Population Dynamics of the Sand Shiner (Notropis stramineus) in Non-Wadeable Rivers of lowa

Abstract

The sand shiner (Notropis stramineus) is a common cyprinid found throughout the Great Plains region of North America that plays an important ecological role in aquatic systems. This study was conducted to describe population dynamics of sand shiners including age structure, growth, mortality, and recruitment variability in 15 non-wadeable rivers in Iowa. Fish were collected during June-August (2007-2008) using a modified Missouri trawl, a seine, and boat-mounted electrofishing. Scales were removed for age and growth analysis. A total of 3,443 fish was sampled from 15 populations across Iowa, of which 676 were aged. Iowa's sand shiner populations consisted primarily of age-1 fish (53% of all fish sampled), followed by age-2 fish (30%), age-0 fish (IS%), and age-3 fish (2%). Sand shiners grew an average of 38.5 mm (SE = 5.7) during their first year, 13.8 mm (4.5) during their second year, and 9.0 mm (6.9) during their third year. Total annual mortality varied from 35.0% to 92.3% among populations with a mean of 77.9% (0.2). Incremental mortality rates were 84.5% (0.2) between age 1 and age 2, and 92.0% (0

Shape analysis of the jaws between two minnow species over ontogeny

“…However, few studies detail the relationship between ontogenic shifts in diet and morphological shape changes of the oral and pharyngeal jaw (Hellig et al, ). The present study provides evidence for a change in the oral and pharyngeal jaw shape in sand shiner and silverjaw minnows corresponding with the dietary shift reported in the literature from insect larvae to small invertebrates (Smith et al, ). Despite the fact that we did not observe such marked shift in our own content analysis, we saw a considerable less reliance on filamentous algae in larger size classes which could also be related to the erosion of gape limitations for prey capture.…”

“…The Cyprinidae family makes up 64% to 83% of species found in the Great Plains rivers of North America (Berry, ). Within this family, sand shiner and silverjaw minnows are among the most abundant species (Hoyt, ; Smith, Neebling, & Michael, ). These two species are known to overlap in distribution, habitat, and prey selection (Gillen & Hart, ).…”

“…Silverjaw minnows reach maturity after one year as well and lay their eggs on the stream benthos (Wallace, ). Reported maximum sizes for the species from the literature are 82 mm for sand shiner minnows (Smith et al, ) and 98 mm for silverjaw minnows (Hoyt, ). However, in Kickapoo Creek, IL where our specimens were collected, fish maximum recorded values are 86 mm for sand shiner and 126 mm for silverjaw minnows.…”

“…However, in Kickapoo Creek, IL where our specimens were collected, fish maximum recorded values are 86 mm for sand shiner and 126 mm for silverjaw minnows. Sand shiner and silverjaw minnows are benthic feeders, and both species have been documented to undergo a prey shift from insect larvae to terrestrial and aquatic invertebrates (Smith et al, ; Wallace, ). Even though these two minnows' diets overlap, they do vary in the proportions of prey they choose to feed on (Gillen & Hart, ; Wallace, ).…”

Seasonality, floods and droughts structure larval fish assemblages in prairie rivers

“…Variable environmental conditions in the Great Plains region seem to result in erratic recruitment among years; however, protracted spawning seasons and spawning events in response to particular environmental cues provide these species ample opportunity to persist (Smith, Beebling, & Quist, ). Subtle variability in spawning tactics of prairie fishes and an apparent seasonal progression of larval fish taxa that secondarily respond to disturbance regimes suggests that reproductive efforts are adapted to maximise the potential for successful recruitment in these dynamic systems.…”