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Last modified
7/14/2009 5:02:35 PM
Creation date
5/18/2009 12:34:22 AM
Metadata
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UCREFRP
UCREFRP Catalog Number
9420
Author
Maddux, H. R., J. A. Mizzi, S. J. Werdon and L. A. Fitzpatrick.
Title
Overview of the Proposed Critical Habitat for the Endangered and Threatened fishes of the Virgin River Basin.
USFW Year
1995.
USFW - Doc Type
Salt Lake City.
Copyright Material
NO
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The Virgin spinedace is primarily an insectivore (Rinse 1971, Gregor and Deacon 1988, <br />Angradi et al. 1991), and its feeding habits are dependent on food availability. Angradi et <br />al. (1991) found that spinedace fed continuously throughout the day. Spinedace position <br />themselves in the midwater column and rise to the surface to feed on floating plant material, <br />aquatic and terrestrial invertebrates (primarily dipteran and coleopteran larvae), and debris <br />(Rinse 1971, Rinse and Minckley 1991) . The amount that each food category is eaten is <br />dependent on season and size of fish. However, Rinse (1971) found that when the fish fed <br />predominantly on plant material they were in poor physical condition. <br />Virgin spinedace generally live about three years and are sexually mature at one year of age. <br />Rinse (1971) reported that in the Santa Clara River spinedace spawn from April to June at <br />mean daily water temperatures of 13 to 17°C (55 to 63°F) with maximum temperatures at <br />21 °C (70°F), and when photoperiod was greater than about 13 hours/day. Additionally, <br />peak spawning was closely correlated with peak discharge. Spawning occurs at depths of 15- <br />30 cm (5-12 in) over gravel and sand substrates at the shallow downstream end of deep pools <br />where a single female deposits eggs that are fertilized by several males. As with many <br />fishes, the important factors controlling spawning appear to be photoperiod and temperature. <br />Rinse (1971) found that one year old fish had the lowest mean relative fecundity with an <br />average of 459 eggs, while two year olds averaged 788 eggs, and three year olds averaged <br />693 eggs. Although two and three year old females produced a greater number of eggs than <br />one year olds, the two and three year olds often represented less than 10 percent of the <br />population. <br />23 <br />
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