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太湖新银鱼繁殖生物学与资源动态研究
Alternative TitleStudies on reproductive biology and resource fluctuation of icefish Neosalanx taihuensis Chen
龚望宝
Subtype博士
Thesis Advisor谢松光 ; 解绶启
2009-06-03
Degree Grantor中国科学院水生生物研究所
Place of Conferral水生生物研究所
Keyword太湖新银鱼 春季繁殖群体 秋季繁殖群体 性腺发育 繁殖生物学特征 生长 种群波动 天鹅洲故道 三峡水库
Abstract太湖新银鱼(Neosalanx taihuensis Chen)是长江中下游及其附属水体重要的小型经济鱼类。由于营养丰富,经济价值高,已被广泛移殖到全国近20个省市的湖泊或水库。然而,在一些水体中,种群常不稳定,爆发式增长后,突然显著下降,甚至绝产。同时太湖新银鱼的种群爆发常导致其它土著鱼类资源衰退。太湖新银鱼是长江天鹅洲故道的优势鱼类种群之一,2003年该种群显著下降。三峡水库蓄水后,太湖新银鱼种群显著上升,已成为库区重要的渔业对象之一。本文研究了长江天鹅洲故道和三峡水库太湖新银鱼的性腺周年发育和繁殖生物学特征,并比较了不同采样年间、不同种群间的繁殖生物学特征和不同种群间仔鱼的生长,主要目的在于了解太湖新银鱼的生活史,揭示不同种群资源变动的繁殖生物学机制,并为银鱼种群资源预报提供重要信息。主要结果和结论如下: 1. 天鹅洲故道和三峡水库太湖新银鱼都有两个繁殖群体,即春季繁殖群体(春群)和秋季繁殖群体(秋群)。春群的繁殖季节为1月至5月,秋群的繁殖季节为9月至11月。根据体长频率分布,春群后代的生命周期为一年,春季孵化出来后,到翌年春季性成熟产卵,产完卵后不久就死亡;一部分秋季繁殖的个体可能来自于当年春季繁殖个体的后代,还需要通过耳石分析进一步确证。秋群后代的生命周期也还需要通过耳石分析进一步确证。 2. 天鹅洲故道和三峡水库太湖新银鱼春群和秋群的繁殖生物学特征都存在显著性差异。两种群的春群都较秋群个体大、性体指数高和繁殖力强,表明两种群的春群都较秋群的个体繁殖投入高。另外,春群的卵径也都较秋群大,其后代的存活率可能更高。由于春季繁殖群体的个体数量也都较秋季繁殖群体多,因此,春季繁殖个体对种群补充的贡献较秋季繁殖个体大。因此,春群应该是太湖新银鱼种群补充的主要贡献者。太湖新银鱼的渔业管理和资源监测应主要考虑春群的特征。 3. 天鹅洲故道太湖新银鱼2007年的捕捞量较2006年增加。本研究发现天鹅洲故道太湖新银鱼春群的繁殖生物学特征在2006年和2007年之间存在显著性差异。2007年较2006年相对条件指数高、性体指数高、繁殖力强和卵径大,表明2007年春群的个体繁殖投入高。2007年春群后代的相对条件指数也较2006年高,表明繁殖投入会进一步增加,天鹅洲故道太湖新银鱼种群可能正在逐步恢复之中。 4. 太湖新银鱼春群的繁殖生物学特征在天鹅洲故道种群和三峡水库种群之间存在显著性差异。三峡水库种群较天鹅洲故道种群个体大、相对条件指数高、繁殖力强和卵径大,表明三峡水库种群个体生长快和繁殖投入高。结合三峡水库种群的群体丰度高于天鹅洲故道种群,我们认为繁殖投入是调节太湖新银鱼种群波动的重要因子。因此,种群繁殖生物学特征分析可能是太湖新银鱼种群动态监测的有效手段。太湖新银鱼种群丰度上升对三峡水库库区其它鱼类资源及鱼类群落演替过程的影响需要进一步研究。 5. 太湖新银鱼春群幼鱼的矢耳石呈圆形。耳石原基和核,圆形,且清晰可见。耳石上有清晰的轮纹,前40个轮纹清晰可读,但耳石边缘轮纹不可读。耳石半径随体长增加而增加。三峡水库种群的耳石核半径显著大于天鹅洲故道种群,结合三峡水库种群的卵径也大于天鹅洲故道种群,其后代的存活率可能更高。第19个轮纹宽度至第35个轮纹宽度,三峡水库种群的轮宽显著高于天鹅洲故道种群,表明在太湖新银鱼的仔鱼阶段,三峡水库种群的生长要快于天鹅洲故道种群。
Other AbstractNeosalanx taihuensis Chen is a freshwater resident icefish mainly inhabiting the middle and lower reaches of the Yangtze River, including its tributaries, and is recognized as the most dominant fish in some lakes affiliated to it. Because of its high commercial value and popularity as a food fish, N. taihuensis has been introduced into lakes and reservoirs in over 20 provinces of China, and has become the most commercially exploited icefish in the country. Populations of N. taihuensis in some waters often showed considerable fluctuation, i.e., rapidly expanding in some years and drastically declining in others. Furthermore, icefish introduction has been observed to induce endangerment (and even extinction) of some native fishes, most notably in some Yunnan lakes. N. taihuensis was one of the most abundant fish species in the Tian-e-zhou Oxbow (TEO), but annual commercial catch of N. taihuensis in the oxbow has declined dramatically since 2003. Abundance of this species has significantly increased following impoundment in 2003 and became a major commercial species in the Three-Gorges Reservoir (TGR). In this study, we investigated the annual reproductive cycle of female N. taihuensis in the TEO and in the TGR. We also compared the reproductive characteristics of the spring mature female between 2006 and 2007 in the TEO, and between TEO population and TGR population. The growth of the spring spawning fish larvae were compared between two populations based on the otolith analyses. The main objective was to reveal the life history characteristics of N. taihuensis, and to provide critical information to understand the biological mechanisms underlying population fluctuations. Essential information for population forecasts, helping in the effective management of this fish are also given. The main results and conclusions were listed as following: 1. Both in the TEO and TGR, two separate spawning seasons were identified based on the annual reproductive cycles of the females, designated as the spring spawning season from January to May and the autumn spawning season from September to November. Life span of the offspring of the spring-spawning fish was 1 year, with them dying shortly after the subsequent spring spawning season. Autumn-spawned females seem to be the offspring of the spring-spawning fish, based on monthly changes in the length-frequency distributions, but this needs to be confirmed with otolith analysis. Fate of the offspring of the autumn spawning fish also needs further investigation. 