Aspectos bioecológicos del pejerrey Odontesthes bonariensis de la laguna de Monte

• Autores: Fabián Grosman, Pablo Sanzano, Daniela Agüeria
• Localización: Revista del Museo Argentino de Ciencias Naturales, ISSN-e 1853-0400, ISSN 1514-5158, Vol. 4, Nº. 1, 2002, págs. 13-23
• Idioma: español
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• Resumen

  • In 1997and 1998, two limnological processes of high relevance occurred in the Monte laguna: the invasion of Potamagetonpectinatlls and an extraordinary flood. The magnitude of theBe events affected the different components of theecosystem on a greater or smaller scale. The aims of this paper are to know the present status of the fish communityand the population ofpejerrey Odontesthes bonariensis, relating the results to the mentioned events. A limnologicsampling considering physical and chemical parameters of water, quantification of macrozooplankton, and structureof the fish community, was carried out. In the case of pejerrey, the cpue, the length-weight relationship, the Kfactor, cephalic index, health status, age and growth, relative numerosity, reproductive and feeding aspects wereobtained. The physical-chemical composition of water is standard for this type of environment; the presence oforganochlorates conforms a symptom of alarm. The zooplankton was abundant and object of a strong predationpressure by the fish. The present structure of the ichtyocenosis includes the carp, Cyprinus carpio. The capturesof pejerrey presented a marked decrease of the intermediate lengths, corresponding to 3+ and 4 + age, whichwould be the annual classes most affected by the mentioned events. The causes of this could be an increase ofmortality because of greater predation pressure of larvae and juvenile)lsh and passive or active migration. Thus,the present population is conformed by specimens 0[0+, 1 + and 2+ age, and those of a gt'eater size which survivedthe flood and the presence of P pectinatus.