Hybridization with Domesticated Rainbow Trout (Oncorhynchus mykiss) Reduces Seasonal Variation in Growth of Steelhead Trout (O. mykiss)

1993 ◽  
Vol 50 (3) ◽  
pp. 480-487 ◽  
Author(s):  
Jörgen I. Johnsson ◽  
W. Craig Clarke ◽  
Ruth E. Withler
Keyword(s):  
Growth Rate ◽  
Seasonal Variation ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Natural Waters ◽  
Salt Water ◽  
Feeding Activity ◽  
Steelhead Trout ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Winter Conditions

We tested the hypothesis that hybridization with domesticated rainbow trout (Oncorhynchus mykiss) reduces the seasonal variation in growth in both fresh and salt water in anadromous steelhead trout (O. mykiss). The seasonal variation in freshwater growth was more pronounced in the steelhead trout than in the hybrid and domesticated trout. Consequently, differences in growth rate among groups were considerably higher during winter than in fall or spring. We suggest that high feeding activity during unfavourable winter conditions in natural waters is maladaptive, but is not selected against in protected hatchery environments with a continuous food supply. This may lead to genetic divergence in feeding physiology and/or behaviour between steelhead trout and domesticated rainbow trout. Growth rates in experimental groups transferred to seawater in December relative to groups transferred in April were faster in rainbow and hybrid trout than in steelhead trout. The results support the hypothesis that seasonal variation in seawater growth in steelhead trout is reduced by crossing with domesticated rainbow trout.

Digestive characteristics and blood chemistry profile of triploid rainbow trout Oncorhynchus mykiss: influence of body size and seasonal variation

2019 ◽  
Vol 85 (6) ◽  
pp. 1001-1010 ◽  
Author(s):  
Yuqiong Meng ◽  
Buying Han ◽  
Changzhong Li ◽  
Kangkang Qian ◽  
Xiaohong Liu ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Rainbow Trout ◽  
Body Size ◽  
Oncorhynchus Mykiss ◽  
Blood Chemistry ◽  
Rainbow Trout Oncorhynchus Mykiss

Individual variation and interrelationships between swimming performance, growth rate, and feeding in juvenile rainbow trout (Oncorhynchus mykiss)

1998 ◽  
Vol 55 (7) ◽  
pp. 1583-1590 ◽  
Author(s):  
T Ryan Gregory ◽  
Chris M Wood
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Plasma Cortisol ◽  
Positive Relationship ◽  
Swimming Performance ◽  
Individual Performance ◽  
Significant Positive Relationship ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss

Variation among individuals in specific growth rate (SGR), feeding, and two measures of swimming performance and their possible interrelationships were investigated in juvenile rainbow trout (Oncorhynchus mykiss) kept in groups on either satiation or half-satiation rations. Maximum sustainable velocity (Ucrit) was measured as an index of aerobic swimming performance and stamina (fatigue time in a fixed-velocity test at 6 body lengths ·s-1) as an index of anaerobic performance. Individual performance in both of these tests was found to be significantly repeatable. Trout fed on half-satiation ration exhibited significantly lower mean values of SGR and body size and higher levels of aggression-related fin damage, but no significant differences in stamina, relative or absolute Ucrit, glycogen content, or plasma cortisol. However, in these fish, there was a significant negative relationship between SGR and relative Ucrit, a significant positive relationship between SGR and stamina, and a significant positive relationship between SGR and total daily meal. None of these relationships were seen in fish fed to satiation. Plasma cortisol and tissue glycogen stores were not related to SGR. These results indicate that under the intensified competition of restricted ration, there are trade-offs between growth, feeding, and different types of swimming performance.

Diurnal and nocturnal feeding activity in Arctic char (Salvelinus alpinus) and rainbow trout (Oncorhynchus mykiss)

1997 ◽  
Vol 54 (12) ◽  
pp. 2894-2900 ◽  
Author(s):  
Anders Alanärä ◽  
Eva Brännäs
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Salvelinus Alpinus ◽  
Feeding Activity ◽  
Activity Patterns ◽  
Arctic Char ◽  
Diel Activity ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Nocturnal Feeding ◽  
Nocturnal Fish

When food is limited and competition for it is high, individual fish may adopt different diel activity patterns. We followed individual feeding activity in groups of 10 Arctic char (Salvelinus alpinus) and rainbow trout (Oncorhynchus mykiss) using a combined self-feeding and PIT-tag system. Food was supplied at low and high rewards to five replicate groups of Arctic char and rainbow trout. Four categories were identified in both species: high-triggering diurnal (diurnal fish with the highest self-feeding activity), low-triggering diurnal, nocturnal, and nontriggering fish. On average, the photophase proportion of the total daily activity was approx 90% in diurnal and approx 20% in nocturnal individuals. Rainbow trout offered high rewards did not show any diel preferences. Diurnal Arctic char and rainbow trout with the highest self-feeding activity were initially larger and had the highest growth rates, indicating a high social position. Nocturnal fish were initially smaller and their proportion of trigger actuations much lower than the high-triggering diurnal fish. These still grew successfully whereas nontriggering fish grew significantly less. Thus, some individuals with a low social status may apply an alternative strategy to attain adequate growth by feeding at night when dominant individuals are less aggressive. This may be referred to as concurrent dualism (diurnalism and nocturnalism).

RNA/DNA ratios in white muscle as estimates of growth in rainbow trout held at different temperatures

1990 ◽  
Vol 68 (7) ◽  
pp. 1494-1498 ◽  
Author(s):  
Moira M. Ferguson ◽  
Roy G. Danzmann
Keyword(s):  
Growth Rate ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
White Muscle ◽  
Specific Growth ◽  
Fish Size ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Different Temperatures ◽  
Specific Growth Rates ◽  
Rna And Dna

The concentrations of RNA, DNA, and protein in white muscle from 240 uniquely tagged rainbow trout (Oncorhynchus mykiss) held at three temperatures (5, 8 (control), and 11 °C) were measured. Both RNA and RNA/DNA ratios were better predictors of recent length- and weight-specific growth rates than they were of absolute fish size. Furthermore, RNA concentrations were better predictors of growth than RNA/DNA ratios. The strength of the regression between either RNA/DNA ratio or RNA and growth rate did not differ consistently among temperatures. Fish reared at warmer temperatures had lower concentrations of RNA for both a given growth rate and a given DNA concentration compared with cold-reared trout. Warm-reared fish also had lower concentrations of DNA and higher protein/DNA ratios than cold-reared trout when fish size was standardized. The concomitant decrease in both RNA and DNA concentrations resulted in marginally lower RNA/DNA ratios in warm-reared fish.

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