Δυναμική της μετανάστευσης των νεαρών σταδίων του χελιού (Anguilla anguilla, L. 1758) στα εσωτερικά νερά της δυτικής Ελλάδας και η αλιευτική του εκμετάλλευση

• Main Authors: Zompola, Spyridoula, Ζόμπολα, Σπυριδούλα
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: University of Patras 2008
• Subjects: Ευρωπαϊκό χέλι; Γυαλόχελο; Δυναμική μετανάστευσης; Περιβαλλοντικές παράμετροι; Βιομετρία; Χρωματικά στάδια; Αλιευτική παραγωγή; European eel; Glass eel; Migration dynamics; Environmental factors; Biometrics; Pigmentation stages; Fisheries production; Φυσικές Επιστήμες; Βιολογία; Natural Sciences; Biological Sciences; Anguilla anguilla
• Online Access: http://hdl.handle.net/10442/hedi/17794; https://doi.org/10.12681/eadd/17794

In Greece, despite the economic importance of the European eel (Anguilla anguilla), the available biological data are scarce and limited. The aim of the present study is to analyze the current eel exploitation status as well as the glass eel migration dynamics in Greek inland waters in an area close to the eastern limit of the species geographical distribution. Towards this aim, eel production data were gathered from all official Greek authorities. Analysis of these data showed that the existing time series are insufficient, heterogeneous and usually contradicting. The exploitation pattern showed a pronounced regional character with great heterogeneity. The Greek eel fishery is mainly based on silver eel stage and showed a clear temporal pattern (November-February). A significant decrease in eel production was observed in the 80’s. In order to study the glass eel entrance in Greek inland waters as well as their biological characteristics, experimental fishing was carried out in two sites (Sagiada marsh and Alfios river - western Greece) from 1998 to 2000 and from 2001 to 2002. The main period of the glass eel entrance was from December to March and the migration pattern was similar to those observed along the Atlantic coast of southwestern Europe, despite the greater distance of Greek coast from the suggested spawning grounds. However, the temporal pattern was characterized by short term fluctuations. The majority of the catches were recorded from mid November until late March in Sagiada, while in Alfios about one month later, from mid December to mid April. These differences were attributed to the specific local environmental parameters. The data analysis showed that glass eel short-term freshwater migration consisted of waves with periods from 5 to 40 days and was correlated with environmental factors such as water temperature, atmospheric pressure, rainfall and moonlight. The present results showed that glass eel size (mean length: 6.02 cm±0.34 and mean weight: 0.19 g±0.05) was smaller compared to those ...