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1.
The spatial extent of small pelagic fish spawning habitat is influenced by environmental factors and by the state of the adult population. In return, the configuration of spawning habitat affects recruitment and therefore the future structure of the adult population. Interannual changes in spatial patterns of spawning reflect variations in adult population structures and their environment. The present study describes the historical changes in the spatial distribution of spawning of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Bay of Biscay during two periods: 1967–72 and 2000–2004. Using data from egg surveys conducted in spring, the spatial distributions of anchovy and sardine eggs are characterized by means of geostatistics. For each survey, a map of probability of egg presence is constructed. The maps are then compared to define (1) recurrent spawning areas, (2) occasional spawning areas and (3) unfavourable spawning areas during each period. Sardine spawning habitat is generally fragmented and appears spatially limited by the presence of cold bottom water. It is confined to coastal or shelf break refuge areas in years of restricted spawning extent. For anchovy, recurrent spawning sites are found in Gironde and Adour estuaries whilst spawning can extend further offshore in years of more intense spawning. For both species, the mean pattern of spawning has changed between 1967–72 and 2000–2004. Noticeably, the spatial distribution of anchovy eggs in spring has expanded northward. This trend possibly results from changes in environmental conditions during the last four decades. 相似文献
2.
Large amplitude variations in recruitment of small pelagic fish result from interactions between a fluctuating environment and population dynamics processes such as spawning. The spatial extent and location of spawning, which is critical to the fate of eggs and larvae, can vary strongly from year to year, as a result of changing population structure and environmental conditions. Spawning habitat can be divided into ‘potential spawning habitat’, defined as habitat where the hydrographic conditions are suitable for spawning, ‘realized spawning habitat’, defined as habitat where spawning actually occurs, and ‘successful spawning habitat’, defined as habitat from where successful recruitment has resulted. Using biological data collected during the period 2000–2004, as well as hydrographic data, we investigate the role of environmental parameters in controlling the potential spawning habitat of anchovy and sardine in the Bay of Biscay. Anchovy potential spawning habitat appears to be primarily related to bottom temperature followed by surface temperature and mixed‐layer depth, whilst surface and bottom salinity appear to play a lesser role. The possible influence of hydrographic factors on the spawning habitat of sardine seems less clear than for anchovy. Modelled relationships between anchovy and sardine spawning are used to predict potential spawning habitat from hydrodynamical simulations. The results show that the seasonal patterns in spawning are well reproduced by the model, indicating that hydrographic changes may explain a large fraction of spawning spatial dynamics. Such models may prove useful in the context of forecasting potential impacts of future environmental changes on sardine and anchovy reproductive strategy in the north‐east Atlantic. 相似文献
3.
本文用2种不同培育方式对台湾海峡野生牙鲆亲鱼培育与促熟的效果进行了比较。结果表明,土池培养的亲鱼移入土池网箱中培育促熟,当性腺发育成熟时再从土池网箱移到室内水泥池产卵是亲鱼促熟产卵的较佳方式。 相似文献
4.
Towards the end of the 1980s, when the spawning grounds in the northwestern shelf (NWS) of the Black Sea were lingering with the effects of eutrophication and of an exotic invasive ctenophore, a series of basin‐wide international ichthyoplankton surveys pointed out an increase in the anchovies spawning in the southern half of the Black Sea. Later, with the help of international conservation efforts, several key littoral ecosystem components within the anchovy's historical spawning grounds showed signs of recovery. However, the fate of the spawning stock anchovy in the south remained unanswered. In order to present the current situation in the southern Black Sea after two decades, an ichthyoplankton survey adopting the same methodology as previously used was undertaken during the peak spawning season of the Black Sea anchovy (BSa). The survey showed that the density of eggs was by far greater than for any of the surveys conducted previously. A wider geographical distribution of the eggs indicated an increase in the number of vagrants which had drifted away from the known spawning grounds. In contrast, the increased reproductive activity in the south signifies existence of a growing, non‐migrating southern BS stock. This stock seems to utilize the coastal hydrographic features associated with the rim current facilitating escape (loophole) from gelatinous predators such as Mnemiopsis leidyi and Aurelia aurata. 相似文献
5.
