Adult Yellow Perch Research Articles

Exploitation and survival of Yellow Perch introduced into community ponds

Increased urbanization paired with stagnant or decreasing fishing license sales has bolstered the importance of community fishing programs. Community fisheries require fish introductions, have highly variable chemical and physical characteristics, and are situated in urban settings with non-traditional fishers that can prefer unique species. Community ponds also often receive high angling pressure and exploitation that can hinder the establishment of sustainable populations. We evaluated angler exploitation and its effects as well as biotic (i.e., stocking density, predator relative abundance) and abiotic (i.e., water temperature, pond size, pond depth) factors affecting survival of stocked adult Yellow Perch Perca flavescens in community ponds. We tagged 580 adult Yellow Perch (≥150 mm) and stocked them into four community ponds at 74 or 148 fish/ha in September 2018. We collected two years of fishery dependent (angler tag reporting) and independent recapture data to estimate angler exploitation and survival of Yellow Perch using a joint live-recapture and dead-recovery model. We estimated anglers harvested 44% (95% CI ± 6%) of stocked Yellow Perch across the four ponds in two years, with the majority (81%) coming from one pond. Additionally, anglers harvested 66% of captured Yellow Perch and harvest probability increased with fish size. Seasonal exploitation ranged from 0% to 37% and was more prevalent in cold water seasons. Yellow Perch survival was negatively related to harvest (β = −0.14; 95% CI = −0.17 to −0.10) and a quadratic effect of water temperature (temperature: β = 0.28; 95% CI = 0.02–0.53; temperature2: β = 0.01; 95% CI = −0.01–0.01). Yellow Perch survival was not related to stocking density or pond characteristics. After two years, cumulative survival in three ponds ranged from 0.83 to 0.87 whereas survival in one pond with high exploitation was 0.22. Our results suggest Yellow Perch can be successfully introduced in community fisheries, but populations may not be sustainable when harvest is high. Thus, management strategies to mitigate excessive harvest or multiple put-and-take stockings may be necessary to maintain Yellow Perch populations in community fishing programs.

Hydroacoustic Surveys Underestimate Yellow Perch Population Abundance: The Importance of Considering Habitat Use

AbstractWhen estimating fish population abundance, it is important to recognize that differing habitat use may cause one gear type to be more effective and less biased than another. We generated and compared population abundance estimates (PE) for adult Yellow Perch Perca flavescens in Crystal Lake, Wisconsin using a spring mini‐fyke net mark–recapture survey and summer hydroacoustic surveys. Mean PE from the spring mark–recapture survey was 11,051 adult Yellow Perch (95% confidence limits of 9,878 and 12,541). This mean was 4.0–8.5 times greater than the range of mean summer hydroacoustic estimates (mean ± 95% CI = 1,291 ± 312 and 2,912 ± 703). Due to Yellow Perch spawning behavior, we assumed that the spring mark–recapture survey sampled the entire adult population, while summer hydroacoustics sampled the postspawn pelagic component. Using the mean of all hydroacoustic surveys (PE = 2,492; n = 5), we estimated that approximately 22% of adult Yellow Perch selected for pelagic habitats postspawn. Our study emphasizes the importance of evaluating gear bias and has implications for future assessments, particularly when the target species may exhibit multiple habitat preferences within a lake.

Seasonal trophic variation of yellow perch exceeds spatial variation in a large lake basin

Abstract Trophic structuring of complex food webs may vary at multiple spatial and temporal scales, both in terms of direct trophic connections and underlying energy pathways that support production. In large freshwater systems, the prey and primary producers that support individual higher-order consumers may vary across seasons and habitats due to differences in food availability, predator consumption patterns, seasonal succession of organisms at lower trophic levels, and heterogeneous nutrient inputs. We examined spatial and temporal variation in stomach contents, fatty acids, and stable isotopes of yellow perch (Perca flavescens) across seasons and across sites spanning approximately 200 km in Lake Erie's Central Basin (LECB). Stomach contents provided a short-term index of trophic patterns, while biochemical markers (fatty acids and stable isotopes) provided a more temporally integrated description of underlying energy pathways and trophic links. We found limited spatial variation of biochemical indicators and documented seasonal variation for all three trophic indicators, especially fatty acid profiles. Differences in stomach contents were driven by relative chironomid consumption, the most abundant prey resource, while fatty acid profiles were predominantly influenced by seasonal fluctuations in C22:6n-3 (DHA). Seasonal trends were evident in δ13C and δ15N; however, they varied within a narrow range of values. Our findings suggest that adult yellow perch in LECB showed little differentiation in resource use across space in 2014, but their diets and biochemical compositions varied seasonally.

