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

Abstract

We used mark-recapture data from shovelnose sturgeon (Scaphirhynchus platorynchus) to describe range-wide growth characteristics and developed a model to estimate ages. Data were solicited throughout much of the current distribution of shovelnose sturgeon, specifically from the mainstem Missouri and Mississippi rivers and their tributaries. Shovelnose sturgeon exhibited variable growth among locations; however, adult fish exhibited almost no growth after they reached a particular size, presumably the size at sexual maturity. Shovelnose sturgeon from the Mississippi River basin attained greater maximum sizes and ages compared with the Missouri River basin. However, two populations from the Mississippi River that received high exploitation from commercial harvest had truncated age distributions with smaller asymptotic lengths. Lower Missouri River populations were characteristic of exploited populations (i.e., smaller fish and reduced longevity), presumably a result of anthropogenic effects. Wide discrepancies in maximum age and size suggest shovelnose sturgeon are capable of displaying phenotypic plasticity in response to exploitation or environmental influences. Determining metapopulation dynamics is a priority because it is unknown how population connectivity may influence dynamic rate functions and persistence of large-river fishes. Identifying potential source-sink connections in terms of population dynamics may provide a template for direction of future restoration and recovery efforts.Résumé : Nous avons utilisé des données de marquage-recapture d'esturgeons scaphirhynques (Scaphirhynchus platorynchus) pour en décrire les caractéristiques de croissance sur l'ensemble de leur aire de répartition et élaborer un modèle pour estimer les âges. Des données ont été sollicitées dans la majeure partie de l'aire de répartition actuelle de l'espèce, plus précisément des bras principaux de la rivière Missouri et du fleuve Mississippi et leurs affluents. Si la croissance des esturgeons scaphirhynques varie selon la localité, les poissons adultes ne présentent presque aucune croissance après avoir atteint une taille donnée, vraisemblablement leur taille à maturité sexuelle. Les esturgeons scaphirhynques du bassin du Mississippi atteignent des tailles et des âges maximums supérieurs à ceux du bassin de la rivière Missouri. Cependant, deux populations du Mississippi faisant l'objet d'une forte exploitation commerciale présentent des distributions d'âges tronquées et des longueurs asymptotiques plus faibles. Les populations du cours inférieur de la rivière Missouri sont caractéristiques des populations exploitées (c.-à -d. poissons plus petits de longévité réduite), vraisemblablement le résultat d'effets d'origine humaine. De grandes divergences sur le plan de l'âge et de la taille maximums donnent à penser que les esturgeons scaphirhynques peuvent faire preuve de plasticité phénotypique en réaction à l'exploitation ou à des influences environnementales. La détermination de la dynamique des métapopulations constitue une prio...

Habitat use and population characteristics of potentially spawning shovelnose sturgeonScaphirhynchus platorynchus(Rafinesque, 1820), blue sucker (Cycleptus elongatus(Lesueur, 1817), and associated species in the lower Wisconsin River, USA

“…We observed negligible growth in shovelnose sturgeon and very slow growth in blue sucker, <1% per year. A meta‐analysis of 14 shovelnose sturgeon populations (including the LWR) throughout the species range concluded that most fish had almost no growth in length after they reached maturity (Hamel et al., ). In the Red Cedar‐Chippewa River system, Wisconsin, recaptured shovelnose sturgeon had only grown an average of 0.75 mm/year since tagging (Christenson & Hatzenbeler, ), well within the range of measurement error (Phelps et al., ).…”

“…These three aforementioned explanations are not mutually exclusive and could all be occurring in the LWR, although we believe that number three is most important. A von Bertalanffy analysis for LWR shovelnose sturgeon estimated a maximum age of over 60, the highest of any of 14 populations analyzed (Hamel et al., ). However, the oldest ages ever actually reported for any populations based on fin rays were 43 for shovelnose sturgeon (Everett et al., ) and 37 for blue sucker (Bednarski & Scarnecchia, ).…”

Influence of PIT tags on growth and survival of banded sculpin (Cottus carolinae): implications for endangered grotto sculpin (Cottus specus)

“…Such mark-recapture studies can provide a nonlethal way to monitor and assess population characteristics, thus being an effective tool for monitoring endangered species. Specifically, the information that can be provided by mark-recapture studies includes insight into growth, recruitment, and mortality, providing insight into the ecological function of a species which is essential for fisheries conservation and restoration decisions (Gibbons and Andrews, 2004;Ruetz III et al, 2006;Skalski et al, 2009;Hamel et al, 2015;Ruetz III et al, 2015). Mark-recapture studies are an effective tool when evaluating population dynamics and ecological role and can allow researchers the ability to make better restoration decisions concerning grotto sculpin and the cave ecosystems they inhabit.…”

“…Previous researchers have used mark-recapture studies to evaluate fish population dynamics (Hamel et al, 2015;Ruetz III et al, 2015). Data garnered from these studies generally include measures of growth, movement, habitat use, and survival, all of which are imperative for fisheries conservation or restoration (Hamel et al, 2015;Ruetz III et al, 2015).…”

“…Data garnered from these studies generally include measures of growth, movement, habitat use, and survival, all of which are imperative for fisheries conservation or restoration (Hamel et al, 2015;Ruetz III et al, 2015). However, obtaining these data requires utilization of batch marking or individual recognition methods, which can be problematic, especially on small fishes (Baras et al, 1999;Brown et al, 1999;Skalski et al, 2009).…”