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Duluth, MN, United States

Myers R.A.,Dalhousie University | Smith M.W.,Virginia Institute of Marine Science | Hoenig J.M.,Virginia Institute of Marine Science | Kmiecik N.,Great Lakes Indian Fish and Wildlife Commission | And 4 more authors.
Transactions of the American Fisheries Society | Year: 2014

Estimates of size- and sex-specific gear selectivity are important for making informed management decisions. Sex-specific selectivity curves may be needed for two-sex statistical catch-at-age models when information about sex ratios in the catch is unavailable. We used data from three tagging programs in Minnesota and Wisconsin to estimate the size- and sex-specific selectivity of angling and spearing for Walleyes Sander vitreus. We estimated capture selectivity (the relative catchability of each component of the population) and harvest selectivity (the combined effect of capture selectivity and the decision to retain or release a fish from a given component). These components are of interest because (1) the hooking mortality of released fish contributes substantially to total mortality, so that it is important to know how harvest and release vary by size; and (2) capture selectivity is likely similar across lakes, such that data from other lakes may provide information on capture selectivity for the lake of interest, while harvest selectivity is lake specific. Estimates were obtained using generalized linear models to determine the significance of the individual and interactive effects of length and sex on selectivity. Angling capture and harvest selectivity were both greater for females than males of every length. In contrast, spearing harvest selectivity was greater for males. For both sexes, harvest selectivity for angling and spearing peaked at around 400-450 mm. The capture selectivity of anglers peaked at 350-375 mm. The interaction between sex and size was significant for capture selectivity for angling, with the sex effect for small fish being less than that for large fish. Above 400 mm, spearing selectivity did not appear to vary with length for either sex, but at lengths below that it was lower for males. Received March 20, 2013; accepted October 29, 2013. © 2014 Taylor & Francis Group, LLC. Source

Bettoli P.W.,Tennessee Technological University | Goldsworthy C.,351 North Shore Drive
Southeastern Naturalist | Year: 2011

Abstract We used lighted larval traps to assess reproduction by fishes inhabiting nine spring pools in the Barrens Plateau region of middle Tennessee between May and September 2004. The traps (n = 162 deployments) captured the larval or juvenile forms of Etheostoma crossopterum (Fringed Darter) (n = 188), Gambusia affinis (Western Mosquitofish) (n = 139), Hemitremia flammea (Flame Chub) (n = 55), the imperiled Fundulus julisia (Barrens Topminnow) (n = 10), and Forbesichthys agassizii (Spring Cavefish) (n = 1). The larval forms of four other species (Families Centrarchidae, Cyprinidae, and Cottidae) were not collected, despite the presence of adults. Larval Barrens Topminnow hatched over a protracted period (early June through late September); in contrast, hatching intervals were much shorter for Fringed Darter (mid-May through early June). Flame Chub hatching began before our first samples in early May and concluded by late-May. Juvenile Western Mosquitofish were collected between early June and late August. Our sampling revealed that at least two species (Flame Chub and Fringed Darter) were able to reproduce and recruit in habitats harboring the invasive Western Mosquitofish, while Barrens Topminnow could not. Source

Miller L.M.,University of Minnesota | Ward M.C.,7316 State Highway 371 | Schreiner D.R.,351 North Shore Drive
Journal of Great Lakes Research | Year: 2014

Reduced reproductive success of hatchery fish spawning in the natural environment will reduce the ability of stocking programs to enhance wild populations. We used DNA-based parentage assignment to compare the reproductive success of wild fish and first-generation hatchery fish from a smolt stocking program that used broodstock from within the naturalized steelhead Oncorhynchus mykiss population in a Minnesota tributary to Lake Superior. The reproductive success of hatchery females was significantly lower than that of wild females (approximately 60%) in all three study years; however, the reproductive success of hatchery males was only significantly lower in one year. Higher reproductive success of wild fish was attributed to greater probability of success (i.e., having at least one offspring) and not differences in numbers of offspring among successful parents. Generalized linear models indicated that run timing was associated with probability of success although this did not explain differences between hatchery and wild fish. Despite runs that extended 7-9 weeks, most successful adults arrived in the first three weeks of the run (85-98% of all successful females, 98-100% of successful males). The early part of the run corresponded to periods of high flow, which likely increased access to quality spawning and rearing habitat higher upstream in the system. Relationships between fish length and reproductive success were inconsistent. Managers may minimize potential environmental and genetic contributors to reduced performance by hatchery fish, but continued reliance on hatchery supplementation may hinder achievement of the long-term goal of a fishery supported largely by naturally reproducing populations. © 2014 Elsevier B.V. Source

