Jason A. DeBoer

Using the internet to understand angler behavior in the information age

ABSTRACT Declining participation in recreational angling is of great concern to fishery managers because fishing license sales are an important revenue source for protection of aquatic resources. This decline is frequently attributed, in part, to increased societal reliance on electronics. Internet use by anglers is increasing and fishery managers may use the Internet as a unique means to increase angler participation. We examined Internet search behavior using Google Insights for Search, a free online tool that summarizes Google searches from 2004 to 2011 to determine (1) trends in Internet search volume for general fishing related terms and (2) the relative usefulness of terms related to angler recruitment programs across the United States. Though search volume declined for general fishing terms (e.g., fishing, fishing guide), search volume increased for social media and recruitment terms (e.g., fishing forum, family fishing) over the 7-year period. We encourage coordinators of recruitment programs to c...

Movement and Habitat Use by Mottled Sculpin After Restoration of a Sand-Dominated 1st-Order Stream

Abstract Anthropogenic activities have greatly altered the natural flow regime of lotic ecosystems in many ways, including dams and culverts, which restrict sediment transport and fragment fish habitat. Sculpins, Cottus spp., are an important food-web link between macroinvertebrates and larger stream fishes and are greatly affected by culverts. Results from a previous study indicate a substantial increase in the relative abundance of mottled sculpin, Cottus bairdii, was observed upstream of a renovated road-stream crossing during the first season after construction. Redistribution of this nature from a putatively sedentary species would have required substantial movement. Our objectives were to quantify post-restoration mottled sculpin movement and habitat use in a restored stream reach. The extent of post-restoration mottled sculpin movement and habitat use were directly measured using telemetry of Passive Integrated Transponder (PIT) tag-marked fish. The maximum linear distance moved by a marked mottled sculpin was 839 m; 23% of marked mottled sculpin moved >100 m. The number of detections of marked mottled sculpin in each segment was significantly correlated with the amount of small wood (5–10 cm diameter). Increased distribution of mottled sculpin in previously unavailable upstream habitats coupled with substantial post-restoration movement distances provides new insight on their potential for redistribution following habitat reconnection, which is an important consideration for stream restoration projects.

Freshwater mussel shells (Unionidae) chronicle changes in a North American river over the past 1000 years

The Illinois River was substantially altered during the 20th century with the installation of navigational locks and dams, construction of extensive levee networks, and degradation of water quality. Freshwater mussels were affected by these changes. We used sclerochronology and stable isotopes to evaluate changes over time in age-and-growth and food sources for two mussel species: Amblema plicata and Quadrula quadrula. Specimens were collected in years 1894, 1897, 1909, 1912, 1966, and 2013, and archeological specimens were collected circa 850. The von Bertalanffy growth parameter (K) was similar between 850 and 1897, but it increased by 1912 and remained elevated through 2013. Predicted maximum size (Linf) increased over the past millennium, and 2013 individuals were over 50% larger than in 850. Growth indices showed similar patterns of continual increases in growth. Shells were enriched in 13C and 15N during the 20th century, but exhibited a partial return to historical conditions by 2013. These patterns are likely attributable to impoundment, nutrient pollution and eutrophication beginning in the early 20th century followed by recent water quality improvement.

The influence of a severe reservoir drawdown on springtime zooplankton and larval fish assemblages in Red Willow Reservoir, Nebraska

