Oysters, Crassostrea virginica, are considered relatively long-lived protandrous hermaphrodites exhibiting aggregated recruitment that, in turn, facilitates fertilization during broadcast spawning. While recovering from major epizootics in the 1990s through early 2000s, current oyster populations in the Virginia Chesapeake Bay remain size and age truncated. Oysters in excess of 5y and 140 mm shell length (SL) are rare, yet fossil records indicate that ages in excess of 20 y and 160mm SL were commonplace. We explore the question “how does age truncation influence egg production across the extant demographic among oyster populations in the sub-estuaries of the Virginia Chesapeake Bay?” Source demographic data is taken from quantitative long-term population surveys and focused examination of the size and age at transition from male to female as described by Harding et al (DOI: https://doi.org/10.1017/S002531541200032X). Initial exploration indicates that the abundance of 2y old oysters, at sub market size of <76mm SL, can produce approximately half of total egg production depending on year and site – that is egg production does not appear to be limited by the protandric transition from male to female.
The availability of both egg production and recruitment data (from population demographics) prompts a second question “what is the relationship between the two parameters?” Substantial efforts have been made by fisheries biologists to describe stock-recruit (S/R) relationships in fish stocks. There are, however, strong arguments that these have limited applicability in bivalves (Timbs et al https://doi.org/10.2983/035.037.0507), especially so for oysters where substrate availability is critical for recruitment. None the less, the egg production versus recruitment comparison represents a rare occasion (throughout marine invertebrate larval ecology, not just oysters) wherein mortality in this critical early life period is quantified over both time and space in several populations. We discuss these observations in the context of larval mortality versus loss and/or supplementation through advection in these sub-estuarine locations.