Browsing by Subject "Salmonids"

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    Assessment of Habitat and Biota in the West Branch of the Knife River, MN
    (University of Minnesota Duluth, 2014-03) Dumke, Josh; Brady, Valerie; Hell, Robert V
    The Lake Superior Steelhead Association (LSSA) received funding from the Lessard-Sams Outdoor Heritage Council in 2012 to fund multiple project phases on the West Branch of the Knife River. The West Knife has received attention by LSSA due to historic reports of this tributary being important for anadromous rainbow trout (steelhead) reproduction, and because most of this watershed lies within public property. In past decades, this watershed has experienced logging, beaver activity, and barriers to migratory fish passage. In 2013 LSSA worked with the Minnesota Department of Natural Resources to improve fish passage conditions over the second falls of the Knife River. Mixed tree species were also planted in one beaver impacted meadow, and there are plans to expand the tree planting activities to other areas within the watershed in 2014. Pre-restoration surveys are important for demonstrating the effect of restoration activities. Good documentation of stream condition, and the organisms that live there, allow post-restoration comparisons, assessment of the most cost-effective restoration activities, and the ability to track trends over time. Natural Resources Research Institute staff were hired by LSSA to complete pre-restoration surveys of seven reaches on the West Branch Knife River; five on the main stem and two on tributaries. Fish and stream habitat were surveyed in all reaches, and aquatic macroinvertebrates were sampled in two reaches (reaches 2 and 3), with a cursory survey on a third reach (reach 1). The pre-restoration survey revealed that rainbow trout (steelhead) were present in all sampled reaches except the farthest upstream reach, which was apparently inaccessible to migratory fish due to beaver activity downstream. Brook trout were the dominant salmonid in all sampled reaches, and were at the greatest densities in the two small tributaries. One of these tributaries (reach 7) had indications of strong groundwater inputs based on water temperature and specific conductivity. This tributary appears to be an important area for brook trout reproduction and as a nursery for juveniles, but had few pools to hold larger fish. Stream bottom substrates in this tributary had large proportions of sand and silt, which are suboptimal habitat conditions for the aquatic macroinvertebrates that provide food for trout and other fish. Most pool habitats were found in downstream sections of the West Knife main stem that were influenced by beaver (reaches 1 and 2). However, these beaver meadow areas contained more nontrout species, which indicates these reaches may periodically have summer water temperatures above the thermal optimum for trout. The stream bottom in reaches 1 and 2 contained rocks that were surrounded and buried in sands, silts, and clays, reducing the amount of living space (habitat) for fish fry and aquatic macroinvertebrates. Thus, aquatic macroinvertebrate assemblages in these two reaches were in poorer condition (rated moderate-low) when compared to other North Shore streams NRRI researchers have sampled. Biotic habitat was best in reach 3, followed by reach 5 (both on the main stem, upstream of reaches 1 and 2). Reach 3 had the most young rainbow trout, as well as a nice population of brook trout, but the macroinvertebrate community was not in as good a condition as expected based on the very good habitat conditions. We speculate that the gravels in this reach are easily moved during high flow (flood) events; this lack of stream bottom stability leaves macroinvertebrates (and often fish fry) with few refugia from high flows, causing many of them to be dislodged and washed downstream. We speculate that this issue may be the reason why macroinvertebrate assemblages do not compare as favorably with those of other north shore streams as we expected. Reach 5 was located within a beaver meadow, but our stream measures indicate that the only measureable negative impact was a loss of riparian tree canopy to shade the stream.
