Evidence of environmental effects on reproductive characteristics of Nile tilipia (Oreochromis niloticus) populations from man-made lakes of Ivory Coast

La comparaison des caractéristiques de reproduction des femelles #Oreochromis niloticus$ dans neuf petits barrages de Côte-d'Ivoire a révélé d'importantes différences entre les populations. Ces différences pouvaient être dues à une adaptation rapide des poissons à leur environnement ou à un processus évolutif plus long. Afin de le vérifier, des poissons de deux des populations présentant les paramètres de reproduction les plus différents ont été capturés vivants et placés dans un environnement commun en situation d'élevage. L'analyse génétique des poissons des deux populations, réalisée en utilisant quatre marqueurs microsatellites, a révélé qu'ils étaient issus d'une même souche ("souche Bouaké"), constituée à partir de géniteurs provenant des bassins du Nil et de la Volta. Après avoir partagé un environnement commun (étang ou aquarium) pendant 5 mois, la fécondité, le poids ovocytaire moyen et la fréquence de ponte des femelles des deux populations, qui étaient significativement différents dans leurs milieux respectifs, ne différaient plus. Ces résultats indiquent que les différences de reproduction observées en milieu naturel entre les deux populations sont principalement le fait de la plasticité phénotypique de l'espèce face à des conditions environnementales différentes. (Résumé d'auteur

Seasonality of reproduction of Piaractus brachypomus in South Bolivia

The reproductive period of Piaractus brachypomus is short in South Bolivia. This area is close to the Southern limit of the species and conditions favourable to its reproduction last for only a few months. In order to increase fry production, we studied the possibility of extending its spawning period in captivity

Upstream dam impacts on gilded catfish Brachyplatystoma rousseauxii (Siluriformes: Pimelodidae) in the Bolivian Amazon

This paper explores the effects of two run-of-river dams (Jirau and Santo Antônio) built in cascade in the middle Madeira River (Brazil) on the interruption of long-distance migration routes of the gilded catfish (Brachyplatystoma rousseauxii). A participative monitoring system was set up to compare capture by commercial fishers approximately 1500 km upstream ofthe dams in Bolivia, before (1998-2007) and after (2015-2017) dam closure. A significant decrease in gilded catfish catches and in catch per unit effort was observed after dam closure, whereas no significant difference in mean weight was found. Back-estimation of age suggests that the few individuals remaining after dam closure in 2009 are a mixture of old homers that returned upstream before dam closure, and residents hatched after dam closure and trapped in the upper Madeira. Unless fishways in the Madeira River dams improve their efficiency, the gilded catfish might become rare and in danger of regional extinction in the upper Madeira basin in the next few years, negatively affecting river fisheries.Fil: Van Damme, Paul A.. Instituto de Investigación Aplicada de Recursos Acuáticos; Bolivia. Universidad Mayor de San Simón; BoliviaFil: Córdova Clavijo, Leslie. Instituto de Investigación Aplicada de Recursos Acuáticos; BoliviaFil: Baigún, Claudio Rafael M.. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Hauser, Marilia. Universidade Federal de Rondônia; Brasil. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; FranciaFil: da Costa Doria, Carolina R.. Centre National de la Recherche Scientifique. Institut de Recherche pour le Développement; Francia. Universidade Federal de Rondônia; BrasilFil: Duponchelle, Fabrice. Universidade Federal de Rondônia; Brasi

PRIMER ESTUDIO DE LA VARIABILIDAD GENÉTICA DE LA ARAHUANA Osteoglossum bicirrhosum (Cuvier, 1829) EN LA REGIÓN LORETO (AMAZONÍA PERUANA)

