Abundances and biological traits of the juveniles salmon sampled in the survey of Salmon abundance Indices in the Nivelle river (France)

A survey started in 2003 is conducted every year in early autumn (late
September to early October) to quantify the abundance of juvenile
Atlantic salmon in the Nivelle in Pays Basque. The electric fishing
protocol of Prévost and Baglinière (1995) is used. It targets Atlantic
salmon young of the year (0+ parr), but older fish (juvenile salmon
≥1+) are also caught and included in this dataset. Sampling is
restricted to areas with shallow running water flowing on coarse
bottom substrate, i.e. the preferred habitat of young of the year
salmon. The data consist of abundance indices and biological traits
measured on the fish sampled: sex, maturity status, 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.