La Trobe

Faster juvenile growth promotes earlier sex change in a protandrous hermaphrodite (barramundi Lates calcarifer)

Download (1.23 MB)
journal contribution
posted on 2023-01-16, 05:43 authored by BH Roberts, JR Morrongiello, DL Morgan, Alison KingAlison King, TM Saunders, David CrookDavid Crook
The relationship between growth and sexual maturation is central to understanding the dynamics of animal populations which exhibit indeterminate growth. In sequential hermaphrodites, which undergo post-maturation sex change, the size and age at which sex change occurs directly affects reproductive output and hence population productivity. However, these traits are often labile, and may be strongly influenced by heterogenous growth and mortality rates. We analysed otolith microstructure of a protandrous (i.e., male-to-female) fish (barramundi Lates calcarifer) to examine growth in relation to individual variation in the timing of sex change. Growth trajectories of individuals with contrasting life histories were examined to elucidate the direction and extent to which growth rate influences the size and age individuals change sex. Then, the relationships between growth rate, maturation schedules and asymptotic maximum size were explored to identify potential trade-offs between age at female maturity and growth potential. Rapid growth was strongly associated with decreased age at sex change, but this was not accompanied by a decrease in size at sex change. Individuals that were caught as large females grew faster than those caught as males, suggesting that fast-growing individuals ultimately obtain higher fitness and therefore make a disproportionate contribution to population fecundity. These results indicate that individual-level variation in maturation schedules is not reflective of trade-offs between growth and reproduction. Rather, we suggest that conditions experienced during the juvenile phase are likely to be a key determinant of post-maturation fitness. These findings highlight the vulnerability of sex-changing species to future environmental change and harvest.

Funding

The research team acknowledge Traditional Owners across our study region, and recognise their continuing connection to land and water. We are grateful to the Murdoch University researchers, volunteers, many recreational fishers and the commercial fisher Ferdy Bergmann who provided fish frames that were used in this study. We would specifically like to thank Joe Duncan, Mark Herbert, Jim Kelly, Big Barra's One Stop Shop (Derby), Dean Thorburn, Mark Allen, Simon Visser, Howard Gill, Stephen Beatty, Mervin Street, Mary Aitken, Kevin Tromp, Mark Horstman, Patsy Bedford, the Kimberley Land Council, Mary Island Fishing Club and the people of the West Kimberley for assistance with the collection of barramundi samples. We thank Osmar Luiz and Derek Ogle for assisting with the otolith back-calculation model. The research was supported through funding from the Australian Government's National Environmental Science Program (Northern Australia Environmental Resources Hub), Charles Darwin University, Murdoch University and an Australian Government Research Training Program Stipend Scholarship to BR.

History

Publication Date

2021-12-01

Journal

Scientific Reports

Volume

11

Issue

1

Article Number

ARTN 2276

Pagination

10p.

Publisher

Springer Nature

ISSN

2045-2322

Rights Statement

© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.