Asymmetry in specimens of Odontesthes bonariensis in artificial environments.

MARIELA CUELLO; MIRTA GARCÍA; A. SOLARI; GUSTAVO M. SOMOZA

La Plata

Congreso; IX Congreso Nacional de la Sociedad de Ciencias Morfológicas de La Plata.; 2007

In the first decades of the 20th century, the fish culture of a local species, the pejerrey bonaerense (Odontesthes bonariensis) was initiated in Argentina. This activity transcended to other countries and in 1966, embryos from the Chascomús lagoon were introduced in Japan, where the development of this specie's pisciculture was successfully achieved. Four decades later, fecundate eggs from descendents of the first O. bonariensis specimens bred in the Kanagawa Prefecture Experimental Station (Japan) were imported by the IIB-INTECH, Chascomús, Argentine, for the raising and sowing of the Pampasian lagoons. The objective of this work was to analyze the morphological variations of the IIB-INTECH specimens. Individuals under study came from natural-spawning eggs, which were transferred to reservoirs of 3,000 and subsequently 20,000 litres with 1.5% salinity, temperatures from 18 to 20ºC, natural photoperiod and fed with Artemia nauplii and artificial food for pejerrey. More than thirty specimens, from 71 to 430 mm of standard length were analyzed. Thirty-seven morphometric and 11 meristic characters were measured. Principal Component Analysis (PCA) and MANOVA were chosen to test differences between groups in all the size range analyzed. We observed malformations in gill rakers in all specimens, while the largest individuals examined showed cranial asymmetry, exophthalmia and modifications in the head anterior region. These changes are produced as an answer to environmental conditions and have been described in other fish cultured-species, like salmons (Salmo salar), trouts (Onkorynchus mykiss), carps (Cyprinus carpio) and some Perciformes (Dicentrarchus labraxand Lates calcarifer).Odontesthes bonariensis) was initiated in Argentina. This activity transcended to other countries and in 1966, embryos from the Chascomús lagoon were introduced in Japan, where the development of this specie's pisciculture was successfully achieved. Four decades later, fecundate eggs from descendents of the first O. bonariensis specimens bred in the Kanagawa Prefecture Experimental Station (Japan) were imported by the IIB-INTECH, Chascomús, Argentine, for the raising and sowing of the Pampasian lagoons. The objective of this work was to analyze the morphological variations of the IIB-INTECH specimens. Individuals under study came from natural-spawning eggs, which were transferred to reservoirs of 3,000 and subsequently 20,000 litres with 1.5% salinity, temperatures from 18 to 20ºC, natural photoperiod and fed with Artemia nauplii and artificial food for pejerrey. More than thirty specimens, from 71 to 430 mm of standard length were analyzed. Thirty-seven morphometric and 11 meristic characters were measured. Principal Component Analysis (PCA) and MANOVA were chosen to test differences between groups in all the size range analyzed. We observed malformations in gill rakers in all specimens, while the largest individuals examined showed cranial asymmetry, exophthalmia and modifications in the head anterior region. These changes are produced as an answer to environmental conditions and have been described in other fish cultured-species, like salmons (Salmo salar), trouts (Onkorynchus mykiss), carps (Cyprinus carpio) and some Perciformes (Dicentrarchus labraxand Lates calcarifer).