Modeling the importance of fish condition, overall health, and disease on the fecundity of White Perch in the Choptank River

ObjectiveModeling of fecundity with allometric, nutritional, and environmental covariates has increased sensitivity of reproductive metrics in many fish species. In estuaries with heavy anthropogenic influence, resident species often experience sublethal health impacts because of increased stress, which can include increases in gonadal pathology, intersex, or potential reproductive failure. This study models the fecundity of the estuarine species White Perch Morone americana in response to health parameters identified as signals of habitat stress, including gross pathology presentation, nutritional condition, and disease presence.MethodsSubpopulation fecundity in the Choptank River (Maryland) of the Chesapeake Bay was estimated using stereological fecundity sampling methods and modeled using information-theoretic approaches of model selection. Nutritional and health parameters identified through health assessment techniques, specific somatic indices, and disease presence were selected as covariates.ResultNutrition demonstrated limited influence on model fit as compared to models with only conventional allometric variables such as weight and length. Of the health variables, gross pathology and somatic indices showed minimal influence on selection, but mycobacterial infection, a chronic condition in the Chesapeake Bay among temperate basses, showed measurable influence. Models with mycobacteriosis included were 40 times more likely the best fit when compared to models with only allometric parameters.ConclusionWhether this has a region-wide influence on all subpopulations will require further research and sampling of the magnitude of mycobacteriosis infection. Pollution can change reproduction in everything from humans to insects. Like the other organisms around us, fish are not immune to changes in health as a result of changes in their habitat. In the Chesapeake Bay, resident fish are subjected to habitat contamination, low oxygen, and high disease rates, all of which can reduce reproductive health and reproductive success. If these populations are to survive future threats such as climate change and invasive predators, they must reproduce effectively and we must be able to monitor how our actions change reproductive potential.Impact statement