Effect of d-Lys6 salmon sGnRH alone and in combination with domperidone on the spawning of common carp during the late spawning season

The effect of [d-Lys6] salmon gonadotropin-releasing hormone alone (sGnRH) and in combination with domperidone, a dopamine antagonist, on the spawning of common carp, Cyprinus carpio, was investigated during the late spawning season (when mature fish stop spawning under natural conditions when males and females are put together). Fish were induced to spawn by [d-Lys6]-sGnRH salmon gonadotropin-releasing hormone analogue (sGnRH-X) only when injected in combination with domperidone at doses of 10 g kg-1 and 20 mg kg-1 body weight respectively. [d-Lys6]-sGnRH-X alone did not induce spawning at a dose as high as 100 g kg-1 body weight. Fish injected with domperidone alone did not spawn either. These results demonstrate that [d-Lys6]-sGnRH-X in combination with a dopamine antagonist is effective in inducing spawning during the late spawning season.     

光滑河蓝蛤生殖习性初步研究

光滑河蓝蛤一年有2次产卵高峰期,分别为在5月初和9月底。在产卵高峰期,通过人工授精方法,可获得受精卵并正常发育。在秋季性腺切片中发现1例雌性滤泡周围有呈集中式分散状态分布的精子,经分析初步认定是雌雄同体现象。     

The importance of individual behaviour for successful settlement of juvenile plaice (Pleuronectes platessa L.): a modelling and field study in the eastern Irish Sea

To study the transport of plaice (Pleuronectes platessa L.) eggs and larvae in the eastern Irish Sea, we constructed a 3D‐baroclinic physical model and coupled it to a particle‐tracking scheme that allowed aspects of larval behaviour to be simulated. Starting positions for eggs were based upon data from a series of ichthyoplankton surveys and final positions were compared with results of settled plaice distributions from two beam trawl surveys conducted on beaches around the eastern Irish Sea. If simulated larval behaviour was limited to passive drift or horizontal swimming, the particles diffused away from the spawning areas but failed to reach nursery grounds in significant numbers (85–90% remaining offshore). In contrast, switching on circatidal vertical swimming significantly increased the numbers of larvae reaching the coast (only 23–30% remained offshore). Particles tended to accumulate in bays and estuaries and this pattern compared well with the distribution of settled plaice from the field surveys. Studies in the southern North Sea (where spawning and nursery grounds are widely separated) have also demonstrated the importance of selective tidal stream transport for successful recruitment of settling plaice to nursery grounds. Although our understanding of the ontogeny of this behaviour is still poor, the model results presented suggest that this aspect of behaviour is a key factor influencing plaice settlement success.     

The spawning migration and conservation of smelt Osmerus eperlanus in the River Cree, southwest Scotland

The anadromous smelt Osmerus eperlanus population associated with the River Cree on the Solway Coast, southwest Scotland, is the only one remaining from several which previously occurred in that area. Their spawning migration was studied as a basis for conservation and management proposals. The timing and location of the onset of spawning in February/March was determined by regular inspection of the river bed for smelt eggs. The thermal regime in the lower river during preceding weeks is considered the primary factor in initiating spawning, but prevailing temperature, tide and flow conditions determine exactly where and when. Several local factors must be addressed for future conservation and management, e.g. commercial netting, pollution and the present physico-chemical character of the river. The reintroduction of smelt to other rivers on the Solway Coast should now be seriously considered.     

长江刀鲚生殖洄游过程中血清能量指标变动

为探究刀鲚(Coilia nasus)生殖洄游过程中血清能量指标的变动情况,于2019年4月15日 ~ 6月5日,在长江崇明段、镇江段和安庆段使用刺网采集刀鲚,对49尾刀鲚血清样本的能量指标进行测定分析。结果显示,自崇明至安庆的洄游过程中血糖、总胆固醇、低密度脂蛋白含量均无显著差异(P>0.05),血清总蛋白、甘油三酯、高密度脂蛋白和游离脂肪酸含量在镇江至安庆段均无显著差异(P>0.05),出现显著差异的过程主要集中在崇明至镇江段,总蛋白和甘油三酯含量显著降低(P<0.05),分别下降19.36%和29.29%;高密度脂蛋白和游离脂肪酸含量显著升高(P<0.05),分别上升60.38%和23.65%;安庆段卵巢发育至不同时期的刀鲚样本中,Ⅳ期样本的甘油三酯含量于Ⅱ期和Ⅲ期样本均存在显著差异(P<0.05),分别上升67.24%和53.75%,其余指标在各发育期样本间均无显著性差异(P>0.05)。综上所述,自崇明至镇江段,刀鲚血清样本甘油三酯、高密度脂蛋白和游离脂肪酸等血脂相关指标出现显著性变化(P<0.05),表明刀鲚在洄游前期脂质代谢活跃,脂肪应是其洄游及发育的主要供能物质;自镇江至安庆段,其代谢水平对洄游及性腺发育的能量需求逐渐适应,因此洄游后期刀鲚血清能量指标总体趋于平稳。     

