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Descroix A.,CNRS Microorganisms Laboratory: Genome and Environment | Desvilettes C.,CNRS Microorganisms Laboratory: Genome and Environment | Bec A.,CNRS Microorganisms Laboratory: Genome and Environment | Martin P.,Conservatoire National du Saumon Sauvage | Bourdier G.,CNRS Microorganisms Laboratory: Genome and Environment
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2010

The influence of macroinvertebrate diet on growth and fatty acid profiles of Atlantic salmon (Salmo salar) parr released at the fry stage in three different riffles was studied in a large temperate river (Allier, France). Comparisons were made between sites and between restocked parr and hatchery-reared counterparts fed with a traditional fish diet. Significant differences were observed along the longitudinal gradient of the river and between restocked and hatchery-reared parr. Growth performance and nutritional status were higher in the hatchery and in downstream riffles and low in the most upstream site. These differences appeared to be related to different types of diet and consequently to variations in polar and neutral lipid intakes. The most favorable site for optimum growth appeared to be the intermediary riffle, with values close to those achieved in the hatchery. Simuliids and baetids, preferentially consumed in downstream sites, constitute an interesting type of food, showing quite different fatty acid composition from vegetable oils. This could be of interest for composing a new diet formula for young salmon intended for river restocking, imitating these macroinvertebrate fatty acid profiles. Source


Nisembaum L.G.,CNRS Integrative Biology of Marine Organisms | Besseau L.,University Pierre and Marie Curie | Paulin C.-H.,University Pierre and Marie Curie | Charpantier A.,University Pierre and Marie Curie | And 5 more authors.
Endocrinology | Year: 2015

Photoperiod plays an essential role in the synchronization of metabolism, physiology, and behavior to the cyclic variations of the environment. Invertebrates, information is relayed by the pineal cells and translated intothe nocturnal production of melatonin. The duration of this signal corresponds to the duration of the night. In fish, the pinealocytes are true photoreceptors in which the amplitude of the nocturnal surge is modulated by temperature in a species-dependent manner. Thus, the daily and annual variations in the amplitude and duration of the nocturnal melatonin signal provide information on daily and calendartime. Both light and temperature act on the activity of the penultimate enzyme in the melatonin biosynthesis pathway, the arylalkylamine N-acetyltransferase (serotonin →N-acetylserotonin). Although the mechanisms of the light/dark regulation of melatonin secretion are quite well understood, those of temperature remain unelucidated. More generally, the mechanisms of thermoreception are unknown in ectotherms. Here we provide the first evidence that two thermotransient receptor potential (TRP) channels, TRPV1 and TRPV4, are expressed in the pineal photoreceptor cells of a teleost fish, in which they modulate melatonin secretion in vitro. The effects are temperature dependent, at least for TRPV1. Our data support the idea that the pineal offish is involved in thermoregulation and that the pineal photoreceptors are also thermoreceptors. In other nervous and nonnervous tissues, TRPV1 and TRPV4 display a ubiquitous but quantitatively variable distribution. These results are a fundamental step in the elucidation of the mechanisms of temperature transduction in fish. © 2015 by the Endocrine Society. Source


Martin P.,Conservatoire National du Saumon Sauvage | Rancon J.,Conservatoire National du Saumon Sauvage | Segura G.,Conservatoire National du Saumon Sauvage | Laffont J.,Institute Des Science Of Lingenieur | And 2 more authors.
Aquaculture | Year: 2012

