U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2007-3026

April 2007

Biomarker Benchmarks: Reproductive and Endocrine 

Biomarkers in Largemouth Bass and Common Carp from 

United States Waters

Printed on recycled paper

The U.S. Geological Survey (USGS) 

has developed a national database and 

report on endocrine and reproductive 

condition in two species of fish 

collected in U.S. streams and rivers. 

This information provides scientists 

with a national basis for comparing 

results of endocrine measurements in 

fish from individual sites throughout 

the country, so that scientists can better 

ascertain normal levels of biomarkers. 

The database includes information on 

several measures of reproductive and 

endocrine condition for common carp 

and largemouth bass. Data summaries 

are provided by reproductive season and 

geographic region. The report’s authors 

are Steven Goodbred (USGS), Stephen 

Smith (USGS), Patricia Greene (USGS), 

Richard H. Rauschenberger (FWS), and 

Timothy Bartish (USGS). 

A national-scale reconnaissance 

investigation was initiated in 1994 by 

the USGS that utilized a suite of biological assays (biomarkers) as indicators of 

reproductive health, and potentially, 

endocrine disruption in two widely 

distributed species of teleost (bony) fish, 

largemouth bass (Micropterus salmoides) 

and common carp (Cyrinus carpio). 

The suite of assays included plasma 

sex-steroid hormones, stage of gonadal 

development, and plasma vitellogenin, 

an egg protein that indicates exposure 

to estrogenic compounds when found in 

male fish. More than 2,200 common carp 

and 650 largemouth bass were collected 

at 119 rivers and streams (Figure 1). The 

full report and database can be found at 

http://fisc.er.usgs.gov/Endocrine_Data_

Report.pdf.

To establish national and regional 

baselines for land use, researchers 

selected sites that represented a diverse 

range of land uses and levels of disturbance. The sites were sampled during 

both non-reproductive and reproductive 

seasons to include this source of variation 

in the data. Fish in many aquatic ecosystems were sampled, including the Mississippi, Columbia, Colorado, Willamette, 

Potomac, Red River of the North, Platte, 

Hudson, Missouri, and Connecticut rivers.

Carp and bass have different exposures to contaminants, and thus, could 

be expected to have different responses. 

Carp are a bottom-dwelling fish whose 

feeding habits expose them to many 

different types of environmental contaminants found in water, sediments, and 

food. Largemouth bass, an important 

recreational species, are predators and 

thus are also exposed to contaminants 

that accumulate in higher trophic levels. 

Additionally, the toxicological response 

of the two species to chemicals in the 

environment differs because of their 

disparate physiology and genetics. As a 

result, the two fish species represent different types of sentinels of environmental 

quality in the aquatic ecosystem.

The fish biomarkers measured in this 

database are important regulators of critical life-history functions. They help to 

control spermatogenesis, egg production, 

hatchability, fertility, fertilization, behavior, viability of young, and development 

into a sexually mature fish. Although 

many of these important endpoints can be 

measured, they require a larger commitment of resources and are not practical to 

measure in a national study such as this 

one. This work is a geographically extensive survey of a subset of biomarkers that 

are physiologically associated with these 

life-history changes.

—By Steven L. Goodbred and others

Figure 1. National map with regional boundaries and collections sites for common carp ● 

(magenta), largemouth bass ● (blue), and both common carp and largemouth bass ● (gold).