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Effect of the structure of cage on the aggressive behaviour and social stress in Nile Tilapia

Grant number: 11/18530-0
Support Opportunities:Scholarships in Brazil - Doctorate
Effective date (Start): May 01, 2012
Effective date (End): February 28, 2014
Field of knowledge:Agronomical Sciences - Fishery Resources and Fishery Engineering - Aquaculture
Principal Investigator:Eliane Gonçalves de Freitas
Grantee:Camila Nomura Pereira Boscolo
Host Institution: Centro de Aquicultura (CAUNESP). Universidade Estadual Paulista (UNESP). Campus de Jaboticabal. Jaboticabal , SP, Brazil


In aquaculture production system in cages has been widely used because it allows the exploitation of water resources to produce large quantities of fish in a small space. This production system has a high rate of water renewal and has no substrate. The Nile tilapia is a fish species that communicate their social position, in part, through chemical communication. Thus, the renewal of water can wash the chemical cues. Thus, the absence of chemical signals in the environment can affect the recognition of social status between individuals. Moreover, the Nile tilapia uses the substrate for nest construction and defense of territory, spend much of his time to this activity. Thus, it is possible that the absence of this element increases the time available for aggressive interactions. Thus it will be tested the thesis that the absence of indicators of social position caused by the structure of cages increases the social stress in territorial fish by the increase in aggressive interactions and social instability. For this, will be tested four treatments (n = 20), composed of aquariums containing a network structure (similar to the cages), with groups of five adult males: 1 - Substrate and water renewal. 2 - No substrate and water renewal. 3 - Substrate and without water renewal. 4 - No substrate and without water renewal. The animals are grouped by five days where levels of aggressive interactions will be evaluated by the frequency and type of attacks sent and received between individuals. The social stress is measured by plasma cortisol levels, liver glycogen and liver lipids. Social stability is measured by correlations between index of dominance of animals along to the observations. The sex steroids testosterone and 11 - Ketotestosterona will be evaluated as another way to infer dominance and social stability. The frequency of aggressive behaviors, indicators of stress hormones among the treatments will be evaluated by one-way ANOVA. The frequency of aggressive behavior over the five days will be assessed by Mixed Model ANOVA. (AU)

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Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
BOSCOLO, Camila Nomura Pereira. Ambiete de tanque-rede aumenta as interações agressivas e o estresse social na tilápia-do-Nilo. 2014. Doctoral Thesis - Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal Jaboticabal.

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