Sea lamprey (Petromyzon marinus L.) spawning migration in the Vouga river basin (Portugal): poaching impact, preferential resting sites and spawning grounds

• Type: Article in International Scientific Journal
• Date: 2007

Authors

Andrade, NO (Author) Other; Quintella, BR (Author) Other; Ferreira, J (Author) Other; Pinela, S (Author) Other; Posova, I (Author) Other; Pedro, S (Author) Other; Pedro Almeida (Author) Other

Journal

Title: Hydrobiologia

Vol. 582

Pages: 121-132

ISSN: 0018-8158

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 30 Citations

Scopus - 40 Citations

Other information

Authenticus ID: P-004-A97

DOI: 10.1007/s10750-006-0540-2

Abstract (EN): Historical spawning grounds for sea lampreys (Petromyzon marinus L.) in most Portuguese river basins are becoming inaccessible due to the construction of impassable dams and/or weirs. Studies like the one described in this paper are particularly important in areas like the Vouga river basin, where there is a considerable fishing effort from both professional fishermen and poachers. In fact, for management and conservation purposes, it is important to clarify several aspects of the sea lamprey spawning run in this particular watershed. Therefore, a total of 30 radio tagged, migrating sea lampreys were released in the River Vouga and some of its main tributaries during 2004 and 2005. Results from the tracking sessions were used to determine the effect of poaching on the spawners' population and the characteristics of the resting sites used during the upstream movement. The rivers' stretches were also characterized according to the type of substrate present in the riverbed and flow type, in order to determine its aptitude to constitute appropriate spawning habitats for sea lampreys. We have identified in the upstream stretches of River Vouga, and in the tributary River Caima, characteristics that are particularly suitable for the construction of nests by the spawners. Presence of larvae provided evidence that spawners migrated into the River Vouga's upper reaches. However, abundance and age class diversity appeared to be higher downstream of Sernada and Carvoeiro weirs, corroborating the telemetry data which suggested difficulty in passing these obstacles during low precipitation years. In the River Caima, migration was most predictable, which might be related to daily water releases from a small hydropower dam at dusk, that stimulated the lampreys to resume migration. Poaching has had a considerable negative effect on the success of the tagged lampreys' migration: 76% of the animals released during 2005 were captured.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12