Terrestrial and Semi-Aquatic Vertebrates in Diets of Largemouth Bass in Central Nebraska

Largemouth bass (Micropterus salmoides) are opportunistic predators often feeding in littoral areas during crepuscular periods (Snow 1971). Adult largemouth bass primarily are piscivorous, whereas juveniles generally consume zooplankton, insects, and small fish (Zweiacker and Summerfelt 1974, Carlander 1977, Post 2003). Age-0 largemouth bass generally consume zooplankton and macroinvertebrates (Keast and Webb 1966, Keast 1985, Phillips et al. 1995, Post 2003) and shift to piscivory at 50-70 mm in length (Phillips et al. 1995, Olson 1996, Post 2003). Few studies have documented detailed accounts of other vertebrates besides fish in diets of largemouth bass, which include amphibians (Hodgson and Kitchell 1987, Hodgson and Hansen 2005), reptiles (Hodgson and Kitchell 1987, Britson and Gutzke 1993), birds (Hodgson and Hansen 2005), and mammals (Clady 1974, Hodgson 1986, Hodgson and Kitchell 1987, Hodgson and Kinsella 1995). Depending on location and season, non-fish vertebrates can contribute substantially to diets of largemouth bass. For example, small mammals composed over 50% of the volume of bass diets in May-June in Cub Lake, Michigan (Clady 1974). To our knowledge, no study in the Great Plains has documented terrestrial or semi-aquatic vertebrates in largemouth bass diets to date. Herein we report on the presence of terrestrial and semi-aquatic vertebrates in largemouth bass diets in borrow- pit lakes in central Nebraska, representing several new species of prey items for largemouth bass

Terrestrial and Semi-Aquatic Vertebrates in Diets of Largemouth Bass in Central Nebraska

Largemouth bass (Micropterus salmoides) are opportunistic predators often feeding in littoral areas during crepuscular periods (Snow 1971). Adult largemouth bass primarily are piscivorous, whereas juveniles generally consume zooplankton, insects, and small fish (Zweiacker and Summerfelt 1974, Carlander 1977, Post 2003). Age-0 largemouth bass generally consume zooplankton and macroinvertebrates (Keast and Webb 1966, Keast 1985, Phillips et al. 1995, Post 2003) and shift to piscivory at 50-70 mm in length (Phillips et al. 1995, Olson 1996, Post 2003). Few studies have documented detailed accounts of other vertebrates besides fish in diets of largemouth bass, which include amphibians (Hodgson and Kitchell 1987, Hodgson and Hansen 2005), reptiles (Hodgson and Kitchell 1987, Britson and Gutzke 1993), birds (Hodgson and Hansen 2005), and mammals (Clady 1974, Hodgson 1986, Hodgson and Kitchell 1987, Hodgson and Kinsella 1995). Depending on location and season, non-fish vertebrates can contribute substantially to diets of largemouth bass. For example, small mammals composed over 50% of the volume of bass diets in May-June in Cub Lake, Michigan (Clady 1974). To our knowledge, no study in the Great Plains has documented terrestrial or semi-aquatic vertebrates in largemouth bass diets to date. Herein we report on the presence of terrestrial and semi-aquatic vertebrates in largemouth bass diets in borrow- pit lakes in central Nebraska, representing several new species of prey items for largemouth bass

Population Characteristics of Co-Managed White Bass and Hybrid Striped Bass in Lake McConaughy, Nebraska

White Bass (Morone chrysops) and Hybrid Striped Bass (M. saxatillis × M. chrysops) populations often coexist in the same waterbody and are known to achieve different lengths, have differing reproductive success, and provide different opportunities for anglers. However, comparative population dynamics from systems where Moronids are managed with the same regulation is often lacking. This study aimed to assess the recruitment, mortality, and growth of these species from seasonal samples collected at Lake McConaughy in 2015 and fall 2016. White Bass demonstrated highly variable recruitment in Lake McConaughy despite stocking efforts (mean recruitment variability index = 0.157). Hybrid Striped Bass year class strength was also variable, but RVI was not calculated as the number of missing year classes exceed the number of present year classes. Total annual mortality estimates for Hybrid Striped Bass (39.7%) and White Bass (41.4%) were consistent with values reported in other populations, but both species were observed to achieve uncommon longevity. Both species exhibited sexual size dimorphism, and growth was moderate and consistent with average values presented for North American populations. This study provides insight into the population dynamics of two species with trophy potential managed by the same regulation in Lake McConaughy. Differences in growth patterns indicate the current regulation affects each species differently, and managers may be able to utilize this to inform decisions about management of coexisting Moronid populations

