Frontiers in Marine Science (Oct 2015)
Preliminary results on the biology of the European eel (Anguilla anguilla) in the European Southern tip
Abstract
In the context of the European Eel Recovery Plan, managers need confident biological information based on its own geographical areas. In the specific case of Andalusia (Southern Spain), we are developing a capture-recapture experiment based in the use of PIT-tags in order to obtain information that we lack for the species in the study area. In this communication, we focus on the biology of the species. Firstly, we carried out an ex-situ experiment to check the effect of the PIT-tag on the individuals of the eel. Once we ascertained there were no significant effects in the survival, length, and weight of the marked eels, we proceeded with the study in situ (Guadiaro river). Between October 2014 and July 2015 we captured 1011 eels (539 tagged; 252 recaptured). Approximately 90% of their lengths were between 16-40 cm (minimum 16.3 cm; maximum 67 cm). Eel’s length in March, April and May was significantly lower than those captured in the rest of months, probably because longer eels migrated before spring and only small eels remained in the population. More than 90% of the eels captured in all months were resident, and the higher proportions of migrants were detected in October 2014, November 2014 and July 2015. Mean lengths registered per maturation stage were notably lower than those found in other populations. The growth values showed in this population were higher in autumn (0.195 mm/day) than in winter (0.091 mm/day) and summer (0.096 mm/day), and residual condition factor showed normal values in comparison with other populations with minimum values in autumn.
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