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1.
Abstract –  Lake Pamvotis is a tertiary natural shallow lake located in the NW of Greece. For biogeographical reasons, it historically contained only four fish species: two endemics ( Phoxinellus epiroticus , Squalius pamvoticus ), one native to the West Greece ( Barbus albanicus ) and the ubiquitous Anguilla anguilla . These species were almost exclusively present in the lake before 1920, forming remarkable commercially exploited populations. From the 1930s through the 1990s, 20 species were introduced into the lake for purposes of eutrophication control or to enhance the fishery. These introductions, some of them accidental have led to the apparent decline, even loss, of the native species. During the last three decades the fish fauna of the lake has shifted from the native, clear-water species to a predominance of introduced species, mainly those adapted for turbid eutrophic water ( Rutilus panosi , Cyprinus carpio and Carassius gibelio , and several Asian cyprinids). The current fish assemblage in the lake is dominated by introduced species particularly the Mosquitofish ( Gambusia affinis ) and the Lourogobios ( Economidichthys pygmaeus ) in the littoral zone, the benthopelagic allogynogenetic Prussian carp ( C. gibelio) , and the opportunistic Trichonis roach ( R. panosi ), in the pelagic zone.  相似文献
2.
Habitat use of an artificial wetland by the invasive catfish Ameiurus melas   总被引:1,自引:0,他引:1  
Abstract –  This study examined the distribution and habitat selection of the invasive black bullhead [ Ameiurus melas (Rafinesque)] in the ditches and surrounded temporary flooded habitats of an artificial wetland in western France. A multiscale approach was used to quantify patterns of A. melas abundance in relation to physical habitat characteristics in the ditch network. Young-of-the-year (YOY) and adult A. melas largely dominated the local fish assemblage but were highly variable among sites. Although we found evidence for some fine-scale habitat differences for YOY and adult individuals, the abundance of A. melas was positively and consistently related to the dominance of reed beds. Furthermore, A. melas preferentially used reed beds as opposed to marsh meadows during the flooding period. The results from this study suggest that the invasion of A. melas has been facilitated by the expansion of reed beds associated with the diminution of agricultural pressure in recent decades. This study represents an unusual example where human activities can have had an unexpected effect by facilitating an invasive fish species.  相似文献
3.
Nomoto K, Omiya H, Sugimoto T, Akiba K, Edo K, Higashi S. Potential negative impacts of introduced rainbow trout on endangered Sakhalin taimen through redd disturbance in an agricultural stream, eastern Hokkaido.
Ecology of Freshwater Fish 2010: 19: 116–126. © 2009 John Wiley & Sons A/S
Abstract –  Sakhalin taimen ( Hucho perryi ) populations have decreased in Hokkaido, northernmost Japan, primarily because of overexploitation and habitat degradation. Here we document another threat to this species, that of spawning redd superimposition by artificially introduced rainbow trout ( Oncorhynchus mykiss ). Sakhalin taimen and rainbow trout are the only spring-spawning salmonid species in Hokkaido. In 2006–2008, spawning activities of both these species were observed in a Hokkaido stream, and it was determined that their spawning periods overlapped during mid-late April. They also spawned at similar water velocities, depths and substrate compositions. Although female Sakhalin taimen were larger than female rainbow trout, their egg burial depths were nearly identical. During the observation period, rainbow trout redds were approximately five times more abundant than Sakhalin taimen redds, and about 30% of the observed Sakhalin taimen redds were superimposed by rainbow trout redds. The high degree of spatial and temporal overlap in spawning, the similar egg burial depths of both species, and the high proportion of superimposed redds suggest that the introduced rainbow trout impact the endangered Sakhalin taimen in Hokkaido, and possibly, in other areas where the two species occur together.  相似文献
4.
Biological invasions are a major factor for biodiversity loss, particularly in freshwater environments. Largemouth bass Micropterus salmoides is native to North America and is invasive on the Iberian Peninsula, primarily to provide angling opportunities in reservoirs. However, this species is a threat to the endemic Iberian fauna via predation and competition. Currently, there is little information on largemouth bass in European streams. Thus, we assessed the trophic plasticity and body condition of young largemouth bass in both invasive (the regulated Bullaque River) and native (Murray Creek) streams. Abundance of juvenile largemouth bass, percentage of full stomachs and body condition were higher in Bullaque River. Largemouth bass preyed on benthic invertebrates much more heavily in the Bullaque River, whereas fishes were the most important prey in Murray Creek. Prey richness, diet diversity and trophic niche breadth were higher in the Bullaque River population. Largemouth bass preferred water-column fishes as prey and avoided consuming benthic fishes in Murray Creek, whereas water-column fishes were avoided in Bullaque River. These results demonstrate that largemouth bass display substantial trophic plasticity which possibly facilitates its success as invasive species. Regulated Iberian streams may provide both suitable food and habitat resources with minimal predation pressure, and hence may serve as recruitment sources for this invasive fish.  相似文献
5.
