Mark A. Kaemingk

Effect of Passive Integrated Transponder Tag Implantation Site on Tag Retention, Growth, and Survival of Two Sizes of Juvenile Bluegills and Yellow Perch

Abstract Passive integrated transponder (PIT) tags are commonly used to monitor growth, habitat use, activity rates, and survival of individual fish. However, for successful completion of research objectives, the tags must be retained and must not affect fish growth or survival. We compared the effects of PIT tagging location on tag retention, growth, and survival of juvenile bluegills Lepomis macrochirus and yellow perch Perca flavescens. In total, 80 bluegills and 80 yellow perch from two size-classes (75–101 and 128–162 mm total length) were randomly assigned to a control or to one of three tagging location treatments: isthmus, body cavity, or dorsal musculature. Fish received daily ad libitum rations and were monitored for survival. On days 14, 28, and 42, the fish were measured, weighed, and checked for tag retention. Use of the isthmus as a tagging location resulted in lower tag retention for both species and both size-classes relative to the body cavity and dorsal musculature locations. Tagging loc...

Are We Preparing the Next Generation of Fisheries Professionals to Succeed in their Careers?: A Survey of AFS Members

Natural resource professionals have frequently criticized universities for poorly preparing graduates to succeed in their jobs. We surveyed members of the American Fisheries Society to determine which job skills and knowledge of academic topics employers, students, and university faculty members deemed most important to early-career success of fisheries professionals. Respondents also rated proficiency of recently hired, entry-level professionals (employers) on how well their programs prepared them for career success (students and faculty) in those same job skills and academic topics. Critical thinking and written and oral communication skills topped the list of important skills and academic topics. Employers perceived recent entry-level hires to be less well-prepared to succeed in their careers than either university faculty or students. Entry-level hires with post-graduate degrees rated higher in proficiency for highly important skills and knowledge than those with bachelors degrees. We conclude that a...

Exploring spatial distributions of larval yellow perch Perca flavescens, bluegill Lepomis macrochirus and their prey in relation to wind

The objectives of the present study were to determine if spatial differences existed between zooplankton, larval yellow perch Perca flavescens and bluegill Lepomis macrochirus (<13 mm total length, L(T)) in Pelican Lake (332 ha), NE, U.S.A. It was hypothesized that wind could act as a transport mechanism for larval fishes in this shallow lake, because strong winds are common at this geographic location. Potential spatial differences were explored, relating to zooplankton densities, size structure and densities of larval P. flavescens and L. macrochirus. Density differences (east v. west side of the lake) were detected for small- (two occasions), medium- (two occasions) and large-sized (one occasion) L. macrochirus larvae. No density differences were detected for small P. flavescens larvae; however, densities of medium- and large-sized P. flavescens were each higher on the west side of the lake on two occasions. There was no evidence that larval P. flavescens and L. macrochirus distributions were related to wind because they were not associated with large wind events. Likewise, large wind event days did not result in any detectable spatial differences of larval P. flavescens and L. macrochirus densities. There appeared to be no spatial mismatch between larval densities and associated prey in the years examined. Thus, wind was not apparently an influential mechanism for zooplankton and larval P. flavescens and L. macrochirus transport within Pelican Lake, and spatial differences in density may instead be related to vegetation and habitat complexities or spawning locations within this shallow lake.

Temperature, Hatch Date, and Prey Availability Influence Age-0 Yellow Perch Growth and Survival

AbstractThroughout their range, Yellow Perch Perca flavescens are an important ecological and economic component of many fisheries, but they often exhibit highly variable recruitment. Much research effort has been devoted to better understanding the mechanisms responsible for these erratic recruitment patterns, yet few studies have examined this process at the detail necessary to reveal complex interactions that may exist across multiple early life stages. Our current understanding of the early life recruitment patterns of Yellow Perch suggests a strong abiotic component. Using existing information, we developed three working hypotheses to examine Yellow Perch recruitment at two larval stages (5–14 and 15–24 d old) and to further identify the overarching mechanisms (abiotic versus biotic) related to Yellow Perch recruitment in 332-ha Pelican Lake, Nebraska, during 2004–2012. Larval Yellow Perch growth and mortality were largely regulated by hatching date, temperature, and zooplankton availability. The gro...

Pressures to Publish: Catalysts for the Loss of Scientific Writing Integrity?

ABSTRACT Publishing research is the final step in the scientific process and is used as the primary means for disseminating research findings to the scientific community. Publishing can embody many personal motivations (e.g., gratification, seeing a finished product in print, desire to further science) for authors as well as professional benefits (e.g., promotion, tenure, future funding opportunities). As the scientific workforce and competition for jobs and funding increase, publishing productivity has become a driving factor for many authors, which may lead to writing practices that violate integrity. In this essay, we discuss writing actions that may be considered a violation of integrity in the context of traditional manuscript sections (introduction and discussion, methods, and results). We define “integrity” as consistency of actions that reflect honesty and truthfulness. Writing the introduction and discussion can be compared to an artistic creation because the rendition of the data may vary depend...

A Survey of Aquatic Invertebrate Communities in Nebraska Sandhill Lakes Reveals Potential Alternative Ecosystem States

Abstract Aquatic invertebrate communities are important to shallow lake ecosystem form and function, providing vital components to the food web and thereby important to achieving lake management goals. We characterized lake invertebrate communities and physicochemical variables in six Nebraska Sandhill lakes and examined these characteristics within an alternative stable state framework. Surveys were conducted during 2005 within each of these lakes by sampling aquatic macroinvertebrate abundance, zooplankton abundance and biomass, phytoplankton biomass, and physicochemical variables. When placed within an alternative stable state framework, the response variables exhibited a gradient of different ecosystem states. Two lakes appeared congruent with the clear water state (dense submergent vegetation, high invertebrate abundance and diversity, and low phytoplankton), two lakes were congruent with the turbid water state (high phytoplankton, low vegetation coverage, and low invertebrate abundance and diversity...

