Movements through a fish ladder: temporal patterns and motivations to move upstream

Detalhes bibliográficos
Autor(a) principal: Agostinho,Carlos Sérgio
Data de Publicação: 2007
Outros Autores: Pereira,Celiana Ribeiro, Oliveira,Rafael José de, Freitas,Iriene Siqueira, Marques,Elineide Eugênio
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Neotropical ichthyology (Online)
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252007000200010
Resumo: Fish passages are constructed with the aim of reestablishing connectivity between critical habitats, in order to sustain those species that move over a large area during their lives. The upstream movements of most of the known migratory species are made for purposes of reproduction (adults) or dispersal (juveniles). The present study was conducted at the ladder constructed at Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power), on the Tocantins River. The objective was to assess whether there is a temporal pattern in the abundance of fish below the dam and in the ladder, that correlates with their breeding seasons. Additionally, it was examined whether reproduction is the predominant motivation of the shoals of fish that ascend the ladder. Samples were taken monthly from November, 2002 through October, 2003, downriver from the dam with gillnets, and in the resting pools of the fish ladder with cast nets. The analysis of seasonality in the aggregation of the shoals was based on the temporal variations in abundance and species richness. The possibility of a reproductive motivation for ascending the ladder was inferred from the frequency of the stages of gonadal development. However, during the entire study period we observed a high frequency of individuals with gonads in the pre-vitellogenic stage for all analyzed species, both downriver from the dam (97%) and in the fish ladder (98%). These findings suggest that there was no reproductive motivation for the aggregation of the fish downstream and for their entry into the ladder. On the other hand, the dominance of these stages downriver suggests that the spawning habitats are distant, and that the upstream movements occur for other reasons such as dispersal and search for more appropriate habitats for feeding and growth. The entrance into the ladder resulted more from rheophilic behavior, which is more pronounced in migratory species, than from an endogenous motivation linked to reproductive migration.
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spelling Movements through a fish ladder: temporal patterns and motivations to move upstreamFish migrationFish conservationBiodiversityReservoirSeasonalityFish passages are constructed with the aim of reestablishing connectivity between critical habitats, in order to sustain those species that move over a large area during their lives. The upstream movements of most of the known migratory species are made for purposes of reproduction (adults) or dispersal (juveniles). The present study was conducted at the ladder constructed at Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power), on the Tocantins River. The objective was to assess whether there is a temporal pattern in the abundance of fish below the dam and in the ladder, that correlates with their breeding seasons. Additionally, it was examined whether reproduction is the predominant motivation of the shoals of fish that ascend the ladder. Samples were taken monthly from November, 2002 through October, 2003, downriver from the dam with gillnets, and in the resting pools of the fish ladder with cast nets. The analysis of seasonality in the aggregation of the shoals was based on the temporal variations in abundance and species richness. The possibility of a reproductive motivation for ascending the ladder was inferred from the frequency of the stages of gonadal development. However, during the entire study period we observed a high frequency of individuals with gonads in the pre-vitellogenic stage for all analyzed species, both downriver from the dam (97%) and in the fish ladder (98%). These findings suggest that there was no reproductive motivation for the aggregation of the fish downstream and for their entry into the ladder. On the other hand, the dominance of these stages downriver suggests that the spawning habitats are distant, and that the upstream movements occur for other reasons such as dispersal and search for more appropriate habitats for feeding and growth. The entrance into the ladder resulted more from rheophilic behavior, which is more pronounced in migratory species, than from an endogenous motivation linked to reproductive migration.Sociedade Brasileira de Ictiologia2007-01-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252007000200010Neotropical Ichthyology v.5 n.2 2007reponame:Neotropical ichthyology (Online)instname:Sociedade Brasileira de Ictiologia (SBI)instacron:SBI10.1590/S1679-62252007000200010info:eu-repo/semantics/openAccessAgostinho,Carlos SérgioPereira,Celiana RibeiroOliveira,Rafael José deFreitas,Iriene SiqueiraMarques,Elineide Eugênioeng2007-07-24T00:00:00Zoai:scielo:S1679-62252007000200010Revistahttp://www.ufrgs.br/ni/https://old.scielo.br/oai/scielo-oai.php||neoichth@nupelia.uem.br1982-02241679-6225opendoar:2007-07-24T00:00Neotropical ichthyology (Online) - Sociedade Brasileira de Ictiologia (SBI)false
