Freshwater mussels are a globally diverse and fundamental group in aquatic ecosystems. However, 65% of freshwater mussel species have become endangered over the past century and 10% of them are ...already extinct. Natural population preservation and restoration efforts have been expedited, but the complicated life history of this taxon presents many challenges since species‐specific ecology involved in restoration projects is often poorly understood.
Lampsilis cardium is an imperilled freshwater mussel in Nebraska, USA. A reintroduction project has been carried out to restore L. cardium populations among three streams in Nebraska, during autumn 2016 and summer 2017. A 2‐year mark–recapture study was used to determine habitat, timing and size‐at‐introduction effects on mussel survival and growth following introduction. Water quality and habitat parameters were seasonally recorded from each site to assess potential effects on mussel growth and survival.
The highest daily growth rates of L. cardium ranged between 145 and 185 μm d−1, whereas the lowest daily growth rates observed were ∼88–107 μm d−1, with the greater rate of shell growth always recorded for those individuals introduced in spring and lower for those individuals introduced in summer or autumn. Survival models indicated that mussels were most susceptible to mortality immediately following introduction in spring, whereas size at introduction had almost no effect on survival. At each site, habitat parameter measurements recorded during different seasons indicated that calcium availability, water temperatures, water depth and water quality may contribute to differences in growth and survival rates.
Survival rate estimation and population growth predictions are essential knowledge to understand population dynamics; this study provides useful information and a framework for management decisions that may influence L. cardium population dynamics, such as identifying more suitable habitats and introduction times not only for this species but also other similar unionids.
•The quantity of use that natural resource systems receive is often unknown.•Natural resource system size indicates the quantity of resource use received.•Resource size-use models can improve natural ...resource management.
Outdoor recreation provides societal benefits that are often measured by the amount of use natural resource systems receive. Still, the amount of resource use natural resource systems receive is often unknown or unstudied. Monitoring and quantifying resource use is often logistically difficult and costly but is paramount to optimize societal benefits. Identifying a simple and readily available metric that can indicate the quantity of recreational use of natural resource systems would benefit natural resource management. Using recreational angler participation data during an 11-year study period from 73 public waterbodies in Nebraska, USA, we developed a resource size-use model that demonstrates the ability of natural resource system size to indicate the quantity of recreational use they receive. We demonstrate how resource size-use models can estimate use for unsampled systems, produce broad-scale estimations of use, guide the allocation of resources, and predict how changes in resource system size may affect use. Resource size-use models provide opportunities to manage recreational use, which has been previously elusive for social-ecological systems.
Handling freshwater mussels may have negative impacts on their survival, growth, or reproduction, and this may affect our interpretation of how mussels respond to research and conservation actions. ...The goal of this study was to investigate how repeated dislodgement and emersion during handling affects survival and growth of plain pocketbook
Lampsilis cardium
. Sixty mussels were exposed to one of the four handling rates: (1) control (no handling), (2) handled every other week, (3) handled once per week, or (4) handled twice per week, during an 85-day laboratory experiment in 2017. Absolute daily growth rates were compared among control and treatment group mussels. Growth rates were positive for > 98% of mussels and no mortality occurred. A likelihood ratio test indicated that growth rates did not differ among treatment groups (
χ
2
(3) = 1.32,
P
= 0.72). The best growth rate model was an intercept-only model which predicted that an average mussel grew 0.0088 mm/day (95% confidence interval 0.0070–0.0106). Our results suggest that
L. cardium
survival and growth is not compromised by short-term, repeated handling as often as twice per week, but consideration of handling procedures and mussel characteristics is necessary to fully understand how handling may affect other mussels.
Bighead and silver carp are well established in the Mississippi River basin following their accidental introduction in the 1980s. Referred to collectively as Asian carp, these species are filter ...feeders consuming phytoplankton and zooplankton. We examined diet overlap and electivity of Asian carp and three native filter feeding fishes, bigmouth buffalo, gizzard shad, and paddlefish, in backwater lakes of the Illinois and Mississippi rivers. Rotifers, Keratella spp., Brachionus spp., and Trichocerca spp., were the most common prey items consumed by Asian carp and gizzard shad, whereas crustacean zooplankton were the preferred prey of paddlefish. Bigmouth buffalo diet was broad, including both rotifers and crustacean zooplankton. Dietary overlap with Asian carp was greatest for gizzard shad followed by bigmouth buffalo, but we found little diet overlap for paddlefish. Diet similarity based on taxonomy correlated strongly with diet similarity based on size suggesting filtration efficiency influenced the overlap patterns we observed. Although rotifers were the most common prey item consumed by both bighead and silver carp, we found a negative relation between silver carp CPUE and cladoceran density. The competitive effect of Asian carp on native fishes may be forestalled because of the high productivity of Illinois and Mississippi river habitats, yet the potential for negative consequences of Asian carp in less productive ecosystems, including Lake Michigan, should not be underestimated.
