scholarly journals The effect of visual isolation on territory size and population density of juvenile rainbow trout (Oncorhynchus mykiss)

2002 ◽  
Vol 59 (2) ◽  
pp. 303-309 ◽  
Author(s):  
I Imre ◽  
J WA Grant ◽  
E R Keeley
Keyword(s):  
Rainbow Trout ◽  
Population Density ◽  
Oncorhynchus Mykiss ◽  
Experimental Tests ◽  
Territory Size ◽  
Control Treatment ◽  
Stream Channels ◽  
Juvenile Salmonids ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Experimental Treatments

Visibility is thought to affect the territory size of visually oriented animals but there have been few experimental tests of the hypothesis. We re-examined the relationship between visibility and territory size in juvenile salmonids to test the hypothesis that increasing habitat heterogeneity results in a reduction in territory size and consequently in higher population densities. Equal densities of young-of-the-year rainbow trout (Oncorhynchus mykiss) were stocked in two experimental treatments with low visibility and a control treatment with high visibility. Visibility was decreased by placing large stones or plywood dividers onto the substrate of experimental stream channels. As predicted, the size of individual territories decreased with decreasing visibility of the habitat. However, the treatments did not differ significantly in population density or growth rate of the fish. While this study confirms the inverse relationship between habitat visibility and territory size, the decrease in territory size did not produce an increase in population density of juvenile salmonids.

scholarly journals Population density and territory size in juvenile rainbow trout, Oncorhynchus mykiss: implications for population regulation

2012 ◽  
Vol 69 (6) ◽  
pp. 1121-1128 ◽  
Author(s):  
J.L.A. Wood ◽  
J.W.A. Grant ◽  
M.H. Belanger
Keyword(s):  
Rainbow Trout ◽  
Population Density ◽  
Oncorhynchus Mykiss ◽  
Population Size ◽  
Local Population ◽  
Minimum Size ◽  
Territory Size ◽  
Stream Channels ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss

We manipulated population density of juvenile rainbow trout ( Oncorhynchus mykiss ) across a range of realistic densities in artificial stream channels, while controlling food abundance in two different ways: in Experiment 1, the total amount of food was held constant over a threefold increase in density, whereas in Experiment 2, the per capita amount of food was held constant over an eightfold increase in density. We tested the contrasting predictions that territory size (i) is not affected by population density; (ii) decreases with population density as 1/n, where n = the local population size; or (iii) decreases with population density but towards an asymptotic minimum size. In Experiment 1, territory size decreased with increasing population density. With the broader range of densities used in Experiment 2, territory size initially decreased with density and then leveled off at a minimum territory radius of 20–30 cm. Our results suggest an asymptotic minimum size of about 0.2 m2 for a 5 cm rainbow trout, similar to what is observed for high-density conditions in the wild. This minimum territory size could potentially set an upper limit on local population density and help regulate the population size of stream salmonids.

Histopathology of Rainbow Trout (Oncorhynchus mykiss) after Long-Term Exposure to Biologically Treated Bleached Kraft Mill Effluent in Experimental Stream Channels

1992 ◽  
Vol 49 (5) ◽  
pp. 939-944 ◽  
Author(s):  
Timothy J. Hall ◽  
Richard K. Haley ◽  
Dennis L. Borton ◽  
Alexander H. Walsh ◽  
Richard E. Wolke
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Exposure Period ◽  
Stream Channels ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Natural Streams ◽  
Tissue Changes ◽  
Kraft Mill Effluent ◽  
Secondary Parasite ◽  
Kraft Mill

Outdoor experimental streams were used to determine the effects of effluent on histopathology of rainbow trout (Oncorhynchus mykiss). Studies were conducted for 10–11 mo using biologically treated bleached kraft mill effluent at concentrations ranging from 0.5 to 2.0 mg∙L−1 of effluent BOD5 (1.3–5.1% v/v) and for 42 mo at 0.5 BOD5 addition (1.5% v/v). Twenty different tissues from randomly selected fish were examined at the end of each exposure period. Lesions or tissue changes observed in fish from both control and effluent-treated streams were of primary or secondary parasite-induced etiology, a condition typical of natural streams. There was an absence of neoplasia over the range of concentrations. Hematocrit, leucocrit, and liver somatic index remained normal throughout the course of effluent exposure. These data corroborate the lack of effluent effects as determined from measurements of trout growth, survival, production, and reproduction.

Use of Dissolved Strontium in Scale Marking of Juvenile Salmonids: Effects of Concentration and Exposure Time

1992 ◽  
Vol 49 (4) ◽  
pp. 780-782 ◽  
Author(s):  
Randal J. Snyder ◽  
Brian A. McKeown ◽  
Konrad Colbow ◽  
Robert Brown
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Exposure Time ◽  
Chemical Markers ◽  
Ambient Water ◽  
Specific Chemical ◽  
Twofold Increase ◽  
Juvenile Rainbow Trout ◽  
Juvenile Salmonids ◽  
Rainbow Trout Oncorhynchus Mykiss

Strontium (Sr), which is chemically similar to calcium and can substitute for this element in bony tissues of fishes, shows promise as an inexpensive and efficient means of chemically marking juvenile salmonids. This study examines the effects of three different Sr concentrations in water (1.8, 3.6, and 5.4 mg/L) and two different exposure times (30 and 60 d) on uptake of Sr into the scales of juvenile rainbow trout (Oncorhynchus mykiss). Doubling and tripling the Sr concentration in the ambient water produced corresponding twofold and threefold increases in final scale (Sr). A twofold increase in exposure time produced nearly the same effect as a twofold increase in concentration. Widespread adoption of this technique will require establishment of optimal concentration and exposure times, validation of methods for compensating for Sr incorporated during seawater residence, and development of hatchery-specific chemical markers using combinations of several different elements.

The essential oils of some medicinal plants on the immune system of rainbow trout (Oncorhynchus mykiss)

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
A Ghasemi Pirbalouti ◽  
E Pirali ◽  
G Pishkar ◽  
S Mohammadali Jalali ◽  
M Reyesi ◽  
...  
Keyword(s):  
Immune System ◽  
Rainbow Trout ◽  
Medicinal Plants ◽  
Oncorhynchus Mykiss ◽  
Essential Oils ◽  
Rainbow Trout Oncorhynchus Mykiss

Nuclear distribution of genotoxic damage in rainbow trout (Oncorhynchus mykiss) sperm after cryopreservation

2014 ◽  
Author(s):  
Silvia Gonzalez-Rojo ◽  
Cristina Fernandez-Diez ◽  
Marta Lombo ◽  
Vanesa Robles Rodriguez ◽  
Herraez Maria Paz
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Genotoxic Damage ◽  
Nuclear Distribution ◽  
Rainbow Trout Oncorhynchus Mykiss
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