Douglas J. Dieterman

Instream Evaluation of Passive Integrated Transponder Retention in Brook Trout and Brown Trout: Effects of Season, Anatomical Placement, and Fish Length

Abstract We examined effects of tagging season, anatomical placement of tags, and fish total length (TL) at tagging on 2-month retention of passive integrated transponder (PIT) tags in 181 brook trout Salvelinus fontinalis (99–302 mm TL) and 709 brown trout Salmo trutta (122–511 mm TL) in small streams of southeastern Minnesota. A lower percentage of brown trout retained their tags in spring (56%) than in fall (68%), but season did not affect tag retention in brook trout. Retention rates varied with anatomical placement for both species. For brook trout, retention was 70% when the PIT tag was placed into the body cavity using an insertion point that was posterior to the pelvic fins and 100% when the tag was placed into the dorsal musculature. Among brown trout, PIT tag retention was 56% for body cavity placement (posterior insertion) and 95% for dorsal musculature placement. Tag retention was not associated with fish TL for brown trout and was only weakly associated with TL of brook trout. Although report...

Demography of Juvenile and Adult Brown Trout in Streams of Southeastern Minnesota

Abstract We assessed recruitment, survival, emigration, and immigration of brown trout Salmo trutta in six interconnected stream reaches to quantitatively estimate how much immigrants contributed to population size in reaches in southeastern Minnesota. We also examined the influence of reach and season on estimates of survival and emigration via mark and recapture of individual trout representing three groups (age-0 juveniles, age-1 and age-2 adults, and age-3+ large adults). Immigration was calculated as 1 minus emigration. Recruitment varied among the six reaches and 3 years of this study (range, 0–1,292 fish/km). Survival of the age-0 group and that comprising ages 1 and 2 varied by season but not reach. Survival was highest in winter for both groups but lowest in spring for age-0 trout and in fall for age-1 and age -2 trout. Emigration varied by season for age-0 trout but by reach for trout of ages 1 and 2. For age-3+ trout, survival and emigration only varied by reach. Survival was highest and emigra...

Winter feeding, growth and condition of brown trout Salmo trutta in a groundwater-dominated stream

Winter can be a stressful period for stream-dwelling salmonid populations, often resulting in reduced growth and survival. Stream water temperatures have been identified as a primary mechanism driving reductions in fitness during winter. However, groundwater inputs can moderate water temperature and may reduce winter severity. Additionally, seasonal reductions in prey availability may contribute to decreased growth and survival, although few studies have examined food webs supporting salmonids under winter conditions. This study employed diet, stable isotope, and mark-recapture techniques to examine winter (November through March) feeding, growth, and condition of brown trout Salmo trutta in a groundwater-dominated stream (Badger Creek, Minnesota, USA). Growth was greater for fish ≤ 150 mm (mean = 4.1 mg g−1 day−1) than for those 151–276 mm (mean = 1.0 mg g−1 day−1) during the winter season. Overall condition from early winter to late winter did not vary for fish ≤150 mm (mean relative weight (Wr) = 89.5) and increased for those 151–276 mm (mean Wr = 85.8 early and 89.4 late). Although composition varied both temporally and by individual, brown trout diets were dominated by aquatic invertebrates, primarily Amphipods, Dipterans, and Trichopterans. Stable isotope analysis supported the observations of the dominant prey taxa in stomach contents and indicated the winter food web was supported by a combination of allochthonous inputs and aquatic macrophytes. Brown trout in Badger Creek likely benefited from the thermal regime and increased prey abundance present in this groundwater-dominated stream during winter.

Lake Sturgeon Population Status and Demography in the Kettle River, Minnesota, 1992–2007

Abstract We assessed population status and estimated selected demographic parameters for lake sturgeon Acipenser fulvescens in the Kettle River, Minnesota, using capture–recapture tagging data collected from 1992 to 2007. The lake sturgeon is an imperiled species of special concern in Minnesota, with population declines attributed to overfishing, pollution, and establishment of dams. In 1995, the recreational fishery was closed and the only dam on the Kettle River (Sandstone Dam) was removed, in part to promote lake sturgeon recovery. Recent incidental capture of lake sturgeon by anglers is prompting interest in re-opening the recreational fishery. We gathered information to determine (1) status and demography of the Kettle River population, (2) the effect of dam removal, and (3) the feasibility of re-opening the recreational fishery. Open-population capture–recapture models were used to examine population status and estimate survival, seniority, and the relative importance of survival and recruitment for...