Invasive Silver Carp (
Hypophthalmichthys molitrix
) have established populations throughout the Missouri River basin. The main-stem Missouri River has undergone a multitude of alterations, creating ...a channel with greater mean depths and velocities, limiting optimal habitat for Silver Carp. Tributaries to the Missouri River may provide refuge from the swift flows within the main-stem Missouri River and, therefore, may play a vital role in the life-cycle of Silver Carp throughout the basin. Understanding the spatial extent under which these invasive fish function in this large, open river system is crucial to inform management efforts. Here, we used otolith microchemistry of Silver Carp from the Kansas River, a major tributary to the Missouri River, to reconstruct environmental histories as a means to assess the proportions of resident (individuals who never left the Kansas River system) and transient (individuals who at some point occupied the Missouri River) individuals. Silver Carp within the Kansas River were predominantly residents (adults = 54%; juveniles = 65%) with the majority of reproduction coming from within the Kansas River itself. These results suggest removal efforts in the Kansas River may be effective means of managing this invasive fish species. Transient fish exhibited short durations of signatures indicative of the Missouri River (mean percent of data points for adults = 10% and juveniles = 36%), suggesting movements into the Missouri River were brief. These results highlight the importance of connectivity of tributary habitat among large rivers and provides important information for invasive species management.
The ability to adapt to changing environments is fundamental for species persistence. Both plasticity and genetic selection are potential drivers that allow for traits to be advantageous, thus ...leading to increases in survival or fitness. Identifying phenotypic plasticity in life history traits of long-lived organisms can be difficult owing to high survival, long generation times, and few studies at sufficient spatial and temporal scales to elicit a plastic response within a population. To begin to understand phenotypic plasticity of a long-lived freshwater fish in response to environmental conditions, we used a long-term data set consisting of over 1,200 mark-recapture events to inform our understanding of dynamic rate functions and life history attributes. Furthermore, we used a common garden experimental approach to confirm whether changes in life history traits are in response to plasticity in the reaction norm or are genetically derived. Using these approaches, we demonstrated differences in life history traits among Pallid Sturgeon (Scaphirhynchus albus) occupying river segments of varying physical and hydrological stress. The common garden experiment corroborated plastic phenotypic expression in reaction norms for age at first maturity, longevity, fecundity, and maximum size. These growth-mediated attributes resulted in differences in overall fitness traits, where Pallid Sturgeon fecundity was greater than a tenfold difference and 3-6 times the number of life-time spawning events. Anthropogenic modifications to river form and function are likely responsible for the variation in life history attributes resulting from an increased metabolic demand for maintaining station, foraging, and migration. Collectively, our approach provided surprising insight into the capabilities of a centenarian fish to dramatically respond to a changing environment.
Since the 1970s, waterfowl hunting participation has declined in the United States, which has resulted in socioeconomic consequences for waterfowl conservation and management. Attempts to increase ...the waterfowl hunter population have been difficult, partly due to social factors (e.g., constraints, motivations, demographics) influencing who participates, frequency of participation, and diversity of desired outcomes from hunting experiences. We examined the preferences of 10 potential management options by hunters and anglers from several states in the central U.S. during 2018. Respondents were grouped into the following activity groups based on responses to survey questions: frequent waterfowl hunters, sporadic waterfowl hunters, previous waterfowl hunters, hunters (never hunted waterfowl), and nonhunters (anglers who have never hunted). All ordinal models indicated that the ability of the scenario to increase participation significantly (P < 0.05) depended on the activity group. Scenarios, including Having someone to take the respondent hunting (probability of increasing participation > 0.35 for all activity groups) and Special areas for new waterfowl hunters, had the greatest indication (probability > 0.40) of increased waterfowl hunting participation across activity groups. Frequent and sporadic waterfowl hunters ranked Special areas to allow for a quality hunt highest, while hunters and non‐hunters ranked Someone to take me hunting as the most preferred scenario. Information for what new/inexperienced hunters need, Classes or materials to teach waterfowl ID, and Ability to rent equipment were scenarios consistently ranked as the lowest for all activity groups. Our research underscores that only some of the scenarios had the same appeal to all activity groups, which implies a need for a greater diversity of experiences in the landscape of public waterfowl hunting access. Also, continued promotion of current waterfowl hunters taking new or inexperienced individuals may increase waterfowl hunting participation.