Female reproductive impacts of dietary methylmercury in yellow perch (Perca flavescens) and zebrafish (Danio rerio)

The purpose of this study was to evaluate the effects of environmentally relevant dietary MeHg exposures on adult female yellow perch (Perca flavescens) and female zebrafish (Danio rerio) ovarian development and reproduction. Yellow perch were used in the study for their socioeconomic and ecological importance within the Great Lakes basin, and the use of zebrafish allowed for a detailed analysis of the molecular effects of MeHg following a whole life-cycle exposure. Chronic whole life dietary exposure of F1 zebrafish to MeHg mimics realistic wildlife exposure scenarios, and the twenty-week adult yellow perch exposure (where whole life-cycle exposures are difficult) captures early seasonal ovarian development. For both species, target dietary accumulation values were achieved prior to analyses. In zebrafish, several genes involved in reproductive processes were shown to be dysregulated by RNA-sequencing and quantitative real-time polymerase chain reaction (QPCR), but no significant phenotypic changes were observed regarding ovarian staging, fecundity, or embryo mortality. Yellow perch were exposed to dietary MeHg for 12, 16, or 20 weeks. In this species, a set of eight genes were assessed by QPCR in the pituitary, liver, and ovary, and no exposure-related changes were observed. The lack of genomic resources in yellow perch hinders the characterization of subtle molecular impacts. The ovarian somatic index, circulating estradiol and testosterone, and ovarian staging were not significantly altered by MeHg exposure in yellow perch. These results suggest that environmentally relevant MeHg exposures do not drastically reduce the reproductively important endpoints in these fish, but to capture realistic exposure scenarios, whole life-cycle yellow perch exposures are needed.

Evaluating potential competitive bottlenecks between invasive common carp and native bluegill and yellow perch

AbstractProcesses influencing fish recruitment are often highly complex and inherently difficult to understand. Invasive species may complicate recruitment through habitat and food web modifications resulting in competitive bottlenecks. Common carp Cyprinus carpio have been distributed worldwide, and their introductions have resulted in destructive effects on aquatic ecosystems and food web dynamics. Common carp are highly fecund, and high densities of age‐0 carp may occur in some years that may reduce invertebrate prey resources and adversely affect native age‐0 fishes. We used enclosures and field observations to examine potential effects of age‐0 common carp on growth and survival of age‐0 yellow perch Perca flavescens and bluegill Lepomis macrochirus. Yellow perch and bluegill were stocked into enclosures with and without common carp (31 fish/m3) using a substitution experimental design, and fish growth and survival and invertebrate prey resources were assessed. Common carp reduced growth of yellow perch but not bluegill and did not affect survival of either species in mesocosms. Next, we used patterns of common carp, bluegill, and yellow perch abundance and total length across 38 lake‐years to evaluate potential interspecific interactions in natural systems. Age‐0 common carp abundance was not negatively related to size or abundance of bluegill or yellow perch. However, adult common carp and age‐0 yellow perch abundance were inversely related, suggesting a potential competitive bottleneck. Thus, age‐0 common carp may suppress growth of yellow perch when prey is limited, but adult common carp may have larger effects than early life stages on native juvenile fishes.