Reservoirs can be dynamic systems, often prone to unpredictable and extreme water-level fluctuations, and can be environments where survival is difficult for zooplankton and larval fish. Although numerous studies have examined the effects of extreme reservoir drawdown on water quality, few have examined extreme drawdown on both abiotic and biotic characteristics. A fissure in the dam at Red Willow Reservoir in southwest Nebraska necessitated an extreme drawdown; the water level was lowered more than 6 m during a two-month period, reducing reservoir volume by 76%. During the subsequent low-water period (i.e., post-drawdown), spring sampling (April–June) showed dissolved oxygen concentration was lower, while turbidity and chlorophyll-a concentration were greater, relative to pre-drawdown conditions. Additionally, there was an overall increase in zooplankton density, although there were differences among taxa, and changes in mean size among taxa, relative to pre-drawdown conditions. Zooplankton assemblage composition had an average dissimilarity of 19.3% from pre-drawdown to post-drawdown. The ratio of zero to non-zero catches was greater post-drawdown for larval common carp and for all larval fishes combined, whereas we observed no difference for larval gizzard shad. Larval fish assemblage composition had an average dissimilarity of 39.7% from pre-drawdown to post-drawdown. Given the likelihood that other dams will need repair or replacement in the near future, it is imperative for effective reservoir management that we anticipate the likely abiotic and biotic responses of reservoir ecosystems as these management actions will continue to alter environmental conditions in reservoirs.

Ecological Recovery of a River Fish Assemblage following the Implementation of the Clean Water Act

The twentieth century spanned an era that included nadirs in environmental quality and subsequent efforts to improve ecological conditions. The Illinois Waterway, a large river system in Illinois, experienced prolonged degradation followed by a dramatic recovery. In the 1950s, a standardized sampling program was initiated that has continued for six decades. The resulting record documents profound ecological changes, demonstrating the potential for river ecosystems to recover following the successful implementation of large-scale policies, notably the Clean Water Act. Over six decades, native species diversity has increased, and one of the most prolific invasive fish species has collapsed. In addition, the sampling record highlights the recovery of socioeconomically valuable sport-fish populations. We examined the causes and consequences of change in a large river using data from a long-term monitoring program with unique spatial and temporal extent. The trends documented in the Illinois Waterway are relevant for the restoration of river systems worldwide.

A 100-year Flood in a Low-Gradient Stream: Response of the Resident and Non-resident Fish Assemblages

Abstract Resident fish exhibited higher short-term resiliency than did non-resident fish to a 100 y flood in a low-gradient stream. In Jun. 2008, a substantial flood (400% higher than mean daily discharge) occurred in the Big Manistee River watershed in Michigan. Pre- and post-flood fish communities were sampled at two sites on Bear Creek, a 4th order tributary of the Big Manistee River. One site was low-gradient and dominated by sand; the second site was higher gradient and dominated by large woody debris and fine gravel. At both sites, post-flood fish communities were similar to pre-flood communities (Morisitas Index (Im) ≈ 0.8), especially for resident fish (Im ≈ 0.95). Total Catch Per Unit Effort (CPUE) of non-resident fish declined dramatically (5.2 to 1.4 fish per minute) in post-flood surveys, whereas CPUE of resident fish increased slightly (4.3 to 4.7) post-flood. Individual species response was site-dependent and mixed: CPUE of mottled sculpin and burbot increased post-flood, whereas CPUE of other resident species decreased. Resident non-native (i.e., rainbow trout) and non-resident non-native salmonids (i.e., Chinook salmon) experienced the most negative response, suggesting life-history traits of native fish encompass evolutionary adaptations to better persist through extreme disturbance events as compared to non-native salmonids.

Survey of Intersex Occurrence in Largemouth Bass (Micropterus salmoides) from the Upper Illinois River Waterway

Abstract Intersex condition (ooctyes in testicular tissue) has been documented in many watersheds among a diverse variety of fishes worldwide. However, few studies have tested for the occurrence of the condition in fishes from rivers of the American Midwest. Midwestern watersheds, such as the Illinois River Waterway, U.S.A. may provide important new information about the effects of endocrine disrupting chemicals (EDCs) on fishes because of the variety of urban, industrial, and agricultural land uses within the watersheds. A first step in the study of EDCs in any ecosystem is a survey to document the symptoms of EDC exposure, such as intersex condition. Our objective was to test for intersex condition in male largemouth bass Micropterus salmoides in the lower Des Plaines River, an area directly affected by surface runoff and wastewater effluents from the Chicago Metropolitan Area. Histological analysis indicated that testicular oocytes were present in 21 of 51 (41%) largemouth bass sampled and oocyte numbers ranged from 1–25/thin section among intersex individuals. Our study details the severity of intersex in a population of largemouth bass near a major metropolitan area, which represents an important contribution to the understanding of fish reproductive ecology in ecosystems with a history of environmental disturbance and recovery such as the Illinois River Waterway.

