Sources of coaster brook trout (Salvelinus fontinalis) revealed by genomic analysis of brook trout populations along Minnesota’s shoreline with Lake Superior

Knowledge of population-level relationships and how these relationships pertain to different life history forms is critical to developing effective management plans for native trout, char, and salmon. In the Lake Superior basin, identifying effective restoration strategies for coaster brook trout (Salvelinus fontinalis), a lake-inhabiting form of brook trout, is hampered by limited information on genetic connectivity and source-sink dynamics among brook trout populations. Here, we infer these relationships by surveying 8,178 single nucleotide polymorphisms in 234 brook trout from seven rivers along the Minnesota shoreline with Lake Superior, including from reaches above and below natural waterfalls that prevent upstream movement. We identified well-differentiated above-barrier populations that supply brook trout to below-barrier reaches. We also compared within-river brook trout to 26 coaster brook trout from Lake Superior. We identified at least four source populations for these coaster brook trout, three of which were located within rivers. Additionally, we estimated N_E for within-river populations and detected a decline across recent generations, with the most recent estimates approaching critical thresholds. Finally, comparisons with 94 domestic brook trout representing nine hatchery strains revealed a lack of domestic introgression into wild populations, demonstrating the importance of natural reproduction to population persistence. Our results offer novel insights into sources of coaster brook trout and highlight the role of within-river populations in supporting the coaster life history. Management efforts focused on instream restoration may be more important to rehabilitating coaster brook trout than previously thought and are urgently needed given the population-level conservation status reported here.     

Characterizing physical habitat preferences and thermal refuge occupancy of brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo salar) at high river temperatures

Anthropogenic influences, including climate change, are increasing river temperatures in northern and temperate regions and threatening the thermal habitats of native salmonids. When river temperatures exceed the tolerance levels of brook trout and Atlantic salmon, individuals exhibit behavioural thermoregulation by seeking out cold‐water refugia – often created by tributaries and groundwater discharge. Thermal infrared (TIR) imagery was used to map cold‐water anomalies along a 53 km reach of the Cains River, New Brunswick. Trout and salmon parr did not use all identified thermal anomalies as refugia during higher river temperature periods (>21°C). Most small‐bodied trout (8–30 cm) were observed in 80% of the thermal anomalies sampled. Large‐bodied trout (>35 cm) required a more specific set of physical habitat conditions for suitable refugia, that is, 100% of observed large trout used 30% of the anomalies sampled and required water depths >65 cm within or adjacent to the anomaly. Densities of trout were significantly higher within anomalies compared with areas of ambient river temperature. Salmon parr were less aligned with thermal anomalies at the observed temperatures, that is, 59% were found in 65% of the sampled anomalies; and densities were not significantly different within/ outside anomalies. Salmon parr appeared to aggregate at 27°C, and after several events over 27°C variability in aggregation behaviour was observed – some fish aggregated at 25°C, others did not. We stipulate this is due to variances of thermal fatigue. Habitat suitability curves were developed for velocity, temperature, depth, substrate, and deep water availability to characterize conditions preferred by fish during high‐temperature events. These findings are useful for managers as our climate warms, and can potentially be used as a tool to help conserve and enhance thermal refugia for brook trout and Atlantic salmon in similar systems.     

Visual perception of Fourier rainbow holographic display

The rainbow hologram provides views of reconstruction with rainbow color within a large viewing zone. In our recent paper, a Fourier rainbow holographic display using diffraction grating and a white‐light LED source was introduced. In this technique, the rainbow effect is realized by the dispersion of white‐light source on diffraction grating, while the slit is implemented numerically by reducing the demands of the space‐bandwidth product of the display. This paper presents a novel analysis on the visual perception of the Fourier rainbow holographic display using Wigner distribution. The view‐dependent appearance of the image, including multispectral field of view and viewing zone, is investigated considering the observer and the display parameters. The resolution of the holographic view is also investigated. For this, a new quantitative assessment for image blur is introduced using Wigner distribution analysis. The analysis is supported with numerical simulations and experimentally captured optical reconstructions for the holograms of the computer model and real object generated with different slit size, reconstruction distance, and different observation conditions.     

Effects of active chitosan-flaxseed mucilage-based films on the preservation of minced trout fillets: A comparison among aerobic,vacuum, and modified atmosphere packaging