光泽黄颡鱼繁殖的初步研究

对嘉陵江中的光泽黄颡鱼的繁殖作了初步研究。其中主要研究了光泽黄颡鱼的生殖群体、繁殖力和胚胎发育。采用LRH-A加鲢鱼脑垂体催产光泽黄颡鱼获得成功,催产适宜水温22-25℃,效应时间10-18h,胚胎发育较快,感官、上颌须、心脏跳动等在出膜之前出现。     

Early assessment of gilthead sea bream (Sparus aurata) spawning dynamics by mini‐broodstocks

The implementation of any sustainable breeding program requires a maximization of effective size (Ne) to maintain inbreeding rate at minimum levels. However, the control of Ne remains a major challenge for those species whose reproduction in captivity is based on a spawning strategy where there is no control over the established matings. The present study aims to assess the spawning dynamic of gilthead sea bream (Sparus aurata) at different dates from two mini‐broodstocks (4 ♀ and 4 ♂). Here we report the use of a simple protocol based on the genotyping of fertilized eggs from a reduced set of microsatellite loci which provides a quick evaluation of daily spawning in terms of family structuring (number of active breeders and number and family size). According to our results, the daily spawning dynamics is characterized by a fluctuation in the number of active breeders, reaching maximum values (until 100%) during peak production phase. However, the proportion of possible mating (families) in a single daily spawning never exceeded more than 81%. Unbalanced parental contributions were highly frequent, with extreme cases involving the assignment of 50%–90% of the offspring to a single family. Therefore, the use of mini‐broodstocks and the grouping of spawning harvested at different dates are proposed as strategies to minimize the inbreeding risk by providing a more optimal pattern of family structuring (increase in the number of families obtained and a more balanced parental contributions) that entails a more conservative Ne/N ratio.     

Artificial reproduction protocol,from spawning to metamorphosis,through noninvasive methods in Patella caerulea Linnaeus, 1758

Controlled reproduction is a requirement for developing effective mollusc cultivation for commercial or restoration purposes. In this study, a protocol for spawning induction using noninvasive methods in limpets was developed, using the common Mediterranean species, Patella caerulea Linnaeus, 1758. Six nonlethal spawning induction treatments were tested: three chemical (two concentrations of H₂O₂ and KCl) and three physical (bubbling, warm and cold thermal shock). All treatments, except thermal shocks, induced the spawning of fertile gametes. Bubbling resulted the best treatment in providing spawning response, being the easiest and least invasive method tested. After eggs fertilization, larval development was followed until metamorphosis, testing fed and unfed conditions. Settlement took place after 7 days. The developed protocol represents a benchmark for further application to other limpets, for aquaculture or repopulation.     

Physiological condition and migratory experience affect fitness‐related outcomes in adult female sockeye salmon

Relating fish physiology, behaviour and experience to fitness‐related outcomes at the individual scale is ecologically significant, but presents difficulties for free‐ranging fishes in natural systems. Physiological state (e.g. level of stress or maturity) and experience (e.g. habitat use or exposure to stressors) may alter the probability of survival or reproduction. This study examined the relative influence of physiology and migratory experience on survival, migration duration, reproductive longevity, and egg retention in adult female sockeye salmon (Oncorhynchus nerka) from a Fraser River population. One hundred and thirty‐five females were plasma sampled and tagged with radio transmitters and archival temperature loggers. Fish were tracked 55 km through two natal lakes to spawning grounds, following passage of a hydroelectric dam. For 39 females, we assessed the proportion of time within an optimal temperature (T_optAS) window (13.4–19.5°C), which provides ≥90% of maximum aerobic scope. Females with lower plasma glucose concentrations were more likely to reach spawning grounds. Early migrants spent longer in natal lakes. More time in the T_optAS window was associated with greater reproductive longevity and lower probability of egg retention. Later arriving females had reduced longevity on spawning grounds, as did females that retained eggs. Exposure to higher dam discharge was associated with reduced reproductive longevity and greater probability of egg retention, but not lower survival, indicating a delayed effect of dam passage. Our results underscore the complexity of factors governing fitness‐related outcomes for salmonids, particularly the importance of female experience in the days and weeks prior to spawning.     

水电站下游鱼类产卵场水温的人工神经网络预报模型

丰满电站下游松花江水文站河段分布有一系列鱼类产卵场,电站拟通过分层取水调控下泄水温,改善下游鱼类生存环境。该文基于大量实测数据分析,建立了松花江站水温的人工神经网络预报模型,通过输入上游吉林水文站的水温与流量,以及地区气象条件,可计算出下游松花江站2日后的水温变化。根据中长期天气预报数据与电站泄流计划,采用该模型通过2日递推的方法,可预测出下游鱼类产卵场的水温变化过程。运用2006-2013年实测数据对网络模型进行训练,然后对2014年松花江站水温变化过程进行计算,计算值与实测值的变化过程甚为吻合,相关系数为0.992,水温平均误差为0.51℃。在水温生态调度运行期间,根据产卵场水温变化的预报数据,可适当调控电站下泄水温,保持适宜的鱼类产卵条件。