Comparison of Two Zooplankton Sampling Gears in Shallow, Homogeneous Lakes

We compared two zooplankton collection gears, Wisconsin nets and column samplers, to evaluate the effectiveness of each gear in quantifying inshore and offshore zooplankton density and size structure in shallow, homogeneous lakes. Zooplankton densities (within gear) did not differ (P \u3e 0.05) between inshore and offshore sites in either study lake, with the exception of Wisconsin-netted Cyclops sp. in Lake Goldsmith. Wisconsin net samples produced a higher mean zooplankton density than column samplers for Bosmina sp., Cyclops sp., and Daphnia sp. in East Oakwood Lake and for Cyclops sp. (inshore), Daphnia sp., and Diaptomus sp. in Lake Goldsmith. Zooplankton densities had greater variability (coefficients of variation) in 4 of 5 taxa collected with the Wisconsin net in both study lakes. Zooplankton size structure did not differ (P\u3e 0.05) between gears in either study lake, with the exception of Diaptomus sp. in East Oakwood Lake. Our results suggest that column samplers have higher precision than Wisconsin nets when sampling common zooplankton species in shallow, homogeneous lakes

ACCURACY OF ANTLER METRICS IN PREDICTING AGE OF WHITE-TAILED DEER AND MULE DEER

Electronic deer check systems offer state natural resource agencies alternatives to mandatory in-person check stations, resulting in potential savings in money and personnel. However, a reliable means for hunters to classify the age of harvested antlered deer must be established so that important management indices such as antlered yearling harvest can continue to be used to set future management goals. Therefore, we evaluated the use of six different antler metrics to predict age class of white-tailed and mule deer (1.5 and \u3e/= 2.5 years). We used discriminant analysis to determine the number of deer correctly classified into each age class based on the antler metric with the greatest degree of separation for each species. Of those evaluated, main beam length and inside spread were the two most accurate measurements for both species. For white-tailed deer, 93% (114 of 123) of the 1.5-year age class and 93% (251 of 271) of the \u3e/= 2.5-year age class were correctly classified using main beam length with a cutoff of 364 mm. For mule deer, 100% (12 of 12) of the 1.5-year age class and 97% (35 of 36) of the \u3e/= 2.5-year age class were correctly classified using main beam length with a cutoff of 352 mm. Antler metrics of both deer species can be used to accurately classify age class while likely saving funds and personnel hours

Food habits of imperiled Plains Topminnow and diet overlap with invasive Western Mosquitofish in the Central Great Plains

Plains Topminnow (Fundulus sciadicus) populations have experienced large declines throughout the Central Great Plains, with Western Mosquitofish (Gambusia affinis) introductions suggested as a contributing factor. There are limited studies identifying the food habits of Plains Topminnow and the trophic interactions with Western Mosquitofish. This study sought to determine if a diet overlap exists between the Plains Topminnow and the introduced Western Mosquitofish by identifying the feeding habits of both species. We analyzed diets from lentic and lotic populations of Plains Topminnow captured in August and found lentic topminnows employed a generalist diet while lotic topminnow selected for gastropods. Additionally, Western Mosquitofish diets from regionally proximate lotic and lentic populations also displayed a generalist diet consisting of benthic, littoral and terrestrial macroinvertebrates. The two species did not show overlapping diets based on Schoener’s Index. Therefore we suggest the introduced Western Mosquitofish do not likely impact Plains Topminnow populations through food resource competition

Genetic protocols for DNA extraction from white-tailed deer cast antlers to confirm individuality