Ichthyochory in a temperate river system by common carp (Cyprinus carpio)

ABSTRACT Some fish are important dispersal vectors of aquatic plants (i.e., ichthyochory), yet few examples have been documented outside of the Neotropics. Although highly modified and degraded, the upper Illinois River Waterway supports common carp (Cyprinus carpio) populations and abundant aquatic vegetation. As common carp have been previously documented to consume aquatic vegetation seeds, we assessed diets to determine the potential for common carp to function as dispersal vectors for aquatic vegetation seeds that may be important for restoration of rivers and floodplain wetlands. Whole seeds occurred at a high frequency and 42 seed taxa were discovered in the digestive system of common carp. Electivity analysis indicated that most seeds present were incidentally ingested; however, common carp diets contained seeds of wild celery (Vallisneria americana) at rates greater than expected by random chance. Our study indicates common carp may fill a similar functional role of seed dispersal for aquatic plant communities in temperate large river systems as they do for fruiting plants in the Neotropics. Our results highlight an understudied aspect of temperate freshwater ecology – fish as a potential influence on plant dynamics and resources in rivers. Fish-mediated seed dispersal has important but poorly understood implications and should be further explored.

Estimating the Effects of Environmental Variables and Gear Type on the Detection and Occupancy of Large-River Fishes in a Standardized Sampling Program Using Multiseason Bayesian Mixture Models

AbstractSampling in non-wadeable rivers presents methodological challenges for monitoring fish species. Changing environmental conditions may affect the ability to accurately capture species (i.e., detection) and consequently may lead to inappropriate inferences on occupancy rates. We used hierarchical Bayesian multiseason mixture models to estimate occupancy and detection of 41 of 52 fish species in the Kankakee River, Illinois, by using data from a standardized monitoring program. Fish were sampled with AC boat electrofishing and shoreline seining over 7 years. Some centrarchids (e.g., Smallmouth Bass Micropterus dolomieu) were efficiently sampled by boat electrofishing, whereas most other species had low detection probabilities. Moderate changes in environmental conditions, such as water velocity and temperature, produced moderate changes in detection and occupancy. Generally, when species had high detection probabilities, changes in environmental conditions produced relatively small changes in the est...

Masked expression of life-history traits in a highly variable environment

Differing life-history strategies may act as a constraint on reproductive expression that ultimately limits the ability of individual species to respond to changes in the magnitude or frequency of environmental variation, and potentially underlies the variation often inherent in phenotypic and evolved responses to anthropogenic change. Alternatively, if there are environmental cues that predict reproductive potential, differential expression of life-history strategies may represent differences in the adaptive capacity to optimize current reproductive value given variation in environmental conditions. We compared several aspects of walleye Sander vitreus spawning ecology at two reservoirs that differ in environmental variability (i.e., annual water-level fluctuation) to identify the capacity of phenotypic expression and the corresponding association with age. Despite significant differences in female body and liver masses between reservoirs that differ in environmental variability, we found no difference in reproductive investment measured by egg size and fecundity. Walleye in a highly variable environment appear to exhibit reproductive traits more typical of a short-lived life-history strategy, which may be resultant from the interaction of environmental and anthropogenic pressures. This finding emphasizes the need to identify the degree to which life-history expression represents physiological constraints versus ecological optimization, particularly as anthropogenic change continues to alter environmental conditions.