Purging a Muddy–Earthy Flavor Taint from Rainbow Trout (Salmo gairdneri) by Transferring to Artificial and Natural Holding Environments

1976 ◽  
Vol 33 (1) ◽  
pp. 160-166 ◽  
Author(s):  
D. G. Iredale ◽  
R. K. York

Studies were conducted to determine the length of time required to purge a muddy–earthy flavor taint from pond cultured rainbow trout (Salmo gairdneri) transferred to two different clear water environments. Sensory data from trained judges show that this required 5 days for fish transferred to a rapidly changing purified artificial water environment and 16 days for fish transferred to a relatively static natural water environment to reduce this taint to or below threshold levels of recognition.

1977 ◽  
Vol 34 (7) ◽  
pp. 996-1003 ◽  
Author(s):  
H. Tsuyuki ◽  
S. N. Williscroft

Rainbow trout (Salmo gairdneri) homozygous for liver lactate dehydrogenase alleles ldhHαA and ldhHαB were artificially propagated and their swimming stamina compared. The time required to fatigue 50% of the HαAHαA phenotypes in fixed water velocity tests was 2.3 times greater on the average than that of HαAHαB phenotypes.Likewise, LDH phenotypes HαAHαA, HαAHαB, and HαAHαB of steelhead trout from the Thompson River were artifically propagated and their swimming stamina compared. In contrast to the rainbow trout, significant differences in stamina among the three phenotypes of steelhead were not evident in the stocks from this river nor between phenotypes HαAHαB and HαBHαB from another stream, the Vedder River, which has a very low frequency of the ldhHαA allele. The stamina of young steelhead from the Thompson River was, however, 3.8 times greater than that of those from the Vedder River. Key words: stamina, LDH, rainbow trout, steelhead, phenotype, swimming, fatigue


1991 ◽  
Vol 69 (3) ◽  
pp. 578-582 ◽  
Author(s):  
A. Kurt Gamperl ◽  
Dan L. Schnurr ◽  
E. Don Stevens

Fast-start acceleration performance of rainbow trout (Salmo gairdneri) was measured after 9 weeks of sprint training (30°s duration, every 2nd day). Response latency and time required to complete the first two stages of a fast start were unaffected by the sprint-training protocol. Maximum acceleration (trained 1985 ± 176 (SE) cm/s2; control 1826 ± 144 cm/s2) and maximum velocity (trained 130 ± 7 cm/s; control 134 ± 14 cm/s) were also not significantly different following training. However, trained fish reached high rates of acceleration before control (untrained) fish. Thus, acceleration was higher in trained fish from 20 to 35 ms postshock. When fish are separated by start type, trained fish consistently had greater acceleration than control fish between 30 and 45 ms postshock. Alterations in fast-start performance due to sprint training may improve predator avoidance ability. Sprint training did not change critical swimming speed as measured using two separate protocols.


1977 ◽  
Vol 34 (7) ◽  
pp. 1034-1039 ◽  
Author(s):  
Ibrahim H. Zeitoun ◽  
Leroy D. Hughes ◽  
Duane E. Ullrey

Blood was pooled from randomly selected 3-yr-old rainbow trout (Salmo gairdneri) before addition of chlorine to their water environment and afterward when fish began to gulp for air and lose equilibrium. In five duplicate tests, plasma concentrations of phosphorus, magnesium, iron, copper, zinc, and potassium increased substantially in the stressed fish. Calcium concentration was also higher, but not significantly so in the plasma of the test fish as compared with those of the controls. Sodium was the only electrolyte that dropped substantially (P < 0.01) in the test fish as compared with the controls.Chlorine toxicity appeared to disturb the mineral homeostasis in the fish blood. Rapid recruitment of electrolytes from the environment and movement into the plasma, a strong mineral retention mechanism, or mobilization of body mineral stores worked together or individually to compensate for those minerals lost with water during hemoconcentration. Key words: rainbow trout, plasma electrolytes, chlorine, hemolysis, hematology, toxicology


1976 ◽  
Vol 33 (11) ◽  
pp. 2587-2591 ◽  
Author(s):  
Ibrahim H. Zeitoun ◽  
Duane E. Ullrey ◽  
Werner G. Bergen ◽  
William T. Magee

Rainbow trout (Salmo gairdneri) eggs were collected from three females, fertilized by the milt of two males per female, and incubated separately. Samples were taken before fertilization, at +0.5 h and on days 1, 1.5, 3, 4, 5, 13, 17, 21, at hatching (23 days), and on day 37, immediately after postyolk absorption. The water environment contributed an estimated minimum 26% of the Na, 30% of the Fe, and 13% of the Zn found at hatching. Derivation of Ca, Na, K, Fe, and Zn from the water environment at postyolk absorption was estimated to be at least 70, 76, 45, 68, and 2%, respectively. All the P and Cu at hatching and in the larva could have been derived from the unfertilized oocyte.


1971 ◽  
Vol 28 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
R. W. McCauley ◽  
W. L. Pond

Preferred temperatures of underyearling rainbow trout (Salmo gairdneri) were determined in both vertical and horizontal temperature gradients. No statistically significant difference was found between the preferred temperatures by the two different methods. This suggests that the nature of the gradient plays a lesser role than generally believed in laboratory investigations of temperature preference.


1979 ◽  
Vol 20 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Torill Bergsjø ◽  
Inger Nafstad ◽  
Kristian Ingebrigtsen

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