Juvenile Drift of Round Goby as a Means of Range Expansion in the French Creek Watershed, Pennsylvania

Grace L. Hemmelgarn^1,*, Casey Bradshaw-Wilson¹, and Lee M. Demi¹

¹Allegheny College, 520 North Main Street, Meadville, PA 16335. *Corresponding author.

Northeastern Naturalist, Volume 32, Issue 1 (2025): 80–102

First published early online: 8 February 2025

Abstract
An ongoing invasion of Neogobius melanostomus (Round Goby) is threatening the unique biodiversity of the French Creek watershed (FCW), a tributary to the Allegheny River located primarily in northwestern Pennsylvania. Management strategies depend on knowledge of dispersal mechanisms. Juvenile drift is an important mechanism of Round Goby dispersal in other populations that is currently unexamined in this system. Our objective was to document the presence of juvenile Round Goby drift, describe temporal drift patterns, and describe the community of drifting fish families in the presence and absence of Round Goby within the FCW. We collected drifting larval fishes with drift nets twice a month from June to August 2021 at 3 sites in the FCW: 1 with an established Round Goby population in LeBoeuf Creek (LC), 1 at the invasion front in the French Creek main stem (FCI), and 1 not currently known to be colonized by Round Goby in the French Creek main stem (FCII). Across all sampling dates and sites, we collected 2689 fishes from 9 families, with 71.5% of drift occurring in June. We captured a total of 172 Round Goby, representing 17.5% of drift (163 individuals) at LC and 1.7% of drift (9 individuals) at FCI. No drifting Round Goby were captured at the currently uninvaded FCII site. All Round Goby drift occurred entirely after sunset. Goby total length was consistent from June to early August with a mean of 7.8 mm. This study presents the first documented evidence of Round Goby juvenile drift in the FCW, which may inform management strategies to limit the spread of this invasive species to larger waterways downstream.

Download Full-text pdf (Accessible only to subscribers. To subscribe click here.)