Schmalz P.J.,351 North Shore Drive | Luehring M.,Great Lakes Indian Fish and Wildlife Commission | Dan Rose J.,Great Lakes Indian Fish and Wildlife Commission | Hoenig J.M.,Virginia Institute of Marine Science | Treml M.K.,00 Lafayette Road
North American Journal of Fisheries Management | Year: 2016

Abstract: There is a fundamental conflict between harvesting fish and conserving their biomass. Managers mediate this conflict with regulations that control fishery methods and amounts of harvest. In most recreational fisheries, aside from closed seasons, the precise control of fishing effort is difficult to achieve because fisher entry into a managed area is often unlimited and because effort can be influenced by both direct and indirect factors. Choosing the best fishing regulations is also complicated by a need to jointly regulate and accommodate the desires of different user groups who share the fishery. Regulations may need to account for (1) low-consumptive uses of fish populations that occur from catch-and-release fishing by recreational anglers and/or (2) both tribal subsistence and commercial fishers. We applied a suite of graphical techniques to data on a shared fishery, that for Walleye Sander vitreus in Mille Lacs Lake, Minnesota, to examine the trade-offs between fishery yield and spawner biomass on a per-recruit basis across a range of harvest tactics, so that fisheries managers could simultaneously evaluate a variety of regulations. We also used Bluegill Lepomis macrochirus data from several Minnesota lakes to further evaluate the utility of our approach. Some regulations were uniformly better than others because they provided higher yield for a given spawning biomass, and higher spawning biomass for a given yield at equilibrium, under a range of plausible levels of fishing effort. For a given level of fishing effort, we were able to identify a frontier in the yield–biomass space whereby an increase in either the yield or the biomass could only be achieved by a reduction in the other. In the absence of density-dependent changes to growth, maturity, or mortality, regulations that included a minimum length produced more optimal yield and spawner biomass than those that did not include a minimum length. We reduced the daunting task of choosing from dozens of regulations by considering just a few graphs that best demonstrated the trade-offs offered by a suite of regulations. Received December 24, 2014; accepted August 21, 2015 © 2016, © American Fisheries Society 2016. Source

Negus M.T.,351 North Shore Drive | Schreiner D.R.,351 North Shore Drive | Ward M.C.,7316 State Highway 371 | Blankenheim J.E.,351 North Shore Drive | Staples D.F.,463 C West Broadway
Journal of Great Lakes Research | Year: 2012

Hatchery augmentation of steelhead Oncorhynchus mykiss was evaluated over 20. years in Minnesota tributaries of Lake Superior using three approaches - stocking fry or yearlings of a naturalized strain (STT), and yearlings of a domesticated strain (KAM). The STT strain was introduced over 100. years ago and became naturalized to Lake Superior and its tributaries, unlike KAM, which has not been shown to reproduce successfully in streams. We compared smolt-adult return rates to anglers and in-river traps, and production costs per adult for these three programs in the French and Knife rivers. STT smolts derived from stocked fry in the French River resulted in the highest smolt-adult return rates to traps and anglers (13.3%), and lowest cost per returning adult ($46). STT stocked as yearling smolts produced the lowest return rate (1.5%) and highest cost per returning adult ($192) for both rivers combined. KAM stocked as yearling smolts were intermediate in return rate (2.6%) and cost per adult ($90). Differences in return rates of the three strains were attributable to the extent of domestication selection, size at stocking, season of stocking, and summer lake temperatures. Smolts derived from fry-stocked STT were strongly influenced by summer lake temperatures in their first lake year. Yearling-stocked STT were influenced by size at stocking and summer lake temperatures. KAM yearlings benefitted from summer stocking at larger sizes. Based on poor survival and fiscal constraints, the STT yearling program was discontinued. Stocking programs will continue to evolve according to changing biological, financial, social, and political pressures. © 2012 Elsevier B.V. Source

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