Angela Cuttitta Bernardo Patti Teresa Maggio Enza Maria Quinci Anna Maria Pappalardo Venera Ferrito Vito De Pinto Marco Torri Francesca Falco Aldo Nicosia Marianna Musco Grazia Maria Armeri Francesco Placenti Giorgio Tranchida Roberta Mifsud Angelo Bonanno Salvatore Mazzola 《Fisheries Oceanography》2015,24(2):135-149
In order to investigate the larval population structure, specimens of Engraulis encrasicolus larvae from five different locations in the Strait of Sicily were analyzed by means of otolith readings, morphometric and genetic techniques. The distribution of age in day, identified by means of the otolith readings and associated with the oceanographic parameters, was useful to identify possible spawning areas and transport dynamics. The presence of more than one spawning area suggested the possibility that two or more sub‐populations may co‐exist in the study area. The morphometric characteristics were more adequate than genetic parameters to discriminate the different larval groups. The most relevant variables for the separation were the mouth length (ML) and the body diameter (BD). The population structure by means of genetic data reported the presence of two phylogroups co‐occurring among samples in each sampling locations specimens. The pattern of genetic divergence among anchovy larvae in the Strait of Sicily was congruent with previous studies conducted on adult populations present in other Mediterranean areas with different molecular markers. The habitat‐specific nature of the morphological variation and the lack of corresponding genetic variation among larvae from the different locations suggested that the observed differences in morphology could be linked to environmental parameters. The body form differences among different larvae samples could reflect the nutritional status of larvae. In fact, these differences were found among anchovy larvae collected in areas with different oxygen and fluorescence, which is an index of primary productivity and is linked to the availability of food for anchovy larvae. 相似文献
6.
试验表明台湾海峡牙鲆亲鱼不同雌雄比例与产卵量和受精卵有直接的关系.亲鱼雌雄比例为1:0.625时,每尾雌鱼的产卵量仅为13.7万粒,平均受精率为82.3%;当亲鱼雌雄比例为1:1.702时,每尾雌鱼的产卵量可达43.79万粒;平均受精率为88.6%. 相似文献
7.
Marcos Arteaga;Sebastián I. Vásquez;Sergio Neira;Luis Cubillos; 《Fisheries Oceanography》2024,33(5):e12677
Recruitment is a critical process in the dynamics of fish populations since it represents the abundance of new fish that enter a population each year. In Ekman-type upwelling ecosystems, wind is a critical factor for small pelagic fish recruitment, as it controls food availability and physical constraints such as turbulence and offshore advection. In this study, we evaluate the effect of wind, chlorophyll-a, and spawning biomass as independent variables on anchovy recruitment. Using generalized additive models (GAMs), we tested (i) the significance of each factor, (ii) the shape of the relationship between recruitment and predictors variables, (iii) recruitment regimes in the series, and (iv) whether extended windy events are associated with low recruitment levels potentially related to offshore transport of early life stages. The study period spanned from 1990 to 2021, focusing on the austral spring in south-central Chile (35–40°S) when both upwelling and anchovy spawning are maximized. GAMs revealed a parabolic relationship between the velocity of upwelling-favorable winds and anchovy recruitment. Maximized recruitment occurred at wind speeds around 6 m s−1 but decreased with winds above 7 m s−1 and below 5 m s−1, and during periods of extended windy events (i.e., those lasting more than 15 days). Chlorophyll-a showed no significance on anchovy recruitment, suggesting that phytoplankton were not a limiting factor for anchovy early survival. We also found that anchovy recruitment regimes were associated with specific wind intensities. We discussed the pertinence of incorporating a recruitment index based on wind in the fishery management of the anchovy in south-central Chile. 相似文献
8.
