Comparative study of reproductive biology in single- and multiple-spawner cyprinid fish. I. Morphological and histological features

Authors

  • J. Rinchard,

    Corresponding author
    1. Unité d'Ecologie des Eaux Douces, Facultés Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur, Belgium
      Tel.: +32 81724363; fax: +32 81724420.
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  • P. Kestemont

    Corresponding author
    1. Unité d'Ecologie des Eaux Douces, Facultés Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur, Belgium
      Tel.: +32 81724363; fax: +32 81724420.
    Search for more papers by this author

Tel.: +32 81724363; fax: +32 81724420.

Abstract

To clarify the dynamics and regulation of oogenesis in single- and multiple-spawning cyprinid fish with group-synchronous oocyte development, a multidisciplinary approach to their reproduction was undertaken using three species from the River Meuse (Belgium): the roach Rutilus rutilus as a single spawner, and the bleak Alburnus alburnus and the white bream Blicca bjoerkna as multiple spawners. The gonadosomatic index (GSI) and histomorphometric changes (distribution of oocyte size, relative proportion of the various oocyte stages) in the ovary are compared. Different patterns of GSI and oocyte growth were observed both between the single- and multiple-spawner fish and between the two multiple spawners. Maximum GSIs were higher in roach (21%) than in bleak and white bream (17.7 and 14.5%, respectively), and compared to the rapid decline of GSI in the roach population, the GSI of multiple spawners decreased progressively during the spawning season. In roach, a short gonadal quiescent period and an early onset of vitellogenesis was recorded from late summer onwards whereas, in bleak and white bream, exogenous vitellogenesis was not systematically observed before winter. A protracted spawning season and/or a low water temperature in autumn are hypothesized to explain this long period of gonadal quiescence. In bleak, during the spawning season, the oocytes recruited arose from the stock of endogenous vitellogenesis and attained the final maturation stage very rapidly. This recruitment occurred during the whole spawning season. In white bream, the differentiation of vitellogenic oocytes from smaller oocytes was completed before the onset of the spawning season. During the spawning period, the proportion of vitellogenic oocytes decreased progressively whereas the percentage of oocytes in the final maturation stage remained approximately constant.

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