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<br />r~organic (ammonium phosphate) and organic (com-
<br />mercial trout starter) fertilizers were added to produce
<br />a" plankton bloom. Zooplankton, predominately
<br />cladocerans, were observed in 10 days. " ;
<br />-" Measurements of egg diameter, newW hatched
<br />larvae, and fingerlings were to the nearest 0.5 mm, and
<br />averages were to the nearest whole millimeter. The
<br />numbers of eggs spawned naturally by wild fish on
<br />cobble substrate were roughly estimated by visual
<br />observations, and the numbers of larvae hatched were
<br />based on the fertility rate of eggs. Fry were visually
<br />enumerated before they were placed into the rearing
<br />facilities.
<br />
<br />Results
<br />
<br />Uninjected Fish
<br />
<br />The wild squawfish in raceway A9 were closely
<br />Jbserved. Three females began spawning at 1800 h on
<br />14 June. The spawning area covered 1.2 X 3.0 m in a
<br />vater depth of 25-45 cm; water temperatures were
<br />;0-21oC. Two to three males pursued each female,
<br />;ppearing to guide her to the selected spawning site.
<br />~he female slowly settled to the bottom while two
<br />nales, one on each side, nudged her genital papillae.
<br />"his caused the female to initiate a rapid opercular
<br />10vement, followed by a body vibration or shudder
<br />od a release of eggs. The males would fertilize the eggs
<br />od all fish would swim off. After 3-4 min, the same
<br />~males and presumably the same males would re-
<br />ppear and repeat the behavior. Spawning was observed
<br />ver a 48-h period. Patten and Rodman (1969) observed
<br />milar spawning behavior for the northern squawfish.
<br />An estimated 25,000 eggs were spa wned by the three
<br />ninjected females. Egg diameters varied from 1.5 to
<br />o mm. Since all eggs were adhering to the cobble,
<br />ley were allowed to hatch on the substrate. Hatching
<br />~gan at 96 h and was completed by 144 h; newly
<br />itched fry ranged from 6.5 to 7.0 mm (total length).
<br />!lis extended incubation period was probably due to
<br />e extended spa wning period of the three females. An
<br />timated 7,500 fry were hatched from the 25,000 eggs.
<br />
<br />ljected Fish
<br />
<br />Wild fish transferred to raceway A3 were checked
<br />ld observed daily. One female spawned within 24 h
<br />" receiving the first carp pituitary injection, three
<br />males spawned within 24 h of receiving the second
<br />jection, and a fifth female spawned 24 days after the
<br />~ond injection. No difference in fertility was observed
<br />tween the first or last spawn. The spawning areas
<br />vered 1.2 X 1.2, 1.2 X 5.0, and 1.0 X 1.0 m in water
<br />pths of 10,20-55, and 20-25 cm, respectively; water
<br />
<br />ag. Fish-Cult.tf3 (4), October 1981
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<br />temperatures were 23, 24, and 220 C, respectively.
<br />The estimated number of eggs spawned by the five
<br />injected wild females was 55,000. Egg diameters varied
<br />.from 1.5 to 2.5 mm. All but 5,000 eggs were allowed to
<br />hatch on the cobble subtrate in raceway A3. The 5,000
<br />eggs were removed from the raceway and placed on a
<br />slanted screen tray in a water temperature of 20-21 0 C.
<br />Hatching began in raceway A3 at 90 h and was
<br />completed at 130 h; newly hatched fry ranged in length
<br />from 6.5 to 7.5 mm. Eggs placed on the slanted screen
<br />tray began hatching at 90 h and were completely
<br />hatched by 120 h; lengths of these newly hatched fry
<br />also varied from 6.5 to 7.5 mm. An estimated 32,500
<br />fry hatched from the 50,000 eggs in raceway A3 and
<br />4,500 fry hatched from the 5,000 eggs placed on the
<br />slanted screen tray.
<br />Ten hatchery-reared females (ranging in total length
<br />from 425 to 441 mm and in weight from 675 to 830 g)
<br />ovulated 24 h after receiving one carp pituitary
<br />injection. Five fish had been injected at 4 mg/ kg and
<br />five at 8 mg/kg body weight. No difference in maturity
<br />or fecundity was noted between the two treatments.
<br />Water temperatures were 18-190C. Fecundity for the
<br />10 hatchery-reared females was 78,540 (average, 10,542
<br />eggs per kilogram of body weight). Egg diameters
<br />varied from 1.5 to 2.0 mm. Eggs (70,000) placed in the
<br />warm water (20-210 C) began hatching at 96 hand
<br />hatching was completed at 121 h; length of newly
<br />hatched fry varied from 6.0 to 6.5 mm. Eggs (8,540)
<br />placed in the cold water (l2-130C) began hatching at
<br />145 h and hatching was completed by 180 h; lengths of
<br />these newly hatched fry also ranged from 6.0 to
<br />6.5 mm. No difference in egg fertility or fry survival
<br />was noted between the two water temperatures. A low
<br />fertility (less than 3%) resulted from the eggs obtained
<br />from the hatchery-reared females. A total of 2,000 fry
<br />were hatched from the 78,540 eggs.
<br />
<br />
<br />Culture
<br />
<br />When the fry began swimming to the surface, 72 to
<br />96 h after hatching, they were removed from the
<br />spawning raceways and hatching troughs by seines or
<br />dip nets, enumerated, and transferred to the three
<br />recirculating systems. A total of 19,000 fry were placed
<br />in A9 and AIO, 10,000 in Bl and B2, and 14,000 in Cl
<br />and C2.
<br />
<br />During the first 7 days the fry were very active and
<br />swam from the surface to the bottom, feeding primarily
<br />on the cladocerans present in the recirculating systems.
<br />Schooling behavior was observed, but by day 21 the
<br />fry (average, 14 mm TL) had scattered throughout the
<br />systems.
<br />On day 28, zooplankton began declining and a
<br />supplemental dry diet (commercial trout starter) was
<br />provided. The fry were fed three to four times daily
<br />
<br />175
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