栉孔扇贝大规模死亡致病病原的研究

对2000-2002年山东沿海6个疫区患病栉孔扇贝进行电镜观察，在消化腺、外套膜、肾和肠的结缔组织细胞和间质细胞中发现一种球形病毒．并引起相直的病理学变化。该病毒具囊膜，直径为130～170nm，核衣壳直径为90～140nm。病毒分离纯化后．观察到的病毒囊膜表面覆有长20nm的纤突。病毒在细胞质中的囊泡样结构内完成装配，其内未发现包涵体存在。从发病疫区栉孔扇贝组织中分离出病毒毒种对键康扇贝进行人工感染。结果显示，各感染实验组发病扇贝表现出与自然海区发病扇贝相同的临床症状。病毒注射组死r二率为?5％，病毒浸浴组死亡率为68．7％．灭活病毒注射组和空白对照组死亡率皆为12．5％。病毒注射、浸浴组与灭活病毒注射组、空白对照组死亡率差异显著。电镜复检结果显示，各感染实验组发病扇贝组织中分布有大量病毒粒子，与自然海区发病扇贝组织所观察到的病毒粒子在形态特征和病理学特征上完全一致。以上结果证明，病毒是导致栉孔扇贝大规模死亡的直接病原。     

Discovery of a synergistic effect of oxytocin on the efficacy of Alpha-Chloralose,a drug used for capturing and controlling birds

Overdose and death of both target and non-target species are not uncommon when α–chloralose is used for animal control. Alpha–chloralose appears to depress the central nervous system by having an affect on the GABA-A receptor in a manner similar to ethanol. Recently central administration of oxytocin was shown to block ethanol-induced impairment in rodents. Our study investigates whether IM administration of oxytocin speeds avian recovery from α–chloralose and reduces mortality under simulated field conditions. We found that when injected twice with oxytocin (30 uL/kg) chickens entered α–chloralose narcosis more quickly and showed greater behavioral impairment. When fed the LD₅₀ dose of α–chloralose, repeated injection with oxytocin produced no significant difference in mortality rate or time to death in comparison to the control group. The effects of peripheral oxytocin on female chicks were different than results found previously in cockerels given oxytocin centrally. Oxytocin is not a suitable antidote for α–chloralose overdose during animal capture in the field but instead accentuates α–chloralose narcosis, making capture more likely and efficient.     

Comparative virulence of Infectious salmon anaemia virus isolates in Atlantic salmon, Salmo salar L.

Infectious salmon anaemia virus (ISAV) surveillance in the Bay of Fundy has identified the existence of a large number of genetically distinct ISAV isolates which appear to be of variable virulence. Genetically distinct isolates are currently being designated based on sequencing of the hyper polymorphic region (HPR) of genomic segment 6, which encodes the haemagglutinin–esterase protein, but it has been difficult to elucidate a clear association between these molecular variations and variations in virulence. This has hampered the establishment of proactive management decisions regarding infected fish, and ISAV infections, regardless of type, must be treated as one. Field data of ISAV infections is difficult to collect and to compare between infections because of a wide range of confounding factors including time of year, fish stock, cage site location, mitigating factors and stressors. An important tool in determining the relationship between molecular differences and virulence comes from analysis of quarantine studies. The goal of this study was to compare the virulence, by co-habitation and intraperitoneal injection, of four regionally common and recent ISAV isolates in a controlled environment. We found significant differences in mortality between ISAV molecular isolates, and present data showing that survival of ISAV infection confers significant resistance to re-infection with a different ISAV isolate. These findings, if borne out in field studies, will significantly alter the way ISAV infections are managed in the Bay of Fundy and elsewhere.     

The understudied and underappreciated role of predation in the mortality of fish released from fishing gears

The assumption that animals released from fishing gears survive has frequently been scrutinized by researchers in recent years. Mortality estimates from these research efforts can be incorporated into management models to ensure the sustainability of fisheries and the conservation of threatened species. Post‐release mortality estimates are typically made by holding the catch in a tank, pen or cage for short‐term monitoring (e.g. 48 h). These estimates may be inaccurate in some cases because they fail to integrate the challenges of the wild environment. Most obvious among these challenges is predator evasion. Stress and injury from a capture experience can temporarily impair physiological capacity and alter behaviour in released animals, a period during which predation risk is likely elevated. In large‐scale commercial fisheries, predators have adapted their behaviour to capitalize on impaired fishes being discarded, while in recreational catch‐and‐release fisheries, exercise and air exposure can similarly impede the capacity for released fish to evade opportunistic predators. Owing to the indirect and often cryptic nature of this source of mortality, very few studies have attempted to document it. A survey of the literature demonstrated that <2% of the papers in the combined realms of bycatch and catch‐and‐release have directly addressed or considered post‐release predation. Future research should combine field telemetry and laboratory studies using both natural and simulated predation encounters and incorporate physiological and behavioural endpoints. Quite simply, predation is an understudied and underappreciated contributor to the mortality of animals released from fishing gears.     

