Food is one of the most important items in fish culture economy. Juvenile fish prove the fastest growth rates and that is the reason why their appropriate nourishment is so important. Surface drift of terrestrial insects provides an excellent food for rheophilic fish species . Reophilic fishes are able to utilise also plants and particularly algae too. Terrestrial insects can be attracted to water surface by various ways. Is it a light trap during the night. The installation of colour traps is another possibility of insect enticement, for example when located several centimetres bellow the water. We can use various coloured traps {--} yellow, red, blue and other. Light is very attractive for night insects, killing them by electricity. Insects which fall down to water provide an excellent complementary food sources. The experiments were performed with young chub (Leuciscus cephalus). Coloured traps (yellow and red), raffia mats supproting algal growth and electric insect killer were tested. No-trap tanks served as a control. The experiment was run for two growing seasons.. As compared to control, the variants provided with coloured traps proved significantly better results regarding fish growth and condition. However, the best results were achieved using the light trap. Basing on the study results, it can be concluded, that the traps can contribute to successful breeding of juveniles of reophilic fish.

Streams are important habitats, providing shelter and feeding opportunities for a wide range of organisms. The species depending on running waters includes a wide array of fish species, using these waters for their whole or parts of their lifecycle. Streams are also the subject of different anthropogenic impact, e.g. hydropower development. Hydropower development usually means lost connectivity, altered flow regimes and channelization. Channelization is one of the major factors causing stream habitat loss and degradation and thereby a threat to biodiversity of running waters. In the present study, the ecological impact of channelization on the fish fauna along a gradient of channelization severeness was examined. Besides channelization, stream velocity and depth were taken in to account. The study was carried out in two adjacent nemoboreal streams, Gavleån and Testeboån. The study was conducted between the 6th of June and the 10th of October 2012 at 15 sites. Sites were selected using historical maps and field observations and graded 0-3 depending on the degree of channelization. Fish community were sampled with, Nordic multi-mesh Stream Survey Net (NSSN). In all, 1.465 fish were captured, representing 15 species and seven families. The sites differed in species richness, abundance and proportion of individuals. Based on the results from rarefaction curves and ANOVA, channelization was found to be the main factor affecting the fish biota, both in abundance as well as species richness and composition. In general the rheophilic species declined along the gradient of increasing channelization severeness, while limnophilic species increased

Orientador: Sergio Ricardo Batlouni / Banca: Renata Guimarães Moreira / Banca: Irene Bastos Franceschini Vicentini / Resumo: O desenvolvimento de técnicas para indução à reprodução de peixes migradores (espécies reofílicas) de água doce possibilitou uma produção consistente de larvas destas espécies, embora, seja comum deparar-se com relatos de produtores sobre fêmeas que não ovulam adequadamente ou simplesmente não ovulam após os procedimentos de desova induzida. Algumas evidências sugerem que a origem deste problema pode estar ligada ao manejo inapropriado das matrizes. Infelizmente pouco se sabe sobre o manejo correto de reprodutores de peixes reofílicos em cativeiro. Deste modo, a proposta deste estudo foi avaliar comparativamente o processo de desenvolvimento ovocitário de reprodutores de Prochilodus lineatus mantidos em dois sistemas de criação: viveiros escavados (VE) e tanques rede (TR), seguindo as densidades de 1 peixe.m2 e 17 peixes.m3 respectivamente. A escolha do TR se deu por ser um sistema que simula experimentalmente muitas das condições inapropriadas de manejo empregadas em diversas pisciculturas, tais como: elevadas densidades de estocagem e água de má qualidade. A cada dois meses foram feitas amostragens de 30 animais de cada tratamento, de onde 5 fêmeas foram escolhidas ao acaso e sacrificadas para remoção das gônadas, fígado e vísceras para determinação dos índices gonado (IGS), hepato e viscero-somático, fator K, e para as análises histomorfométricas dos ovários. Amostras de sangue foram coletadas para a determinação da variação anual dos níveis de esteróides gonadais (estradiol e 17-alfa-hidroxiprogesterona)... