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Known as the four famous carps in China, black carp ( Mylopharyngodon piceus), grass carp ( Ctenopharyngodon idella), silver carp ( Hypophthalmichthys molitrix) and bighead carp ( Hypophthalmichthys nobilis) are commercially important fish species with a high production in China. To reveal the relationships between meteorological conditions and the natural spawning behavior of these fishes, we considered six meteorological factors (including wind, rainfall, temperature, air pressure, sunshine hours and humidity) and the weather conditions in 80 spawning events. The results showed that the spawning activities were more likely to be activated in consecutive rainy days or days when weather changed drastically, while the spawning activities showed no tendency for the weather type except consecutive rainy days. Our analyses also showed that the average rainfall in the initial spawning days is higher than that in the spawning time windows (the time from the earliest spawning activity to the latest spawning activity), while other meteorological elements remained at more or less the same values in both time periods; spawning activity tended to happen in days when the average air pressure was going down or the average temperature going up, while the other meteorological elements showed no consistent tendency. [ABSTRACT FROM AUTHOR]

The bronze gudgeon, Coreius heterodon (Bleeker), is an economically important species, which only inhabits the Yangtze River. The stock declined drastically in recent years due to dam construction, over-fishing, and pollution. Little is known about its population genetic structure. In this study, the sequences of the mitochondrial DNA (mtDNA) control regions of natural bronze gudgeon was determined for fish collected from four sites in the Yangtze River ( n = 102). The molecular data were used to estimate the genetic diversity and differentiation of the bronze gudgeon. The results showed that 28 haplotypes and 22 variable sites were found, and the haplotype diversity ( π) and nucleotide diversity ( h) were 0.849 and 0.00257, respectively. A low level of genetic diversity exists in the bronze gudgeon. Analysis of molecular variance (AMOVA) suggests that 98.8% of the genetic variability occurred within the populations; the site of collection had little influence on diversity. Future research should focus on investigating the genetic divergence of populations in different tributaries and using additional polymorphic markers, such as microsatellite DNA, to verify the results and improve interpretation. [ABSTRACT FROM AUTHOR]