Gonadal development in pejerrey (Odontesthes bonariensis) during spawning season in relation with sex steroids and temperature variation in Gómez lake (Pampas region, Argentina).

Pamela S Del Fresno,Leandro A Miranda,Gustavo E Berasain,Darío C Colautti

doi:10.1590/0001-3765202120190795

Abstract

Gómez lake (34 ° 39 'S 61 ° 01' W) is a typical shallow lake of Pampas region placed in the upper area of the Salado river. The most abundant fish species in this lake is the pejerrey (Odontesthes bonariensis) valued due to the quality of its flesh and its attractiveness as a game fish. The aim of this study was to describe for the first time in this pejerrey wild population the gonadal stages during three consecutive spawning seasons (August to December) in relation with sexual steroids and temperature in this lake. In general, pejerrey gonadal development, the gonadosomatic index and the plasma levels of estradiol and testosterone varied in relation to air temperature. During the sampling period, pejerrey females started to ovulate in early August (winter), with a peak in October and ending in December with some of them with atretic oocytes. For males, it was possible to find spermiating animals during the whole spawning season and some arrested animals only in December. Our results confirm the relationship with pejerrey maturation and temperature and can be useful for decision making in the management of this natural resource.

Highlights

Lagoons are distinctive elements of the Pampas landscape and represent a very important resource for the regional economies
In August 2013, the majority of the females were in cortical alveoli (CA) (80%) and the rest of them were in vitellogenic stages
This study describes for the first time the reproductive status of pejerrey population of Gómez lake using gonadal histology, gonadosomatic indexes and T and E2 plasma levels during three consecutive spawning seasons

Summary

Introduction

Lagoons are distinctive elements of the Pampas landscape and represent a very important resource for the regional economies They are shallow water bodies with an average depth of about 3 meter and are characterized by a high degree of natural eutrophication, which is often increased by different anthropic activities (Quirós et al 2002, Diovisalvi et al 2015). Due to these characteristics, shallow lakes are sensitive to climatic variations, influencing their functioning (Jeppesen et al 1998, Diovisalvi et al 2015, Elisio et al 2018). Pampas lakes are very dynamic ecosystems, exposed to changes caused by external and internal factors that force the organisms that inhabit them to make the corresponding adjustments to adapt and avoid extinction (Padisák & Reynolds 2003).

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