Interstate 80 Lakes — Grand Island to Elm Creek Fish Survey Results - Spring 2013

Spanning a stretch of 150 miles along Interstate 80 from Grand Island to Hershey more than 60 small lakes are available for public fishing. Fisheries staff from the Kearney office has the management responsibility for the Interstate lakes located from Grand Island to Elm Creek. These man-made lakes, most of which were created for fill material when the Interstate system was developed in the 1960’s, range in size from 1 to 42 acres. The ground water fed lakes have excellent shoreline access for anglers and usually contain clear water and abundant aquatic vegetation, providing excellent habitat conditions for largemouth bass and bluegill. In addition, most of the lakes contain channel catfish, while others have crappie, rock bass, walleye, and northern pike. The fish populations are surveyed on a five year rotation and the following graphs and text display these results. Largemouth Bass Largemouth bass are present in all of the Interstate lakes in the central portion of Nebraska, with the exception of War Axe, which has smallmouth bass. Lakes with high densities of smaller bass, include Windmill, Ft. Kearny, West and Middle Mormon Island, Bufflehead, Kea Lake, Coot Shallows, and Sandy Channel #2. Lakes that traditionally produce large bass include Cheyenne, Windmill #1, Bassway Strip, Bufflehead, Blue Hole West, and Sandy Channel #8. Most of the I-80 lakes have a 15-inch minimum length limit on black bass. Exceptions include; Mormon Island SRA, Cheyenne, West Wood River, War Axe, and Archway Lakes, all of which have a 21-inch minimum length limit. In addition, Kea West is designated as a catch and release only lake for all species. Anglers are encouraged to practice catch and release on bass in the I-80 Lakes as they are easily over-harvested

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

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements