养殖密度对鱼类福利影响的研究进展I．死亡率、生长、摄食以及应激反应

养殖密度影响鱼类福利是鱼类生理生态学、福利学和种群生态学研究中的关键问题,已受到各国学者的关注。文章综述了养殖密度影响鱼类福利的主要研究进展,讨论了鱼类死亡率、生长、摄食以及应激反应等福利指标随养殖密度变化的规律及其描述方法；在此基础上,对鱼类福利指标随不同放养密度变化规律的研究以及应用前景进行了展望。     

无源蓄冷控温运输箱设计与试验

针对蓄冷运输箱信息化程度低、控温时间短、控温困难等问题,设计了一款集控温、远程监控、定位、故障诊断等功能于一体的蓄冷运输箱。以脐橙为试验对象,结合能耗模型,对蓄冷控温箱控温性能进行了研究。结果表明,箱内各截面温度不均匀系数分别为0.38、0.47、0.78,温度极差最大值为2.8℃,均匀性较好;当蓄冷剂用量为180 kg,预冷脐橙660 kg,在外部环境平均温度26.39℃的条件下,总控温时长为122 h,风机共执行控温21次,且随着蓄冷量减少,风机开启控温所用时间呈指数上升趋势,决定系数不小于0.928 0;结合能耗模型分析得出,该箱体在广州夏季高温环境下可控温5 d以上,能够满足远距离运输要求。     

土壤耕深对寒地山药生长发育及产量的影响

为确定适宜的土壤耕深度,为优质、高产栽培提供科学依据.以兴凯湖山药为试材,通过4种不同耕作深度的处理,研究了土壤耕作深度对寒地山药生长发育及产量的影响.结果表明:耕作深度对山药地上部茎叶的生长及生育时期无影响,但对地下部块根的延长生长、加粗生长,以及产量的形成具有显著的作用,土壤耕作深度以110 cm为宝.     

渤海对虾流网作业中掉虾数量及其成活率的研究

根据对虾流网结构特点设计兼有捕虾和接获网上掉虾功能的专用网具,研究了对虾流网作业全过程的掉虾数量;同时还对暂养模拟掉虾和对虾在网上直接死亡率作了调查;并研究了流网掉下对虾的成活率。所得结果为调整渤海区秋季对虾汛的捕捞结构,实行以流网代替拖网作业的管理决策提供了科学依据。     

Prespawn mortality in adult spring Chinook salmon outplanted above barrier dams

Keefer ML, Taylor GA, Garletts DF, Gauthier GA, Pierce TM, Caudill CC. Prespawn mortality in adult spring Chinook salmon outplanted above barrier dams.
Ecology of Freshwater Fish 2010: 19: 361–372. © 2010 John Wiley & Sons A/S Abstract – Dams without fish passage facilities block access to much of the historic spawning habitat of spring Chinook salmon (Oncorhynchus tshawytscha) in Oregon’s Willamette River basin. Adult salmon are routinely outplanted above the dams to supplement natural production, but many die before spawning despite extensive suitable habitat. In 2004–2007, we examined prespawn mortality patterns using live detection and carcass recovery data for 242 radio‐tagged outplants. Total prespawn mortality was 48%, but variability was high, ranging from 0% to 93% for individual release groups. Prespawn mortality was strongly condition dependent, consistently higher for females than males and higher for early release groups. Across years, warm water temperature in the migration corridor and at the collection site was associated with sharply higher mortality. Results highlight a need for better evaluations of the effects of adult mortality on population reintroduction and recovery and relationships among prespawn mortality, dam‐related temperature change and salmon life history and behaviour.     

外源ABA对低温胁迫下青花菜植株生长及若干生理特性的影响

对低温胁迫下不同品种青花菜生长情况及SOD和POD酶活性进行分析,并以‘翠绿’品种为试材,研究外源ABA对植株低温胁迫的缓解作用.结果表明:(1)低温胁迫抑制株高、茎粗的增长,SOD、POD活性及可溶性糖含量显著降低;不同品种对低温胁迫的响应不同,‘翠绿’、‘蔓陀绿’品种受低温胁迫的影响较大,‘优秀,、‘DICICCO' (AU)品种受低温胁迫的影响较小.(2) 100mg· L-1脱落酸(ABA)处理对提高‘翠绿’的株高、茎粗效果显著; 50、100、150 mg·L-1 ABA处理的植株SOD、POD活性均显著高于对照(0mg·L-1ABA),其中,100 mg·L-1 ABA对SOD、POD活性的提高效果最为显著.(3)外源ABA可显著提高‘翠绿’植株可溶性糖含量,在低温处理15 d并恢复处理15 d后,50、100、150 mg· L-1 ABA处理的可溶性糖含量均显著高于对照并保持在较高水平.     

