Seasonal reproduction of sailfish Istiophorus platypterus from the southeast Mexican Pacific

Abstract

Quantitative histology was used to analyse the seasonal reproductive characteristics of the Istiophorus platypterus sailfish obtained from bycatch and recreational catches in the southeast Mexican Pacific. The analysis revealed five stages of ovarian development, eight kinds of oocytes, and one postovulation structure. The species shows an asynchronous ovary development and indeterminate fecundity. Gonadosomatic indices (GSI) indicated that sailfish have a reproductive period with peaks in September and October (mean monthly GSI=1.9 and 1.8). Females were more abundant during the second quarter, whereas males were more abundant in the third and fourth quarters. We found that the estimates of the frequency distribution of whole oocytes showed that this analysis may be useful as a tool to assess maturity. The estimated size at sexual maturity for this species in the Gulf of Tehuantepec was 150.2 cm eye–fork length.

Keywords:

• Size at sexual maturity
• oocyte development
• oocyte cohort analysis
• Gulf of Tehuantepec
• sailfish reproduction

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

Thanks to the sponsor Consejo Nacional de Ciencia y Tecnología for support received through the project contract SEP-CONACYT 60376. The authors are indebted to Gabriela González-Medina, Carmen Alejo-Plata, Samuel Ramos-Carrillo and Tania Martínez-Peña of the Universidad del Mar who participated in field data collection and María Eulalia Meza Chávez for histological processing. We thank two anonymous reviewers who offered valuable suggestions that greatly improved the presentation and readability of this article. AHH and AAC received fellowships from the Comisión de Operación y Fomento de Actividades Académicas del Instituto Politécnico Nacional, and Programa de Estímulos al Desempeño de los Investigadores del Instituto Politécnico Nacional.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark