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Last modified
7/14/2009 5:02:34 PM
Creation date
5/20/2009 10:39:09 AM
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Template:
UCREFRP
UCREFRP Catalog Number
9338
Author
Schler, P. J.
Title
Colorado Pikeminnow Culture Manual.
USFW Year
2001.
USFW - Doc Type
FY92-37,
Copyright Material
NO
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<br />10 <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />the best growth and survival. Fry accepted food at lower temperatures (530 and 600 F), but growth <br />was marginal and most fish eventually died. Fingerlings and larger pikeminnow survived <br />temperatures 53-660 F, but there was little growth. Fingerling and larger pikeminnow survived abrupt <br />temperature changes (530_700 F) from cold to warmer and warm to colder. <br /> <br />Activity level of the fish increased in warmer water; therefore, it was found that either amount <br />of feed fed had to be increased or the nutritional requirements of the feed had to be higher to maintain <br />this higher metabolism. <br /> <br />Body Size And Age <br />Almost all pikeminnow reared at the were transferred from the unit prior to reaching 6 inches <br />in length. Depending on culturing practices employed, it required 13-18 months to rear a 6-inch <br />pikeminnow. <br /> <br />OXYGEN REQUIREMENTS <br /> <br />Pikeminnow were reared in conditions of 6.4-8.4 ppm oXygen (68-700 F). It was assumed <br />oxygen levels were well above the critical level, but no studies were done to determine the lower <br />threshold for dissolved oxygen. <br /> <br />Oxygen utilization by pikeminnow was studied in February 1991 for one month with fish from <br />the 1990-91 lot received from DNFH. Results indicated that 2-inch fish at approximately 1.5-2.2 <br />pounds per cubic foot utilized 0.34 pounds of oXygen to metabolize a pound offeed. It was also <br />observed that daily oXygen utilization patterns were very similar to salmonids. While monitoring'the <br />oxygen concentrations continuously, the following situations occurred: (1) Using artificial light had <br />a noticeable impact on oXygen usage by fish. When lights are turned on, oxygen levels' declined, and <br />could take up to one hour to regain normal. levels. (2) Feeding depressed oxygen levels for 6-8 hours. <br />Hand-feeding had a combined effect of increasing activity and causing a sharp increase in oxygen <br />usage. (3) Simple activities like walking by a trough increased the oxygen usage ofthe fish because <br />of either fright or feeding response. (4) Cleaning hatchery troughs reduced oXygen levels for at least <br />one hour due to increased fish activity. <br /> <br />WATER FLOWS <br /> <br />Due to the endangered listing, pikeminnow were reared in optimum water quality. Fresh water <br />exchange rates of 6-12 per hour were used in most rearing containers. The size of the container <br />determined the actual gallons per minute and number of exchanges per hour. The stainless steel <br />troughs (4ft x 1ft x 1ft) had approximately 1.5 gpm of fresh water constantly flowing into each <br />trough, with a water depth of 3.5 and 7 inches. <br /> <br />WATER DEPTH <br /> <br />A two-month study was done to determine if depth of the water column would affect growth. <br /> <br />. <br />
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