (Richardson) are heterogeneous and data‐poor. Fishery‐dependent monitoring was conducted from 2010 to 2017, including a target season during an aggregation of this species to estimate data‐poor fishery indicators. During the target season, the average sizes for females and males (95.3 and 89.8 cm total length, respectively) were recorded, a global male sex bias (1:1.7), the highest percentage of mature sharks for all years (>89%), the highest values of CPUE (20.1 sharks/day) and size‐selectivity higher than the size at maturity. The spawning potential ratio was over 0.6 (reference point of 0.71) in the combined (target and non‐target) and target seasons for all years, which suggests that the fishery stock is not healthy. Annual assessment of this fishery can be carried out through monitoring during the target season, where management is more feasible to implement.     

Conservation of spawning time between years in lumpfish Cyclopterus lumpus and potential impacts from the temporal distribution of fishing effort

Lumpfish, Cyclopterus lumpus L., has an extended ovary development period and a relatively long spawning season. It therefore seems unlikely that individuals spawning later in the season would be able to recover from spawning and develop their gonads in time to spawn during the early part of the season the following year. The hypothesis that individuals spawning early or late in a spawning season would spawn early or late the following year was tested using fish tagged in Iceland between 2008 and 2017. The tagging date and recapture date the following year were positively correlated with an average of 356 days at large (DAL). Fish sampled from the fishery indicate that tagging/recapture date gives an indication of spawning time. From this, it was concluded that spawning time in the current year can be used to predict spawning time the following year. As fishing effort was greatest at the end of April/beginning of May, it seems likely that fish that come to spawn at this time will be subject to a higher fishing mortality. Therefore, they will be less likely to spawn successfully than fish spawning earlier or later in the year. If spawning time is under genetic control, then this could have consequences for the spawning phenology of lumpfish.     

Palm kernel meal (Elaeis guineensis) as a substitute for corn (Zea mays) in diets of Tambaqui (Colossoma macropomum)

Two experiments were carried out to evaluate the effects of palm kernel meal (Elaeis guineensis) as corn (Zea mays) substitutes in tambaqui (Colossoma macropomum) diets based on zootechnical performance, health, characteristics of the muscle, yield and economic efficiency. The first one was carried out in a recirculation aquaculture system for 75 days wherein tambaquis received diets with 0% (T0), 25% (T25), 50% (T50), 75% (T75) and 100% (T100) of corn replacement by palm kernel meal. The second experiment, conducted in ponds for 184 days, tambaquis were fed T0 and T25 diets (selected because showed greater weight gain without health damage). Final weight and weight gain of tambaquis were impaired by the increasing levels of this ingredient on diets, and the feed conversion ratio was worse. The protein efficiency ratio and specific growth rate gradually reduced, while the total number of leucocytes and neutrophils gradually increased. Cholesterol and triglycerides decreased in T75 and T100. Variables analysed in experiment 2 were not affected by treatment, except muscle lipids. Palm kernel meal can replace up to 25% of corn in tambaqui diets since it maintains a balance in economic and zootechnical performance of production.     

Implications of fisheries‐induced evolution for population recovery: Refocusing the science and refining its communication

The argument that sufficiently high fishing mortality (selective or not) can effect genetic change in fished populations has gained considerable traction since the late 1970s. The intervening decades have provided compelling experimental and model‐based evidence that fisheries‐induced evolution (FIE) can cause genetic changes in life history, behaviour and body shape, given sufficiently high trait heritability, selection intensity and time. Fisheries‐induced evolution research has also identified or inferred negative implications to population recovery and sustainable yield, prompting calls for evolutionarily enlightened management to reduce the probability of FIE and mitigate its risks. Sufficient time has now elapsed to evaluate whether predicted negative consequences to recovery have been empirically realized. We find that many FIE‐implicated populations have recovered rapidly to management‐based targets following cessation of overfishing. We conclude that FIE is generally of minor importance to recovery when compared with overfishing, magnitude of depletion and natural mortality. By posing a series of questions and responses, we illustrate how science advice pertaining to human‐induced evolution in fishes can be strengthened. We suggest that FIE research be refocused and its communication refined to: (a) better integrate FIE within existing stock‐assessment modelling frameworks; (b) pose questions of greater relevance at the science:policy interface; and (c) concentrate research on questions pertaining to the subset of depleted populations for which the implications of FIE are likely to be magnified because of their synergistic interactions with other correlates of recovery and yield.     

功能性电极快速伏安检测孔雀石绿

用阴离子表面活性剂十二烷基硫酸钠(SDS)修饰导电炭黑糊电极,制备了对孔雀石绿(MG)具有高灵敏度的功能传感器。实验对MG在该功能电极上的电化学行为进行了研究,并对影响测定的各种条件(制备糊电极所用导电材料种类;功能试剂修饰量;支持电解质的离子强度、pH值、种类;富集电位与时间等)进行了优化。在优化条件下,MG的氧化峰电流(ipa)与其浓度在5～200μg/L范围内呈线性关系,检测限为1.5μg/L(S/N=3)。该方法具有较高的灵敏度、良好的重现性和稳定性。应用于测定经过简单过滤预处理后的淡水渔业水样,平均回收率为90%。