Population Characteristics of Shovelnose Sturgeon in the Upper Wabash River, Indiana

Abstract

Shovelnose sturgeon Scaphirhynchus platorynchus support a commercial fishery throughout much of the Mississippi and Missouri River drainages. There is concern that harvest closures for Eurasian sturgeons (Acipenseridae) may result in increased exploitation of shovelnose sturgeon to meet global demands for caviar. Population attributes of shovelnose sturgeon were examined in the upper Wabash River, Indiana, from April 2003 through November 2004 between Wabash and Terre Haute. Fish (N ¼ 4,849) were captured by direct current electrofishing, experimental gill nets, and benthic trawls. Electrofishing catch per unit effort varied on a temporal basis, being highest for both reaches from March through May. The fork length of captured fish ranged from 273 to 858 mm, but few fish less than 550 mm were captured. Median fork length and wet weight were 683 mm and 1,208 g, respectively (ranges ¼ 273-858 mm and 52-3,381 g). Shovelnose sturgeon ranged from ages 2 to 30, with 95% of the fish between ages 9 and 20. Total annual mortality for fish between ages 13 and 18 was 20%. Empirical growth rates derived from recaptured fish were slow; 74% of the fish exhibited negative or no growth. The population characteristics of shovelnose sturgeon in the upper Wabash River were within the ranges reported for other river systems, but fish attained a larger body size, reached older age-classes, and experienced lower mortality rates than did some other populations. The results from this study will allow for the detection of shifts in abundance, size and age structure, and gender ratio in response to harvest or natural perturbations and promote the development of appropriate management actions to ensure the sustainability of this species and its fishery.

A Comparison of Methods to Estimate Shovelnose Sturgeon Mortality in the Mississippi River Adjacent to Missouri and Illinois

“…In our study, FL frequency distributions, age estimates, and length-atage data were within the range of other similar studies (Figure 1; Morrow et al 1998;Kennedy et al 2007), suggesting a potential lack of aging error. As for other assumptions associated with catch-at-age models, constant recruitment is rarely observed in fish stocks (Maceina and Pereira 2007;Miranda and Bettoli 2007;Phelps et al 2010).…”

Blue sucker stock characteristics in the Wabash River, Indiana–Illinois, USA

“…1). The drainage area is approximately 85 500 km 2 (Kennedy, Daugherty, Sutton & Fisher 2007). The upper section of the Wabash River (upstream of Lafayette‐West Lafayette, Indiana) is characterised by shallow (0.3–3 m) water depths and sand, gravel, cobble and bedrock substrates.…”

Range-wide age and growth characteristics of shovelnose sturgeon from mark–recapture data: implications for conservation and management

“…Interpreting age and growth from calcified structures assumes that annuli are formed at a constant frequency and the distance between annuli is proportional to a fish's somatic growth (Campana and Neilson 1985). However, the accuracy of age estimates obtained from such structures is rarely successfully validated (i.e., absolute age; Campana 2001), and several authors have reported use with caution especially with shovelnose sturgeon (Scaphirhynchus platorynchus) (Whiteman et al 2004;Jackson et al 2007;Kennedy et al 2007;Killgore et al 2007). Recent work by Hamel et al (2014) concluded that the assumptions of consistent annuli deposition and proportionality of annuli spacing to fish somatic growth are violated for pallid sturgeon (Scaphirhynchus albus).…”