K. Alexandra Curtis 《Fisheries Oceanography》2004,13(4):239-254
Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax) eggs exhibited different spatial structure on the scale of 0.75–2.5 km in two egg patches sampled in the Southern California Bight in April 2000. Plankton samples were collected at 4‐min intervals with a Continuous Underway Fish Egg Sampler (CUFES) on 5 × 5 km grids centered on surface drifters. Variograms were calculated for sardine and anchovy eggs in Lagrangian coordinates, using abundances of individual developmental stages grouped into daily cohorts. Model variograms for sardine eggs have a low nugget effect, about 10% of the total variance, indicating high autocorrelation between adjacent samples. In contrast, model variograms for anchovy eggs have a high nugget effect of 50–100%, indicating that most of the variance at the scales sampled is spatially unstructured. The difference between observed spatial patterns of sardine and anchovy eggs on this scale may reflect the behavior of the spawning adults: larger, faster, more abundant fish may organize into larger schools with greater structure and mobility that create smoother egg distributions. Size and mobility vary with population size in clupeoids. The current high abundance of sardines and low abundance of anchovy off California agree with the greater autocorrelation of sardine egg samples and the observed tendency for locations of anchovy spawning to be more persistent on the temporal scale of days to weeks. Thus the spatial pattern of eggs and the persistence of spawning areas are suggested to depend on species, population size and age structure, spawning intensity and characteristic physical scales of the spawning habitat. 相似文献
9.
We use trivariate kernel density estimation to define spawning habitat of northern anchovy ( Engraulis mordax ) and Pacific sardine ( Sardinops sagax ) in the California Current using satellite data and in situ egg samples from the Continuous Underway Fish Egg Sampler (CUFES) deployed during surveys in April by the California Cooperative Oceanic Fisheries Investigations (CalCOFI). Observed egg distributions were compared with monthly composite satellite sea surface temperature (SST) and surface chlorophyll a (chl a ) data. Based on the preferred spawning habitat, as defined in SST and chl a space, the satellite data were used to predict potential spawning habitat along two areas of the west coast of North America. Data from the southern area (21.5 to 39°N) were compared to observations from the CUFES data for the period 1998–2005. Northern anchovy and Pacific sardine exhibited distinctly different spawning habitat distributions. A significant relationship was found between satellite-based spawning area and that measured during surveys for sardine. CUFES area estimated for sardine was similar in magnitude to that estimated from satellite data (∼60 000 km2 ). In contrast, spawning habitat of anchovy averaged between 1000 and 200 000 km2 for the period 1998–2005, for CUFES and satellite estimates, respectively. Interannual variability in the area (km2 ) and duration (months) of estimates of suitable habitat varied between species and between the northern (39 to 50.5°N) and southern portions of the California Current. Long-term monitoring of habitat variability using remote sensing data is possible in the southern portion of the California Current, and could be improved upon in the northern area with the addition of surveys better timed to describe relationships between observed and estimated spawning habitats. 相似文献
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长江江苏溆浦段2015 年发现中华鲟野生幼鱼的形态和分子鉴定 总被引:1,自引:1,他引:1
在葛洲坝下中华鲟(Acipenser sinensis)产卵场连续两年未监测到自然繁殖的情况下,2015年6月在江苏溆浦段发现15尾疑似中华鲟幼鱼。本研究通过形态学和分子生物学方法对该15尾幼鲟进行鉴定。形态学度量结果显示,除1尾个体外,新发现的14尾幼鲟与历史记载的中华鲟野生幼鱼生物学性状完全一致,但其体长和体重低于历史同期出现在该区域的中华鲟。同时采用11个多态微卫星位点,对15尾幼鲟样本和分布于我国的3种鲟鱼,包括30尾中华鲟(A.sinensis)、39尾达氏鲟(A.dabryanus)和33尾施氏鲟(A.dabryanus)进行遗传分析,发现这15尾幼鲟与中华鲟的遗传距离最近(F_(st)=0.039,P0.05),其次为达氏鲟(F_(st)=0.108,P0.05),最远为施氏鲟(F_(st)=0.209,P0.05),从遗传和进化的角度判定该批幼鱼为中华鲟,该结果暗示中华鲟在葛洲坝下游极有可能找到了新的产卵场,为中华鲟的繁殖群体和幼鱼的种群监测提供了依据。遗传多样性分析显示,该批鱼的遗传多样性(SW=1.998)略低于野生中华鲟(SW=1.886),暗示中华鲟幼鱼遗传多样性水平降低,野生亲本的数量仍不容乐观。 相似文献
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14.
