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。     

Multiple spawning events promote increased larval dispersal of a predatory fish in a western boundary current

Transport of larvae by ocean currents is an important dispersal mechanism for many species. The timing and location of spawning can have a large influence on settlement location. Shifts in the known spawning habitat of fish, whether due to climate or the discovery of new spawning stock, can influence the distribution of juveniles and our understanding of connectivity. The globally distributed species; Pomatomus saltatrix, is one such example where a previously unrecognised summer spawning event and a more southern latitudinal extent was recently reported for the southwest Pacific population. Although restrictions are in place to protect the traditional spawning event, the importance of the newly recognised summer spawning event is uncertain. Here, we investigate larval dispersal of P. saltatrix using particle tracking simulations to identify the contributions of the different spawning events to settlement. By modelling dispersal of larvae released in northern and mid‐latitude regions over the Austral spring and summer, we show that the newly recognised mid‐latitude summer spawning event contributes over 50% of the larvae reaching southern latitudes. This is due to a reduced (1–2 days) pelagic larval duration (associated with temperature), resulting in reduced larval mortality, and the seasonal (summer) strengthening of the East Australian Current (EAC) transporting particles ~50 km further south. These findings demonstrate that in dynamic boundary current systems such as the EAC, the final settlement location of larvae that are transported by ocean currents can vary considerably depending on the timing and location of spawning and that multiple spawning events are important for maximum dispersal.     

鞍带石斑鱼人工繁殖技术研究

在试验条件下,对网箱培育鞍带石斑鱼亲鱼人工培育的方法和人工催产受精卵的情况进行了详细的描述,并对比不同的生物饵料作为鞍带石斑鱼仔鱼的开口饵料的开口成功率,从而选择更合适的开口生物饵料,提高仔鱼的成活率。结果表明:在2007年7—9月,人工催产了55尾鞍带石斑鱼亲鱼,产卵11 559 g,获得的受精卵较少,仅725 g,受精率只有4.42%~8.78%,鞍带石斑鱼于3日龄开始摄食,投入原生动物的仔鱼成活率最高,投入轮虫的次之。     

Reproduction of sea urchin <Emphasis Type="Italic">Loxechinus albus</Emphasis> in Chiloé Island,Chile

ABSTRACT:   During 1986–1989, the seasonal maturation and gonad index (gonad weight/body weight × 100) of adult Loxechinus albus were examined at nine sites, and the appearance of four-armed echinopluteus larvae was investigated at three sites off the eastern coast of Chiloé Island, Chile. Spawning occurred during November–January when the gonad indices fell to a minimum, the number of mature specimens decreased and four-armed larvae appeared, corresponding to the rise in water temperature. The number of four-armed larvae appearing at the northern site was markedly less than that at the southern site. The sea urchins matured in January and February immediately after spawning at many sites and a high percentage of maturation lasted for a long period at some sites. These findings are considered to be associated with high food availability and annual narrow ranges of water temperature.     

Reproductive performance of gilthead seabream (Sparus aurata L., 1758) fed two combined levels of carotenoids from paprika oleoresin and essential fatty acids

Despite carotenoids and essential fatty acids seem to play important roles in fish reproduction, no studies have yet been conducted to determine the effect of dietary carotenoids on gilthead seabream broodstock performance and their relation as antioxidants with dietary n‐3 highly unsaturated fatty acid (HUFA) levels. In addition, the high cost of synthetic sources of carotenoids is leading to the search for new natural carotenoid sources such as paprika oleoresin. Four experimental diets containing two combined levels of carotenoids from paprika oleoresin (40 and 60 mg kg^?1) and n‐3 HUFA (25 and 40 g kg^?1) were respectively fed to triplicate groups of gilthead seabream (Sparus aurata) broodfish. Elevation of n‐3 HUFA dietary levels from 25 to 40 g kg^?1 significantly improved gilthead seabream broodstock performance in terms of egg viability, hatching rates and fecundity. Besides, it markedly increased egg contents in HUFAs which play important energetic and structural roles and improve embryo development. Both arachidonic acid and eicosapentaenoic acid (20:5n‐3) egg contents were more readily affected by dietary n‐3 HUFA than docosahexaenoic acid. HUFA levels did not caused any negative effect suggesting an optimized content of antioxidants in broodstock diets. Increase in dietary carotenoids from 40 to 60 mg kg^?1 increased carotenoid contents in eggs and significantly improved egg fertilization rates suggesting an important sperm cell’s protective role by reducing the risk of lipid peroxidation which is detrimental for sperm motility. The increased inclusion of dietary paprika oleoresin enhanced egg carotenoid deposition and improved fish reproductive performance, denoting the high nutritional value of this product as a source of carotenoids for broodstock of this species.     

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.     

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...