Methods for Fish Biology, 2nd edition

Chapter 12: Reproduction

J. Adam Luckenbach and José M. Guzmán

doi: https://doi.org/10.47886/9781934874615.ch12

The ability to survive and pass one’s genes to the next generation through reproduction is key to the perpetuation of life. Reproduction influences species survival and abundance in the wild and levels of production in agriculture. It is therefore unsurprising that the study of reproduction and development of methodologies to assess it has been an important research area in fisheries and aquaculture science.

Since the first edition of this book, the era of molecular biology was born. Advancements in so-called “’omics technologies” (e.g., genomics, transcriptomics, proteomics), mostly driven by human medicine and pharmacology, have changed the methods landscape and are now frequently applied to model and even nonmodel fish species. Every year, in fact, conducting large-scale molecular studies in nonmodel species becomes significantly more achievable and affordable. The development and availability of molecular biology methods has by no means led to wholesale replacement or antiquation of classical methods; quite the contrary, as many classical techniques such as histology remain the gold standards for fish reproductive assessments.

In this chapter we briefly cover some of the most widely used methods for the study of fish reproductive physiology, including classical and newer approaches. The main audiences using these techniques are fishery and aquaculture scientists, and though there is limited interaction between these disciplines, many methods are shared, and research in each discipline does indeed inform the other; hence, both are considered here. We have adopted the standardized terminology proposed by Brown-Peterson et al. (2011) for describing reproductive development in fishes. This classification is based on the premise that most female and male teleost fishes go through a similar cycle of preparation for spawning, including development and growth of gametes, spawning, cessation of spawning, and preparation for the subsequent reproductive season. Following this scheme, fish can be classified within the following reproductive phases based on both macroscopic and microscopic/histological features: immature phase, developing phase, spawning capable phase, regressing phase, or regenerating phase (for details, see Brown-Peterson et al. 2011). It is also important to note that the terms mature or maturation are used to refer to the initial, one-time attainment of sexual maturity (i.e., puberty or adulthood), and not to individuals that are developmentally and physiologically able to spawn. Thus, a fish that has attained sexual maturity will never exit the reproductive cycle and return to the immature phase. Given the diversity of fishes (>33,000 extant species identified), it should also be noted that this scheme may need to be adapted to the reproductive specificities of each species (e.g., semelparity, hermaphroditism, live-bearing) and the scope of the study under consideration.