With waterfowl hunting participation declining, we assessed ten hypothetical management actions to increase participation. Overall, respondents were likely to increase or maintain participation for the management actions being assessed. Based on our results, easy management actions may not have the ability to increase overall participation and expanding and altering traditional approaches may be necessary.
Telemetry and mark-recapture provide movement information, but each approach comes with tradeoffs, potentially producing conflicting understandings of fish movement patterns. Using a Bayesian ...framework that allows exchanging priors from either method may help assess these inconsistencies. We evaluated channel catfish Ictalurus punctatus movements in the Red River of the North and Lake Winnipeg system, which impacts harvest management across different jurisdictions and affects different ecosystems (e.g., lotic and lentic). Channel catfish were tagged with T-bar tags or acoustic transmitters. The resulting movement data were modeled using a Bayesian multi-state Cormack-Jolly-Seber model to estimate survival, movement, and recapture probabilities. Model estimates with uninformative priors showed a greater tendency of downstream movement from the Red River into Lake Winnipeg for the T-bar tags. In contrast, the telemetry method showed fish predominantly stay in the river. However, exchanging increasingly stronger prior information from the alternative method's model revealed that telemetry movement estimates were less sensitive than the T-bar model to informative priors. Using priors from both methods provided a transparent means to assessing tagging approach tradeoffs quantitatively.
Understanding movement and dispersal dynamics of mobile, large‐river fishes is essential to adopting an ecologically relevant spatial scale for research and management. Movement and dispersal ...patterns of Blue CatfishIctalurus furcatus, a large‐river specialist, have been mostly investigated in large river systems within their native range, with little emphasis on tributaries and the influence of connectivity. Here, we examine longitudinal movement patterns, natal environments, and population demographics of Blue Catfish in a tributary system of a large Great Plains river. Blue Catfish tagged in the Kansas River were recaptured in five different rivers of varying size and order, and individual movement was highly variable (0–475 rkm). Adult fish (>400 mm) collected within segments (i.e., Segment 1 and 2) of the Kansas River with connectivity to the Missouri River displayed relatively equal natal contributions from the Kansas River (34–48%) and Missouri River (38–65%) while disconnected river segments contained a high percentage (64–87%) of individuals that originated from reservoirs located on tributaries to the Kansas River. The Kansas River segments (Segment 1 and 2) connected with the Missouri River had lower instantaneous mortality (Z = 0.19, SE = 0.05) and higher proportions of large fish (PSD‐M = 9 & 11, PSD‐T = 3 & 5, respectively) compared to disconnected reaches (Z = 0.27, SE = 0.08; PSD‐M = 3, PSD‐T = 0). Mean length of Blue Catfish collected in disconnected reaches were greater than those from connected reaches for individuals at age‐3 and age‐6, and relatively equal at age‐10. Our data provide additional resolution to movement and dispersal patterns of Blue Catfish within large‐river tributary systems, highlight the role of localized reservoir stock contributions, and illustrate species plasticity across varying levels of river network connectivity.
Motivations for hunting and fishing extend beyond harvesting game and include social, psychological, emotional, and physical benefits. We used data from a web-based questionnaire to compare ...relationships between preferred hunting or fishing activity types, state of residence, and motivations of hunters and anglers across the central United States (U.S.). Exploratory factor analysis yielded four motivation factors: nature, social, food, and challenge. Differences in terms of state were negligible across all motivation factors (
), indicating similarity across states. Nature (
) and social (
) factors were the first and second most important factors across activity types. We observed larger differences among the challenge (
), and food (
) factors, primarily driven by big game hunters. Big game hunters rated the food motivation factor greater than the other activity types. Overall, our results indicate that there might be a greater universality in these motivation factors among activity types and locations in the U.S.
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