Investigations were conducted on the flathead flouder Hippoglossoides dubius to analyze the environmental conditions around the spawning grounds and the maturational status of spawners in the Sea of
Japan off Niigata. In both sexes, larger fish matured earlier than smaller individuals, and participated in breeding from
the early part of the spawning season. Males were always the predominant sex found within the spawning ground, likely because
males spent longer periods in the spawning grounds than females. This finding further suggests that males matured earlier
and maintained sexual activity for longer periods than females within the spawning grounds. Submarine topography and water
temperature were concluded to be important factors affecting the formation of the spawning grounds. The spawning ground was
located within a restricted area where bathymetric lines curve towards a shallow area. Adult fish usually occur in the Japan
Sea Proper Water (<1 °C), but spawners gathered just below the surface mixing layer where water temperature was 5–10°C. Hence,
it was thought that the flounder spawn at the upper tolerable water temperature limit (i.e. the shallowest accessible depth)
to release their offspring into the surface layer. 相似文献
15.
F. H. Page M. Sinclair C. E. Naimie J. W. Loder R. J. Losier P. L. Berrien & R. G. Lough 《Fisheries Oceanography》1999,8(3):212-226
The seasonal and geographical patterns of spawning for Georges Bank cod ( Gadus morhua ) and haddock ( Melanogrammus aeglefinus ) are estimated using composite distributions of stage I eggs derived from the Marine Resources Monitoring, Assessment and Prediction (MARMAP) data set (1977–1987). The inferred mean spawning locations are compared with patterns in particle residence times derived from a three-dimensional prognostic circulation model that estimates the tidal and seasonal mean circulation. The comparisons indicate that cod and haddock spawning occurs at times and locations characterized by model residence times in excess of 35 d. The results are discussed in the context of fish population regulation theory, particularly the member/vagrant hypothesis and the concept of abundance-dependent vagrancy. 相似文献
16.
Larvae, juveniles, and adults of Japanese anchovy, Engraulis japonicus , were distributed throughout the Kuroshio-Oyashio transition region off northern Japan as far offshore as 170°E in 1996 and 1997. The growth trajectories of individual larvae and early juveniles were backcalculated using the biological intercept method based on the allometric relationship between otolith radius and somatic length. Mean larval growth rates ranged from 0.49 to 0.71 mm day–1 in the transition region, and were comparable to those reported from the Pacific coastal waters of central Japan, which is the principal distribution range of E. japonicus . In terms of growth, the Kuroshio-Oyashio transition region seemed to be a favourable nursery area for larval E. japonicus . Larval growth tended to decline from the inshore to the offshore waters in the transition region. Thermal conditions did not show an inshore–offshore trend in the survey area and did not explain the longitudinal trend in growth rates. 相似文献
17.
Gonosomatic indices and egg and larval densities observed from 1986 to 2001 suggest that the peak spawning season of the Australian anchovy (Engraulis australis) in South Australia occurs during January to March (summer and autumn). This coincides with the spawning season of sardine (Sardinops sagax) and the period when productivity in shelf waters is enhanced by upwelling. Anchovy eggs were abundant throughout gulf and shelf waters, but the highest densities occurred in the northern parts of Spencer Gulf and Gulf St Vincent where sea surface temperatures (SST) were 24–26°C. In contrast, larvae >10 mm total length (TL) were found mainly in shelf waters near upwelling zones where SSTs were relatively low (<20°C) and levels of chlorophyll a (chl a) relatively high. Larvae >15 mm TL were collected only from shelf waters near upwelling zones. The high levels of larval abundance in the upwelling zones may reflect higher levels of recruitment to later stages in these areas compared with the gulfs. The sardine spawns mainly in shelf waters; few eggs and no larvae were collected from the northern gulfs. The abundance of anchovy eggs and larvae in shelf waters increased when sardine abundance was reduced by large‐scale mortality events, and decreased as the sardine numbers subsequently recovered. We hypothesize that the upwelling zones provide optimal conditions for the survival of larval anchovy in South Australia, but that anchovy can only utilize these zones effectively when the sardine population is low. At other times, northern gulf waters of South Australia may provide a refuge for the anchovy that the sardine cannot utilize. 相似文献
18.