Reconstructing fish movements between coastal wetland and nearshore habitats of the Great Lakes

The use of resources from multiple habitats has been shown to be important to the production of aquatic consumers. To quantify the support of Great Lakes coastal wetland (WL) and nearshore (NS) habitats to yellow perch, we used otolith microchemistry to trace movements between the habitats. WL and NS water and fish samples were collected from lakes Huron and Michigan for water and otolith trace element analysis. Recently deposited otolith-edge Sr : Ca and Ba : Ca from otoliths were strongly correlated with the chemistry of the water in which fish were caught. In general, Sr : Ca and Ba : Ca in otoliths were significantly greater for individuals collected from WL areas. Because of these observed chemical differences between WL and NS habitats, quadratic discriminant function analysis (QDFA) was used to classify individuals with high accuracy to the habitat from which they were collected. We then combined the predictive abilities of QDFA with the otolith chemistry transect data that represents an individuals' entire life, to classify habitat use through each fish's life. Our results suggest larval use of WL habitats as well as three life histories for adult yellow perch. These strategies include (1) fish utilizing WL once annually (2) WL residents (3) WL residence as juveniles followed by movement to nearshore as adults. This application represents a novel use of transect otolith microchemistry to reconstruct fish movements between freshwater environments across entire life spans at fine scales. These results suggest that regular movements of fish may facilitate the production of coastal fishes in the Great Lakes.

Species‐specific effects of subdaily temperature fluctuations on consumption, growth and stress responses in two physiologically similar fish species

AbstractFluctuations in water temperature can have important physiological consequences for fishes. Effects of daily thermal cycles are well studied and can be beneficial, increasing prey consumption and growth rates when mean and maximum temperatures of the fluctuations are at or below the species’ optimum temperature. While less studied, subdaily temperature fluctuations are also common in many aquatic habitats and can be caused by both natural and anthropogenic processes. We performed laboratory experiments to examine how two fish species (yellow perch, Perca flavescens, and walleye, Sander vitreus) with similar thermal preferences respond to chronic exposure to subdaily temperature variability. We selected temperature treatments that reflected observed thermal variation after examining water temperature data from multiple aquatic systems. We then separately exposed yellow perch and walleye to a stable 23 °C treatment and 12‐h cycles of 23 ± 2 °C or 23 ± 4 °C for 45 days. Adult yellow perch exposed to fluctuations of 23 ± 4 °C over 12 h expressed higher consumption, growth and food conversion efficiency than fish experiencing stable 23 °C. Temperature fluctuations, though, resulted in mortalities and the development of skin ulcers in yellow perch that did not occur under stable temperatures. In contrast, the same 12‐h temperature fluctuations did not result in mortalities or stress responses in juvenile walleye. Moreover, unlike yellow perch, growth rates of walleye were lower under 12‐h temperature fluctuations compared with the stable 23 °C treatment. Our results indicate that species with similar thermal preferences can respond differently to the same subdaily temperature fluctuations.

How temperature affects timing and duration of yellow perch spawning in the Indiana waters of Lake Michigan

Adult yellow perch were collected from the Indiana waters of Lake Michigan during 2009, 2011, and 2012 to estimate the length and timing of the yellow perch spawning season. Sampling was conducted using gill nets at three zones near East Chicago, Burns Harbor, and Michigan City from May to August in 2009 and 2011; however, sampling was conducted twice in April before continuing from May to August in 2012. After collection, yellow perch were measured, counted, and sexed and then the maturity state was determined. Logistic regression was used to model the proportion of post-spawn (spent) fish over time for each year. The resulting models estimated the timing and duration of yellow perch spawning and allowed the determination of peak spawn (50% spent) for each year. We found that yellow perch spawning started when mean daily water temperatures at the sample sites reached approximately 11 °C and lasted two to four weeks with cessation occurring when water temperatures exceeded 13 °C. In 2009 and 2011, spawning began in mid-May and was finished in early June, while in 2012 spawning started in early May and finished before June. These differences were likely in response to unseasonably warm lake temperatures caused by record high springtime air temperatures in the Great Lakes region. These findings suggest global climate change will alter yellow perch reproductive cycles.

