نتایج جستجو برای: fishes population
تعداد نتایج: 710990 فیلتر نتایج به سال:
—Working in the Galápagos Islands and surrounding areas, we examined the relationship between population structure, a precursor to allopatric speciation, in species of reef fishes that exhibit different life history traits and three types of distributions in a nested setting: endemic (restricted to the Galápagos Islands), insular (Galápagos and neighboring islands), and Panamic (tropical easter...
The bald eagle (Haliaeetus leucocephalus) population in North America declined greatly after World War II due primarily to the eggshell thinning effects of p,p'-DDE, a biodegradation product of DDT. After the banning of DDT in the United States and Canada during the early 1970s, the bald eagle population started to increase. However, this population recovery has not been uniform. Eagles nesting...
Recent reports of localized larval recruitment in predominately small-range fishes are countered by studies that show high genetic connectivity across large oceanic distances. This discrepancy may result from the different timescales over which genetic and demographic processes operate or rather may indicate regular long-distance dispersal in some species. Here, we contribute an analysis of mtD...
Historically, coastal fisheries biology has focused on the theme of estuarine dependency with emphasis on microhabitat use. Ironically, however, few fishes that we associate with estuaries are in fact obligatory users. What then are the causes and consequences of estuarine habitat use? At the Estuarine Research Federation 2003 Seattle Meeting, we explored ‘‘connectivity’’ in the life cycles of ...
Artificial stocking practices are widely used by resource managers worldwide, in order to sustain fish populations exploited by both recreational and commercial activities, but their benefits are controversial. Former practices involved exotic strains, although current programs rather consider artificial breeding of local fishes (supportive breeding). Understanding the complex genetic effects o...
A rejoinder to our recent paper suggests that there has been confusion over our central point. The 85 IUCN Red List Threatened species that the International Game Fish Association issues world records became threatened due to commercial overfishing, not recreational. However, given that they are threatened now, we have concerns about trophy fishing for them, at least in the current form that pr...
this study was carried out to investigate the genetic diversity and population structure of 90 specimens of oxynoemacheilus argyrogramma collected from sepidbarg, gamasiab and ghaleji rivers, in the west of iran. analyses using three microsatellite loci indicated that the average number of alleles in the population was 12, which was well above the reported values for freshwater fishes. the expe...
Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important cha...
Fishes can play important functional roles in the nutrient dynamics of freshwater systems. Aggregating fishes have the potential to generate areas of increased biogeochemical activity, or hotspots, in streams and rivers. Many of the studies documenting the functional role of fishes in nutrient dynamics have focused on native fish species; however, introduced fishes may restructure nutrient stor...
Terrestrial food subsidies are important energy sources to stream fishes worldwide. However, their importance is not fully understood, except perhaps for some salmonid communities. Using the published literature, we investigated patterns of fish taxonomy and jaw morphology in the consumption of terrestrial food subsidies by nonsalmonid stream fishes in the USA. We hypothesised that: (1) in gene...
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