Understanding the Decline in Yellow Perch Angling Success in Lake Erie’s Western Basin
Invasive species can threaten fishing success and fisheries production by altering food web structure and dynamics. In this vein, Bythotrephes longimanus, a large-bodied, invasive zooplankton species that has recently colonized Lake Erie’s west basin, may underlie the recent decline in angler harvest rates of Yellow Perch (Perca flavescens) despite population size remaining stable. Given previous research conducted in Lake Erie’s central and east basins, which has established that Yellow Perch consume Bythotrephes when present in the water column, we hypothesized that increased availability and consumption of Bythotrephes is responsible for decreased angling success by reducing the effectiveness of artificial prey (i.e., fishing lures). Towards this end, we have been conducting a “natural” experiment replicating angler behavior using three common gear types (e.g., spreader, crappie, and Sabiki rigs) across a range of Bythotrephes densities and environmental conditions (e.g., light, time of day, temperature).
Additionally, we have been analyzing the diets of angled Yellow Perch to determine how feeding varies with these factors. Preliminary analysis of data collected in June demonstrated no significant difference in angling success among gear types between sites with control (density = 0 individuals/m 3) versus low (n = 2-6 individuals/m3) Bythotrephes densities (two-way ANOVA, P > 0.05). This non-significant result could be attributed to a small sample size and little difference in Bythotrephes density between treatment groups. By continuing to collect data across the Bythotrephes production season (July through September), we expect to better understand the relationship between Bythotrephes density and Yellow Perch angling success, which could enhance the ability of agencies to anticipate harvest, manage angler expectations, and maximize angling success.
We have been investigating the potential effects of the spiny water flea (Bythotrephes longimanus, an invasive zooplankton species that recently colonized the west basin, on Yellow Perch angling success in western Lake Erie. Preliminary results of this study revealed that there were no significant effects of Bythotrephes density on Yellow Perch angling success. However, research is ongoing, and we expect to better learn how Bythotrephes influences angling success by sampling more sites across a wider range of Bythotrephes densities in future months. By investigating the potential effects of increasing densities of Bythotrephes, this study addresses a critical knowledge gap regarding the influence of invertebrate prey on recreational fishing. Additionally, this study contributes to a broader understanding of interactions between invasive invertebrate species, freshwater fish populations, and angler communities. Overall, the results of this study would equip the ODNR-DOW with a better ability to predict harvest, set realistic angler expectations, and offer insights on how to improve angling success.
Understanding the degree to which Bythotrephes, an invasive zooplankton species, affects western Lake Erie Yellow Perch angling success would benefit fisheries management (e.g., setting harvest quotas and angler expectations) and help to improve angling experiences.
Comparing the Success of Yearling- and Fingerling-stocked Channel Catfish
Although Channel Catfish naturally reproduce in many of Ohio’s reservoirs, the ODNR-DOW regularly stocks CCF into reservoirs due to its popularity with anglers. Management agencies often stock yearling CCF because fingerling CCF are more vulnerable to predation. However, Becher et al. (2021) found that fingerlings in ponds with no predators had a similar survival rate as those in ponds with predators and alternative prey. The ODNR-DOW has historically stocked yearling CCF even though they are more expensive to produce, and more pond space is needed. Meanwhile, fingerlings are less expensive to produce and could be an adequate stocking substitution. No system-based experiment has been conducted to compare the stocking success of these lifestages in Ohio reservoirs. Therefore, in 2016, 12 Ohio reservoirs were stocked with both lifestages of CCF, each differentially marked with coded-wire tags. In 2023, we sampled 5 reservoirs using standard tandem, baited hoop nets. We found that stocked fingerling and yearling Channel Catfish returns differed. Reservoir productivity (Secchi depth) enhances fingerling growth and survival. Additionally, the ratios of fingerlings to yearlings varied greatly when Largemouth Bass CPUE was low. However, when Largemouth Bass CPUE exceeded 100, the ratios were consistently low. The ODNR-DOW should consider stocking fingerlings in Ohio reservoirs. However, it is crucial to consider factors such as Largemouth Bass CPUE and reservoir productivity before stocking. During 2024, we plan on sampling the 7 remaining reservoirs.
To identify cost-effective Channel Catfish stocking and assessment protocols, we differentially tagged and stocked two lifestages of Channel Catfish in 12 Ohio reservoirs during 2016 and found that age-0 fingerlings can be stocked in reservoirs with low Largemouth Bass abundance and high reservoir productivity.
Analysis of expert opinion and monitoring data indicates that reservoir littoral zone degradation decreases largemouth bass abundance
Largemouth Bass (Micropterus salmoides) are an important sportfish in Ohio. Due to this, maintaining successful populations is crucial for managers. Largemouth Bass largely rely on littoral zones characterized by aquatic macrophytes and rocky substrate. However, maintaining this zone's quality is challenging due to factors like sedimentation from watershed activities and reservoir aging. We employed a comprehensive survey approach by gathering reservoir characteristics from sport fish managers throughout Ohio to determine if managers’ perception of a lower quality littoral zone 1) reduced Largemouth Bass abundance and 2) was associated with higher functional ages previously calculated from in-reservoir measurements. Through generalized linear models (GLM), we compared insufficient structural habitat and excessive aquatic macrophytes, as proxies for littoral habitat quality, to catch per unit effort (CPUE). Our findings revealed an increase in Largemouth Bass abundance with sufficient structural habitat and presence of aquatic macrophytes (R = 0.2, p < 0.05) highlighting the efficacy of using expert based survey approaches for fishery management. Additionally, we found evidence of a reduction in littoral zone quality, represented by littoral zone steepness and excessive suspended sediments, with higher functional ages (R = 0.3, p < 0.05). This provides evidence that the functional age metric from in-reservoir measurements can be a valuable tool for assessing habitat quality and in-reservoir measurements accurately capture difficult to measure littoral habitat quality. Overall, this research offers valuable insights for reservoir management, highlighting the importance of preserving high-quality littoral zones to support healthy Largemouth Bass populations and the potential benefits of the functional age index for management.
With Largemouth Bass being a vital economic resource, their habitats need management. We found that littoral zone quality impacts Largemouth Bass abundance in Ohio reservoirs. Keeping the quality of the littoral zone high will positively affect Largemouth Bass abundance.