Wild fish from the Bay of Quinte Area of Concern contain elevated tissue concentrations of PCBs and exhibit evidence of endocrine-related health effects

The Bay of Quinte (BOQ) is an Area of Concern listed under the Great Lakes Water Quality Agreement. The presence of dioxins and dioxin-like PCBs in fish in the BOQ AOC has led to restrictions on fish consumption by humans, which is a beneficial use impairment. Adult yellow perch (Perca flavescens) and brown bullhead (Ameiurus nebulosus) were sampled from Trenton, Belleville, and Deseronto (reference site) in the BOQ. A suite of hormone assays and various measures of exposure and/or sublethal health effects were used to assess the health status of fish of both species and sex. Condition factor, hepatosomatic index, ethoxyresorufin-O-deethylase activity, circulating steroid and thyroid hormones, thyroid activation, oocyte size distribution, spermatogenic cell stages, and plasma vitellogenin were among the endpoints that were significantly (p<0.05) affected by location. Many of those effects corresponded with significantly (p<0.05) greater tissue concentrations of polychlorinated biphenyls (PCBs) at Belleville and Trenton. Hepatic extracts from brown bullhead sampled from Trenton had significantly (p<0.05) greater binding activity to the androgen receptor and sex steroid binding protein. Taken together, these data and preliminary data from a concomitant study suggest that PCBs are likely being hydroxylated in vivo, resulting in enhanced bioactivity at endocrine receptors and measurable health responses. The present study supports the growing body of evidence that PCBs and their metabolites can affect fish thyroid and steroid hormone systems.

Utilizing random forest analysis with otolith mass and total fish length to obtain rapid and objective estimates of fish age

Age estimates from otolith morphometrics represent a rapid and objective alternative to traditional ageing techniques though use has been limited to marine and short-lived freshwater species. We utilized random forest analysis with otolith mass, total length, and several temporal and spatial predictor variables to assess variable importance and accuracy of age estimates for age-0 through age-11 yellow perch (Perca flavescens) in southwestern Lake Michigan. Accuracy of age predictions decreased with increasing age as 95% of juvenile (age-0 through age-2) ages were predicted correctly compared with 55% for adults (age-3 through age-11). Precision of age estimates within 1 year of reader-assigned age were high for both juvenile and adult yellow perch at 100% and 86%, respectively. Otolith mass was the most important predictor variable; however, substantial overlap existed among adult ages. Random forest analysis utilizing otolith mass, total length, and other pertinent predictor variables represents an applicable tool to reduce subjectivity and resource expenditure while providing accurate age estimates for juvenile and short-lived fishes.

Reproductive health of yellow perch Perca flavescens in selected tributaries of the Chesapeake Bay

Reduced recruitment of yellow perch has been noted for a number of years in certain urbanized watersheds (South and Severn Rivers) of the Chesapeake Bay. Other rapidly developing watersheds such as Mattawoman Creek are more recently showing evidence of reduced recruitment of anadromous fishes. In this study, we used a battery of biomarkers to better document the reproductive health of adult yellow perch collected during spring spawning in 2007–2009. Perch were collected in the South and Severn Rivers, Mattawoman Creek and the less developed Choptank and Allen's Fresh watersheds for comparison. Gonadosomatic indices, plasma reproductive hormone concentrations, plasma vitellogenin concentrations and gonad histology were evaluated in mature perch of both sexes. In addition, sperm quantity (cell counts) and quality (total and progressive motility, spermatogenic stage and DNA integrity), were measured in male perch. Many of these biomarkers varied annually and spatially, with some interesting statistical results and trends. Male perch from the Choptank and Allen's Fresh had generally higher sperm counts. In 2008 counts were significantly lower in the perch from the Severn when compared to other sites. The major microscopic gonadal abnormality in males was the proliferation of putative Leydig cells, observed in testes from Severn and less commonly, Mattawoman Creek perch. Observations that could significantly impact egg viability were an apparent lack of final maturation, abnormal yolk and thin, irregular zona pellucida. These were observed primarily in ovaries from Severn, South and less commonly Mattawoman Creek perch. The potential association of these observations with urbanization, impervious surface and chemical contaminants is discussed.

