Conspecific skin extracts elicit antipredator responses in juvenile rainbow trout (Oncorhynchus mykiss)

1997 ◽  
Vol 75 (11) ◽  
pp. 1916-1922 ◽  
Author(s):  
Grant E. Brown ◽  
R. Jan F. Smith
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Whole Body ◽  
Antipredator Behaviour ◽  
Skin Extract ◽  
Distilled Water ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Antipredator Responses ◽  
Body Extract

We investigated, under laboratory conditions, the presence of chemical alarm signals in juvenile rainbow trout (Oncorhynchus mykiss). In an initial experiment, we exposed trout to a whole-body extract from conspecifics or a distilled-water control. When exposed to whole-body extract, trout significantly (i) decreased time spent swimming, (ii) increased time taken to resume foraging, and (iii) decreased the number of food items eaten. These data indicate a significant chemically mediated antipredator response. A second experiment was conducted to determine (i) if this is a generalized response to injured fish or a specific response to injured conspecifics, and (ii) if the chemical signal is localized in the skin. We exposed juvenile trout to one of three chemical stimuli: (1) trout skin extract, (2) trout body extract, or (3) swordtail (Xiphophorus helleri) skin extract. Significant antipredator responses were observed in trout exposed to conspecific skin extract, but responses of those exposed to conspecific body extract or swordtail skin extract did not differ from those of distilled-water controls. These data strongly suggest that juvenile rainbow trout possess a chemical alarm signal, localized in the skin, that elicits antipredator behaviour when detected.by conspecifics.

scholarly journals Acquired predator recognition in juvenile rainbow trout (Oncorhynchus mykiss): conditioning hatchery-reared fish to recognize chemical cues of a predator

1998 ◽  
Vol 55 (3) ◽  
pp. 611-617 ◽  
Author(s):  
Grant E Brown ◽  
R Jan F. Smith
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Chemical Cues ◽  
Antipredator Behaviour ◽  
Skin Extract ◽  
Distilled Water ◽  
Water Control ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Area Use

In this study, we exposed predator-naive, hatchery-reared juvenile rainbow trout (Oncorhynchus mykiss) to the chemical stimuli from northern pike (Esox lucius) and either trout skin extract (a chemical alarm signal) or a distilled water control to test for acquired recognition of a novel predator. Trout exposed to conspecific skin extract and pike odour significantly increased antipredator behaviour (i.e., decreased foraging and area use and increased shoaling and freezing), while those exposed to distilled water and pike odour did not. Conditioned trout were exposed to pike odour alone (versus a distilled water control) either 4 or 21 days later. When presented with pike odour 4 days postconditioning, trout significantly increased antipredator behaviour (i.e., decreased foraging and area use and increased time under cover and freezing). Trout tested 21 days postconditioning still exhibited a significant increase in antipredator behaviours when presented with pike odour alone (i.e., decreased foraging and increased freezing). These data are the first to demonstrate that hatchery-reared trout can be conditioned to recognize the chemical cues of a predator and suggest that this may serve as a strategy to train hatchery-reared fish to recognize predators prior to stocking into natural waterways.

Effects of different ligands on the bioaccumulation and subsequent depuration of dietary Cu and Zn in juvenile rainbow trout (Oncorhynchus mykiss)

2006 ◽  
Vol 63 (2) ◽  
pp. 412-422 ◽  
Author(s):  
Victoria A Kjoss ◽  
Chris M Wood ◽  
D Gordon McDonald
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Metal Accumulation ◽  
Whole Body ◽  
Control Fish ◽  
Dietary Copper ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Control Food ◽  
Cu And Zn

The effects of different ligands on the bioavailability of dietary copper (Cu) and zinc (Zn) to fish have not been thoroughly investigated. We therefore exposed juvenile rainbow trout (Oncorhynchus mykiss; ~200 mg body weight) to control food or to food supplemented with different Cu (~400 µg·g–1 food) or Zn (~1000 µg·g–1 food) compounds. Tissue metal accumulation was compared among groups. Fish fed CuO showed no differences in tissue Cu concentrations relative to control fish, suggesting that Cu was not readily available for uptake in this form. In contrast, Cu in the form of CuSO4, Cu-proteinate, or Cu-lysine was much more available for uptake, resulting in substantial increases in liver, gut tissue, and whole-body Cu concentrations during the loading phase and decreases during depuration, although liver and whole-body levels remained elevated after 2 weeks. We found no differences in tissue Cu accumulation among these three complexes. There were no effects on growth. For Zn, we found no differences among any of the treatments, including controls, in Zn accumulation or growth. Overall, there was homeostasis of whole-body and tissue-specific Zn concentrations despite the large differences in dietary Zn loads.