Fish Assemblage Shifts and Population Dynamics of Smallmouth Bass in the Beaver Archipelago, Northern Lake Michigan: A Comparison between Historical and Recent Time Periods amidst Ecosystem Changes

Abstract The ecological and economic importance of Great Lakes nearshore areas and the paucity of information on nearshore Lake Michigan fish assemblages prompted us to document changes that occurred from a historical time period (1969–1972, 1975, 1977, and 1984) to a recent period (2005–2008) in a nearshore northern Lake Michigan (Beaver Archipelago) fish assemblage, with an emphasis on smallmouth bass Micropterus dolomieu. From historical to recent periods, the Beaver Archipelago fish assemblage shifted from predominantly brown bullheads Ameiurus nebulosus to predominantly smallmouth bass. Relative abundance of brown bullheads and white suckers Catostomus commersonii declined from historical to recent time periods, as did overall species richness. The relative abundance, recruitment variability, and mortality rates of smallmouth bass have not significantly changed since the historical time period, whereas both condition (ages 5–7) and growth (ages 2–7) of this species have significantly increased. Our r...

Common Carp Disrupt Ecosystem Structure and Function Through Middle-out Effects

Middle-out effects or a combination of top-down and bottom-up processes create many theoretical and empirical challenges in the realm of trophic ecology. We propose using specific autecology or species trait (i.e. behavioural) information to help explain and understand trophic dynamics that may involve complicated and non-unidirectional trophic interactions. The common carp (Cyprinus carpio) served as our model species for whole-lake observational and experimental studies; four trophic levels were measured to assess common carp-mediated middle-out effects across multiple lakes. We hypothesised that common carp could influence aquatic ecosystems through multiple pathways (i.e. abiotic and biotic foraging, early life feeding, nutrient). Both studies revealed most trophic levels were affected by common carp, highlighting strong middle-out effects likely caused by common carp foraging activities and abiotic influence (i.e. sediment resuspension). The loss of water transparency, submersed vegetation and a shift in zooplankton dynamics were the strongest effects. Trophic levels furthest from direct pathway effects were also affected (fish life history traits). The present study demonstrates that common carp can exert substantial effects on ecosystem structure and function. Species capable of middle-out effects can greatly modify communities through a variety of available pathways and are not confined to traditional top-down or bottom-up processes.

Consequences of Hatch Phenology on Stages of Fish Recruitment.

Little is known about how hatch phenology (e.g., the start, peak, and duration of hatching) could influence subsequent recruitment of freshwater fishes into a population. We used two commonly sympatric fish species that exhibit different hatching phenologies to examine recruitment across multiple life stages. Nine yellow perch (Perca flavescens) and bluegill (Lepomis macrochirus) annual cohorts were sampled from 2004 through 2013 across larval, age-0, age-1, and age-2 life stages in a Nebraska (U.S.A.) Sandhill lake. Yellow perch hatched earlier in the season and displayed a more truncated hatch duration compared to bluegill. The timing of hatch influenced recruitment dynamics for both species but important hatching metrics were not similar between species across life stages. A longer hatch duration resulted in greater larval yellow perch abundance but greater age-1 bluegill abundance. In contrast, bluegill larval and age-0 abundances were greater during years when hatching duration was shorter and commenced earlier, whereas age-0 yellow perch abundance was greater when hatching occurred earlier. As a result of hatch phenology, yellow perch recruitment variability was minimized sooner (age-0 life stage) than bluegill (age-1 life stage). Collectively, hatch phenology influenced recruitment dynamics across multiple life stages but was unique for each species. Understanding the complexities of when progeny enter an environment and how this influences eventual recruitment into a population will be critical in the face of ongoing climate change.

Overwinter Mortality of Sympatric Juvenile Bluegill and Yellow Perch in Mid-Temperate Sandhill lakes, Nebraska, U.S.A

Substantial mortality can occur in age-0 fish populations during their first year of life, especially in winter; this can potentially influence overall recruitment into the adult population. As such, we compared relative abundances be- tween fall and spring catches of sympatric juvenile bluegill Lepomis macrochirus Rafinesque and yellow perch Perca flavescens (Mitchill) to evaluate the magnitude of overwinter mortality across locations (five lakes for two years) and through time (one lake for six years). In addition, we compared both quantile-quantile and increment plots, based on length-frequency histograms from fall- and spring-caught cohorts from 2004 to 2010, to determine if mortality was size- selective while accounting for over winter growth. Bluegill relative abundances (as indexed by catch-per-unit-effort) sig- nificantly decreased from fall to spring, although size-selective mortality was not detected in 10 instances. Yellow perch relative abundances were similar from fall to spring in five Nebraska Sandhill lakes; however, size-selective mortality was detected, with size-selective over winter mortality of smaller individuals occurring in one of eight instances, whereas greater mortality in larger individuals occurred in two instances. Positive growth occurred in both species but was variable among lakes and appeared to be system-specific. In Nebraska Sandhill lakes, over winter mortality likely differs between these two species in its severity, size-selective effect, and scale (i.e., lake-specific vs. large-scale processes), and is likely influenced by combinations of these (and potentially other) factors.