Neuroendocrinologie de la reproduction de l'Anguille : de la recherche fondamentale aux problèmes appliqués

Dufour, Sylvie

doi:10.1051/kmae:1994013

Cited by 22 publications

(9 citation statements)

References 23 publications

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“…Our method, which aims at quickly identifying in the field a silver eel ready to migrate, in a standard way and without sacrificing fish, is based on the analysis of three standard macroscopic criteria which constitute adaptations to migration in the deep sea. At the term of their continental phase, the silver eel Gonado-Somatic Index does never exceed 2 % (Fontaine 1994, Marchelidon et al 1999, Acou et al 2003 whereas it can attain 80 % under experimental conditions simulating hydrostatic pressure conditions of the Sargasso Sea spawning site (Dufour 1994). Thus, silver eels are not able to reproduce at the end of their life in fresh waters, and they can be said to be "subadult" individuals that have already undergone a series of adaptations.…”

Section: Discussionmentioning

confidence: 98%

Towards a standardized characterization of the potentially migrating silver European eel (Anguilla anguilla, L.)

Acou¹,

Boury²,

Laffaille³

et al. 2005

archiv_hydrobiologie

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We defined a standardized method for discriminating candidate silver eels that may undergo catadromous migration in the following season from the sedentary fraction of a population. A combination of two qualitative criteria (state of differentiation of the lateral line and colour contrast) and one quantitative criterion (Ocular Index OI) was used to determine the development toward silvering. In the non-migratory phase, we found a gradient of the three criteria between yellow (0 criterion), presilver (1 to 2 criteria) and silver (3 criteria) eels. In the migrant phase, silver eels had ended their metamorphosis process and were characterized at the same time by the presence of the 3 silvering criteria. A mark-recapture survey using PIT-tags provided evidence that only identified silver eels (3 silvering criteria present) in the catchment actually emigrated the following season. Moreover, the use of a single criterion of silvering among the three generated large variation in the estimated proportion of candidates for emigration which varied between-22 % and + 63 %. Such a result confirmed that a multicriteria approach is needed to characterize in a standard way the potentially migrating silver eel.

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Section: Discussionmentioning

confidence: 98%

Towards a standardized characterization of the potentially migrating silver European eel (Anguilla anguilla, L.)

Acou¹,

Boury²,

Laffaille³

et al. 2005

archiv_hydrobiologie

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“…If we keep these animals in aquarium boxes, there is no further development of the gonad; external environmental triggers for gonad maturation are lacking. Dufour (1994) demonstrated, a prepubertal neuroendocrine blockage in the European eel at in the silver stage. Gonadotropin-releasing hormone (GnRH) in the pituitary is deficient in this blockage, and an inhibition by dopamine was found (Dufour 1994).…”

Section: Maturation Of European Eel By Environmental Factorsmentioning

confidence: 94%

“…Dufour (1994) demonstrated, a prepubertal neuroendocrine blockage in the European eel at in the silver stage. Gonadotropin-releasing hormone (GnRH) in the pituitary is deficient in this blockage, and an inhibition by dopamine was found (Dufour 1994). Both factors are responsible for the lack of production of gonadotropin (GTH) by the pituitary and a blockage in the release of GTH resulting in immature gonads.…”

Section: Maturation Of European Eel By Environmental Factorsmentioning

confidence: 94%

The European eel (Anguilla anguilla, Linnaeus), its Lifecycle, Evolution and Reproduction: A Literature Review

Ginneken¹,

Maes

2005

Rev Fish Biol Fisheries

271

241

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“…It has recently been demonstrated, in European eels in the silver stage, that there is a prepubertal blockage of gonadal maturation at the neuroendocrine level because of a deficiency of gonadotropinreleasing hormone (GnRH) at the level of the pituitary, resulting in a lack of production of gonadotropin (GTH). Furthermore, there is an inhibition of GTH release by dopamine (Dufour, 1994). Both factors are responsible for an immature gonad.…”

Section: Introductionmentioning

confidence: 99%

Gonad development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.)

Ginneken

Vianen²,

Muusze³

et al. 2005

Animal Biol

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Gonadal development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.) was studied. Treatment of males with Human Chorionic Gonadotropin (HCG; 1 IU g/week) resulted in a Gonado-Somatic Index (GSI) of 10.88 ± 3.39 and spermiation. Treatment of females with carp Pituitary suspension (cPs) (20 mg cPs/kg body weight per week) resulted in oogenesis with a GSI of 20.0 ± 11.3 (n = 7), and the number of eggs per female was 1874 * 10 3 ± 1116 * 10 3 ; (n = 7). Ovulation of the females was induced with 17α, 20β dihydroxyprogesteron (DHP) at 2 µg/g bodyweight. Eggs of European eel were found to be non-sticky and typically pelagic. Maximum speed of eggs rising to the surface in a water column was 2.24 ± 0.33 metres (m) per hour (h). To study behaviour in a qualitative way, two females were used together with three groups of three males. During a 283 minute (min) observation of the two females, we observed female-female interaction: 'lethargic behaviour' (33.6%) vs. 'cruising together' (66.4%). In the period when males and females were together (188 min), we observed 'approaching the head region of the female' (57.7%), 'touching the operculum' (39.4%), or 'approaching the urogenital area' (2.9%) by the males (total 725 seconds (s)). Sperm release in the presence of a female took 115 s of the total approaching time of 725 s (15.9%), while in the case of male-male interaction this was only 15 s of the total period of 116 s (12.9%). Induced spawning behaviour of eels was collective and simultaneous, corresponding to spawning in a group. This is the first time group spawning behaviour has ever been observed and recorded in eels.

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Neuroendocrinologie de la reproduction de l'Anguille : de la recherche fondamentale aux problèmes appliqués

Cited by 22 publications

References 23 publications

Towards a standardized characterization of the potentially migrating silver European eel (Anguilla anguilla, L.)

Towards a standardized characterization of the potentially migrating silver European eel (Anguilla anguilla, L.)

The European eel (Anguilla anguilla, Linnaeus), its Lifecycle, Evolution and Reproduction: A Literature Review

Gonad development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.)

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