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Cleithra are thought to accurately record age information and produce the most reliable age estimates relative to other calcified structures (e.g., scales) for long-lived species of Esocidae such as muskellunge Esox masquinongy and northern pike E. lucius. Sagittal otoliths provide the most accurate and precise age estimates for other fish species, yet sagittal otoliths have never been evaluated for age estimation of any species of Esocidae. Our objectives were to determine if: 1) sagittal otoliths provided more precise age estimates than cleithra for northern pike from two populations, and 2) sagittal otolith age estimates differed systematically from cleithrum age estimates for two populations of northern pike. Ages were estimated by three independent individuals with different experience levels from sagittal otoliths and cleithra collected from 66 northern pike (32–101 cm total length) from Devils Lake, North Dakota and 45 northern pike (27–52 cm total length) from Cable Lake, Wisconsin. Cleithrum age estimates were more precise than those from sagittal otoliths for northern pike from Devils Lake, and were similar to sagittal otolith age estimates for northern pike from Cable Lake. Sagittal otolith age estimates were similar to cleithrum age estimates for northern pike from Devils Lake, but were dissimilar for northern pike from Cable Lake. We recommend using cleithra for estimating age of northern pike given that no specialized equipment is required for processing and age estimation. However, other studies are needed to further investigate the use of sagittal otoliths to estimate age of northern pike.

Otoliths generally provide more accurate and precise age estimates for crappies Pomoxis spp. than do scales, but sacrificing crappies for otolith removal may not be desirable in all situations. We evaluated the use of dorsal spines and scales as nonlethal alternatives to otoliths for estimating the ages of black crappies P. nigromaculatus using 111 fish collected from two Minnesota lakes. Among‐reader precision was similar for ages estimated from scales and dorsal spines (coefficients of variation [CVs] = 10–14%), but the precision associated with both structures was substantially lower than that observed for otoliths (CVs = 0.12–1.3%). Complete reader agreement (i.e., all three readers agreed on age) for dorsal spines (44–51%) and scales (33–36%) was substantially lower than that observed for otoliths (87–98%). Partial agreement (i.e., at least two of three readers agreed on age) was 100% for both otoliths and dorsal spines and between 79% and 89% for scales. Scale ages assigned by individual readers agreed with consensus otolith ages less than 70% of the time; agreement of individual spine ages with consensus otolith ages was 33% or less. Mean scale ages were usually similar to consensus otolith ages for crappies between the ages of 2 and 6 years, while mean spine ages were consistently lower than consensus otolith ages. Thin‐sectioning dorsal spines did not significantly change the number of annuli detected by individual readers. Our results suggest that dorsal spines are not a useful alternative to scales for estimating black crappie age in a nonlethal manner. A conspicuous lumen located in the center of each dorsal spine partially or fully obscures at least one annulus. When otolith removal is not desirable, use of scales and multiple readers may provide mean age estimates that are similar to consensus otolith ages, but we suggest that otolith analysis remains the most reliable method for estimating black crappie age, regardless of latitude.

This Article is brought to you for free and open access by the Natural Resources, School of at DigitalCommons@University of Nebraska -Lincoln. It has been accepted for inclusion in Papers in Natural Resources by an authorized administrator of DigitalCommons@University of Nebraska -Lincoln.Breeggemann, Jason J.; Kaemingk, Mark A.; DeBates, Timothy J.; Paukert, Craig P.; Krause, Jacob R.; Letvin, Alexander P.; Stevens, Tanner M.; Willis, David W.; and Chipps, Steven R., "Potential Direct and Indirect Effects of Climate Change on a Shallow Natural Lake Fish Assemblage" (2016 ). Bioenergetics models were used to simulate the effects of climate change on growth and food consumption using predicted 2040 and 2060 temperatures in a shallow Nebraska Sandhill lake, USA. The patterns and magnitude of daily and cumulative consumption during the growing season (April-October) were generally similar between the two predators. However, growth of northern pike was always reduced (À3 to À45% change) compared to largemouth bass that experienced subtle changes (4 to À6% change) in weight by the end of the growing season. Assuming similar population size structure and numbers of predators in 2040-2060, future consumption of bluegill and yellow perch by northern pike and largemouth bass will likely increase (range: 3-24%), necessitating greater prey biomass to meet future energy demands. The timing of increased predator consumption will likely shift towards spring and fall (compared to summer), when prey species may not be available in the quantities required. Our findings suggest that increased water temperatures may affect species at the edge of their native range (i.e. northern pike) and a potential mismatch between predator and prey could exist.

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 depending on the intentions and experience of the author. Some authors may be tempted to relate their research to a hot topic (e.g., climate change, model selection) in an attempt to increase publication success digitalcommons.unl.edu

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