浙江南部近海小黄鱼生长、死亡和单位补充量渔获量

浙江南部近海是东海种群小黄鱼(Larimichthys polyactis)的重要繁殖和育肥场所。根据2016年2月、5月、8月和11月采集的2023尾浙江南部近海小黄鱼全长、体长和体重等生物学信息,利用体长频率分布估算小黄鱼种群生长、死亡参数,并利用Beverton-Holt动态综合模型评估探讨单位补充量渔获量在不同自然死亡系数和渔具选择下随捕捞死亡系数的变化趋势。研究结果表明小黄鱼von Bertalanffy生长参数为渐近体长L_∞=22.58 cm,生长速率K=0.78/a,初始年龄t_a=-0.37 a;自然死亡系数M值为1.343,总死亡系数Z值为4.432,捕捞死亡系数F为3.089,开发率E为0.697,表明资源处于过度开发状态;小黄鱼的首次捕捞体长L_(50)=13.11cm,对应首次捕捞平均年龄t_c=0.743 a,小于临界年龄(0.886a)和体重生长的拐点年龄(0.979a),渔业主要捕捞对象为幼鱼和补充群体,无法保证资源的有效补充;根据B-H动态模型,当前的YPR值为15.279 g/ind,若降低捕捞强度到1.685,对应YPR_(max)为17.061 g/ind,与当前产量相比增幅11.66%;若提高开捕体长(13.11cm→16.0cm),YPR_(cur)会出现显著提高(15.279 g/ind→18.766 g/ind),增幅达22.82%,表明提高开捕体长要优于降低捕捞强度。当前东海小黄鱼群系处于小型低龄化和过度开发状态,建议将小黄鱼的开捕体长提高为15 cm,保证小黄鱼的产卵亲体量及资源的可持续发展。     

小兴安岭谷地云冷杉林土壤酶活性的异质性

利用传统统计学与地统计学相结合的方法对小兴安岭谷地不同死亡程度云冷杉林表层土壤（0~20cm）酶活性空间异质性和格局进行研究。结果表明：①土壤脲酶变异函数曲线的理论模型符合线性模型,土壤转化酶、碱性磷酸酶和过氧化氢酶的理论模型符合指数模型或球状模型。②土壤酶活性各项指标的空间变异主要是由结构性因素引起,土壤碱性磷酸酶活性和过氧化氢酶活性指标的空间自相关程度均属较强以上（空间结构比均在75%以上）,土壤转化酶为中等（空间结构比均在25%以上）,土壤脲酶在较弱到中等之间变化。③云冷杉林表层土壤过氧化氢酶的自相关范围最大（0.58~3.08 m）,转化酶和碱性磷酸酶分别为1.41~3.98 m和0.91~4.29 m,而土壤脲酶自相关范围最小（15.426~16.673 m）。④土壤转化酶、碱性磷酸酶和过氧化氢酶活性的空间格局明显,土壤转化酶、碱性磷酸酶、过氧化氢酶和土壤脲酶的分数维分别为1.930~1.990,1.910~1.986,1.923~1.997和1.936~1.970。     

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.     

Putting the pieces together: Recent growth,nutritional condition,and mortality of Engraulis anchoita larvae in the Southwest Atlantic

Dynamics of clupeiform fish populations such as anchovy are frequently impacted by environmental variations which can affect the success of the species recruitment. Herein, we have analyzed recent otolith growth rate, RNA/DNA nutritional condition index (sRD), and mortality rate of argentine anchovy larvae Engraulis anchoita from three different nursery areas in the Southwest Atlantic. We have evaluated the relationship between the environmental variables (abundance of copepod nauplii, temperature, chlorophyll‐a concentration, and abundance of E. anchoita larvae) and larval endogenous variables (size, weight, age, and otolith radius) to sRD and recent growth rate. Fast larval growth rates were observed toward the northern sector of the studied area, characterized by higher temperature. High values of sRD were associated with higher nauplii abundance in the proximity of coastal fronts. The larvae with the lowest growths and lowest minimum values of nutritional condition coincided with the area where there was less abundance of nauplii and higher larval mortality. Larval size and nauplii abundance were positive explanatory factors for both recent growth rate and sRD index. Temperature had a positive effect on recent growth rate and a negative effect on sRD index. This condition index was poorly explained in terms of model fit in comparison with the growth model. The results herein provided could be significant to better understand the recruitment of the species, as to determining favorable areas for the growth and survival of anchovy larvae.     

热水处理对扶桑棉粉蚧的致死作用

本文研究了热水处理对扶桑绵粉蚧的杀灭作用,结果表明,在49℃、50℃、51℃、52℃和53℃时扶桑绵粉蚧1龄若虫死亡率达到100%的处理时间分别为240min、150min、60min、40min和6min。分析显示,热水温度和处理时间长度的复合作用导致了扶桑绵粉蚧的死亡。建立了热水温度(X1)、处理时间(X2)和扶桑棉粉蚧死亡率(Y)之间的模型方程为Y=-9.466+0.192X1-0.0000240X22+0.000218X1X2。给出了不同温度热水处理时扶桑绵粉蚧100%死亡的时间长度。     

超声波对粘虫的处理效果

以常见害虫粘虫为试验材料,用不同剂量超声波处理成虫,观察处理后期粘虫发育阶段的死亡率和羽化率变化情况。结果表明:随着超声波剂量的增大,粘虫死亡率呈明显上升趋势,羽化率有明显下降趋势,超声波作用生物效应显著,当作用时间为140 s时,成虫死亡率急剧升高,高于50%,当作用时间超过180 s时,几乎没有羽化的粘虫。