A Standardized Terminology for Describing Reproductive Development in Fishes

As the number of fish reproduction studies has proliferated, so has the number of gonadal classification schemes and terms. This hasmade it difficult for both scientists and resourcemanagers to communicate and for comparisons to be made among studies. We propose the adoption of a simple, universal terminology for the phases in the reproductive cycle, which can be applied to all male and female elasmobranch and teleost fishes. These phases were chosen because they define key milestones in the reproductive cycle; the phases include immature, developing, spawning capable, regressing, and regenerating. Although the temporal sequence of events during gamete development in each phase may vary among species, each phase has specific histological and physiological markers and is conceptually universal. The immature phase can occur only once. The developing phase signals entry into the gonadotropin-dependent stage of oogenesis and spermatogenesis and ultimately results in gonadal growth. The spawning capable phase includes (1) those fish with gamete development that is sufficiently advanced to allow for spawning within the current reproductive cycle and (2) batch-spawning females that show signs of previous spawns (i.e., postovulatory follicle complex) and that are also capable of additional spawns during the current cycle. Within the spawning capable phase, an actively spawning subphase is defined that corresponds to hydration and ovulation in females and spermiation in males. The regressing phase indicates completion of the reproductive cycle and, for many fish, completion of the spawning season. Fish in the regenerating phase are sexually mature but reproductively inactive. Species-specific histological criteria or classes can be incorporated within each of the universal phases, allowing for more specific divisions (subphases) while preserving the overall reproductive terminology for comparative purposes. This terminology can easily be modified for fishes with alternate reproductive strategies, such as hermaphrodites (addition of a transition phase) and livebearers (addition of a gestation phase)

Emerging Issues and Methodological Advances in Fisheries Reproductive Biology

Although incorporating detailed reproductive data into all stock assessments is not a practical goal, the need to understand how reproductive biology affects population productivity is being increasingly recognized. More research focused on reproductive biology-coupled with a shift towards a resilience perspective in fisheries science-is resulting in challenges to many long-held assumptions; the emergence of important new issues; and identification of the need to improve data and methods used in reproductive studies. Typically, data for reproductive studies are based on an assessment of gonadal development, which is most accurately evaluated with histology. This special section of Marine and Coastal Fisheries contains contributions from a workshop on the gonadal histology of fishes that was held in Cadiz, Spain, during June 2009. These papers cover a wide range of species and reproductive topics while introducing improved and new histological techniques. In this introduction, we address the following needs: (1) to employ standardization, thereby improving our ability to conduct comparative studies; (2) to better understand patterns of gonadal development and spawning events over time; and (3) to move beyond the spawning stock biomass paradigm. We identify the contributions of special section papers to these topics and conclude by suggesting needs for future research and integration of reproductive data into both conceptual and quantitative models to better understand how reproductive performance affects population dynamics

Introduction to Special Section on Research Activities at the Iztacala Campus of the Universidad Nacional Autónoma de México, México

In October 2002, we had the opportunity to initiate a long-term collaboration with colleagues from the Iztacala campus of the Universidad Autónoma de México (UNAM), whose research interests focus on coastal and nearshore fishes and decapod crustaceans of Veracruz state, Mexico. This is an undergraduate campus with a strong Biology department whose faculty also maintain research programs despite limited sources of funding and a heavy teaching load. During the course of our initial visit, we realized that there is a wealth of unpublished undergraduate student research on understudied fish species

Introduction to Special Section on Research Activities at the Iztacala Campus of the Universidad Nacional Autónoma de México, México

In fall 2002, we had the opportunity to initiate a long-term collaboration with colleagues from the Iztacala campus of the Universidad Autónoma de México (UNAM), whose research interests focus on coastal and nearshore fishes and decapod crustaceans of Veracruz state, Mexico