Fifty years later: trophic ecology and niche overlap of a native and non-indigenous fish species in the western basin of Lake Erie

Since the introduction of white perch (Morone americana) into Lake Erie over 50 years ago, the population size of native yellow perch (Perca flavescens) has decreased up to 79 % and significant changes to the ecosystem have occurred. We examined long-term population estimates and used stable isotopes of carbon (δ 13C) and nitrogen (δ 15N) paired with stomach content analysis to quantify the trophic ecology and niche overlap of adult yellow perch and white perch in the western basin of Lake Erie. We found that changes in yellow perch abundance since 1979 appeared to be better correlated with changes in fishery exploitation rates than with food competition effects from white perch. At the time of this study, yellow perch were found to have higher δ 13C values, indicating greater utilization of benthic food resources than white perch, and white perch occupied higher trophic positions based on δ 15N. The diets of both species varied spatially and seasonally based on stable isotopes and stomach contents, likely driven by changes in prey abundance. Comparison of niche widths using stable isotope population metrics and Schoener diet similarity index suggested a low to moderate degree of niche overlap between species. Isotopic niches of white perch were generally larger than those of yellow perch demonstrating broader resource utilization by this non-indigenous species. We submit that isotopic niche overlap comparisons are more appropriate for studies seeking to understand interactions among populations over course temporal scales, while diet overlap indices, such as the Schoener index provide a means to study fine-scale interactions such as ontogenetic and seasonal diet shifts.

Long‐Term and Interannual Dynamics of Walleye and Yellow Perch in Saginaw Bay, Lake Huron

AbstractWalleye Sander vitreus and yellow perch Perca flavescens are well‐studied, ecologically important fish species that co‐occur in a wide range of systems and experience complex interactions; on the one hand, they are physiologically and ecologically similar and therefore may respond analogously to environmental variation, while on the other hand they interact antagonistically as competitors, predators, and prey. In Saginaw Bay, Lake Huron, walleyes and yellow perch have supported a combination of commercial and recreational fisheries and have been exposed to a series of ecosystem‐level stressors and management actions that may have impacted these populations via multiple pathways. We used dynamic factor analysis and correlation analysis of walleye and yellow perch annual fall trawl catch data to elucidate the overall trends in walleye and yellow perch populations in Saginaw Bay. The results suggest that walleyes and yellow perch trend differently; while the relative abundance of age‐0–2 walleyes generally increased and their mean length decreased from 1980 to 2008, the trends in yellow perch abundance and length differed among the young‐of‐year, yearling, and age‐2 age‐classes. Moreover, interannual negative associations between yellow perch relative abundance and mean size are suggestive of compensatory, density‐dependent control on growth, while similar evidence is lacking for walleyes. Correlation analyses indicate that walleye year‐class strength is set by the fall of age 0, while the age at which recruitment is set for yellow perch is less clear and may not occur until the fall of age 1. Thus, we suggest that future studies evaluating environmental determinants of year‐class strength in Saginaw Bay evaluate age‐0 walleyes and age‐1 yellow perch. Finally, while age‐0 yellow perch and age‐0 walleyes appear to respond similarly to annual environmental conditions, the recent increase in walleye abundance and decrease in the mean size of age‐0 yellow perch may have contributed to the reduced abundance of adult yellow perch via walleye predation and overwinter mortality.

Size preferences and behaviors of native yellow perch foraging on invasive round gobies

Predation is one of the primary mechanisms that shape aquatic food webs and predator–prey interactions are typically highly dependent on sizes of both forager and its prey. Round goby Neogobius melanostomus is a recent invader to the Great Lakes and can be an important prey item for native predators. However, predation patterns on round gobies have received limited attention. We assessed size-specific predator–prey interactions between invasive round gobies and native yellow perch Perca flavescens by comparing prey preferences for three size classes of adult yellow perch foraging on six size classes of round gobies. Small yellow perch preferred the smallest round gobies available, medium sized yellow perch increased the range of round goby sizes consumed but still preferred smaller prey, whereas large yellow perch consumed larger round gobies and excluded the smallest prey size. Yellow perch foraging behaviors indicated that intermediate sizes of round gobies were struck at most frequently and that pursuit and handling time increased whereas capture efficiency and prey profitability decreased with round goby size. Our results indicate that predator–prey interactions between yellow perch and round gobies may be size dependent and heavily influenced by capture efficiency and prey profitability.

