A survey started in 2006 is conducted every year in early autumn (late September to early October) to quantify the abundance of juvenile trout in the Oir river in Normandy. The electric fishing protocol VIGITUITE® is used. It targets trout young of the year (0+ parr), but older fish (juvenile ≥1+) are also caught and included in this dataset. The data consist of abundance indices and biological traits measured on the fish sampled: sex, length, weight and age. The latter is ascertained from scale samples taken from the fish which size does not allow to determine their age unambiguously. The survey is carried out under the Research Observatory on Diadromes Fishes in Coastal Streamss (ERO DiaPFC) program. The data are stored in the database of the ERO. They are used to develop predictive models and tools for providing scientific advice to improve the management of this heritage species.
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Occurrence; Observation; population density; trout; Salmo trutta; Population distribution; Catch effort; Occurrence
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The Oir river in Normandy (France). http://services.sandre.eaufrance.fr/Courdo/Fiche/client/fiche_courdo.php?CdSandre=I9280600
|Bounding Coordinates||South West [48.599, -1.295], North East [48.685, -1.099]|
No Description available
|Species||Salmo trutta (Truite, trout)|
|Start Date / End Date||2006-09-19 / 2021-09-14|
The Research Observatory on Diadromous Fish in Coastal Streams (ORE DiaPFC) is a research infrastructure steered by INRA in partnership with AFB and part of the AFB-INRA R&D center. It’s focused on the study of the evolution of diadromous fish populations under the influence human induced environmental changes that affect these rivers (mainly climate and effects of agriculture). Diadromous species of primary interest are salmon (Salmo salar), trout (Salmo trutta), eel (Anguilla Anguilla), shads (Alosa sp.), and lampreys (Lampetra sp. and Petromyzon marinus). These species are threatened by the consequences of human activities. They are flagship species for the biodiversity of coastal streams. Nowadays, these streams are the main refuges for diadromous fish that have disappeared or dramatically declined on larger rivers. This ERO DiaPFC is a Research Infrastructure based on four coastal streams of the Atlantic and Channel coast of France: the Bresle and the Oir in Normandy, the Scorff in Brittany and the Nivelle in the Pays Basque. These four rivers are equipped with diadromous fish trapping facilities and are thoroughly and continuously surveyed from the mid 1980s. They are twinned with experimental ecology facilities located in Rennes (Brittany) and Saint-Pée-sur-Nivelle (Pays Basque). This set of facilities is complemented by individual-based eco-genetic simulators for in silico experimentation on virtual populations.
|Title||ORE-DiaPFC Observatoire de Recherche en Environnement des poissons diadromes sur les Petits Fleuves Côtiers - ERO DiaPFC Ecological Research Observatory on Diadromous Fish in coastal streams|
|Funding||INRAE : French National Institute for Agricultural, Food en Environment Research - OFB : French Office for Biodiversity.|
|Study Area Description||ERO DiaPFC is a Research Infrastructure based on four coastal streams of the Atlantic and Channel coast of France: the Bresle and the Bresle and Oir in Normandy, the Scorff in Brittany and the Nivelle in the Pays Basque|
|Design Description||The issue of 'Research Observatory on Diadromes Fish in Coastal Rivers (ORE DiaPFC) is to study the evolution of diadromous fish populations as a result of environmental changes (climate change and changes related to agriculture ) that affect these rivers.|
The personnel involved in the project:
In the Oir, sampling is conducted at 2 sites spread along the mainstem and other in tributaries. The sites are visited once a year at the beginning of autumn (end of September to early October).
