Morone mississippiensis Jordan and Eigenmann, 1887
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Basis for Listing
The Yellow Bass (Morone mississippiensis) is uncommon in Minnesota, where it reaches the northern limits of its range-wide distribution in the Mississippi River. The species has been reported sporadically in the Mississippi River from pool 8 up to Lake Pepin (Hatch et al. 2003). Dams prevent or curtail the northward migration of this southern species. Given its limited distribution in the state, the Yellow Bass was listed as a special concern species in 1984.
The Yellow Bass is silvery-yellow in color overall, with dark green on its back. It has a laterally compressed body, with 6-9 dark horizontal stripes on the sides. Its soft dorsal fin and spinous dorsal fin are connected, and its anal fin has 3 spines and 9-10 soft rays. The back of its tongue lacks teeth (Hatch et al. in preparation). The stripes on the sides of its body are broken and offset above the front of the anal fin, distinguishing it from White Bass (Morone chrysops), whose stripes are not offset. The Yellow Bass can grow up to 45.7 cm (18 in.) in total length, but rarely reaches lengths greater than 30 cm (12 in.). The largest specimen from Minnesota was 38.9 cm (15.3 in.) long.
The species is very similar in appearance to White Bass and White Perch (M. americana) (Lyons et al. 2012). In Minnesota, however, Yellow Bass is a species associate of only White Bass. Distinguishing characteristics of Yellow Bass include: body profile somewhat arched anteriorly, dorsal fins slightly connected by a membrane, second and third anal spines about equal in length, 8-10 rays in anal fin, no teeth present on tongue, and black, horizontal stripes that are often broken and offset above the anal fin.
Yellow Bass occur in large rivers and their backwaters, impoundments, and sloughs. Historically in Minnesota, they occurred in river lakes such as Lake Pepin, but today they are only known to occur in the Mississippi River south of Red Wing.
In Mississippi River Pool 8, fish surveys from 1991-2015 reported 28 specimens that were found in the following habitats: backwaters (13 fish), tailwater zones of dams (7), side channel borders (5), main channel borders (2), and impounded shoreline (1). Secchi disc readings (transparency) ranged from 37-92 cm (15-36 in.), depths from 0.7-2.2 m (2.3-7.2 ft.), and velocities from 0.0-0.28 m/s (0.0-.9 ft./s). (LTRMP 2016).
Biology / Life History
Little is known about the life history of the Yellow Bass in Minnesota. It breeds in the spring, most actively when water temperatures are 20-22°C (68-72°F). Eggs are fertilized in the open and receive no care. Its diet includes mostly invertebrates and small fishes. Adults will, at times, eat small Yellow Bass and Gizzard Shad (Dorosoma cepedianum) along with insects (Hatch et al. in preparation). The species sexually matures at age-3, and few live beyond five years.
Conservation / Management
The Yellow Bass is vulnerable to impacts to its river environment. Furthermore, dams prevent or curtail the northward migration of this southern species, limiting its abundance in the state.
Conservation Efforts in Minnesota
The Minnesota DNR Division of Ecological Services received a State Wildlife Grant to conduct surveys for rare fish species in the Mississippi River from the Twin Cities to the Iowa border. These surveys were conducted from 2006-2008 (Schmidt and Proulx 2009), and while the Yellow Bass was a targeted species, none were found.
Additional research needs for the Yellow Bass in Minnesota include life history studies, genetic analysis, identification of habitat guilds, and identification of limiting factors and opportunities for fish passage around dams.