The impacts of photoperiod and temperature on the swimming behaviour of hatchery-reared Atlantic salmon smolts were investigated, with a view to optimising salmon restoration strategies in the Loire-Allier basin. A novel experimental design was developed to study individual tagged fish in 9. m diameter hatchery tanks. Movements and swimming speeds were recorded over a period of eight months (January to August), repeated over four consecutive years (2005-2008). Fish switched from positive rheotactic behavior in January-February, to negative rheotactic behaviour at mid-March or April depending on the year, a period corresponding to the start of the downstream migration of wild smolts from the upper river spawning areas. Daily variation in movement and swimming speed occurred with high swimming speeds with the flow during the day and much lower speeds during the night. Swimming speeds could exceed water current velocity, showing hatchery-reared salmon can actively swim with the flow during the day. Experimental changes of photoperiod (constant light or constant darkness) allowed confirmation of the role of photoperiod in the daily variation of swimming activity. Analysis of the relationship between water temperature and swimming speeds over the four year experiments suggested a major role for water temperature in the modulation of swimming activity. Maximal swimming speed was recorded at 10.5 °C and swimming speed was reduced by 80% for temperatures under 4 or above 17 °C. Fish stopped moving above 20 °C. The data highlight the importance of temperature for the modulation of downstream movement, as well as the potential deleterious impact of the anthropogenic increase in river temperature below the spawning and juvenile habitat in the Allier tributary on the success of downstream migration. Better understanding of temperature effects on actual population-specific in-river migration patterns is required to allow managers to identify mitigation measures needed to improve migration success. © 2011 Elsevier B.V. Source


Grant
Agency: Cordis | Branch: H2020 | Program: MSCA-ITN-ETN | Phase: MSCA-ITN-2014-ETN | Award Amount: 3.87M | Year: 2015

The IMPRESS European Training Network will provide a new generation of researchers with the multidisciplinary skills and competences needed to oversee new stocking strategies for Europes most important and threatened freshwater fish species (Atlantic salmon, European eel and sturgeons) thus enabling conservation and growth in a sector of significant economic and societal importance. Freshwater fish populations bring many benefits to Europes citizens through leisure activities, and enhance rural employment through fishing and tourism. The species included in IMPRESS are sentinel species of clean, healthy freshwater ecosystems and of major historical, cultural and economic importance. Over-exploitation and anthropogenic activities have critically endangered wild populations of these fish groups, especially sturgeons. As the main flaw of past stock enhancement is high post-release mortality, the researcher training in IMPRESS will build upon recent scientific advances, especially in fish genomics and enriched hatchery techniques, to develop innovative production regimes resulting in increased survival rates of released fish. This paradigm shift in stock enhancement strategies will require changes at every level of the production cycle, from broodstock management and gamete quality to hatchery design. New in vitro and -omics technologies will be developed to solve current bottlenecks in the production cycle of sturgeons. IMPRESS will also verse young researchers on the social dimensions of this complex issue, including the need to foster closer dialogue with the important stakeholders responsible for national and regional stocking programmes. Further, through dissemination and public engagement, all IMPRESS fellows will work actively to increase public awareness on the importance of these key fish species to freshwater biodiversity, and on the major societal benefits of healthy fish populations, both for recreational activities and for supporting rural employment.


Imbert H.,French Natural History Museum | Martin P.,Conservatoire National du Saumon Sauvage | Rancon J.,Conservatoire National du Saumon Sauvage | Graffin V.,French Natural History Museum | Dufour S.,French Natural History Museum
Cybium | Year: 2013

Smolts of Atlantic salmon Salmo salar of the Loire-Allier system have to perform an exceptional distance of 900 km to reach the ocean from the upstream spawning grounds, while being subjected to connectivity disruption induced by the presence of dams as well as fluctuating climatic conditions. In order to successfully perform their marine entry, smolts should reach the estuary within a limited suitable period. This study concerns smolt emigration dates from upper Allier, and arrival dates in the Estuary, as well as estimation by radio tracking of downstream migration speed. Comparison of these data revealed that a significant fraction of smolts from upper Allier leave breeding areas too late for successful marine entry. This delay may be partly induced by dam retention. We emphasize the importance of the clearing of the Poutès dam planed in 2015 and recommend to pursue and extend the current survey with additional monitoring stations along the migration axis, in order to study the fate of late migrants. These studies have major implications for the restoration of the threatened population of the Loire salmon. © SFI. Source

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