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The development of techniques of induced breeding of South American migratory fresh water fish (rheophilic species) has enabled a consistent production of fingerlings of these species, however nowadays it is very common to come across reports of fingerling producers about females that do not ovulate properly or just do not ovulate. In this context, some evidences suggest that the origin of such problem may be an inappropriate broodstock management. Unfortunately few is known about the proper management of migratory breeders in captivity, thus the main purpose of this study was to evaluate, comparatively, the process of oocyte production in Prochilodus lineatus breeders kept into two distinct production systems: earthen ponds (EP) and cages (C), with the following stocking densities 1fish.m2 and 17fish.m3 respectively. The reasons for the choice of C was because this system shares a number of inappropriate characteristics employed in diverse fish farms, such as high stocking densities and poor water quality. Every two months thirty specimens of one of the EP and C unities were randomly collected for biometric analysis. After that, five specimens of each treatment were randomly chosen to be sacrificed for removal of gonads, liver and viscera for determination of gonadosomatic index (GSI), hepato-and viscero-somatic indexes, K factor, and also for the histomorphometric analysis of the ovaries. Blood samples were also collected for determining the annual variation in plasma gonadal steroids levels (stradiol and 17 alpha-hydroxyprogesterone).The results showed that the process of ovarian maturation is completely compromised in females kept in C, with significant 30 reduction in the volume of vitellogenic oocytes, estradiol, hydroxyprogesterone, and consequently in the GSI values. Besides the reproductive period is shortened and starts late in relation to that of females of VE... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:22:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-21Bitstream added on 2014-06-13T19:27:40Z : No. of bitstreams: 1 hainfellner_p_me_jabo.pdf: 1559702 bytes, checksum: 8fd03c9d0af341bc6a7cf1927ef7d4a9 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O desenvolvimento de técnicas para indução à reprodução de peixes migradores (espécies reofílicas) de água doce possibilitou uma produção consistente de larvas destas espécies, embora, seja comum deparar-se com relatos de produtores sobre fêmeas que não ovulam adequadamente ou simplesmente não ovulam após os procedimentos de desova induzida. Algumas evidências sugerem que a origem deste problema pode estar ligada ao manejo inapropriado das matrizes. Infelizmente pouco se sabe sobre o manejo correto de reprodutores de peixes reofílicos em cativeiro. Deste modo, a proposta deste estudo foi avaliar comparativamente o processo de desenvolvimento ovocitário de reprodutores de Prochilodus lineatus mantidos em dois sistemas de criação: viveiros escavados (VE) e tanques rede (TR), seguindo as densidades de 1 peixe.m2 e 17 peixes.m3 respectivamente. A escolha do TR se deu por ser um sistema que simula experimentalmente muitas das condições inapropriadas de manejo empregadas em diversas pisciculturas, tais como: elevadas densidades de estocagem e água de má qualidade. A cada dois meses foram feitas amostragens de 30 animais de cada tratamento, de onde 5 fêmeas foram escolhidas ao acaso e sacrificadas para remoção das gônadas, fígado e vísceras para determinação dos índices gonado (IGS), hepato e viscero-somático, fator K, e para as análises histomorfométricas dos ovários. Amostras de sangue foram coletadas para a determinação da variação anual dos níveis de esteróides gonadais (estradiol e 17-alfa-hidroxiprogesterona)... / The development of techniques of induced breeding of South American migratory fresh water fish (rheophilic species) has enabled a consistent production of fingerlings of these species, however nowadays it is very common to come across reports of fingerling producers about females that do not ovulate properly or just do not ovulate. In this context, some evidences suggest that the origin of such problem may be an inappropriate broodstock management. Unfortunately few is known about the proper management of migratory breeders in captivity, thus the main purpose of this study was to evaluate, comparatively, the process of oocyte production in Prochilodus lineatus breeders kept into two distinct production systems: earthen ponds (EP) and cages (C), with the following stocking densities 1fish.m2 and 17fish.m3 respectively. The reasons for the choice of C was because this system shares a number of inappropriate characteristics employed in diverse fish farms, such as high stocking densities and poor water quality. Every two months thirty specimens of one of the EP and C unities were randomly collected for biometric analysis. After that, five specimens of each treatment were randomly chosen to be sacrificed for removal of gonads, liver and viscera for determination of gonadosomatic index (GSI), hepato-and viscero-somatic indexes, K factor, and also for the histomorphometric analysis of the ovaries. Blood samples were also collected for determining the annual variation in plasma gonadal steroids levels (stradiol and 17 alpha-hydroxyprogesterone).The results showed that the process of ovarian maturation is completely compromised in females kept in C, with significant 30 reduction in the volume of vitellogenic oocytes, estradiol, hydroxyprogesterone, and consequently in the GSI values. Besides the reproductive period is shortened and starts late in relation to that of females of VE... (Complete abstract click electronic access below)