White-tailed deer (Odocoileus virginianus) are the most sought-after deer species in America. The antlers of mammals, such as deer, are one of the fastest regenerative tissues in the world and are grown and naturally cast every year. Research on cast antlers have been used for a variety of purposes including population comparisons and impacts of deer health due to climatic stressors. When investigating cast antlers, it is important to confirm individuality of match sets in addition to antlers of the same individual between years. Therefore, individuality must be confirmed genetically, and protocols must be developed and established to do so. Our objectives were to 1) establish a genetic protocol to harvest DNA from cast antlers using connective tissue, and 2) determine individuality from subsequent years and match sets. When fresh antlers are cast, they leave behind a viable connective tissue from which DNA can be extracted. The DNA was successfully extracted from the skin rings harvested from naturally cast antlers. This study developed viable methods to confirm individuality, which aid researchers and wildlife biologists in a better understanding of the white-tailed deer herd as they set management goals and harvest regulations

Assessment of Smallmouth Bass Growth and Mortality in Nebraska Waters

Smallmouth bass (Micropterus dolomieu) have been introduced across Nebraska into a variety of waterbodies. However, an estimate of smallmouth bass growth and mortality in Nebraska waters has not been produced. The objectives of this study were to use historic sampling data to describe the growth of smallmouth bass in Nebraska lakes in relation to other regional models, growth among waterbody types (reservoirs, Interstate 80 [I-80] lakes, and rivers), estimates of age at quality, preferred, and memorable lengths, and mortality for Nebraska smallmouth bass populations. Mean length ± SE of Nebraska smallmouth bass at age 7 was 383 ± 21 mm, which is similar to national and regional values. Mean lengths at age of smallmouth bass in I-80 lakes and reservoirs were similar, but lengths were larger in rivers than in I-80 lakes and reservoirs at ages 3–5. Mean total annual mortality measured 0.41 (± 0.06 SE). These growth and mortality rates allow biologists to set appropriate management objectives and assess local sampling results with proper perspectives

Sex-specific Changes in Walleye Abundance, Size Structure and Harvest Following Implementation of Regulation to Protect Broodstock

The popularity of walleye Sander vitreus fishing has resulted in the development of specialized regulations that are designed to protect these fisheries. In the case of Sherman Reservoir, Sherman County, Nebraska, the walleye population provides a sportfishing opportunity and serves as broodstock for the state. In 2009, for the primary purpose of protecting female broodstock, the regulation changed from a harvest limit of four walleye with 457-mm minimum length to allowing a reduced harvest limit of two walleye within a harvest slot (381–508 mm) and one walleye more than 711 mm. This study examined existing data sets to assess the percentage of spawning walleye protected with each regulation, sex-specific differences in relative abundance and size structure during broodstock collection and angler effort, total catch, and harvest of walleye. The new regulation has increased protection of female walleye by more than 90%, but decreased protection of male walleye by more than 60%. The relative abundance of female walleye caught per net during broodstock collection has more than doubled since the regulation was changed, but the size structure of female walleye collected during broodstock operations was similar. Correspondingly, the relative abundance of male walleye has declined since changing the regulation, but size structure remained similar. Effort and total catch of walleye by anglers were similar before and after the regulation was enacted, but harvest has increased by 130%. This regulation appears to protect female broodstock walleye, but it makes male walleye more vulnerable to angler harvest

Age-0 walleye \u3ci\u3eSander vitreus\u3c/i\u3e display length-dependent diet shift to piscivory

The ontogenetic diet shift to piscivory can be energetically beneficial for fish growth and allows larger, more energetically profitable prey to be consumed. A shift to piscivory may be easier for longer individuals within a cohort due to larger gape size, and an early shift is likely advantageous, potentially leading to increased growth rates and survival. Such length-dependent ontogenetic diet shifts may explain the intracohort variability in length that is common for age-0 walleye (Sander vitreus). The objectives of this study were to describe seasonal intracohort variability in length, identify the timing of the shift to piscivory and determine if the onset of piscivory was length-dependent in age-0 walleye. Walleye initially fed on zooplankton, but shifted to piscivory during July of 2010 and June of 2011. The onset of piscivory in age-0 walleye was associated with length-dependent differences during both years, in which longer individuals within the cohort became piscivorous earlier than shorter individuals within the same cohort. Intracohort variability in length was detected and increased postontogenetic diet shift. Age-0 walleye that experience a growth advantage could benefit from increased survival and feeding opportunities