|
The speckled dace (''Rhinichthys osculus''), also known as the spotted dace and the carpita pinta, is a member of the minnow family. It is found in temperate freshwater in North America, from Sonora to British Columbia. Canada is the northern limit of the speckled dace's distribution, and there it is found only in isolated parts of the Kettle and Granby Rivers. It is possible that, along with the Salish sucker (''Catostomus'' sp.), the speckled dace was one of the first fish to recolonize the rivers of British Columbia following the Ice Age. It is believed that spawning in Canada occurs once a year during the summer in fish older than two years. During breeding, many males often accompany a single female who broadcasts adhesive eggs over the gravelly streambed. Each female produces between 200 and 500 eggs. Speckled dace are omnivorous, feeding upon filamentous algae and other plant material, bottom-dwelling aquatic insects and zooplankton. The speckled dace is about long. Canadian populations of the fish were last sampled in 1977, and then only 400 individuals were collected. Few of the fish caught were adults, suggesting that speckled dace mortality may be high. However, not enough data is available to determine accurately whether the population is self-sustaining or in decline. In Canada, the speckled dace is threatened by its limited habitat and by seasonal flooding. There are several subspecies, including: *''R. o. lethoporus'' - Independence Valley speckled dace *''R. o. nevadensis'' - Ash Meadows speckled dace *''R. o. oligoporus'' - Clover Valley speckled dace *''R. o. thermalis'' - Kendall Warm Springs dace ==References== See: Department of Fisheries and Oceans, Canada, website information on Aquatic Species at Risk. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Speckled dace」の詳細全文を読む スポンサード リンク
|