2. Reproductive characteristics of N. taihuensis varied significantly between the spring spawning stock and the autumn spawning stock in the TGR and also in the TEO. Larger body size, higher fecundity and higher GSI of the spring spawners indicated higher individual reproductive investment of the spring spawning stock than the autumn spawning stock. With larger egg size, early survival rate of the offspring of the spring spawning stock may also be higher than the autumn spawning stock. Thus, the individual contribution of the spring spawning stock to the recruitment of the population should be higher than the autumn spawning stock. Also, with higher abundance of the spring spawning stock when compared to the autumn spawning stock, we suggest the spring spawning stock as the major contributor to the recruitment of the N. taihuensis population in the TGR and in the TEO, and monitoring and fisheries management on N. taihuensis in the TGR and in the TEO should mainly consider the spring spawning stock. 3. The reproductive characteristics of mature spring female varied significantly between 2006 and 2007 in the TEO. They had higher values for absolute fecundity, gonadosomatic index, and relative condition factor in 2007 than in 2006. Relative condition factor of the immature female offspring of spring-spawning fish was also higher in 2007 than in 2006, portending a further increase in reproductive investment during the spring spawning of 2008. The increasing reproductive investment suggests that the population of N. taihuensis in the Tian-e-zhou Oxbow is recovering from its recent decline. 4. Reproductive characteristics of the spring spawning stock of N. taihuensis varied significantly between the populations in the TGR and in the TEO. Larger body size, higher condition, higher fecundity and larger oocyte diameter of the spawning stock in the TGR indicated faster individual growth and higher reproductive investment of the TGR population than the TEO population. With higher population abundance associated with higher reproductive investment of N. taihuensis in the TGR than in the TEO population, we suggest that reproductive investment is an important factor regulating resource fluctuation of N. taihuensis populations. The impacts of increasing N. taihuensis population on other fish species and on the fish community succession in the TGR needs to be further investigated. 5. The sagittal otoliths of larval fishes were analysed to understand early growth characteristics of N. taihuensis in the TGR and in the TEO. The primordium and nucleus were round in shape. Fourty clear increments were evident around the nucleus but there was no deposition at the otolith margin. Standard length and otolith radius were linearly correlated. The nuclear radius of N. taihuensis in the TGR was significantly larger than in the TEO. Having a larger oocyte diameter, and larger nuclear radius, the early survival rate of the offspring of the spring spawning stock in the TGR may also be higher than in the TEO. Starting from nineteenth to thirty-fifth increment, the larval population in the TGR was significantly more abundant than in the TEO. The results indicated that the larval growth rates of N. taihuensis in the TGR were higher than in the TEO.
Pages118
Language中文
Document Type学位论文
Identifierhttp://ir.ihb.ac.cn/handle/342005/12396
Collection学位论文
Recommended Citation
GB/T 7714
龚望宝. 太湖新银鱼繁殖生物学与资源动态研究[D]. 水生生物研究所. 中国科学院水生生物研究所,2009.
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