Identifying Relationships between Catches of Spawning Condition Yellow Perch and Environmental Variables in the Western Basin of Lake Erie

AbstractAlthough the reproductive behavior of yellow perch Perca flavescens has been well documented in small systems, relatively little is known about the spawning preferences of yellow perch in large systems, such as the Laurentian Great Lakes. During 2006 and 2007, we compared the presence and abundance adult yellow perch during the spring spawning season with environmental variables in the western basin of Lake Erie. We also estimated the timing of yellow perch spawning by comparing the relative abundance of gravid and spent females collected in our trawls and then comparing the proportion of gravid females with environmental conditions at our sampling sites. Overall, the probability of catching adult yellow perch and the catch per unit effort increased with increasing bottom temperatures in the spring, whereas the probability of catching gravid females increased with increasing Secchi depth. However, the relationships between our catch metrics and environmental variables were not consistent across years, possibly as a result of the very strong 2003 year‐class, which became first‐year spawners in 2006. We also documented that yellow perch spawning occurred when bottom temperatures were between 11°C and 15°C in the western basin; these temperatures were reached on different dates in different parts of the basin and in different years. Thus, we suggest that management agencies consider basing the start of the commercial fishing season on prevailing bottom temperatures rather than using a set date across years and sites.

Seasonal and interannual effects of hypoxia on fish habitat quality in central Lake Erie

SUMMARY 1. Hypoxia occurs seasonally in many stratified coastal marine and freshwater ecosystems when bottom dissolved oxygen (DO) concentrations are depleted below 2–3 mg O2 L )1 . 2. We evaluated the effects of hypoxia on fish habitat quality in the central basin of Lake Erie from 1987 to 2005, using bioenergetic growth rate potential (GRP) as a proxy for habitat quality. We compared the effect of hypoxia on habitat quality of (i) rainbow smelt, Osmerus mordax mordax Mitchill (young-of-year, YOY, and adult), a cold-water planktivore, (ii) emerald shiner, Notropis atherinoides Rafinesque (adult), a warm-water planktivore, (iii) yellow perch, Perca flavescens Mitchill (YOY and adult), a cool-water benthopelagic omnivore and (iv) round goby Neogobius melanostomus Pallas (adult) a eurythermal benthivore. Annual thermal and DO profiles were generated from 1D thermal and DO hydrodynamics models developed for Lake Erie’s central basin. 3. Hypoxia occurred annually, typically from mid-July to mid-October, which spatially and temporally overlaps with otherwise high benthic habitat quality. Hypoxia reduced the habitat quality across fish species and life stages, but the magnitude of the reduction varied both among and within species because of the differences in tolerance to low DO levels and warm-water temperatures. 4. Across years, trends in habitat quality mirrored trends in phosphorus concentration and water column oxygen demand in central Lake Erie. The per cent reduction in habitat quality owing to hypoxia was greatest for adult rainbow smelt and round goby (mean: )35%), followed by adult emerald shiner (mean: )12%), YOY rainbow smelt (mean: )10%) and YOY and adult yellow perch (mean: )8.5%). 5. Our results highlight the importance of differential spatiotemporally interactive effects of DO and temperature on relative fish habitat quality and quantity. These effects have the potential to influence the performance of individual fish species as well as population dynamics, trophic interactions and fish community structure.

A Comparison of Seasonal Movement Patterns of Yellow Perch in Simple and Complex Lake Basins

AbstractDetermining the seasonal movement patterns of fish can provide insight into their spawning behaviors, predator–prey interactions, and habitat preferences. To investigate the seasonal movement patterns of adult yellow perch and how they are affected by lake habitat characteristics, we attached ultrasonic transmitters to two length‐groups (210–235 and 250–280 mm total length) of yellow perch from populations inhabiting two temperate lakes differing in habitat diversity and basin morphology. In the simple lake, yellow perch distributions differed between seasons, mean depth and distance from shore being greatest during the summer. The observed seasonal differences were similar between the two length‐groups. In the complex lake, yellow perch depth varied seasonally, the fish occupying deeper waters during the fall and shallower ones during the summer; however, the distance from shore was consistent among seasons. During the spring, males inhabited areas closer to shore than females in the complex lake, whereas the spatial distributions did not differ between sexes in the simple basin. Yellow perch from both lakes displayed similar seasonal variation in activity, movement rates being highest during the fall and lowest during the summer. Movement rates in the simple lake, however, were higher than those in the complex lake during all three seasons, which suggests that the effectiveness of passive sampling gears may vary in response to habitat complexity. These results reveal several seasonal differences in yellow perch habitat use, distribution, and activity in relation to basin complexity that may provide insight for managers considering sampling plans for individual lake types.

