齐口裂腹鱼卵巢发育的组织学研究

采用石蜡组织切片和扫描电镜法,对齐口裂腹鱼卵巢发育进行了组织学研究。结果表明:卵母细胞的发育分为5个时相,卵巢发育可分为6个时期。第2时相卵母细胞中具有卵黄核、围核透明层,并可见核仁物质外排现象;液泡中的内含物和卵黄颗粒呈现多种形态;卵母细胞发育过程中,核仁数增加较多;卵膜由质膜和放射带组成。在第5时相成熟卵子的受精孔中仍有精孔细胞堵塞。产卵时间为2月下旬至4月下旬,属分批同步产卵类型。     

克氏原螯虾产卵适宜生态环境的研究

通过模仿野生克氏原螯虾(Procam barus ckarkii)繁殖生态条件,利用水泥池设置不同洞穴和覆盖不同水草进行克氏原螯虾批量产卵试验。在人工洞穴研究试验中,使用石棉瓦洞穴的克氏原螯虾抱卵率最高,最终抱卵率可达到75%,其次是砖制洞穴65%,再次是管道洞穴62.5%,无洞穴组抱卵率最低为45%。在水草研究试验中,使用水葫芦水草的克氏原螯虾抱卵率最高75%,水花生为62.5%,不设水草最差为27.5%。     

Migration,homing and spatial ecology of common carp in interconnected lakes

The common carp, Cyprinus carpio, is a large, long-lived, fecund and mobile cyprinid, which evolved in complex inter-braided Ponto-Caspian rivers that experience both springtime flooding and freezing winters. Studies suggest adults often move to productive, shallow lakes and floodplains to spawn because they often lack egg predators and then return to deeper normoxic waters to overwinter. Whether these movements involve individuals consistently selecting, or homing to, the same spawning and refuge lakes as part of a strategy benefiting their reproductive success is unknown. To address this question, we examined the movements of 67 radio-tagged adult carp for 3 years in a watershed with 11 interconnected lakes. Carp were tagged and released into a centrally located, normoxic deep lake in spring and fall. Each spring over 95% of its adults left via a single stream and swam into one of 5 shallow lakes, with most individuals (84%) selecting the same lake(s) in which to spawn each year (median Bhattacharyya affinity coefficient of similarity of 0.82). Young were later found in those lakes without egg predators, which cannot survive winter anoxia. After spawning, carp spent summers moving between productive lakes in an individualistic fashion, presumably foraging, with most (89%) eventually returning to the same deep lake to overwinter (median Bhattacharyya affinity of 1.0). These movements appear to reveal a life-history tactic involving seasonal homing migration, first to a spawning location and later to winter refuges, that is well adapted to productive but highly heterogeneous and interconnected freshwater environments.     

Reproductive resilience or sweepstakes recruitment? Assessing drivers of lifetime reproductive success in exploited marine fish

Understanding the processes that drive reproductive success in marine fish stocks is critical to effective fisheries management. These processes can be difficult to investigate, especially in age-structured populations, because they occur at transgenerational scales. Reproductive success is often attributed to a small portion of the adult population (<0.01%) and thought to be driven primarily by random external factors, consistent with the concept of sweepstake reproductive success (SRS). A competing concept, the reproductive resilience paradigm, posits that fishes have evolved complex spawner-recruit systems to achieve lifetime reproductive success and maintain population stability within highly variable environments. Here, we examine these two concepts. First, we analyse the popular sport fish red drum (Sciaenops ocellatus, Sciaenidae), drawing on genetic and reproductive data to estimate a plausible range for the ratio of effective population size ($N_e$) to adult abundance ($N_A$) and to infer variance in lifetime reproductive success ($V_k^{*}$). Then, we synthesize available data and infer $V_k^{*}$ for two other fishes that have $N_e/N_A$ ratios reportedly >0.10, the southern bluefin tuna (Thunnus maccoyii, Scombridae) and the silver seabream (Chrysophrys auratus, Sparidae). Although commonly regarded as an SRS species, red drum did not meet the SRS criterion. Overdispersed $V_k^{*}$ values were inferred for all three species, with those for red drum and silver seabream being dependent upon population-closure assumptions. Results are presented within the conceptual framework of reproductive resilience, considering the roles of random extrinsic forces versus evolved traits to achieve lifetime reproductive success and population stability in high and variable mortality environments.     

长江鲟亲体对人工模拟产卵底质的偏好性

探究长江鲟(Acipenser dabryanus)自然繁殖对底质环境的偏好性,可为其仿自然人工产卵环境的营造及野外种群重建提供参考。以人工养殖的长江鲟子一代亲本为对象,在直径3.0 m、水深0.8 m的圆形池中铺设长江河道中常见的卵石、砂及人工养殖光滑底质,模拟不同的底质环境,利用发光标记和Ethovision XT行为跟踪技术,研究长江鲟亲鱼对不同底质环境的栖息偏好性和行为活跃性。结果显示,在两两对比的3种实验底质环境中,长江鲟亲本在光滑底质停留时间比57.56%显著长于砂底质42.15%(P<0.05),在光滑底质停留时间比88.63%也显著长于卵石底质10.77%(P<0.05),砂底质中停留时间比75.50%显著长于卵石底质23.89%(P<0.05),表明长江鲟显著喜好停留在光滑底质,其次为砂底质,在卵石底质栖息时间最短,且偏好性无雌雄差异(P>0.05)和昼夜差异(P>0.05)。行为活跃性分析表明,不同底质环境中长江鲟的行为活跃度明显不同,在有卵石底质存在的情况下,其急速游动平均时间要显著高于砂质和光滑底质。结合人工模拟产卵环境中观测到长江...