Spatiotemporal Study of Yellow Perch from Chesapeake Bay Tributaries: Genetics, Hormones, and Histopathology
2019 - 2020
University of Maryland, College Park
Alexander MacLeod, University of Maryland College Park
Strategic focus area:
Sustainable fisheries and aquaculture
Yellow perch have historically been an economically and culturally important fishery to the Chesapeake Bay. Populations, however, have experienced precipitous declines over the past several decades in many regions of the Bay. These declines correlate inversely with percent imperviousness within catchment areas and therefore appear related to human development in the affected watersheds. Females from affected regions are reported to have a high frequency of gamete abnormalities (e.g., thin and irregular zona pellucida (egg envelope), abnormal yolks, and incomplete development at the time of spawn. Additionally, hatching success from impacted populations has declined markedly from > 80% in 1960 to < 10% between 2001 and 2005. Important stages of reproductive development including folliculogenesis and vitellogenesis have not been studied in this species. To that end, we conducted an investigation into the reproductive health of mature male and female yellow perch from several historically important spawning reaches within the Chesapeake Bay watershed. The investigation included areas of varying land use from predominantly agricultural (Choptank River) to moderately (Mattawoman Creek) and substantially (Severn River) suburban/urban. We investigated gonadal histology/histopathology, as well as a battery of molecular biomarkers including plasma vitellogenin, circulating sex steroids (e.g., E2 and T), hormones essential to ovarian maturation (e.g., FSH and LH), gene expression within liver and gonads. Yellow perch were collected beginning in 2017 through 2019 at several month intervals prior to and on the spawn from each system to investigate gene expression, molecular signaling, hormone levels, and tissue conditions during the period of reproductive recrudescence. The primary objective of the study was to determine the stage and manner that populations from impacted regions begin to deviate from normal reproductive development. The requested funding support will be used exclusively for analyzing the hormone profiles in the plasma of field collected yellow perch. This will provide necessary information to connect the observations in gene expression to the tissue changes as part of this holistic study.