scholarly journals Short communication: Response of rainbow trout (Oncorhynchus mykiss) to mirror images

2017 ◽  
Vol 15 (1) ◽  
pp. e05SC02
Author(s):  
Wendy M. Rauw ◽  
Luis A. García-Cortés ◽  
Morris Villarroel ◽  
Luis Gomez-Raya
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Short Communication ◽  
Behavioural Response ◽  
The Other ◽  
Coping Response ◽  
Aggressive Interactions ◽  
Aquarium Fish ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Individual

The response of cultured rainbow trout to their mirrored image was investigated. Thirty fish were placed individually in two novel aquariums consecutively for 10 min each. Walls in one aquarium were covered with mirrors on all four sides, whereas the walls of the other aquarium were non-transparent black. Because all four walls were covered with mirrors, the mirrored image of the fish was reproduced multiple times such that ‘a group’ of fish was created surrounding the individual. Half of the fish started in the aquarium with the mirrors, whereas the other half started in the mirrorless aquarium. Fish swim faster in the aquarium with mirrors than in the mirrorless aquarium (2.95 vs. 2.40 cm/s; p < 0.01), indicating a positive behavioural response towards their mirrored images. Fish did not show aggressive interactions towards their mirrored images. Being confronted with ‘a group’ of fish and not just one ‘opponent’ may have inhibited aggressive behavior, or individuals may not have considered the images to be fellow individuals. Fish that swam faster in the mirrorless aquarium also did so in the aquarium with mirrors (r = 0.73; p < 0.0001), indicating a persistent behavioural coping response (boldness) in response to the two novel environments. Mirrors may be used to influence social behaviour of fish in aquaculture; further research is needed to investigate the influence of mirror placement in tanks of group housed trout on growth and behaviour.

scholarly journals Trade-Offs Underwater: Physiological Plasticity of Rainbow Trout (Oncorhynchus mykiss) Confronted by Multiple Stressors

Fishes ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 49 ◽  
Author(s):  
Elena Wernicke von Siebenthal ◽  
Kristina Rehberger ◽  
Christyn Bailey ◽  
Albert Ros ◽  
Elio Herzog ◽  
...  
Keyword(s):  
Resource Allocation ◽  
Rainbow Trout ◽  
Phenotypic Plasticity ◽  
Oncorhynchus Mykiss ◽  
Multiple Stressors ◽  
Parasitic Infection ◽  
Phenotypic Flexibility ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Trade Offs ◽  
The Individual

Organisms have evolved mechanisms to partition the available resources between fitness-relevant physiological functions. Organisms possess phenotypic plasticity to acclimate to changing environmental conditions. However, this comes at a cost that can cause negative correlations or “trade-offs”, whereby increasing investments in one function lead to decreased investments in another function. The aim of the present study was to investigate the prioritization of resource allocation between growth, pathogen defense, and contaminant response in juvenile rainbow trout (Oncorhynchus mykiss) exposed to changes of resource income or expenditure. We performed a multifactorial experiment with three resource-impacting stressors—limited food availability, a parasitic infection, exposure to a vitellogenesis-inducing contaminant—and combinations thereof. Treatment with the individual stressors evoked the expected responses in the respective physiological target systems—body growth, immune system, and hepatic vitellogenin transcription—but we found little evidence for significant negative relations (trade-offs) between the three systems. This also applied to fish exposed to combinations of the stressors. This high phenotypic flexibility of trout in their resource allocation suggests that linear resource allocations as mechanisms of phenotypic plasticity may be too simplistic, but it also may point to a greater capacity of ectothermic than endothermic vertebrates to maintain key physiological processes under competing resource needs due to lower maintenance costs.

scholarly journals Does the rainbow trout ovarian fluid guide the spermatozoon on its way to the egg?

2021 ◽  
Author(s):  
Vitaliy Kholodnyy ◽  
Borys Dzyuba ◽  
Marek Rodina ◽  
Hermes Bloomfield-Gadelha ◽  
Manabu Yoshida ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Freshwater Fish ◽  
High Velocity ◽  
Chemotactic Response ◽  
Ovarian Fluid ◽  
Motility Pattern ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Male Gametes ◽  
The Individual

Fertilization of freshwater fish occurs in an environment that may affect negatively the gametes, therefore the specific mechanisms triggering the encounters of gametes would be highly expedient. The egg and ovarian fluid (OF) are likely the major sources of these triggers in fish, that we confirmed here for rainbow trout Oncorhynchus mykiss. The ovarian fluid affected significantly the spermatozoa performance: it supported high velocity for a longer period and changed the motility pattern from tumbling in water to straightforward moving in the ovarian fluid. Rainbow trout OF induced a trapping chemotaxis-like effect on activated male gametes and this effect depended on the properties of the activating media. The interaction of the sper-matozoa with the attracting agents was accompanied by their 'turn-and-run' behavior involving asymmetric flagellar beating and Ca2+ concentration bursts in the bent flagella segment, characteristic for the chemotactic response. Collectively, the ovarian fluid creates the optimal environment for rainbow trout spermatozoa performance, being an effective promoter of fertilization. The individual peculiarities of the egg (ovarian fluid)-sperm interaction in rainbow trout reflect the specific features of the spawning process in this species.

