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There is little info on F-1 crosses in colder climates. Flas don't do well in colder climates. I will check some more as it has been a while since the last look.
Try this
Responses of Northern, Florida, and Hybrid Largemouth Bass to
Low Temperature and Low Dissolved Oxygen
GARY J. CARMICHAEL' AND
J. HOLT WlLUAMSON2
U.S. Fish and Wildlife Service
San Marcos, Texas 78666, USA
COLLEEN A. CALDWELL WOODWARD* AND
J. R. TOMASSO4
Aquatic Station
Southwest Texas State University
Low Temperature
Largemouth bass treatment groups that were
cooled slowly and then held at about 2°C for 5 d
demonstrated differing rates of mortality (Figure
1). Mortalities were significantly higher (chi-square)
among Florida fish (48%) than for other strains,
4-5% for F x N fish and nil for N x
F fish. All fish in water that was cooled from 21
to 1°C, held at that temperature briefly, and then
warmed to 21 °C in 90 min survived and fed normally
within 24 h. Feeding behavior was normal
as temperatures dropped to 13°C, fish fed slowly
between 12 and 6°C, and no feeding by any fish
was observed at temperatures below 6°C.
Largemouth bass treatment groups that were
cooled slowly and then held at about 2°C for 5 d
demonstrated differing rates of mortality (Figure
1). Mortalities were significantly higher (chi-square)
among Florida fish (48%) than for other strains,
4-5% for F x N fish and nil for N x
F fish. All fish in water that was cooled from 21
to 1°C, held at that temperature briefly, and then
warmed to 21 °C in 90 min survived and fed normally
within 24 h. Feeding behavior was normal
as temperatures dropped to 13°C, fish fed slowly
between 12 and 6°C, and no feeding by any fish
was observed at temperatures below 6°C.
Dissimilarities in response to low-temperature
challenge is expected between fishes whose native
ranges differ latitudinally. Previous studies have
indicated differences in temperature response between
the northern and Florida subspecies of
largemouth bass (Cichra et al. 1980; Guest 1982,
1985)—as well as similarities (Guest 1980). Direct
comparison of the four strains enabled us to show
that both subspecies and their hybrids tolerated
brief exposure to low temperatures, but that survival
after prolonged exposures was better in N x
N and N x F strains than in F x F and F x N
strains (female first). The responses of both hybrids more closely
resembled the N x N than the F x F fish. Strain
contamination (hybridization) could have significantly
affected previous studies and accounted for
the variable results among those studies. Our results
showed clear-cut differences in mortality due
to cold exposure, and we speculate that exposure
to low temperatures might result in additional response
differences among largemouth bass strains.
For instance, after exposure to cold, the strains
may have different responses to a secondary
stressor or to diseases; for example, exposure to
low temperatures has been shown to alter the response
of largemouth bass to net-confinement
stress (Carmichael et al. 1984b).
Last edited by ewest; 07/04/08 10:15 PM.
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