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Spawning migration of American eel Anguilla rostrata from pristine (1843–1872) to contemporary (1963–1990) periods in the St Lawrence Estuary, Canada

Authors

  • G. Verreault,

    Corresponding author
    1. Ministère des Ressources Naturelles et de la Faune du Québec, 186 rue Fraser, Rivière-du-Loup, Québec, G5R 1C8 Canada
      Tel.: +1 418 862 8213 ext. 306; email: guy.verreault@mrnf.gouv.qc.ca
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  • M. Mingelbier,

    1. Ministère des Ressources Naturelles et de la Faune du Québec, 880 chemin Ste-Foy, Québec, G1S 4X4 Canada
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  • P. Dumont

    1. Ministère des Ressources Naturelles et de la Faune du Québec, 201 Place Charles-LeMoyne, Longueuil, Québec, J4K 2T5 Canada
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Tel.: +1 418 862 8213 ext. 306; email: guy.verreault@mrnf.gouv.qc.ca

Abstract

Daily American eel Anguilla rostrata catches and their dates of passage (starting, median and ending dates) were compared between pristine (1843–1872) and contemporary periods (1963–1990) to determine any changes and see whether these were related to environmental variations and water discharge regulation. Timing and duration of A. rostrata migration patterns differed significantly between the two periods. In the contemporary period, migrating A. rostrata were intercepted significantly earlier than in pristine times (18 days earlier on average), and ended at the same average period. Early A. rostrata migration was also significantly related to high spring flow and secondarily to high spring temperature, while migration ended later when high temperature or low water level occurred during the autumn period. A recent slight increase in the water temperature of the St Lawrence River could partially explain the earlier A. rostrata migration observed during the contemporary period. In return, the effect of high spring flow should have been more contrasted if the river discharge would have not been regulated. Recent A. rostrata production now being mainly restricted to the lower part of St Lawrence River mainstream, resulting shorter travelling distance to the estuary may explain why migrating progress was earlier during the contemporary period.

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