Modeling the effects of temperature on the survival and growth of North Sea cod (Gadus morhua) through the first year of life

Temperature and body size are widely agreed to be the primary factors influencing vital rates (e.g., growth, mortality) in marine fishes. We created a biophysical individual‐based model which included the effects of body size and temperature on development, growth and mortality rates of eggs, larvae and juveniles of Atlantic cod (Gadus morhua L.) in the North Sea. Temperature‐dependent mortality rates in our model were based on the consumption rate of predators of cod early‐life stages. The model predicted 35%, 53% and 12% of the total mortality to occur during the egg, larval and juvenile stages, respectively. A comparison of modeled and observed body size suggested that the growth of survivors through their first year of life is high and close to the growth rates in ad libitum feeding laboratory experiments. Furthermore, our model indicates that experiencing warmer temperatures during early life only benefits young cod (or theoretically any organism) if a high ratio exists between the temperature coefficients for the rate of growth and the rate of mortality. During the egg stage of cod, any benefit of developing more rapidly at warmer temperatures is largely counteracted by temperature‐dependent increases in predation pressure. In contrast, juvenile (age‐0) cod experiences a higher cumulative mortality at warmer temperatures in the North Sea. Thus, our study adds a new aspect to the ‘growth–survival’ hypothesis: faster growth is not always profitable for early‐life stages particularly if it is caused by warmer temperatures.     

Are Acartia tonsa cold‐stored eggs a suitable food source for the marine ornamental species Amphiprion polymnus? A feeding study

Copepods are the natural food items for marine fish larvae but are still difficult to be cultured on a continuous basis. Therefore, suitable storage techniques for copepod subitaneous eggs are of great interest. Cold‐stored copepod embryos still develop and retain a physiological activity during the cold storage period. As a consequence, their nutritional quality may change over the time of storage with these changes possibly affecting both eggs viability and larval fish survival and development. In this study, the clownfish, Amphiprion polymnus, was used as an experimental model to compare, for the first time, the effects of diets based on enriched rotifers and Artemia (control), Acartia tonsa copepods of a continuous culture and A. tonsa originated from 6 months cold‐stored eggs. The effects of the different diets were tested through morphometric, molecular and biochemical approach. This study demonstrated that after a 6 months cold storage period, the quality of copepods obtained from those eggs was suboptimal for A. polymnus larval rearing. In fact, larvae fed those copepods showed lower growth and survival performances respect to the other experimental groups.     

Estimating rates of mortality in stocks of Metapenaeus macleayi in estuaries of eastern Australia

Estimating rates of mortality is important for assessing stocks and for effectively managing seafood resources. This study reports the first estimates of rates of instantaneous fishing mortality (F) and natural mortality (M) for the commercially important school prawn, Metapenaeus macleayi. Replicated tag-recapture experiments were conducted on two stocks (Clarence River and Wallis Lake) to estimate the catchability coefficient (q) and F, whilst M was estimated from meta-analyses. Experiments were conducted across spatial and temporal scales to consider variability between stocks and variability between fisheries targeting this resource. The catchability coefficient was fitted to tag-recapture data in a population model across a range of M values (0.001-0.025 per day) and average daily F values were calculated. Values of q ranged between 2.03E−04 and 5.43E−02 and, 1.29E−04 and 3.41E−03 for the Clarence River and Wallis Lake stocks, respectively. Average daily F ranged between 2.86E−03 and 1.69 for the Clarence stock and 1.71E−03 and 3.44E−02 for the Wallis stock. With one exception (the November 2004 experiment) there were no differences in q and F values between experiments conducted on the Wallis Lake stock. For the Clarence stock values of q and F varied between years and within years. Factors thought to contribute to this variability were changes in prawn behaviour, differences in sizes of prawns tagged between experiments and differences in the survival of tagged prawns. The catchability coefficient for the Clarence River stock was weakly correlated to greater rates of river discharge. Estimates of F for the Wallis stock, the Clarence stock in 2004-05 and estimates of M were comparable to those reported for other penaeid fisheries world wide. There was no consistent pattern in comparisons of q and F values between the predominantly trawling operation of the Clarence River fishery and the seine netting of the fishery in Wallis Lake.     

An assessment of carcass counting surveys with increasing time lapse following a simulated fish kill on a small upland stream

A simulated fish kill was conducted on a small upland stream in Northern Ireland by planting out hatchery‐produced brown trout Salmo trutta L. carcasses of various size categories. Standard, post‐fish kill, assessment walkover surveys were conducted over time intervals to determine the number of carcasses visible. The sample variance between individual surveyors was generally low, with good agreement between the observed counts for the three, discrete, size fractions of fish up to 72 hr after the simulated fish kill. Despite low discharge rates, shallow water and good accessibility to the experimental stream, only 52% of the small category fish (<8 cm L_F) were recorded 4 hr after the start of the simulated fish kill. Larger carcasses (>17 cm L_F) were more visible, and >90% were detected 48 hr after the start of the simulated fish kill. After 96 hr, all size fractions of carcasses had reduced significantly, and the variability between replicate surveys increased markedly.