Spatial variability in young of year Smallmouth Bass infections in the Chesapeake Bay Watershed

Session: Disease and Mortality in Fishes

Megan Schall, Penn State Hazleton, mvk10@psu.edu
Vicki Blazer, U.S. Geological Survey, vblazer@usgs.gov
Heather Walsh, USGS, hwalsh@usgs.gov
Geoffrey Smith, Pennsylvania Fish and Boat Comission, geofsmith@pa.gov
Timothy Wertz, Pennsylvania Department of Environmental Protection, twertz@pa.gov
Tyler Wagner, Pennsylvania State University, txw19@psu.edu

Abstract

Potential disease-causing agents including bacterial and viral pathogens and parasites have been found to co-occur in young of year (YOY) smallmouth bass in the Susquehanna River Basin, Chesapeake Bay Watershed, Pennsylvania. It is not well understood, however, how co-occurrence of infection (coinfection) varies with respect to site-specific characteristics. To evaluate prevalence of infection in YOY smallmouth bass using histology, 1,426 YOY smallmouth bass were collected during 2013-2016 from 46 in- and out-of-basin sites. A hierarchical model was used to quantify spatial variability of specific individual infection prevalence, prevalence of YOY with coinfections, and investigate land use relationships (agriculture and development) with infection. Prevalence of three or more infections was generally higher in the Susquehanna River Basin than out-of-basin sites within Pennsylvania. Coinfection prevalence had a high probability of being positively related to agriculture land use (probability =0.86) and negatively related to development (probability = 0.96) at the catchment scale. To expand modeling efforts, a joint distribution model is being used to partition relationships between infections at multiple spatial scales. Quantifying potential underlying factors for coinfection in YOY smallmouth bass provides insight on risk for future disease outbreaks and prioritization of potential management areas.