在人工蓄养条件下,对半滑舌鳎注射催产激素(促黄体生成激素释放激素类似物和绒毛膜促性腺激素),研究其卵巢生化成分、血浆生殖激素水平及产卵效果的影响。通过对亲鱼采用不注射、一次性注射、二次注射的3种处理,并采用生化方法和双抗体放射免疫法分别测定了卵巢中总蛋白、粗脂肪、总糖、水分含量和血浆中甲状腺素、促卵泡成熟激素、促黄体生成激素含量的变化。试验结果表明,注射催产激素后的亲鱼,卵巢迅速发育并完成物质积累,其中粗脂肪和总糖含量均随卵巢的发育成熟而显著增高(P0.05),产卵完成后明显下降;总蛋白的含量为6.13%~7.07%;水分含量最高,随卵巢发育成熟,先由78.78%降至64.81%,产后升至72.56%。催产剂注射24h后可使血浆甲状腺素含量显著升高(P0.05),有效时间可持续24h以上,且二次注射有利于维持较高的血浆甲状腺素含量。对照组促卵泡成熟激素和促黄体生成激素含量均持续降低,注射组促卵泡成熟激素含量在24~36h时上升,此后明显下降,促黄体生成激素含量变化对催产激素最为敏感,注射后12h即明显上升,二次注射组的促黄体生成激素含量显著高于其他两组(P0.05)。因此,催产激素注射可促进血浆生殖激素水平升高,且二次注射的作用更为明显。催产激素注射还可显著提高总产卵量、上浮卵量和浮卵率,且二次注射效果亦显著优于一次性注射(P0.05)。 相似文献
19.
The Strait of Georgia (SoG), between Vancouver Island and mainland British Columbia, is a larval rearing ground for both hake and herring stocks, which are commercially important. Year‐to‐year variability in larval retention within the strait is examined by simulating drift tracks of larvae for these species using an ocean circulation model and a particle‐tracking model. Larvae with different vertical swimming behaviors were tracked in the springs of 2007, 2008, and 2009. Since herring larvae mostly stay near the surface, their distribution is heavily influenced by the wind. Strong winds to the north soon after the hatching period tend to wash herring larvae out of SoG and winds to the south help retain herring larvae inside the Strait. In 2007, the model indicates a massive wind‐driven export of herring larvae which may have led to the observed failure of herring production. In contrast, hake larvae reside deeper in the water column (50–200 m). Their distribution is less sensitive to surface forcing but is shaped by a deep gyre with cross‐strait currents. This study also suggests that the northern and southern SoG are weakly connected for herring larvae dispersal, which makes both regions potentially important to recruitment. 相似文献
20.
CHEN‐YI TU YU‐HENG TSENG TAI‐SHENG CHIU MAO‐LIN SHEN CHIH‐HAO HSIEH 《Fisheries Oceanography》2012,21(4):255-268
Adult Japanese anchovies (Engraulis japonicus) migrate from the East China Sea to the coastal region of Taiwan to spawn around late winter and early spring and, later, their larvae constitute important fisheries in Taiwan. However, their migration route and its mechanism remain unclear. To investigate their spawning migration, we used a coupled fish behavior–hydrodynamic modeling approach. The physical field is simulated by the Pacific Ocean adaptation of the TaIwan Multi‐scale Community Ocean Model (TIMCOM) and the fish migration by Lagrangian tracer tracking with the aid of approximation of fish swimming behavior. We investigated three fish behavioral scenarios: (i) passive tracking of the current, (ii) swimming along with the current, and (iii) swimming along with the current and then changing to swimming toward the optimal spawning temperature. The comparison with and without Changjiang discharge is used to investigate the impacts of discharge reduction due to the Three Gorges Dam. Our results suggest that spawning migration of Japanese anchovy from the East China Sea to Taiwan may be aided by the China Coastal Current and that adult anchovies cannot reach the spawning site by passive advection alone. Thus, the swimming behavior of anchovies is crucial during the spawning migration, as it provides extra velocity and the orientation to the favorable spawning grounds. In addition, the adult anchovy is unlikely to reach the coastal area of Taiwan without Changjiang discharge. Our findings indicate that a coupled fish behavior–hydrodynamic model can help understand the influences of physical environment on the migration of Japanese anchovies. 相似文献