The objectives of the current study were to examine physical–mechanical, structural, and morphological characteristics of chitosan-flaxseed mucilage films enriched with Ziziphora clinopodioides essential oil (ZEO; 0%, 0.25%, and 0.5%) and sesame oil (SO; 0% and 0.75%) and to provide useful information for the preservation of minced trout fillet's using antimicrobial films under aerobic, vacuum, and modified atmosphere conditions for 16 days. The films showed thickness, tensile strength, puncture force, puncture deformation, water vapor transmission rate, water vapor permeability, swelling index, and oxygen permeability values ranging 0.082–0.86 mm, 33.34–46.83 MPa, 25.69–53.08 N, 11.45–28.45 mm, 17.48–26.73 g/m² h, 8.57–12.49 × 10⁻⁴ g mm/m² h Pa, 12.45–38.43%, and 3.02–13.32 × 10⁻¹² cm³/m² s Pa, respectively. The following order of effect on the microbial spoilage population of treated samples was found in the applied packaging methods: modified atmosphere packaging > vacuum packaging > aerobic packaging. The final microbial population of treated samples was 0.35–4.91 log CFU/g lower than the controls after 16 days of refrigerated storage. At the end of the storage, the total volatile base nitrogen, peroxide value, and thiobarbituric acid reactive substances of untreated samples were 34.02–48.6 mg of N/100 g, 1.43–2.32 meq of peroxide/1000 g, and 3.33–4.24 mg of malondialdehyde/kg, respectively. The lowest corresponding values were recorded for the treated samples with ZEO 0.5% + SO 0.75% films by 14.26–17.73 mg of N/100 g, 0.48–0.86 meq of peroxide/1000 g, and 1.08–1.48 mg of malondialdehyde/kg, respectively.     

Consumer Acceptance of Brown Trout (Salmo trutta) as an Alternative Species to Rainbow Trout (Salmo gairdneri)

Rainbow trout and brown trout were prepared and distributed to consumers for comparative taste tests to determine consumer reaction to brown trout. In-home tests were standardized with paired samples of fish. Color of flesh, odor, flavor, texture and overall acceptability were recorded on a 9-point Hedonic scale. Sensory results indicated that brown trout raised in farm stock ponds were more acceptable than rainbow trout from similar environments, and rainbow trout from natural winter-kill lakes were more acceptable than brown trout from the same or similar lakes. Overall, we conclude that brown trout would be acceptable to consumers. Variations in acceptability related to water body of origin rather than to species of fish. Significant differences occurred in some characteristics but were inconsistent as to species.     

平面合成彩虹全息图

提出一种记录平面合成彩虹全息图的空间分割记录方法.利用这种方法得到的彩虹全息图不仅可以在白光下再现一动态图象,而且可以用常规方法进行模压复制.文中描述了这种方法的基本原理、实验装置及结果.     

Survey of Siscowet Lake Trout at Their Maximum Depth in Lake Superior

The siscowet Salvelinus namaycush is a deepwater morphotype of lake trout in Lake Superior. As part of a standardized lake-wide survey in 2006 to assess siscowet populations, bottom-set, multi-mesh gill nets were fished at 36.6 m depth intervals from near shore areas to the deepest waters in south-central Lake Superior. Siscowet length distributions, diet compositions, and sea lamprey wounding rates were compared for three depth zones: shallow (< 200 m), deep (200–394 m), and deepest (395–399 m). There were 39 siscowets collected in proximity to Lake Superior's greatest recorded depth of 405 m. To our knowledge, this is the greatest depth that fish have been collected in the Great Lakes. Higher proportions of siscowets ≤ 500 mm were caught in the shallow zone compared to deeper zones. Deepwater sculpins were the dominant prey for small siscowets (< 600 mm) across all depth zones. The diet of large siscowets (≥ 600 mm) among all depth zones comprised mostly of coregonines and burbot Lota lota. Terrestrial insects were observed in the diet of siscowets in all depth zones, indicating migration to the surface. Type A sea lamprey wounding rates were higher for large (≥ 600 mm) than small siscowets among all depth zones. The highest wounding rate was observed on large siscowets in the deep zone. Recent work indicates that siscowets are the most abundant lake trout form and this research indicates that siscowets use the maximum depths of Lake Superior.     

周视投影彩虹全息术

本文给出一种可周视观察的投影彩虹全息术,分析了衍射像分离条件,给出了两种实验光路,并作了实验验证。     

The effect of discharge and predation on habitat use by wild and hatchery brown trout (Salmo Trutta)

The effects of trout stock, discharge and predation risk on habitat use by brown trout, Salmo trutta, were studied in four artificial streams. Trout stock had no effect on habitat use as both wild and hatchery fish used similar habitats. The presence of pike (Esox lucius) caused trout to decrease their use of pools, the habitat in which pike occurred, and increase their use of other habitats. Decreasing discharge reduced available area of the stream and resulted in fewer fish in the shallow margins. Both decreased flow and increased predation risk caused more overlap in habitat use, and thus increased the potential for intraspecific competition, predation and the use of poorer habitats. The results illustrate the danger of applying habitat use relationships obtained from one stream to all other streams where habitat availability and biotic interactions may differ.     

基于分布式GPU的彩虹表密码攻击系统

彩虹表是密码破解中最常用的工具。利用CPU构造彩虹表占用时间、空间巨大,已经成为限制彩虹表应用的最大问题。针对彩虹表存在的查找时间、构造时间、占用内存空间瓶颈问题进行了研究。采用高速 GPU 改进彩虹表构造方法,建立彩虹表参数与时空关系模型,分析得出实际中可选取的参数值。设计实现了基于分布式GPU 的彩虹表密码破解优化系统,包括密文提取模块、密文分发模块、GPU 处理模块和彩虹表模块。系统实践证明,该方法能有效提高密码破解效率,降低彩虹表对时间空间资源的占用,增加彩虹表实际可破解的密码长度。