8136

• UCREFRP Catalog Number: 8136
• Author: Bestgen, K. R.
• Title: Growth, survival, and starvation resistance of Colorado squawfish larvae.
• USFW Year: 1995.
• USFW - Doc Type: \
• Copyright Material: YES

204

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50 100 150 200 250 300 350
Food abundance

Fig, 5, Main and interaction treatment effects on mean survival of Colorado squawfish larvae in water temperatures of 18, 22, 26, and
300 C and food abundance levels of 12.5, 28, 63, 142, and 320 nauplii fish-' day-I. Mean (SE) survival for each treatment combination and
the response surface model coefficients are in Tables 1 and 2,

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Fig. 6. Survival of Colorado squawfish larvae (mean of three rep-
licates) denied food for 0 (control), 10, 15, 17.5, and 20 d after fish
were first able to feed; 5 d survival was nearly identical to control
and was not plotted.

30

Optimization analysis suggested survival was
maximized at 95% and 26.20 C and 235 nauplii fish-!
day-I. Survival was lowest when food abundance
was least, and especially so at the highest temper-
atures.
Plots of mortality as a function of time in various
treatments indicated that most fish died 20 d or
more after treatments began (Fig. 4), although high
mortality occurred sooner in most 300 C treat-
ments. In general, mortality was highest at the low-
est food abundance (Fig. 3). Within a single food
abundance level mortality was also higher at warm-
er temperatures than at lower ones. Distribution of
mortalities in treatments where survival was> 90%
were evenly spread through time.
The food x temperature interaction was signifi-
cant (p < 0.0001) and indicated that within the low-
est two food abundance treatments (12.5 and 28
nauplii fish-! day-I), survival decreased as temper-
ature increased (Fig. 5). At 64 nauplii fish-! day-\
survival in 300 C was 25 % less than average survival
in the other three temperature treatments which
had similar survival. As with growth, the survival
response interaction was an orderly one that al-
lowed interpretation of main effects.

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