基于耳石微化学的鄱阳湖与长江口及邻近黄海海域刀鲚间关联性研究

With the support of our solid previous research accumulation , good analytical instruments, and the latest research development in China and abroad， the present study expects to interpret fingerprint patterns of living environmental elements (mainly from water masses) and isotopes (mainly from prey organisms) within otolith of Coilia nasus by an innovative and integrated application of advanced Electron Probe Micro-analysis (EPMA), Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS), and Isotope-ratio Mass Spectrometry (IRMS). All of which are not traditional investigative approaches of fisheries.By utility of established otolith environmental criteria of the elements and isotopes that can objectively reflect freshwater, brackish water, and seawater or spawning-site (natal-site) of C. nasus,this study hope to investigate and locate the spawning sites in the Poyang Lake (located some 800 km of the Changjiang River mouth; to confirm the natal homing migration to the Poyang Lake of anadromous C. nasus; to verify the assumption of the relatively close connectivity between the C. nasus fish spawned in the Poyang Lake and those fish in the Changjiang River mouth, as well as the adjacent Yellow Sea areas; and then, to understand the spatial and temporal dynamics of C. nasus among the spawning site of the Poyang Lake (natal site, nursery site),the migration pathways in the Changjiang River mouth, and the growth areas in the Yellow Sea (feeding sites). It is expected by the present study to provide the hard-won and urgently needed theoretical bases for more effective conservation of diadromous C. nasus from an innovation viewpoint.

在扎实的前期积累、良好的设备条件和国内外洄游性鱼类最新研究进展的支撑下，本研究拟创新性地综合应用先进的电子探针微区、激光烧蚀电杆耦合等离子质谱和稳定同位素质谱分析等非传统水产学研究手段的优势，对保存于刀鲚耳石中对应所生活环境的元素（主要来自水体）/稳定同位素（主要来自饵料生物）"指纹"进行"破译"，再运用所建立的分别客观代表淡水-河口半咸水-海水生境和刀鲚产卵场（出生地）的水环境元素或稳定同位素"指纹"类型标准，探索确定距长江口约800km鄱阳湖中的溯河型刀鲚的产卵场，确认自海洄游入湖繁殖刀鲚的回归性，验证鄱阳湖出生的刀鲚与洄游必经之长江口和邻近黄海海域刀鲚资源具有关联性的假说，进而尝试把握刀鲚在鄱阳湖产卵场（出生地、育幼地）-长江口洄游通道-黄海生长海区（索饵场）间的动态特征，以期从新的角度为有效养护珍贵的长江溯河洄游刀鲚提供难得而又急需的基础理论依据。

刀鲚是长江的一种名贵鱼类，但由于资源量急剧下降，而传统的调查方法均存在有很大的局限，迄今其在长江及河口、通江湖泊以及邻近海区中出生地/育幼地、洄游通道、生长水域/索饵场的确切分布仍为自然之谜。结合良好的设备条件和国内外洄游性鱼类最新研究进展，本研究创新性地综合应用了先进的电子探针微区、激光烧蚀电杆耦合等离子质谱和稳定同位素质谱分析等非传统水产学手段，通过湖-江-海大范围资源捕捞调查，对保存于刀鲚耳石上对应生境的元素/稳定同位素“指纹”进行了“破译”，并有效建立了可分别客观代表淡水-河口半咸水-海水生境和产卵场/出生地的水环境元素及稳定同位素“指纹”类型标准，首次探索确定了距长江口约1000km鄱阳湖中的湖口、星子、都昌、鄱阳、余干等水域存在溯河型刀鲚的分布区，其中在星子县麻头池到都昌县刘家山湖区首次发现了溯河型刀鲚的一个产卵场；并证实了自海洄游入鄱阳湖繁殖刀鲚的回归性，鄱阳湖出生的刀鲚与长江口和邻近黄海海域刀鲚资源具有关联性的假说，把握了刀鲚一个资源群在鄱阳湖产卵场/出生地/育幼地-长江口洄游通道-黄海生长海区/索饵场间的动态特征。此外，本研究证明了传统上用上颌骨长短来判别刀鲚洄游与否的局限性，发现了长江干流及其通江鄱阳湖的刀鲚长颌鲚和短颌鲚生态型中分别存在有淡水定居及溯河洄游个体的现象。长江口刀鲚耳石微化学的类型及在长江口附近水域捕获高性腺成熟度的亲鱼等进展显示长江流域刀鲚的产卵场不止鄱阳湖一处。长江与黄河、钱塘江、瓯江的刀鲚耳石微化学结果的比较进一步证实，这些江河的资源群无明显关联性。本研究还发现了刀鲚进入产卵场水域后会开始摄食，刀鲚耳石微结构形态与凤鲚、七丝鲚存在显著差异等一系列新现象。本研究修正了许多传统观点，从新角度客观地重建了各生态型刀鲚的生活史履历、生境及资源群组成规律、湖-江-海刀鲚资源的关联性特征，为有效养护和管理长江刀鲚资源提供了难得而又急需的理论依据与技术支撑。