This paper examines the changes in the population ecology parameters and biomass of golden grey mullet (Liza aurata) in Iranian waters of the Caspian Sea from 1991 to 2005. For most years during this 14-year period, we estimated the age structure of the catch, length–weight relationship, von Bertalanffy growth parameters, condition factor, natural and fishing mortality and biomass. Growth parameters were estimated as L = 62.7 cm, K = 0.15 year−1, t0 = −0.23 year−1. The instantaneous coefficient of natural mortality was estimated as 0.350 year−1 and the instantaneous coefficient of fishing mortality varied during the 14-year period between 0.111 to 0.539 year−1. Biomass estimates of golden grey mullet, from the biomass-based cohort analysis were increased from 13,527 mt in 1991–1992 to 23,992 mt in 2002–2003. In 2004–2005, it was estimated to be 23,658 mt. We concluded that at the present time, the stock of golden grey mullet is not being over-fished.  相似文献
6.
Abstract –  Rates of annual food consumption and biomass were modeled for several fish species across representative rivers and lakes in eastern North America. Results were combined to assess the relative potential of fish predation to impact zebra mussels ( Dreissena polymorpha ). Predicted annual food consumption by fishes in southern waters was over 100% greater than that in northern systems because of warmer annual water temperatures and presumed increases in metabolic demand. Although generally increasing with latitude, biomasses of several key zebra mussel fish predators did not change significantly across latitudes. Biomasses of some less abundant fish predators did increase significantly with latitude, but increases were not of the magnitude to offset predicted decreases in food consumption. Our results generally support the premise that fishes in rivers and lakes of the southern United States (U.S.) have inherently greater potential to impact zebra mussels by predation. Our simulations may provide a partial explanation of why zebra mussel invasions have not been as rapid and widespread in southern U.S. waters compared to the Great Lakes region.  相似文献
7.
Abstract  To minimise the risks of unintentional translocation and further spread of the non-native cyprinid, Pseudorasbora parva (Temminck & Schlegel) in the UK, various morphological and meristic characters of this species were measured, with a view to isolating the characters which allow reliable identification of this species during the early stages of development. The combination of myomere numbers, the nature of the internal pigmentation associated with the notochord and the lack of a single row of external melanophores along the route of the lateral line organ reliably facilitate the ability to distinguish this species from the native fauna of the British Isles. Thus, for the first time, fishery managers and environmental agencies have a much needed tool to screen for the presence young-of-the-year of this species when authorising movements of other fish species.  相似文献
8.
9.
Although burbot ( Lota lota Gadidae) are widespread and abundant throughout much of their natural range, there are many populations that have been extirpated, endangered or are in serious decline. Due in part to the species' lack of popularity as a game and commercial fish, few regions consider burbot in management plans. We review the worldwide population status of burbot and synthesize reasons why some burbot populations are endangered or declining, some burbot populations have recovered and some burbot populations do not recover despite management measures. Burbot have been extirpated in much of Western Europe and the United Kingdom and are threatened or endangered in much of North America and Eurasia. Pollution and habitat change, particularly the effects of dams, appear to be the main causes for declines in riverine burbot populations. Pollution and the adverse effects of invasive species appear to be the main reasons for declines in lacustrine populations. Warmer water temperatures, due either to discharge from dams or climate change, have been noted in declining burbot populations at the southern extent of their range. Currently, fishing pressure does not appear to be limiting burbot populations world-wide. We suggest mitigation measures for burbot population recovery, particularly those impacted by dams and invasive species.  相似文献
10.
Abstract –  Feeding tactics, body condition and size structure of two populations of pumpkinseed Lepomis gibbosus from Cabañeros National Park (Guadiana River basin, central Spain) were compared to provide insight into the ecological requirements favouring levels of success/failure in relation to human intervention. Habitat, benthic macroinvertebrates and pumpkinseed were quantified in Bullaque (regulated flow, affected by agricultural activities) and Estena (natural conditions) rivers, from May to September of 2005 and 2006. Significant differences were found in the limnological characteristics between the two rivers. Spatial and temporal variations in diet composition were likely related to opportunistic feeding and high foraging plasticity. Diet diversity was higher in Bullaque River. Electivity of benthic prey showed variation between sized individuals and populations. The body condition of pumpkinseed was better in Bullaque River. Current results show that this invasive species is favoured by human intervention in Bullaque River.  相似文献
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