Metabolic Costs and Physiological Consequences of Acclimation to Aluminum in Juvenile Rainbow Trout (Oncorhynchus mykiss). 1: Acclimation Specificity, Resting Physiology, Feeding, and Growth

1994 ◽  
Vol 51 (3) ◽  
pp. 527-535 ◽  
Author(s):  
Rod W. Wilson ◽  
Harold L. Bergman ◽  
Chris M. Wood
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Soft Water ◽  
Negligible Effect ◽  
Whole Body ◽  
Rapid Loss ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Metabolic Costs ◽  
Pronounced Reduction

Juvenile rainbow trout (Oncorhynchus mykiss, 5–13 g) became acclimated (i.e., increased their resistance to lethal Al levels, 162 μg∙L−1, pH 5.2) after only 5 d when exposed to sublethal AS (38 μg∙L−1) in acidified soft water (Na+ = 85, Ca2+ = 28 μEq∙L−1, pH 5.2). Acclimation was associated with reduced ionoregulatory and respiratory disturbances during lethal Al challenge and was maintained for at least 34 d. Acclimation was relatively specific to Al because no consistently improved resistance to lethal Cu (32 μg∙L−1, pH 5.2) was observed. Exposure to sublethal acid alone (pH 5.2) did not result in acclimation to lethal [H+] (pH 4.0) and caused a pronounced reduction in whole-body Na+ and Cl−. Sublethal acid + Al resulted in a more rapid loss of ions than sublethal acid alone over the first 10 d, but both groups subsequently recovered ionoregulatory status after 34 d. Exposure to sublethal acid alone had a negligible effect on feeding or growth. However, growth was impaired by 29% in Al-exposed trout, primarily the result of reduced appetite during the first 10 d. Decreased growth must be considered one of the costs of acclimation during chronic sublethal exposure to Al.

scholarly journals Graded Incorporation of Defatted Yellow Mealworm (Tenebrio molitor) in Rainbow Trout (Oncorhynchus mykiss) Diet Improves Growth Performance and Nutrient Retention

Animals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 187 ◽  
Author(s):  
Paulo Rema ◽  
Subramanian Saravanan ◽  
Benjamin Armenjon ◽  
Constant Motte ◽  
Jorge Dias
Keyword(s):  
Body Composition ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Growth Performance ◽  
Tenebrio Molitor ◽  
Nutrient Digestibility ◽  
Protein Meal ◽  
Yellow Mealworm ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss

Insects are emerging as a sustainable alternative to fishmeal and fish oil in aquafeeds. This study assessed the effect of graded incorporation levels of defatted yellow mealworm (Tenebrio molitor) protein meal on juvenile rainbow trout (Oncorhynchus mykiss) growth performance, body composition, and apparent nutrient digestibility. The trial comprised five dietary treatments: control diet with 25% fishmeal, and four experimental diets with yellow mealworm protein meal at 5%, 7.5%, 15%, or 25%, which corresponded to a fishmeal replacement of 20%, 30%, 60%, or 100%, respectively. After 90 days, the graded incorporation of insect protein meal led to a significant stepwise increase in final body weight, and a significant improvement of specific growth rate, feed conversion ratio, and protein efficiency ratio compared to the control treatment. Regardless of the incorporation level, the insect protein meal had no effects on fish whole-body composition and apparent digestibility coefficients of dry matter, protein, fat, phosphorus, and energy. Protein, phosphorus, and energy retention significantly increased in fish fed the diets with an insect protein meal. In conclusion, the yellow mealworm protein meal could effectively replace 100% of fishmeal in the diet of juvenile rainbow trout with positive effects on its overall zootechnical performance.

Changes in Habitat Use and Feeding Chronology of Juvenile Rainbow Trout (Oncorhynchus mykiss) in Fall and the Onset of Winter in Silver Creek, Idaho

1993 ◽  
Vol 50 (10) ◽  
pp. 2119-2128 ◽  
Author(s):  
Michael D. Riehle ◽  
J. S. Griffith
Keyword(s):  
Rainbow Trout ◽  
Habitat Use ◽  
Oncorhynchus Mykiss ◽  
Density Distribution ◽  
Stomach Contents ◽  
Early Morning ◽  
Invertebrate Drift ◽  
Juvenile Rainbow Trout ◽  
Rainbow Trout Oncorhynchus Mykiss

We assessed changes in density, distribution, and microhabitat of age-0 rainbow trout (Oncorhynchus mykiss) in Silver Creek, a partially spring-fed stream, by periodic snorkeling in August 1987 through January 1988. We examined trout stomach contents and invertebrate drift samples in diel collections in August, September, October, and January to test if the period of feeding shifted from daytime to nighttime, concurrent with a transition to day concealment. In late September, fish aggregated briefly during the day and then began to conceal themselves in macrophyte beds, undercut banks, and submerged sedges and grasses along streambanks as temperature dropped below 8 °C in early October. Fish emerged from concealment at night, and numbers of trout visible were greatest 30–60 min after sunset and about 30 min before sunrise. Periods of peak feeding changed from afternoon and evening in August and September, when fish were day active, to mainly at night in October after the initiation of day concealment. Trout did not feed upon abundant chironomids in the daytime drift in October. In January, fish fed at 1–4 °C on mayflies, and stomachs were fullest in the early morning. Observations suggest that Silver Creek trout experienced a metabolic deficit that began in September.

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