可控水体中达氏鲟重塑自然繁殖的生理基础和环境需求

The ultimate goal of endangered fishes conservation is to maintain or to recovery the ability of one species to sustainably multiply by themselves. As for the critically endangered Dabry’s sturgeon Acipenser dabryanus, which is on the verge of distinction after the cease of natural spawning activities since 2000, restocking with the hatchery produced offsprings is the only choice for their rehabilitating. The success of this conservation strategy will essentially depend on whether the natural spawning will rebuild with the released populations. Hope is coming to answer this question for that a trial of spontaneous reproduction has been successfully realized with outputting 22 larvae by one of four females and at least one of the six males in an environmental enriched tanks with supplying substrates and water current. The proposal will try to repeat the experiments and make it as a reliable way for further conservation practice of Dabry’s sturgeon. The proposal was designed firstly to find out the preferred environmental factors by brood stock of Dabry’s sturgeon that is ready for spawning and built the mimicked natural spawning environment (MNSE); then explain the physiological basis of Dabry’s sturgeon that could spawn spontaneously in the MNSE through monitoring and comparing the behavioral, physiological and endocrinological responses of the Dabry’s sturgeon during or after spawning and the ones with no response; and will also explain what kind of environmental conditions will trigger the spawning activities by monitoring and predicting the environmental parameters during the typical spawning activities and also linking them with effectiveness of reproduction; and finally try to establish a reliable way for producing the offspring of Dabry’s sturgeon in the MNSE. The results will theoretically and practically support the future efforts in restocking, rehabilitation and rebuilding the population of Dabry’s sturgeon.

维持或恢复自然繁衍是物种保护的终极目标。国家一级保护动物达氏鲟的自然繁殖在2000年左右停止，濒临灭绝。人工保育群体放归到河流中能否重塑自然繁殖是决定其资源修复成败的关键。2016年通过布设河床质和营造水流初步实现达氏鲟的自发繁殖成功（未注射激素，1雌和1雄自发交配产卵，获苗22尾），为达氏鲟种群重建带来希望。本项目拟基于性成熟达氏鲟的环境偏好性研究，筛选适合模拟产卵的环境条件；构建并调控仿自然环境，研究比较环境诱导和激素诱导下达氏鲟的行为和生理响应差异，阐明可控环境中达氏鲟重塑自然繁殖的生理基础；基于对繁殖发生关键过程的定位和回顾反演以及对环境参数的实测和模拟解答达氏鲟实现自然繁殖的环境需求。本研究旨在揭示可控环境中达氏鲟实现自然繁殖的内在生理基础和外在环境需求，建立可靠的仿生态繁育技术，开辟保育新途径。为达氏鲟科学放归、自然产卵场修复及最终实现种群重建提供理论基础和技术支撑。

国家一级保护动物长江鲟（Acipenser dabryanus）野生种群几乎消失。人工保育的长江鲟放归后能否重塑自然繁殖是其能否实现野外种群重建的关键。本研究通过室内可控水体的产卵场环境模拟与调控技术，解答诱发长江鲟自然繁殖的环境需求和生理基础。研究结果表明：（1）不同性腺发育阶段（II-IV期）长江鲟成体在栖息分布中均偏好光滑和细砂类型河床质，喜好的流速范围为（0.3-0.9m/s），无显著雌雄差异或昼夜差异。（2）在长椭圆形池、圆形池和长条形池等3种类型池中均已通过环境调控实现长江鲟自然繁殖，项目实施期内累计成功诱导20组次。（3）基于NOLDUS Ethovision XT视频跟踪系统，创新性解决了大型鱼类水下光学跟踪定位技术，解答了长江鲟自然繁殖的环境需求，首次揭示卵石河床质是自然繁殖发生的决定性因素，光滑和砂质河床不能诱发自然繁殖成功。长江鲟自然繁殖的流速需求范围在0.3-0.9m/s。另外，水深0.5-1.5m内均可发生自然繁殖（4）长江鲟的性成熟度会影响诱发繁殖成功效率，到达IV成熟的长江鲟中有60%雌鲟实现成功诱导。但成功诱导组与对照组长江鲟的生殖内分泌水平（雌激素、睾酮、甲基睾丸酮）上未有显著性差异。（5）经过30余组次的实验测试，建立了一整套长江鲟自然繁殖的仿生态繁殖技术，除控制河床质、水流、水深等环境外，繁殖过程中的细砂添加可显著提高长江鲟的自然受精卵（最好达90%）（6）应用自主开发的四倍型微卫星亲子鉴定分析软件，揭示诱导成功的2组长江鲟子代鱼苗分别有82.00%和79.00%的鱼苗可确定其亲本实验鱼，为1雌1雄的交配结果。（7）相关研究成果已被农业农村部采纳列入《长江鲟（达氏鲟）拯救行动计划（2018-2035）》。项目组已累计放流长江鲟亲体505尾，正力图通过产卵场营造和改良，突破野外繁殖成功，为长江鲟的野外种群恢复提供强有力的技术支撑。