Description

SINGLE PAPER

Volume 24, Issue 1 – 05 June 2018

Joseph C. Waddell and William G. R. Crampton: A simple procedure for assessing sex and gonadal maturation in gymnotiform electric fish, pp. 1-8

Abstract

Studies of the reproductive life history of fish populations typically require a reliable assessment of sex and gonadal maturation stage. Some recently published methodologies for describing gonadal maturation involve time-consuming histological analyses. However, histological procedures can be impractical in studies involving large sample sizes of fishes. Here we describe a robust methodology for staging gonadal maturation in gymnotiform fish based on readily identifiable features of gross morphology from dissected gonads. We unify previously published gonadal maturation schemes to describe five gonadal maturation stages in females (1. Immature or Resting; 2. Maturing; 3. Mature; 4. Pre-spawning; 5. Spent) and four stages in males (1. Immature or Resting; 2. Maturing or Spent; 3. Mature;
4. Pre-spawning). The procedure described here permits discrimination of all major gonadal stages (with the exception of some early and late male maturational stages that can only be discriminated using histological techniques) and provides similar levels of subjectivity for separating successive early maturational stages relative to histology-based procedures, but is far less time consuming.