dc.title.none.fl_str_mv Movements through a fish ladder: temporal patterns and motivations to move upstream
title Movements through a fish ladder: temporal patterns and motivations to move upstream
spellingShingle Movements through a fish ladder: temporal patterns and motivations to move upstream
Agostinho,Carlos Sérgio
Fish migration
Fish conservation
Biodiversity
Reservoir
Seasonality
title_short Movements through a fish ladder: temporal patterns and motivations to move upstream
title_full Movements through a fish ladder: temporal patterns and motivations to move upstream
title_fullStr Movements through a fish ladder: temporal patterns and motivations to move upstream
title_full_unstemmed Movements through a fish ladder: temporal patterns and motivations to move upstream
title_sort Movements through a fish ladder: temporal patterns and motivations to move upstream
author Agostinho,Carlos Sérgio
author_facet Agostinho,Carlos Sérgio
Pereira,Celiana Ribeiro
Oliveira,Rafael José de
Freitas,Iriene Siqueira
Marques,Elineide Eugênio
author_role author
author2 Pereira,Celiana Ribeiro
Oliveira,Rafael José de
Freitas,Iriene Siqueira
Marques,Elineide Eugênio
author2_role author
author
author
author
dc.contributor.author.fl_str_mv Agostinho,Carlos Sérgio
Pereira,Celiana Ribeiro
Oliveira,Rafael José de
Freitas,Iriene Siqueira
Marques,Elineide Eugênio
dc.subject.por.fl_str_mv Fish migration
Fish conservation
Biodiversity
Reservoir
Seasonality
topic Fish migration
Fish conservation
Biodiversity
Reservoir
Seasonality
description Fish passages are constructed with the aim of reestablishing connectivity between critical habitats, in order to sustain those species that move over a large area during their lives. The upstream movements of most of the known migratory species are made for purposes of reproduction (adults) or dispersal (juveniles). The present study was conducted at the ladder constructed at Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power), on the Tocantins River. The objective was to assess whether there is a temporal pattern in the abundance of fish below the dam and in the ladder, that correlates with their breeding seasons. Additionally, it was examined whether reproduction is the predominant motivation of the shoals of fish that ascend the ladder. Samples were taken monthly from November, 2002 through October, 2003, downriver from the dam with gillnets, and in the resting pools of the fish ladder with cast nets. The analysis of seasonality in the aggregation of the shoals was based on the temporal variations in abundance and species richness. The possibility of a reproductive motivation for ascending the ladder was inferred from the frequency of the stages of gonadal development. However, during the entire study period we observed a high frequency of individuals with gonads in the pre-vitellogenic stage for all analyzed species, both downriver from the dam (97%) and in the fish ladder (98%). These findings suggest that there was no reproductive motivation for the aggregation of the fish downstream and for their entry into the ladder. On the other hand, the dominance of these stages downriver suggests that the spawning habitats are distant, and that the upstream movements occur for other reasons such as dispersal and search for more appropriate habitats for feeding and growth. The entrance into the ladder resulted more from rheophilic behavior, which is more pronounced in migratory species, than from an endogenous motivation linked to reproductive migration.
publishDate 2007
dc.date.none.fl_str_mv 2007-01-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
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dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252007000200010
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dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.1590/S1679-62252007000200010
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
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dc.publisher.none.fl_str_mv Sociedade Brasileira de Ictiologia
publisher.none.fl_str_mv Sociedade Brasileira de Ictiologia
dc.source.none.fl_str_mv Neotropical Ichthyology v.5 n.2 2007
reponame:Neotropical ichthyology (Online)
instname:Sociedade Brasileira de Ictiologia (SBI)
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collection Neotropical ichthyology (Online)
repository.name.fl_str_mv Neotropical ichthyology (Online) - Sociedade Brasileira de Ictiologia (SBI)
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