Geology topics

William D. Hintz

Publications and source records attributed to William D. Hintz.

5 recordsLinked to original sources

USGS2026

Rearing method has limited effect on post-release movement of reintroduced age-0 Lake Sturgeon

Overfishing, habitat loss, and pollution caused the extirpation of Lake Sturgeon ( Acipenser fulvescens ) throughout much of the Great Lakes. A Lake Sturgeon reintroduction program using two rearing strategies began in 2018 in the Maumee River, a tributary of Lake Erie. We assessed the movement of streamside or traditionally reared age-0 Lake Sturgeon using acoustic telemetry to determine if rearing strategy affected river residency, movement, and the habitat area used. Tagged sturgeon generally left the Maumee River for Lake Erie on average 3–47 days after stocking and spent most of their time in the western basin of Lake Erie. The majority of sturgeon moved through nearshore areas along the south shore of Lake Erie. While we found no differences in post-stocking movements or habitat area used between the two rearing strategies, understanding how older life stages respond to rearing strategy is needed. Adding upstream stocking sites, using source water to raise eggs or larvae if excessive straying becomes evident, and increased acoustic receiver coverage are options to facilitate and evaluate successful recovery of Lake Sturgeon.

Ohio↗

USGS2026

A Bayesian hierarchical modeling approach for species diversity in ecology

Species diversity is the foundation of many ecological disciplines. This metric is often approximated using species richness and evenness, even though actual richness likely exceeds observations due to imperfect sampling methods. Estimating the “true” species richness, which includes identifying the number of missing species, has intrigued ecologists for decades. We adopted a parametric model that appeared in Fisher et al. (1943), which models the numbers of individuals from different species as random samples from a negative binomial distribution, and developed a Bayesian computational approach to directly estimate the distribution model parameters. The model parameters represent species abundance and evenness, and can be used to derive species richness. We evaluated our parametric approach using (1) a simulation study and (2) three historical data sets. Furthermore, we illustrated the hierarchical modeling approach to combine data from multiple parallel studies using a biannual fishery survey data set. Our parametric model formulation is computationally efficient, and the hierarchical structure facilitates embedding diversity estimation into broader application, such as assessing spatial and temporal trends in species diversity associated with environmental stressors. Additionally, because the two parameters of the negative binomial distribution model represent species abundance and evenness of a community, this parametric approach facilitates a deeper understanding of the ecological systems under study. The negative binomial distribution model works with a wide range of species frequency distribution types. As a result, our emphasis on a parametric model can help us characterize the structure of an ecosystem and provide a greater depth of ecologically meaningful information.

Ecological Informatics↗

USGS2025

First-year survival of Lake Sturgeon reintroduced to the Maumee River

Objective Lake Sturgeon Acipenser fulvescens have experienced large population declines due to overfishing, habitat degradation, and pollution. Due to these factors, Lake Sturgeon were extirpated from the Maumee River watershed (Ohio, United States). In 2018, a 20-year reintroduction program began that aims to establish a self-sustaining population in the Maumee River. To understand the potential success of the reintroduction program, our objectives were to estimate poststocking survival of reintroduced Lake Sturgeon from age 0 to age 1. We also wanted to understand whether survival differed between age-0 Lake Sturgeon reared in a streamside facility and those reared in a traditional hatchery. Methods Lake Sturgeon from the two facilities were surgically implanted with acoustic transmitters; tagged fish ( n = 40 per year) were released into the Maumee River in 2018, 2019, and 2021, and their movements were monitored by the Great Lakes Acoustic Telemetry Observation System. Results Approximately 75% of Lake Sturgeon were detected at 100 d after release and 50% were detected at 200 d after release. We found no differences in tag attrition between the two rearing strategies. Monthly survival estimates for Lake Sturgeon were 0.87 (95% CI = 0.81–0.92) in 2018, 0.97 (95% CI = 0.89–0.99) in 2019, and 0.95 (95% CI = 0.90–0.97) in 2021. No differences in survival between rearing strategies within release years existed. Annual survival estimates ranged from 0.19 to 0.71 among the three release years. Conclusions Our results, along with known survival rates for adult Lake Sturgeon, suggest that achieving the goal of 1,500 naturally reproducing individuals in the Maumee River is possible if reintroduced fish return to the Maumee River to spawn as adults.

Ohio↗

USGS2025

Dead giveaway: Rising mortality rates suggest effectiveness of Lake Erie grass carp (Ctenopharyngodon idella) response

Grass carp ( Ctenopharyngodon idella ) are large, invasive fish that threaten Lake Erie’s economy and ecosystem. Incidental catches of grass carp have occurred since the 1980s in Lake Erie, while multi-day removal events were carried out in 2014 and 2017. To mitigate ecosystem impacts, a large-scale, multi-agency response to remove as many grass carp as possible from the Lake Erie basin (“strike teams”) began in 2018 and has increased every year. To date, total annual removals of fish has been the primary measure of progress; however, total annual removals do not indicate how efforts are affecting the grass carp population. Population vital rates, such as mortality rate, can indicate population demographic changes and may provide an alternative approach to measure how removals have impacted the grass carp population. We estimated annual mortality rates using 553 grass carp, representing 82.9 % of all grass carp removed in the Lake Erie basin, using a hierarchical catch-curve model and catch-at-age data from 2014 to 2022. Annual average mortality rates were initially low (4.3 %) and increased between 2017 and 2022 with the highest mortality (13.6 %) observed in 2021. Positive correlations between mortality and the number of fish harvested per year suggest that removals may be driving increases in the grass carp mortality rate. This increase in mortality rate shows promise for controlling the spread of grass carp within the Lake Erie ecosystem. This research supports the needs of fishery managers to better understand grass carp population dynamics and the adaptive management framework identified in the Lake Erie Grass Carp Adaptive Response Strategy.

Lake Erie↗

USGS2021

Towards improving an Area of Concern: Main-channel habitat rehabilitation priorities for the Maumee River

The Maumee River watershed in the Laurentian Great Lakes Basin has been impacted by decades of pollution and habitat modification due to human settlement and development. As such, the lower 35 km of the Maumee River and several smaller adjacent watersheds comprising over 2000 km 2 were designated the Maumee Area of Concern (AOC) under the revised Great Lakes Water Quality Agreement in 1987. As part of pre-rehabilitation assessments in the Maumee AOC, we assessed fish and invertebrate communities in river km 24–11 of the Maumee River to identify: 1) areas that exhibit the highest biodiversity, 2) habitat characteristics associated with high biodiversity areas, 3) areas in need of protection from further degradation, and 4) areas that could feasibly be rehabilitated to increase biodiversity. Based on benthic trawl data, shallow water habitats surrounding large island complexes had the highest fish diversity and catch per unit effort (CPUE). Electrofishing displayed similar fish diversity and CPUE patterns across habitat types early in the study but yielded no discernable fish diversity or CPUE patterns towards the end of our study. Although highly variable among study sites, macroinvertebrate density was greatest in shallow water habitats <2.5 m and around large island complexes. Our results provide valuable baseline data that could act as a foundation for developing rehabilitation strategies in the lower Maumee River and for assessing the effectiveness of future aquatic habitat rehabilitation projects. In addition to increasing in-channel habitat, watershed-scale improvements of water quality might be necessary to ensure rehabilitation strategies are successful.

Ohio↗