Research

Over half of the fish species currently found in streams of the New River drainage, including our favorite gamefishes such as smallmouth, large-mouth, rock, and striped basses, bluegill, crappie, rainbow and brown trout, musky, and bullhead, along with many prey species (various minnows, shad, darters), did not occur here before European settlement, but were intentionally or unintentionally transplanted by humans. Introduced fish are a leading cause of imperilment of native North American fish species, 39% of which are imperiled or extinct. Furthermore, introduced fishes in the U.S. are responsible for $5.4 billion annually in net economic losses.

However, introduced fish are not always detrimental—they can greatly enhance recrea-tional, subsistence, and commercial fisheries, which provide livelihoods and revenue. And, because they often have different habitat preferences than native species, introduced fish are often accepted into a new environment without impacting native species, at least in the short term.

A better understanding of mechanisms driving invasions (i.e., when an introduced species spreads into a new area) and their impacts is important for managing harmful invasive species and assessing risks and benefits of future introductions. Study of invasions also contributes to an overall understanding of how organisms interact with each other and the environment, such as how invaders and natives may rapidly evolve following an introduction, and how communities respond to environmental change such as human alterations to land cover (e.g., deforestation), hydrology (e.g., damming a river), or climate change. But quantitative studies of New River stream-fish invasions are lacking.

For my MS thesis in the Department of Fish and Wildlife Conservation at Virginia Tech, I am exploring stream-fish invasions in the upper (NC portion) and middle (VA portion) New River drainage (Fig. 2) to find out which species have been spreading since the start of the 20th century, and which species traits (biological characteristics such as body size and shape, or feeding, reproduction, and habitat requirements) are associated with spreaders and decliners.

Specifically, my objectives are to:

• 1. Compile a historical fish-collection data set for the upper and middle New River and classify each species of stream fish as a spreader or decliner based on whether the area they occupy has increased or decreased since the early 20^th century;

  2. Compile a “fish-traits” data set consisting of about 30 biological and ecological traits of each of the 77 species of stream fish (including 42 introduced and 35 native species) found in the study area, and use multivariate statistics to identify which traits contribute to a species’ success as a spreader.

Due to widespread deforestation, agriculture, and urbanization in the New River drainage since European settlement, I predict that the most successful spreaders will have traits that help them thrive in human-altered conditions such as warmer, siltier streams.

A deforested, silted stream, Tom's Creek, Montgomery County, VA.