Assessing Relative Habitat Quality of Freshwater Tributaries using Relative Abundance and Size of Resident Fishes

• Thomas Repetz, Marine Science, University of Delaware

• Ed Hale, Marine Science, University of Delaware

Banded killifish (Fundulus diaphanus) and Redbreast sunfish (Lepomis auritus) represent two resident species that inhabit freshwater tributaries of the eastern United States of America. Both species provide critical ecosystem functions serving as prey and predator in many North American freshwater watersheds. The goal of our study was to utilize tributary specific metrics of both species, specifically catch per unit effort (CPUE) and size to assess relative habitat quality across three tributaries of the Delaware River Estuary, including the Brandywine River, Red Clay Creek, and White Clay Creek. A minimum of two locations were used in each tributary to evaluate species specific metrics. Data were summarized and averaged at individual sites, and across sites to provide a quantitative index of habitat performance at each tributary. Sampling took place from mid-July and to mid-October of 2023. Total length was recorded for Banded killifish, while fork and total length (mm) were both recorded for Redbreast sunfish. Physical variables were collected at each sampling event including temperature, dissolved oxygen, salinity, and pH using a YSI multiparameter water quality probe. Trends in CPUE, and size within individual systems through time and across tributaries in relation to physical variables will be evaluated to determine significant associations across space, time and water quality parameters.