Winter diet of brown trout Salmo trutta in groundwater-dominated streams: influence of environmental factors on spatial and temporal variation

Winter diet composition of brown trout Salmo trutta was quantified from November to March in 35 temperate groundwater-dominated streams in south-eastern Minnesota, U.S.A., in relation to stream physical characteristics including drainage area, channel slope and influence of groundwater on stream thermal regime. Aquatic invertebrates made up the majority of S. trutta diet in all streams and sampling periods and individual S. trutta typically had consumed 30 or more prey items at each sampling event. Differences in diet composition were greater among streams than between sampling periods within a stream, with Gammarus spp., Brachycentrus spp., Glossosoma spp., Chironomidae and Physella spp. the most common taxa. Landscape-scale stream characteristics were not significantly associated with S. trutta consumption or diet composition. Winter was period of significant activity in groundwater-dominated streams, as S. trutta fed on a variety of aquatic prey taxa highlighting the importance of winter base-flow in moderating S. trutta populations in seasonally cold catchments.

Brook Trout Distribution, Genetics, and Population Characteristics in the Driftless Area of Minnesota

AbstractThe Driftless Area in southeastern Minnesota is on the southwestern edge of the native range of Brook Trout Salvelinus fontinalis. It was assumed that native Brook Trout were extirpated from this region in the early 1900s due to degraded stream conditions and stockings of eastern-origin Brook Trout and European Brown Trout Salmo trutta. Our objectives were to examine Brook Trout populations in the region to determine their spatial and genetic distribution and quantify population characteristics. Information on presence or absence of Brook Trout was gathered by electrofishing 174 streams in southeastern Minnesota. Brook Trout were present in 68% of coldwater streams compared with only in 3% in the early 1970s. The increase is likely due to increasing stream discharge throughout the Driftless Area, enabling recolonization or successful establishment of stocked populations. Streams with higher base flow discharge also had higher abundance, larger size at maturity, and larger Brook Trout present. Gene...

Effects of Six-Hour Suspended Sediment Treatments on White Sucker (Catostomus commersoni) and Smallmouth Bass (Micropterus dolomieu) in an Artificial Stream

ABSTRACT To examine effects of short-term exposure to two types of sediment on health of warmwater fishes, a controlled experiment was conducted with Micropterus dolomieu and Catostomus commersoni. Fishes were stocked into net pens at upstream and downstream ends of an artificial stream. Following an acclimation period of five to six days, discharge was increased throughout the stream to bankfull levels, and fishes in downstream pens (only) were exposed to sediment concentrations of 200 mg/L of fine sand or 500 mg/L of agricultural soil for six hours in two independent trials. Fishes were then immediately assigned a health assessment index value based on conditions of internal and external organs. There were no significant effects on health assessment indices for either species from the experimental treatments, although the indices may have been more sensitive if fish were afforded a post-treatment latent period to allow stress-induced changes to manifest. Our data agree with existing models that describe effects of smaller sediment particles on warmwater fishes and help address the lack of information on effects of larger, coarser suspended sediment.

The Influence of Angler Values, Involvement, Catch Orientation, Satisfaction, Agency Trust, and Demographics on Support for Habitat Protection and Restoration Versus Stocking in Publicly Managed Waters

Resource managers benefit from knowledge of angler support for fisheries management strategies. Factors including angler values (protection, utilitarian, and dominance), involvement (attraction, centrality, social, identity affirmation, and expression), catch-related motivations (catching some, many, and big fish, and keeping fish), satisfaction, agency trust, and demographics may relate to fisheries management preferences. Using results from a mail survey of Minnesota resident anglers, we explored how these factors were related to budget support for fish stocking relative to habitat protection/restoration. Results suggest that values, angler involvement, catch orientation, satisfaction, total and recent years fishing, age, and education influence relative support for stocking versus habitat protection/restoration. Utilitarian values, angling centrality, an orientation to catch many fish, satisfaction with the number of fish caught, number of recent years fishing, and age positively related to support for stocking over habitat management, while protection values, attraction to angling, total years fishing, and education level were negatively related to relative support for stocking.

Life History Traits and Status of a Peripheral Redside Dace (Clinostomus elongatus) Population in Minnesota

Abstract Redside dace Clinostomus elongatus in Minnesota represent genetically unique peripheral populations on the extreme western edge of their native range with uncertain population status. Electrofishing surveys were conducted in 2017 in the Little Cannon River watershed to ascertain life history traits (e.g., age, growth, reproductive traits) for comparison to core populations in eastern North America and to assess population status. Minnesota redside dace grew faster but lived shorter lives than their core populations/counterparts. Females matured at age-2 and about 80 mm total length and males at age-1 and 70 mm. Females produced up to 962 eggs. Estimated population size for age 1+ dace was 9251 (95% C.I. 8300–10,201) and for age 2+ was 6600 (95% C.I. 5789–7411). These values exceeded a demographic minimum viable population estimate of 3305 (nearly double) suggesting that redside dace should persist in this watershed for at least the next two decades (until ≈ 2040).