Time filter

Source Type

Forest Lake, MN, United States

Pierce R.B.,1201 East Highway 2 | Carlson A.J.,601 Minnesota Drive | Carlson B.M.,University of Michigan | Hudson D.,U.S. Geological Survey | Staples D.F.,463 C West Broadway
Transactions of the American Fisheries Society | Year: 2013

We monitored depths and temperatures used by large (>71-cm) versus small Northern Pike Esox lucius in three north-central Minnesota lakes with either acoustic telemetry or archival tags. Individual Northern Pike demonstrated flexibility in depths used within a season and between years. The fish had some tolerance for low levels of dissolved oxygen (<3 mg/L), but depth selection was generally constrained by low dissolved oxygen in summer and winter. The fish more fully exploited all available depths during winter and thermal turnover periods. During July and August, large Northern Pike tended to follow the thermocline into cooler water as upper water layers warmed. Selection ratios indicated that large Northern Pike preferred water temperatures of 16-21°C during August when temperatures up to 28°C were available. In two lakes providing dense overhead cover from water lilies in shallow water, small Northern Pike used warmer, shallower water compared with large fish during summer. In a third lake providing no such cover, small fish were more often in deeper, cooler water. For small Northern Pike, temperature seemed to be a secondary habitat consideration behind the presence of shallow vegetated cover. This study provided detailed temperature selection information that will be useful when considering temperature as an ecological resource for different sizes of Northern Pike. Received March 27, 2013; accepted June 27, 2013. © 2013 Copyright Taylor and Francis Group, LLC. Source

Verma S.K.,U.S. Department of Agriculture | Carstensen M.,463 C West Broadway | Calero-Bernal R.,U.S. Department of Agriculture | Jiang T.,University of Tennessee at Knoxville | And 2 more authors.
Parasitology Research | Year: 2016

Toxoplasma gondii infections are widespread in white-tailed deer (Odocoileus virginianus) but little is known of its prevalence in other cervids in the USA. Moose (Alces alces) is a popular large game animal, hunted for its meat and trophy antlers. Here, we report seroprevalence, isolation, and genetic characterization of T. gondii from moose from Minnesota. Antibodies against T. gondii were detected in 8 of 79 (10 %) moose tested by the modified agglutination test (MAT 1:25 or higher). The myocardium of 68 moose was bioassayed individually in mice, irrespective of serological status. T. gondii was detected in three moose (2 adults, 1 3 weeks old). The parasite from 2 adults was further propagated in cell culture. PCR-RFLP genotyping of cell culture derived tachyzoites using 10 genetic markers, SAG1, SAG2 (5′ and 3′ SAG2, and alt.SAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico revealed two different ToxoDB PCR-RFLP genotypes (#5, designated TgMooseUS1, and #7, TgMooseUS2). The mice inoculated with myocardium of the juvenile moose developed antibodies against T. gondii, and DNA extracted from infected mouse brain was only partially characterized by PCR-RFLP genotyping, which suggests a potential new genotype. Result documented prevalence of T. gondii in moose, and its possible transplacental/transmammary transmission of T. gondii in moose. © 2015, Springer-Verlag Berlin Heidelberg (outside the USA). Source

LeAnn White C.,U.S. Geological Survey | Ip H.S.,U.S. Geological Survey | Meteyer C.U.,U.S. Geological Survey | Walsh D.P.,U.S. Geological Survey | And 3 more authors.
Journal of Wildlife Diseases | Year: 2015

Morbidity and mortality events caused by avian paramyxovirus-1 (APMV-1) in Double-crested Cormorant (DCCO; Phalacrocorax auritus) nesting colonies in the US and Canada have been sporadically documented in the literature. We describe APMV-1 associated outbreaks in DCCO in the US from the first reported occurrence in 1992 through 2012. The frequency of APMV-1 outbreaks has increased in the US over the last decade, but the majority of events have continued to occur in DCCO colonies in the Midwestern states. Although morbidity and mortality in conesting species has been frequently reported during DCCO APMV-1 outbreaks, our results suggest that isolation of APMV-1 is uncommon in species other than DCCO during APMV-1 outbreaks and that the cause of mortality in other species is associated with other pathogens. Populations of DCCO do not appear to have been significantly affected by this disease; however, because at least 65% of the APMV-1 outbreaks in DCCO in the US have involved APMV-1 strains classified as virulent to poultry (virulent Newcastle disease virus), its persistence and increased occurrence in DCCO warrants continued research and surveillance. © Wildlife Disease Association 2015. 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

Staples D.F.,463 C West Broadway
North American Journal of Fisheries Management | Year: 2011

Gill nets are a versatile fish sampling gear used for many species and habitats; however, their usefulness may be limited by selectivity patterns and reliance on fish movement, which can be influenced by several factors. We evaluated the effect of net length, time of day, sampling date, surface water temperature, soak time, water depth, and location on the number, length, and initial mortality of walleyes Sander vitreus caught in short-term (mean, 38.8 min; range, 10-200 min) gill nets set in Mille Lacs Lake, Minnesota. The number of walleyes caught was best described by a generalized additive model (GAM) that contained all seven covariates and explained 35% of the variation in catch. The length of walleyes caught was best described by a GAM that contained time of day, sampling date, soak time, and sampling location as covariates and explained 11% of the variation in fish length. The initial mortality of walleyes was best described by a GAM that included surface water temperature and soak time as covariates.Walleye catches were higher fromdusk to dawn than at other times, with peak catches occurring around 0500 and 2100 hours, demonstrating the diel activity patterns of walleyes. Catches also increased with surface water temperature and soak time. However, the initial mortality of walleyes also increased with surface water temperature and soak time, with the largest increase in initial mortality at soak times longer than 60 min. Investigators can use these results to assist in designing and planning short-term gill-netting efforts to maximize the catch and minimize the mortality of walleyes. © American Fisheries Society 2011. Source

Discover hidden collaborations