|Study Extent||Oir river, CdSandre=I9280600 Latitude between 48.6840 and 48.5985; longitude between -1.2949 and -1. 0994 Source latitude and longitude : 48.6667 -1.1138 Last confluence point latitude and longitude : 48.6305 -1.2943 Oir river is located at the southern edge of Normandy. It is a tributary of the Sélune, a coastal stream flowing into the Bay of Mont Saint-Michel. The Oir is 21 km long, and has an average gradient of 11 ‰. Its drainage area is 87 km², dominated by sedimentary schist land and corneal including some granitic enclaves. The water pH is near neutral and of reasonably good quality but with high nitrate concentrations. Human activities and land use are mainly from agriculture. The upper Sélune is not accessible to migratory fish. They are blocked at fifteen kilometers from the sea by a dam. The Oir, with 12 km accessible to Atlantic salmon, is the main spawning and most productive tributary of the Sélune hydrographic network.|
Method step description:
- At the selected station, the VIGITRUITE® protocol was designed to ensure that sampling is representative of the range of available habitat conditions, without any a priori bias towards the habitat preferences of the species. This condition is central to meet the objective of standardization, to allow comparison of results from different operators and different watercourses, and to authorize the use of density conversion abacuses per 100 m2. 1. After resetting the counter of the fishing tackle and the hand meter, the operator progresses from downstream to upstream in the watercourse. He is followed by the main operator equipped with the 2 landing nets, who must respect the travel instructions given to him by the operator, as well as by the second operator. 2. The operator follows a predefined zigzag path that takes him from one bank to the other along successive diagonals, at an angle of about 45° to the banks. Along its path, it makes electrode lines about 2 meters long, parallel to the current, and from upstream to downstream. After making the first line along the bank, the operator must visualise the next line before moving: it will be placed on the diagonal, its downstream limit always upstream of the previous line. At the end of the diagonal, if the space is too short for a line along the bank, the line will be placed on the next diagonal, always upstream of the previous line to avoid overlapping. 3. Once the location of the haul has been visualised, the operator indicates to the main fisher where to immerse his semi-circular net, i.e. upstream of the previous haul and offset on the diagonal. The fisher makes sure that the net is well placed on the bottom. If there is any difficulty in placing the net, the operator may decide to shift the position of the haul significantly. The haul is made, then the position of the next haul is displayed, and so on. The result is a sampling by regularly spaced tows from one bank to the other, covering a line of comparable watercourses regardless of the water width of the river. The two stakes marking the downstream and upstream boundaries of the fishing station are also set. 4. For each haul, the operator immerses the electrode about 2 metres upstream of the flat-bottomed landing net. The contact is made when the anode penetrates the water. The fisherman catches the visible fish with his small net, but does not move the large one. The second operator is ready to intervene in case of high abundance. During this operation, it is important that the fishermen catch only the juveniles of the year (0+) and of one year (1+). The presence of larger and older individuals (sub-adults or adults) must not cause a decrease in the team's concentration of juveniles. The hand-held competitor is incremented by one unit at the end of each haul. 5. At the end of the haul, the operator shall leave the anode at the entrance of the large landing net for 1 to 2 seconds before switching off the ignition and instructing the angler to simultaneously raise the flat-bottomed net. The haul made is counted by the hand-counter operated by the bucket holder. Once the collected fish are put in the bucket, the angler follows the operator's instructions to put the large net back in place for the next haul. 6. As the five minutes of fishing approaches, the time counter should be checked before each new haul. Station sampling shall be completed when the effective fishing time (cumulative time of electrical pulses in the water) reaches at least 5 minutes on the counter; no new electrode tows shall be started if the counter already displays 5 minutes. 7. Using the decameter, the width at the downstream stake is measured and its value noted. Then a new width measurement is made by progressing 10 meters upstream, and so on until the end of the station is approached. If necessary, the remaining distance to the upstream post (less than 10 m) is measured to complete the length measurement of the station. This work Biometric measurement of the fish are recorded after their anesthesia with benzocaïne. The fish length is measured from the tip of the mouth to the fork of the caudal fin (1 millimeter precision). Fish are then weighed (0.2 g precision) and maturity status is assessed by a gentle pressure on the belly that allows to get sperm in mature males. All the fish sampled are then released in their original site.
- Age is verified from scale reading according to standard methods described by (Baglinière and Le Louarn, 1987) and (Richard and Bagliniere, 1990).
- Roussel, Jean-Marc, et Dominique Huteau. « Mise au point et validation d’une méthode simple pour estimer l’abondance des juvéniles de truite en cours d’eau ». Rapport de recherche, 2004.
This data set is intended to be updated annually
|Purpose||Monitoring of juvenile recruitment in trout on the Oir river|