La arahuana Osteoglossum bicirrhosum es un importante pez ornamental cuyas larvas y alevinos se exportan al mercado asiático. Esta alta demanda genera grandes presiones de pesca sobre sus poblaciones naturales, siendo necesario generar información genética de sus poblaciones que permitan elaborar planes de manejo para la especie. Para ello, diez loci microsatélites fueron analizados para evaluar la variabilidad genética de 299 individuos de arahuana en cinco localidades de la Amazonía peruana. Los resultados del dendrograma de agrupamiento según la distancia de Nei (1978) muestran que las localidades forman tres grupos principales (Bootstrap = 91): Huicungo-El Dorado (Bootstrap = 73), El Estrecho-Huapapa (Bootstrap = 73) y Rimachi. Estas agrupaciones fueron corroboradas por el estimador F , observándose diferenciación st genética no significante únicamente entre las localidades del El Dorado versus Huicungo y El Estrecho versus Huapapa (F = 0,05 y 0,07 respectivamente). Estos resultados muestran también un aislamiento genético por st la distancia en línea recta entre pares de localidades, demostrando una dispersion de los peces preferencialmente por la llanura de inundación y no por el cauce de los ríos

Age and growth of the Amazonian migratory catfish Brachyplatystoma rousseauxii in the Madeira River basin before the construction of dams

The goliath catfish Brachyplatystoma rousseauxii has crucial economical and ecological functions in the Amazon basin. Although its life history characteristics have been studied in the Amazon, there is little information in the Madeira River basin, which holds genetically distinct populations and where dams were recently built. Using fish collected in Bolivia, Brazil and Peru, this study provides a validation of growth rings deposition and details the growth patterns of B. rousseauxii in the Madeira before the dams' construction. Age structure and growth parameters were determined from 497 otolith readings. The species exhibits two growth rings per year and sampled fish were between 0 and 16 years old. In the Brazilian portion of the basin, mainly young individuals below 5 years old were found, whereas older fish (> 5 years) were caught only in the Bolivian and Peruvian stretches, indicating that after migrating upstream to reproduce, adults remain in the headwaters of the Madeira River. Comparing with previous publications, B. rousseauxii had a slower growth and 20 cm lower maximum standard length in the Madeira River than in the Amazon River. This study provides a baseline for future evaluation of changes in population dynamics of the species following dams closure.Santo Antonio Energia (SAE)Universidade Federal de Rondonia (UNIR)Instituto de Estudos e Pesquisas Agroambientais e Organizacoes Sustentaveis (IEPAGRO)CAPES [1402376, 047/2012, 6632/14-9]CNPq [204344/2015-8]Foundation of Support to Research of the Amazon [PAREV/FAPEAM 019/2010]FAPESP (Sao Paulo Research Foundation) [2016/07910-0]Univ Fed Rondonia UNIR, Dept Biol, Lab Ictiol & Pesca, BR 364,Km 9,5, BR-76801059 Porto Velho, RO, BrazilPrograma Posgrad Rede Biodiversidade & Biotechnol, BR 364,Km 9,5, BR-76801059 Porto Velho, RO, BrazilUAGRM, IRD, IIAP, LMI,EDIA, Montpellier, FranceINPA, Av Andre Araujo 2936, BR-69067375 Manaus, AM, BrazilUniv Fed Alagoas UFAL, Av Lourival Melo Mota,S-N Tabuleiro Martins, BR-57072900 Maceio, AL, BrazilUniv Fed Sao Paulo, Rua Doutor Carvalho Mendonca 144, BR-11070100 Santos, SP, BrazilUniv Fed Amazonas, Av Gen Rodrigo Octavio Jordao Ramos 3000, BR-69077000 Manaus, AM, BrazilIIAP, Vv Jose Quinones Km 2-5,Apartado Postal 784, Iquitos, PeruIRD, UMR BOREA, MNHN, CNRS 7208,SU,UCN,UA,IRD 207, Ave Agropolis 911, F-34394 Montpellier, FranceUMSS, ULRA, FAUNAGUA, ECOSINTEGRALES SRL, Ave Max Fernandez Final S-N, Cochabamba, BoliviaECOSINTEGRALES SRL, Res Act, Carlos Muller St 211, Cochabamba, Cercado, BoliviaInst Amazon Invest Cient SINCHI, Ave Vasquez Cobo Entre Calles 15 & 16, Bogota, ColombiaUniv Fed Sao Paulo, Rua Doutor Carvalho Mendonca 144, BR-11070100 Santos, SP, BrazilCAPES [1402376, 047/2012, 6632/14-9]CNPq [204344/2015-8][PAREV/FAPEAM 019/2010]FAPESP [2016/07910-0]Web of Scienc