Climate-induced year-class fluctuations of whitemouth croaker Micropogonias furnieri (Pisces, Sciaenidae) in the Río de la Plata estuary, Argentina–Uruguay

Authors

  • E. M. ACHA,

    Corresponding author
    1. Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Paseo V, Ocampo Nº1, CC 175, (B7602HSA) Mar del Plata, Argentina
    2. Instituto de Investigaciones Marinas y Costeras (IIMyC), FCEyN, CONICET-Universidad Nacional de Mar del Plata, Dean Funes 3350, (B7602AYL) Mar del Plata, Argentina
    3. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, (C1033AAJ) Ciudad Autónoma de Buenos Aires, Argentina
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  • C. G. SIMIONATO,

    1. Centro de Investigaciones del Mar y la Atmósfera (CIMA/CONICET-UBA), Ciudad Universitaria Pabellón II Piso 2 (C1428EHA) Ciudad Autónoma de Buenos Aires, Argentina
    2. Departamento de Ciencias de la Atmósfera y los Océanos, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabellón II Piso 2 (C1428EHA) Ciudad Autónoma de Buenos Aires, Argentina
    3. UMI Instituto Franco-Argentino para el Estudio del Clima y sus Impactos (UMI IFAECI/CNRS-CONICET-UBA), Ciudad Universitaria Pabellón II Piso 2 (C1428EHA) Ciudad Autónoma de Buenos Aires, Argentina
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  • C. CAROZZA,

    1. Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Paseo V, Ocampo Nº1, CC 175, (B7602HSA) Mar del Plata, Argentina
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  • H. MIANZAN

    1. Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Paseo V, Ocampo Nº1, CC 175, (B7602HSA) Mar del Plata, Argentina
    2. Instituto de Investigaciones Marinas y Costeras (IIMyC), FCEyN, CONICET-Universidad Nacional de Mar del Plata, Dean Funes 3350, (B7602AYL) Mar del Plata, Argentina
    3. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, (C1033AAJ) Ciudad Autónoma de Buenos Aires, Argentina
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e-mail: macha@inidep.edu.ar

Abstract

The whitemouth croaker, Micropogonias furnieri, is exploited by coastal fisheries in the Plata estuary. Its age structure shows the predominance of certain year classes, which are indicative of recruitment variability. The estuary is affected by river discharge variations associated with climatic signals (El Niño Southern Oscillation and others). We hypothesize that recruitment may correlate: (i) negatively with runoff (low runoff would promote the stronger retention of ichthyoplankton); (ii) positively with temperature (higher temperatures should enhance larvae survivorship and/or expand the spawning season); and (iii) positively with the wind zonal component (stronger onshore winds should facilitate the retention of ichthyoplankton). A time series of the relative cohort strengths was constructed for the 1938–2000 period from the age frequencies based on otolith readings. We performed a spectral analysis of the biological and physical series, and we searched for co-movements between them, which suggested the presence of mechanistic links. The results showed co-movements for recruitment, runoff and air temperature series at approximately 6.5, 3.4 and 2.4 yr; the temperature reinforced the runoff effects on recruitment at the 6.5-yr peak, and it weakened them at the 3.4- and 2.4-yr peaks. Wind variability was not relevant for the time scales studied. To explore the mechanisms of retention, we modeled the effects of the runoff fluctuations on the dispersal of the eggs. Both the statistical and modeling results supported the hypothesis that the effects of extreme river discharges on retention may regulate croaker recruitment by promoting high (low) recruitment during low (high) discharge periods.

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