# Ethogram Characteristics of Silver Carp (Hypophthalmichthys molitrix) During the Breeding Period Based on the PAE Coding System

## TL;DR

This study creates an ethogram for silver carp during breeding using the PAE coding system, revealing sex-based differences in behavior and diversity over time.

## Contribution

The study introduces a detailed ethogram and PAE coding system for silver carp reproductive behavior during the breeding season.

## Key findings

- 34 distinct behaviors were identified and categorized into five groups during the breeding period.
- Males showed higher activity and behavioral diversity compared to females throughout the breeding period.
- Behavioral diversity indices peaked 10–15 hours post-spawning and varied significantly by sex.

## Abstract

The establishment of an ethogram for fish facilitates precise behavioral description and classification, contributing to the understanding of their functional roles and interrelationships. This study develops an ethogram and a PAE (Posture-Act-Environment) coding system for silver carp during the breeding season, examining the variation in reproductive behaviors at different time points post-induced spawning and between sexes. A total of 34 distinct behaviors were identified and categorized into five groups. Notable differences in behavioral patterns were observed across post-induction stages and between sexes, with males exhibiting higher activity levels and greater behavioral diversity throughout the breeding period. Behavioral diversity indices initially rose, then declined over time post-spawning, with significant sex-based differences. These results provide essential insights for constructing quantitative ethograms and advancing behavioral ecology research in other fish species.

Animal behavior diversity is a key element of biodiversity, and the establishment of an ethogram provides a crucial framework for exploring the relationship between behavioral patterns and environmental factors. However, the development of ethograms and the quantitative analysis of behavioral diversity in fish remain underexplored. In this study, focal animal sampling and instantaneous scan sampling methods, paired with the PAE (Posture-Act-Environment) coding system, were employed to investigate the ethogram and reproductive behavior diversity of silver carp. The findings revealed 12 postures, 20 actions, and 34 behaviors documented during the breeding period of silver carp. Analysis of reproductive behavior diversity revealed that the absolute behavioral diversity index (H), relative behavioral diversity index (r), and regulated diversity index (r-variable) all peaked during the 10–15 h interval following induced spawning. Notably, significant differences (p < 0.001) were observed in these indices across different post-induction time intervals and between sexes. Throughout the breeding cycle, females demonstrated lower diversity and intensity in reproductive behaviors compared to males, suggesting distinct reproductive strategies between the sexes. The reproductive behavior of silver carp exhibited distinct chronobiological disorganization patterns. This study provides a scientific basis for future research on the behavioral ecology of silver carp and the conservation of their wild populations.