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    Pre-Treatment Assessment of Habitat and Biota in the Knife River Mainstem, MN
    (University of Minnesota Duluth, 2017-03) Dumke, Josh; Kelly, Holly W
    Pre-restoration surveys are important for demonstrating the effectiveness of restoration activities. Good documentation of stream condition, and the organisms that live there, allow post-restoration comparisons, assessment of the most cost-effective restoration activities, and the ability to track trends over time. During 2016 the Lake Superior Steelhead Association (LSSA) requested University of Minnesota Duluth, Natural Resources Research Institute (NRRI) staff to complete surveys of 3 Knife River mainstem reaches (two pre-treatment, and one reference) for fish, macroinvertebrates, and stream habitat. The 2016 Knife River surveys followed our standard methods used in past LSSA contracts. Reaches were named “Reach 12”, “Reach 9”, and “Reference” (listed in upstream progression). Reach 12 and Reach 9 were considered “pre-treatment” assessments, as habitat improvement projects to reduce stream bank erosion and improve pool and cover habitat for larger salmonids in these reaches occurred following our surveys. Data from the Reference reach will be important for distinguishing whether changes detected over time are natural or from the applied stream work. Our surveys revealed that all three reaches were quite similar in habitat, as well as macroinvertebrate and fish communities. Reach 9 had the most fish species due to one very large pool, but otherwise, was not very different from Reach 12. Reaches 12 and 9 had areas with unstable channel conditions and eroding banks, which were not present in the Reference reach. Therefore, the Reference reach ranked highest in the MPCA Stream Habitat Assessment (MSHA) protocol scoring system and percent canopy cover over the stream channel. The Reference reach also had more pools with slower-flowing water and woody debris, which Brook Trout favor. Thus, we found greater Brook Trout abundance and fitness in the Reference reach. In summary, our survey indicates all reaches were relatively similar. This assessment is important because it demonstrates the section of the river we selected for the Reference reach will adequately capture natural changes over time, while still being a comparable river segment to Reach 12 and 9.
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    Seasonal Prey Resource Partitioning Among Salmonids In The Bois Brule River, Wisconsin
    (2024) McCann, Daniel
    Over the past century, intentional introductions of non-native Salmonids into Lake Superior and its tributaries have raised concern about possible interactions with native Brook Trout (Salvelinus fontinalis), which have historically been subject to local extirpations. The Upper Bois Brule River, Wisconsin currently supports a diverse and abundant assemblage of Salmonid species, including Brook Trout, Brown Trout (Salmo trutta), Rainbow Trout (Oncorhynchus mykiss), Coho Salmon (Oncorhynchus kisutch), and Chinook Salmon (Oncorhynchus tshawyscha). To investigate underlying reasons for apparent co-existence of potentially competing species, I documented the seasonal diet characteristics among coexisting Salmonids and compared stomach content data to seasonal prey abundances (macroinvertebrates) in the benthos and stream drift. The primary objective was to determine if niche partitioning reduces competitive interactions between Brook Trout, Brown Trout, Rainbow Trout, and juvenile Coho Salmon in the Bois Brule River, Wisconsin. Results indicated that Brook Trout and Brown Trout had significant diet overlap during spring, summer, and fall sampling dates, while there were no instances of significant dietary overlap between the non-native species. Several positive relationships between diet overlap and the abundances of different prey categories suggest prey resource partitioning in response to competition may underlie the co-occupation of Salmond species in my study area. All Salmonid species showed positive selection for Trichoptera larvae during spring, summer, and fall. In addition, Brook Trout and Brown Trout showed positive selection for Gastropods during every season. Brook Trout were the only species with strong preferences for Crustaceans, while Rainbow Trout were the only species with preferences for Ephemeroptera nymphs. Brook Trout and Rainbow Trout exhibited opportunistic diets, while Brown Trout tended to feed primarily from the benthos and Coho Salmon fed mainly on surface-oriented prey. It’s likely that the persistence of Brook Trout in the presence of non-native Salmonids is attributed to their flexibility in foraging modes, utilization of increased invertebrate drift rates, and consumption of less preferred prey items. This study provides new information on resource utilization, niche partitioning, and resource overlap among multiple coexisting Salmonid species and may be helpful for future research and management with sympatric populations of native and non-native Salmonid species.