9338

• 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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to work in for monitoring fry and maintenance if the fry were released directly into them. Fry
eventually had to be captured and placed in rearing containers (see Egg Trays and Hatching/Rearing
Containers section) so they could be monitored more easily.

In 1991, the FRH redesigned the pikeminnow culturing area to enable rearing many different
lots of genetically diverse progeny. Working with past experiences and the need to have many
individual tanks, hatchery personnel installed 25 stainless steel tanks ( 4ft x 1ft x 1ft). With the use
of the hatching/rearing containers, these tanks were much more suitable for production of
pikeminnow than were the larger tanks.

Each of the stainless steel tanks had a 1.25-inch diameter drain with a stand pipe and a screen
in front of it to prevent escapement. A 3.5-inchtall stand pipe provided 1 cubic foot of rearing space
in the tank, and a 7 inch height provided 2 cubic feet of rearing space. During the sac fry and fry
stages, outlet screens were covered with mosquito netting to prevent escapement.

Circular Tanks
Two circular tanks (4ft x 3ft) were used to hold excess pikeminnow during a study at
Colorado State University. It was found that fish held in these tanks gained more weight than fish
in the experimental rectangular tanks.

RACEWAYS

Outside concrete nurse basins (30ft x 3ft x 3 ft) were used to hold surplus fish until they could
be transported to refugia sites. The amount of rearing space lised in these basins varied according
to number of fish held. Crowding screens and cages were used to reduce the area. All nurse basins
were covered to prevent predation. Water flows varied from 25-75 gpm of 50-550 F water. FRH
used raceways only as holding facilities. An evaluation as to how pikeminnow perform outside with
a natural photoperiod, concrete, or other parameters was not studied.

PONDS

One outside earthen pond (50ft x 25ft x 4ft) held surplus fish until they could be transported
to refugia sites. The usable rearing space was approximately 1800 ft3. The pond was screened with
0.125-inch stainless steel mesh at the inlet and outlet. This. pond was covered by a weather port to
prevent bird and animal predation. Due to cold water temperatures (50-550 F), growth was minimal.

NUTRITION AND FEEDING

FACTORS INFLUENCING NUTRITIONAL REQUIREMENTS

Water Temperature
Water temperatures from 530_700 F were studied. Warmer temperatures (660_700 F) produced

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