Distribution and Population Characteristics of Shadow Bass in Two Arkansas Ozark Streams

Abstract

We examined the longitudinal distribution and population characteristics of shadow bass Ambloplites ariommus in the Spring River and lower Eleven Point River of Arkansas to determine potential length limit regulations for this species. Shadow bass were the second most abundant sport fish species collected in both streams (most abundant sport fish was the smallmouth bass Micropterus dolomieu). Abundances (catch per effort) of shadow bass were greatest upstream and declined significantly downstream (Spring River: 32.6 fish/h upstream versus 3.4 fish/h downstream; Eleven Point River: 13.4 versus 5.0 fish/h). Size distributions and relative weights (Wr) were also greatest upstream (Spring River: Wr = 109 upstream versus 99 downstream; Eleven Point River: Wr = 105 versus 95). Associated with this distribution trend was a downstream decline in stream slope and frequency of riffles. Catch rates and size distributions of shadow bass were greater for the Spring River (proportional size distribution mean = 83) than for the Eleven Point River (mean = 36). Stream differences in preferred size distributions were even greater. Total length at age for shadow bass indicated rapid growth rates compared with results of previous studies; age‐3 fish reached 183 mm total length. The von Bertalanffy equation yielded the following growth model for shadow bass: Lt = 250.8[1 − e−0.381(t−0.477)], where Lt is length at age t. Stomach contents of shadow bass in the Spring River comprised mostly crayfishes, which is consistent with feeding patterns of other rock basses Ambloplites spp. Relative weights were high for shadow bass in both rivers, although Wr was greater for Spring River fish (Wr = 107) than for Eleven Point River fish (Wr = 102). Based on abundance, diet, and condition of shadow bass, upstream reaches of both rivers contain sustainable populations of this species. Despite these positive population and growth features, length limits for shadow bass are not recommended for these streams.

Population Characteristics of Ozark Bass (<i>Ambloplites constellatus</i>) in the Upper White River Basin of Northern Arkansas

“…With increasing age, length differences between Ozark bass and shadow bass became more similar, while differences between rock bass and Ozark bass length became more pronounced with age ( Figure 6). Shadow bass mean annual survival in the Spring River and Eleven Point River in Arkansas was reported at 64% across all age groups [21], which was greater than the mean annual survival of Ozark bass across both streams in this study (52% . Thus, on average, Ozark bass in the present study were shorter than a single nearby rock bass populations in Missouri.…”

“…Ozark bass (squares), rock bass (triangles), and shadow bass (circles) length-at-age data. Shadow bass data were from the Eleven Point and Spring Rivers, Arkansas, from 2003 through 2007[21]. Ozark bass data were from the Buffalo River and Crooked Creek, Arkansas, from summer 2013.…”

Shaping up: a geometric morphometric approach to assemblage ecomorphology

“…Micropterus punctulatus and A . ariommus have very similar diets, yet very different overall body shapes (Scalet, ; Johnson et al , ). This suggests niche partitioning via habitat or feeding site preference.…”

“…The larger mouth, eye size and head size of M. punctulatus would indicate a predatory nature for this species (Gatz, 1979b), which is supported by gut analyses (Scalet, 1977). Micropterus punctulatus and A. ariommus have very similar diets, yet very different overall body shapes (Scalet, 1977;Johnson et al, 2010). This suggests niche partitioning via habitat or feeding site preference.…”