scholarly journals Biomagnification of ionizable organic compounds in rainbow trout Oncorhynchus mykiss

2020 ◽  
Vol 32 (1) ◽  
Author(s):  
Carolin Mueller ◽  
Stefan Trapp ◽  
Fabio Polesel ◽  
Sebastian Kuehr ◽  
Christian Schlechtriem
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Organic Compounds ◽  
Half Life ◽  
Assimilation Efficiency ◽  
Test Results ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Individual ◽  
Strong Acids ◽  
Depuration Rate

Abstract Background The assessment of persistence, bioaccumulation and toxicity (PBT) is part of the regulation process of ionic organic compounds (IOCs) and a major challenge, as a commonly acknowledged approach for the estimation of the bioaccumulation potential of IOCs is still missing. The goal of the present study was, therefore, to experimentally determine the bioaccumulation of fully ionized compounds and to identify screening parameters that can indicate high bioaccumulation potential of IOCs. Three feeding studies with rainbow trout (Oncorhynchus mykiss) were carried out according to OECD TG 305. Separation of liver, gastrointestinal tract (GIT) and carcass allowed to further elucidate the tissue distribution of the individual test substances. The chemicals chosen had characteristics that made them suspect for high bioaccumulation, and included two cations (tetrabutylphosphonium bromide (TBP), trimethyloctadecyl ammonium chloride (TMOA)) and four anions (benzotriazole, tecloftalam, pentachlorophenol (PCP), MEE-phosphonate). Data on the dietary biomagnification of IOCs (strong acids) were also collected from published literature. Results The highest distribution factors were found for the GIT, followed by liver. However, none of the tested IOCs showed a distinct biomagnification potential, as kinetic biomagnification factors (BMFk) ranged between 0.001 and 0.05 g/g (median 0.009 g/g). Cations showed lower assimilation efficiency (α) than anions, except for tecloftalam. In contrast, anions showed a considerably faster depuration rate (half-life less than 0.5 days) compared to cations (half-life of around 5 days). Sixteen potential screening parameters for BMF were calculated with a chemical property estimation tool (ACD/i-Lab) and correlated with the BMF data from this study and from literature. The number of hydrogen bond donors (nHBD) showed the highest correlation to measured BMF, but the prediction is only based on two values (one or two nHBD), while the other descriptors were insignificantly correlated. Conclusion The suspected dietary bioaccumulation potential of the six IOCs could not be confirmed in the feeding studies with rainbow trout. The more than twenty screening parameters showed no particularly high correlation neither with the test results nor with the BMF values collected from literature. The results corroborate earlier findings that ionization lowers the tendency of a chemical for dietary bioaccumulation, compared to non-ionized chemicals. In addition to the lipophobicity of ionic molecule moieties, fast depuration seems to be a major reason for the observed low dietary bioaccumulation of ionic compounds, in particular anions. Fast depuration may happen due to rapid metabolism of charged compounds, and future studies should test this hypothesis.

Increases in steelhead (Oncorhynchus mykiss) redd abundance resulting from two conservation hatchery strategies in the Hamma Hamma River, Washington

2008 ◽  
Vol 65 (4) ◽  
pp. 754-764 ◽  
Author(s):  
Barry A Berejikian ◽  
Thom Johnson ◽  
Richard S Endicott ◽  
Joy Lee-Waltermire
Keyword(s):  
Rainbow Trout ◽  
Reproductive Success ◽  
Oncorhynchus Mykiss ◽  
Natural Environment ◽  
The Other ◽  
Ecological Consequences ◽  
Natural Origin ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Release Group ◽  
Hatchery Program

Conservation hatcheries for anadromous salmonids that aim to increase production and minimizing genetic, ecological, and demographic risks have not been experimentally tested for their ability to increase number of adults spawning in the natural environment. The conservation hatchery program for steelhead (i.e., sea-run rainbow trout, Oncorhynchus mykiss) evaluated in this study caused an increase in the number of redds in the supplemented Hamma Hamma River compared with the presupplementation period. Three control populations (nonsupplemented) either remained stable or declined over the same period. The increase in redds from hatchery-produced spawners did not reduce the redd production from natural-origin spawners. The strategy of rearing and releasing adult steelhead accounted for the greatest proportion of redd abundance increases. Environmentally induced differences in spawn timing between the adult release group and anadromous adults of hatchery and natural origin may explain why the adult release group and anadromous adults assortatively formed pairing combinations on the spawning grounds. Although captively reared adults produced the majority of redds in years they were released in substantial numbers, uncertainty regarding the relative reproductive success of this strategy suggests caution in recommending one strategy over the other. A demographic boost to the naturally spawning population was effected while managing to minimize negative ecological consequences.

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