Glass Eel Recruitment Dynamics in a Southern Europe Estuary (Oria, Spain), 2003-2012

The spatio-temporal migration patterns of European glass eel were studied in a long-standing tradition glass eel fishery estuary, the Oria. Catch logbooks were collected during nine fishing seasons (2003-2012) and fishery-independent experimental surveys were carried out at two sampling points during the fishing season from 2005 to 2012.  Environmental local variables potentially related to glass eel recruitment were recorded during the whole study period. Glass eel used the tidal front to move. At the river mouth, migration started in the deep layers coinciding with the salinity increase. Upstream, as the water was mixed, glass eel were distributed along the whole water column and migration started with current rise. Although a high daily variability was found in glass eel abundance, the general trends showed different behavior along the fishing season in the sampling points: a significant density decrease in the river mouth and an increase upstream. Statistical analysis of the relationship between environmental variables and glass eel density variability is being carried out.