Diel Movement Patterns of Yellow Perch in a Simple and a Complex Lake Basin

AbstractTo investigate the influence habitat may have on fish movement, we tagged two length‐groups of adult yellow perch Perca flavescens with ultrasonic transmitters to determine diel movement patterns in two glacial lakes with differing basin morphometries and habitat characteristics. In both lakes, movement rates increased from dawn to the diurnal period, and decreased from dusk to the nocturnal period, with lowest activity in the nocturnal period. Overall, mean period movement rates for yellow perch were higher in the simple lake than in the complex lake. Offshore movement from the nocturnal to the dawn period and onshore movement from the diurnal to the nocturnal period was evident in both length‐groups in the complex lake, but not evident in the simple lake. Size segregation was apparent in the complex lake, where the small length‐group was located farther from shore than the large length‐group. Yellow perch in the simple lake most often used the deepest depths, whereas yellow perch in the complex lake used moderate depths. These results suggest that habitat characteristics and the complexity of a lake basin may have an influence on behavior and habitat use. With this insight into the movement patterns of yellow perch in two distinct types of lake basins, managers may consider refining sampling plans for individual lake types.

Seasonal and Sex-specific mRNA Levels of Key Endocrine Genes in Adult Yellow Perch (Perca flavescens) from Lake Erie

To better understand the endocrine mechanisms that underlie sexually dimorphic growth (females grow faster) in yellow perch (Perca flavescens), real-time quantitative polymerase chain reaction (qPCR) was used to measure pituitary, liver, and ovary mRNA levels of genes related to growth and reproduction-sex in this species. Adult perch were collected from Lake Erie and body mass, age, gonadosomatic index (I (G)), hepatosomatic index (I (H)), and gene expression for growth hormone (GH), prolactin, somatolactin, insulin-like growth factor Ib (IGF-Ib), estrogen receptor alpha (esr1), estrogen receptor betaa (esr2a), and aromatase (cyp19a1a) were measured. Females had higher body mass, I (H), and liver esr1 mRNA level than males, while males had higher liver IGF-Ib, liver esr2a, and liver cyp19a1a mRNA levels. In both sexes, season had a significant effect on GH and liver IGF-Ib mRNAs with higher levels occurring in spring, which also corresponded with higher liver cyp19a1a mRNA levels. For females, I (G), liver esr1, and ovary cyp19a1a mRNA levels were higher in autumn than the spring, and ovary cyp19a1a mRNA levels showed a significant negative correlation with pituitary GH and liver IGF-Ib mRNA levels. The most significant (p </= 0.001) relationships across the parameters measured were positive correlations between liver IGF-Ib and esr2a mRNA levels and liver IGF-Ib and cyp19a1a mRNA levels. This study shows significant effects of season and sex on adult yellow perch endocrine physiology.

Changes in yellow perch length frequencies and sex ratios following closure of the commercial fishery and reduction in sport bag limits in southern Lake Michigan

Abstract The closure of the Indiana commercial fishery in Lake Michigan in 1997 provided the opportunity to examine the effects of commercial exploitation on the yellow perch, Perca flavescens (Mitchill), population. Data from annual gillnet and trawl sampling, recreational angler creel surveys and commercial fishing harvest were used to determine whether changes in length–frequency distributions and sex ratios were altered following closure. The proportions of large, adult yellow perch were significantly greater after the closure of the commercial fishery. Overexploitation of fish &gt;200 mm by commercial harvest likely truncated the size distribution, but recreational harvest was comparatively small and did not appear to be a factor influencing size distributions. This post‐closure period also had a greater proportion of females in trawl catches, and the mean length of harvested fish increased in the recreational fishery. These findings suggest commercial exploitation influenced yellow perch population dynamics in far southern Lake Michigan.